fix: simplify tests a bit

Signed-off-by: Dr. Carsten Leue <carsten.leue@de.ibm.com>

.github/workflows/build.yml

@@ -28,11 +28,11 @@ jobs:
       fail-fast: false  # Continue with other versions if one fails
     steps:
       # full checkout for semantic-release
-      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4.3.1
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
           fetch-depth: 0
       - name: Set up Go ${{ matrix.go-version }}
-        uses: actions/setup-go@v5
+        uses: actions/setup-go@v6
         with:
           go-version: ${{ matrix.go-version }}
           cache: true  # Enable Go module caching
@@ -66,11 +66,11 @@ jobs:
       matrix:
         go-version: ['1.24.x', '1.25.x']
     steps:
-      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4.3.1
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
           fetch-depth: 0
       - name: Set up Go ${{ matrix.go-version }}
-        uses: actions/setup-go@v5
+        uses: actions/setup-go@v6
         with:
           go-version: ${{ matrix.go-version }}
           cache: true  # Enable Go module caching
@@ -126,17 +126,17 @@ jobs:
     steps:
       # full checkout for semantic-release
       - name: Full checkout
-        uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4.3.1
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
           fetch-depth: 0
 
       - name: Set up Node.js ${{ env.NODE_VERSION }}
-        uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4.4.0
+        uses: actions/setup-node@6044e13b5dc448c55e2357c09f80417699197238 # v6.2.0
         with:
           node-version: ${{ env.NODE_VERSION }}
 
       - name: Set up Go
-        uses: actions/setup-go@v5
+        uses: actions/setup-go@v6
         with:
           go-version: ${{ env.LATEST_GO_VERSION }}
           cache: true  # Enable Go module caching

go.sum

@@ -1,7 +1,3 @@
-github.com/cpuguy83/go-md2man/v2 v2.0.4 h1:wfIWP927BUkWJb2NmU/kNDYIBTh/ziUX91+lVfRxZq4=
-github.com/cpuguy83/go-md2man/v2 v2.0.4/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
-github.com/cpuguy83/go-md2man/v2 v2.0.5 h1:ZtcqGrnekaHpVLArFSe4HK5DoKx1T0rq2DwVB0alcyc=
-github.com/cpuguy83/go-md2man/v2 v2.0.5/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
 github.com/cpuguy83/go-md2man/v2 v2.0.7 h1:zbFlGlXEAKlwXpmvle3d8Oe3YnkKIK4xSRTd3sHPnBo=
 github.com/cpuguy83/go-md2man/v2 v2.0.7/go.mod h1:oOW0eioCTA6cOiMLiUPZOpcVxMig6NIQQ7OS05n1F4g=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
@@ -10,20 +6,8 @@ github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZb
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/russross/blackfriday/v2 v2.1.0 h1:JIOH55/0cWyOuilr9/qlrm0BSXldqnqwMsf35Ld67mk=
 github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
-github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
-github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
-github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
-github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
-github.com/stretchr/testify v1.11.0 h1:ib4sjIrwZKxE5u/Japgo/7SJV3PvgjGiRNAvTVGqQl8=
-github.com/stretchr/testify v1.11.0/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
 github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
 github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
-github.com/urfave/cli/v2 v2.27.4 h1:o1owoI+02Eb+K107p27wEX9Bb8eqIoZCfLXloLUSWJ8=
-github.com/urfave/cli/v2 v2.27.4/go.mod h1:m4QzxcD2qpra4z7WhzEGn74WZLViBnMpb1ToCAKdGRQ=
-github.com/urfave/cli/v2 v2.27.5 h1:WoHEJLdsXr6dDWoJgMq/CboDmyY/8HMMH1fTECbih+w=
-github.com/urfave/cli/v2 v2.27.5/go.mod h1:3Sevf16NykTbInEnD0yKkjDAeZDS0A6bzhBH5hrMvTQ=
-github.com/urfave/cli/v2 v2.27.6 h1:VdRdS98FNhKZ8/Az8B7MTyGQmpIr36O1EHybx/LaZ4g=
-github.com/urfave/cli/v2 v2.27.6/go.mod h1:3Sevf16NykTbInEnD0yKkjDAeZDS0A6bzhBH5hrMvTQ=
 github.com/urfave/cli/v2 v2.27.7 h1:bH59vdhbjLv3LAvIu6gd0usJHgoTTPhCFib8qqOwXYU=
 github.com/urfave/cli/v2 v2.27.7/go.mod h1:CyNAG/xg+iAOg0N4MPGZqVmv2rCoP267496AOXUZjA4=
 github.com/xrash/smetrics v0.0.0-20240521201337-686a1a2994c1 h1:gEOO8jv9F4OT7lGCjxCBTO/36wtF6j2nSip77qHd4x4=

renovate.json

@@ -22,7 +22,8 @@
             "matchDepTypes": [
                 "golang"
             ],
-            "enabled": false
+            "enabled": false,
+            "description": "Disable updates to the go directive in go.mod files - the directive identifies the minimum compatible Go version and should stay as small as possible for maximum compatibility"
         },
         {
             "matchUpdateTypes": [

v2/.bobignore

@@ -0,0 +1 @@
+reflect\reflect.go

v2/DESIGN.md

@@ -584,5 +584,7 @@ func process(input string) types.Result[types.Option[int]] {
 
 For more information, see:
 - [README.md](./README.md) - Overview and quick start
+- [FUNCTIONAL_IO.md](./FUNCTIONAL_IO.md) - Functional I/O patterns with Context and Reader
+- [IDIOMATIC_COMPARISON.md](./IDIOMATIC_COMPARISON.md) - Performance comparison between standard and idiomatic packages
 - [API Documentation](https://pkg.go.dev/github.com/IBM/fp-go/v2) - Complete API reference
 - [Samples](./samples/) - Practical examples

v2/FUNCTIONAL_IO.md

@@ -0,0 +1,829 @@
+# Functional I/O in Go: Context, Errors, and the Reader Pattern
+
+This document explores how functional programming principles apply to I/O operations in Go, comparing traditional imperative approaches with functional patterns using the `context/readerioresult` and `idiomatic/context/readerresult` packages.
+
+## Table of Contents
+
+- [Why Context in I/O Operations](#why-context-in-io-operations)
+- [The Error-Value Tuple Pattern](#the-error-value-tuple-pattern)
+- [Functional Approach: Reader Pattern](#functional-approach-reader-pattern)
+- [Benefits of the Functional Approach](#benefits-of-the-functional-approach)
+- [Side-by-Side Comparison](#side-by-side-comparison)
+- [Advanced Patterns](#advanced-patterns)
+- [When to Use Each Approach](#when-to-use-each-approach)
+
+## Why Context in I/O Operations
+
+In idiomatic Go, I/O operations conventionally take a `context.Context` as their first parameter:
+
+```go
+func QueryDatabase(ctx context.Context, query string) (Result, error)
+func MakeHTTPRequest(ctx context.Context, url string) (*http.Response, error)
+func ReadFile(ctx context.Context, path string) ([]byte, error)
+```
+
+### The Purpose of Context
+
+The `context.Context` parameter serves several critical purposes:
+
+1. **Cancellation Propagation**: Operations can be cancelled when the context is cancelled
+2. **Deadline Management**: Operations respect timeouts and deadlines
+3. **Request-Scoped Values**: Carry request metadata (trace IDs, user info, etc.)
+4. **Resource Cleanup**: Signal to release resources when work is no longer needed
+
+### Why Context Matters for I/O
+
+I/O operations are inherently **effectful** - they interact with the outside world:
+- Reading from disk, network, or database
+- Writing to external systems
+- Generating random numbers
+- Reading the current time
+
+These operations can:
+- **Take time**: Network calls may be slow
+- **Fail**: Connections drop, files don't exist
+- **Block**: Waiting for external resources
+- **Need cancellation**: User navigates away, request times out
+
+Context provides a standard mechanism to control these operations across your entire application.
+
+## The Error-Value Tuple Pattern
+
+### Why Operations Must Return Errors
+
+In Go, I/O operations return `(value, error)` tuples because:
+
+1. **Context can be cancelled**: Even if the operation would succeed, cancellation must be represented
+2. **External systems fail**: Networks fail, files are missing, permissions are denied
+3. **Resources are exhausted**: Out of memory, disk full, connection pool exhausted
+4. **Timeouts occur**: Operations exceed their deadline
+
+**There cannot be I/O operations without error handling** because the context itself introduces a failure mode (cancellation) that must be represented in the return type.
+
+### Traditional Go Pattern
+
+```go
+func ProcessUser(ctx context.Context, userID int) (User, error) {
+    // Check context before starting
+    if err := ctx.Err(); err != nil {
+        return User{}, err
+    }
+    
+    // Fetch user from database
+    user, err := db.QueryUser(ctx, userID)
+    if err != nil {
+        return User{}, fmt.Errorf("query user: %w", err)
+    }
+    
+    // Validate user
+    if user.Age < 18 {
+        return User{}, errors.New("user too young")
+    }
+    
+    // Fetch user's posts
+    posts, err := db.QueryPosts(ctx, user.ID)
+    if err != nil {
+        return User{}, fmt.Errorf("query posts: %w", err)
+    }
+    
+    user.Posts = posts
+    return user, nil
+}
+```
+
+**Characteristics:**
+- Explicit error checking at each step
+- Manual error wrapping and propagation
+- Context checked manually
+- Imperative control flow
+- Error handling mixed with business logic
+
+## Functional Approach: Reader Pattern
+
+### The Core Insight
+
+In functional programming, we separate **what to compute** from **how to execute it**. Instead of functions that perform I/O directly, we create functions that **return descriptions of I/O operations**.
+
+### Key Type: ReaderIOResult
+
+```go
+// A function that takes a context and returns a value or error
+type ReaderIOResult[A any] = func(context.Context) (A, error)
+```
+
+This type represents:
+- **Reader**: Depends on an environment (context.Context)
+- **IO**: Performs side effects (I/O operations)
+- **Result**: Can fail with an error
+
+### Why This Is Better
+
+The functional approach **carries the I/O aspect as the return value, not on the input**:
+
+```go
+// Traditional: I/O is implicit in the function execution
+func fetchUser(ctx context.Context, id int) (User, error) {
+    // Performs I/O immediately
+}
+
+// Functional: I/O is explicit in the return type
+func fetchUser(id int) ReaderIOResult[User] {
+    // Returns a description of I/O, doesn't execute yet
+    return func(ctx context.Context) (User, error) {
+        // I/O happens here when the function is called
+    }
+}
+```
+
+**Key difference**: The functional version is a **curried function** where:
+1. Business parameters come first: `fetchUser(id)`
+2. Context comes last: `fetchUser(id)(ctx)`
+3. The intermediate result is composable: `ReaderIOResult[User]`
+
+## Benefits of the Functional Approach
+
+### 1. Separation of Pure and Impure Code
+
+```go
+// Pure computation - no I/O, no context needed
+func validateAge(user User) (User, error) {
+    if user.Age < 18 {
+        return User{}, errors.New("user too young")
+    }
+    return user, nil
+}
+
+// Impure I/O operation - needs context
+func fetchUser(id int) ReaderIOResult[User] {
+    return func(ctx context.Context) (User, error) {
+        return db.QueryUser(ctx, id)
+    }
+}
+
+// Compose them - pure logic lifted into ReaderIOResult
+pipeline := F.Pipe2(
+    fetchUser(42),                           // ReaderIOResult[User]
+    readerioresult.ChainEitherK(validateAge), // Lift pure function
+)
+
+// Execute when ready
+user, err := pipeline(ctx)
+```
+
+**Benefits:**
+- Pure functions are easier to test (no mocking needed)
+- Pure functions are easier to reason about (no side effects)
+- Clear boundary between logic and I/O
+- Can test business logic independently
+
+### 2. Composability
+
+Functions compose naturally without manual error checking:
+
+```go
+// Traditional approach - manual error handling
+func ProcessUserTraditional(ctx context.Context, userID int) (UserWithPosts, error) {
+    user, err := fetchUser(ctx, userID)
+    if err != nil {
+        return UserWithPosts{}, err
+    }
+    
+    validated, err := validateUser(user)
+    if err != nil {
+        return UserWithPosts{}, err
+    }
+    
+    posts, err := fetchPosts(ctx, validated.ID)
+    if err != nil {
+        return UserWithPosts{}, err
+    }
+    
+    return enrichUser(validated, posts), nil
+}
+
+// Functional approach - automatic error propagation
+func ProcessUserFunctional(userID int) ReaderIOResult[UserWithPosts] {
+    return F.Pipe3(
+        fetchUser(userID),
+        readerioresult.ChainEitherK(validateUser),
+        readerioresult.Chain(func(user User) ReaderIOResult[UserWithPosts] {
+            return F.Pipe2(
+                fetchPosts(user.ID),
+                readerioresult.Map(func(posts []Post) UserWithPosts {
+                    return enrichUser(user, posts)
+                }),
+            )
+        }),
+    )
+}
+```
+
+**Benefits:**
+- No manual error checking
+- Automatic short-circuiting on first error
+- Clear data flow
+- Easier to refactor and extend
+
+### 3. Testability
+
+```go
+// Mock I/O operations by providing test implementations
+func TestProcessUser(t *testing.T) {
+    // Create a mock that returns test data
+    mockFetchUser := func(id int) ReaderIOResult[User] {
+        return func(ctx context.Context) (User, error) {
+            return User{ID: id, Age: 25}, nil
+        }
+    }
+    
+    // Test with mock - no database needed
+    result, err := mockFetchUser(42)(context.Background())
+    assert.NoError(t, err)
+    assert.Equal(t, 25, result.Age)
+}
+```
+
+### 4. Lazy Evaluation
+
+Operations are not executed until you provide the context:
+
+```go
+// Build the pipeline - no I/O happens yet
+pipeline := F.Pipe3(
+    fetchUser(42),
+    readerioresult.Map(enrichUser),
+    readerioresult.Chain(saveUser),
+)
+
+// I/O only happens when we call it with a context
+user, err := pipeline(ctx)
+```
+
+**Benefits:**
+- Build complex operations as pure data structures
+- Defer execution until needed
+- Reuse pipelines with different contexts
+- Test pipelines without executing I/O
+
+### 5. Context Propagation
+
+Context is automatically threaded through all operations:
+
+```go
+// Traditional - must pass context explicitly everywhere
+func Process(ctx context.Context) error {
+    user, err := fetchUser(ctx, 42)
+    if err != nil {
+        return err
+    }
+    posts, err := fetchPosts(ctx, user.ID)
+    if err != nil {
+        return err
+    }
+    return savePosts(ctx, posts)
+}
+
+// Functional - context provided once at execution
+func Process() ReaderIOResult[any] {
+    return F.Pipe2(
+        fetchUser(42),
+        readerioresult.Chain(func(user User) ReaderIOResult[any] {
+            return F.Pipe2(
+                fetchPosts(user.ID),
+                readerioresult.Chain(savePosts),
+            )
+        }),
+    )
+}
+
+// Context provided once
+err := readerioresult.Fold(
+    func(err error) error { return err },
+    func(any) error { return nil },
+)(Process())(ctx)
+```
+
+## Side-by-Side Comparison
+
+### Example: User Service with Database Operations
+
+#### Traditional Go Style
+
+```go
+package traditional
+
+import (
+    "context"
+    "database/sql"
+    "fmt"
+)
+
+type User struct {
+    ID    int
+    Name  string
+    Email string
+    Age   int
+}
+
+type UserService struct {
+    db *sql.DB
+}
+
+// Fetch user from database
+func (s *UserService) GetUser(ctx context.Context, id int) (User, error) {
+    var user User
+    
+    // Check context
+    if err := ctx.Err(); err != nil {
+        return User{}, err
+    }
+    
+    // Query database
+    row := s.db.QueryRowContext(ctx, 
+        "SELECT id, name, email, age FROM users WHERE id = ?", id)
+    
+    err := row.Scan(&user.ID, &user.Name, &user.Email, &user.Age)
+    if err != nil {
+        return User{}, fmt.Errorf("scan user: %w", err)
+    }
+    
+    return user, nil
+}
+
+// Validate user
+func (s *UserService) ValidateUser(ctx context.Context, user User) (User, error) {
+    if user.Age < 18 {
+        return User{}, fmt.Errorf("user %d is too young", user.ID)
+    }
+    if user.Email == "" {
+        return User{}, fmt.Errorf("user %d has no email", user.ID)
+    }
+    return user, nil
+}
+
+// Update user email
+func (s *UserService) UpdateEmail(ctx context.Context, id int, email string) (User, error) {
+    // Check context
+    if err := ctx.Err(); err != nil {
+        return User{}, err
+    }
+    
+    // Update database
+    _, err := s.db.ExecContext(ctx,
+        "UPDATE users SET email = ? WHERE id = ?", email, id)
+    if err != nil {
+        return User{}, fmt.Errorf("update email: %w", err)
+    }
+    
+    // Fetch updated user
+    return s.GetUser(ctx, id)
+}
+
+// Process user: fetch, validate, update email
+func (s *UserService) ProcessUser(ctx context.Context, id int, newEmail string) (User, error) {
+    // Fetch user
+    user, err := s.GetUser(ctx, id)
+    if err != nil {
+        return User{}, fmt.Errorf("get user: %w", err)
+    }
+    
+    // Validate user
+    validated, err := s.ValidateUser(ctx, user)
+    if err != nil {
+        return User{}, fmt.Errorf("validate user: %w", err)
+    }
+    
+    // Update email
+    updated, err := s.UpdateEmail(ctx, validated.ID, newEmail)
+    if err != nil {
+        return User{}, fmt.Errorf("update email: %w", err)
+    }
+    
+    return updated, nil
+}
+```
+
+**Characteristics:**
+- ✗ Manual error checking at every step
+- ✗ Context passed explicitly to every function
+- ✗ Error wrapping is manual and verbose
+- ✗ Business logic mixed with error handling
+- ✗ Hard to test without database
+- ✗ Difficult to compose operations
+- ✓ Familiar to Go developers
+- ✓ Explicit control flow
+
+#### Functional Go Style (context/readerioresult)
+
+```go
+package functional
+
+import (
+    "context"
+    "database/sql"
+    "fmt"
+    
+    F "github.com/IBM/fp-go/v2/function"
+    RIO "github.com/IBM/fp-go/v2/context/readerioresult"
+)
+
+type User struct {
+    ID    int
+    Name  string
+    Email string
+    Age   int
+}
+
+type UserService struct {
+    db *sql.DB
+}
+
+// Fetch user from database - returns a ReaderIOResult
+func (s *UserService) GetUser(id int) RIO.ReaderIOResult[User] {
+    return func(ctx context.Context) (User, error) {
+        var user User
+        row := s.db.QueryRowContext(ctx,
+            "SELECT id, name, email, age FROM users WHERE id = ?", id)
+        
+        err := row.Scan(&user.ID, &user.Name, &user.Email, &user.Age)
+        if err != nil {
+            return User{}, fmt.Errorf("scan user: %w", err)
+        }
+        
+        return user, nil
+    }
+}
+
+// Validate user - pure function (no I/O, no context)
+func ValidateUser(user User) (User, error) {
+    if user.Age < 18 {
+        return User{}, fmt.Errorf("user %d is too young", user.ID)
+    }
+    if user.Email == "" {
+        return User{}, fmt.Errorf("user %d has no email", user.ID)
+    }
+    return user, nil
+}
+
+// Update user email - returns a ReaderIOResult
+func (s *UserService) UpdateEmail(id int, email string) RIO.ReaderIOResult[User] {
+    return func(ctx context.Context) (User, error) {
+        _, err := s.db.ExecContext(ctx,
+            "UPDATE users SET email = ? WHERE id = ?", email, id)
+        if err != nil {
+            return User{}, fmt.Errorf("update email: %w", err)
+        }
+        
+        // Chain to GetUser
+        return s.GetUser(id)(ctx)
+    }
+}
+
+// Process user: fetch, validate, update email - composable pipeline
+func (s *UserService) ProcessUser(id int, newEmail string) RIO.ReaderIOResult[User] {
+    return F.Pipe3(
+        s.GetUser(id),                          // Fetch user
+        RIO.ChainEitherK(ValidateUser),         // Validate (pure function)
+        RIO.Chain(func(user User) RIO.ReaderIOResult[User] {
+            return s.UpdateEmail(user.ID, newEmail)  // Update email
+        }),
+    )
+}
+
+// Alternative: Using Do-notation for more complex flows
+func (s *UserService) ProcessUserDo(id int, newEmail string) RIO.ReaderIOResult[User] {
+    return RIO.Chain(func(user User) RIO.ReaderIOResult[User] {
+        // Validate is pure, lift it into ReaderIOResult
+        validated, err := ValidateUser(user)
+        if err != nil {
+            return RIO.Left[User](err)
+        }
+        // Update with validated user
+        return s.UpdateEmail(validated.ID, newEmail)
+    })(s.GetUser(id))
+}
+```
+
+**Characteristics:**
+- ✓ Automatic error propagation (no manual checking)
+- ✓ Context threaded automatically
+- ✓ Pure functions separated from I/O
+- ✓ Business logic clear and composable
+- ✓ Easy to test (mock ReaderIOResult)
+- ✓ Operations compose naturally
+- ✓ Lazy evaluation (build pipeline, execute later)
+- ✗ Requires understanding of functional patterns
+- ✗ Less familiar to traditional Go developers
+
+#### Idiomatic Functional Style (idiomatic/context/readerresult)
+
+For even better performance with the same functional benefits:
+
+```go
+package idiomatic
+
+import (
+    "context"
+    "database/sql"
+    "fmt"
+    
+    F "github.com/IBM/fp-go/v2/function"
+    RR "github.com/IBM/fp-go/v2/idiomatic/context/readerresult"
+)
+
+type User struct {
+    ID    int
+    Name  string
+    Email string
+    Age   int
+}
+
+type UserService struct {
+    db *sql.DB
+}
+
+// ReaderResult is just: func(context.Context) (A, error)
+// Same as ReaderIOResult but using native Go tuples
+
+func (s *UserService) GetUser(id int) RR.ReaderResult[User] {
+    return func(ctx context.Context) (User, error) {
+        var user User
+        row := s.db.QueryRowContext(ctx,
+            "SELECT id, name, email, age FROM users WHERE id = ?", id)
+        
+        err := row.Scan(&user.ID, &user.Name, &user.Email, &user.Age)
+        return user, err  // Native tuple return
+    }
+}
+
+// Pure validation - returns native (User, error) tuple
+func ValidateUser(user User) (User, error) {
+    if user.Age < 18 {
+        return User{}, fmt.Errorf("user %d is too young", user.ID)
+    }
+    if user.Email == "" {
+        return User{}, fmt.Errorf("user %d has no email", user.ID)
+    }
+    return user, nil
+}
+
+func (s *UserService) UpdateEmail(id int, email string) RR.ReaderResult[User] {
+    return func(ctx context.Context) (User, error) {
+        _, err := s.db.ExecContext(ctx,
+            "UPDATE users SET email = ? WHERE id = ?", email, id)
+        if err != nil {
+            return User{}, err
+        }
+        return s.GetUser(id)(ctx)
+    }
+}
+
+// Composable pipeline with native tuples
+func (s *UserService) ProcessUser(id int, newEmail string) RR.ReaderResult[User] {
+    return F.Pipe3(
+        s.GetUser(id),
+        RR.ChainEitherK(ValidateUser),  // Lift pure function
+        RR.Chain(func(user User) RR.ReaderResult[User] {
+            return s.UpdateEmail(user.ID, newEmail)
+        }),
+    )
+}
+```
+
+**Characteristics:**
+- ✓ All benefits of functional approach
+- ✓ **2-10x better performance** (native tuples)
+- ✓ **Zero allocations** for many operations
+- ✓ More familiar to Go developers (uses (value, error))
+- ✓ Seamless integration with existing Go code
+- ✓ Same composability as ReaderIOResult
+
+### Usage Comparison
+
+```go
+// Traditional
+func HandleRequest(w http.ResponseWriter, r *http.Request) {
+    ctx := r.Context()
+    service := &UserService{db: db}
+    
+    user, err := service.ProcessUser(ctx, 42, "new@email.com")
+    if err != nil {
+        http.Error(w, err.Error(), http.StatusInternalServerError)
+        return
+    }
+    
+    json.NewEncoder(w).Encode(user)
+}
+
+// Functional (both styles)
+func HandleRequest(w http.ResponseWriter, r *http.Request) {
+    ctx := r.Context()
+    service := &UserService{db: db}
+    
+    // Build the pipeline (no execution yet)
+    pipeline := service.ProcessUser(42, "new@email.com")
+    
+    // Execute with context
+    user, err := pipeline(ctx)
+    if err != nil {
+        http.Error(w, err.Error(), http.StatusInternalServerError)
+        return
+    }
+    
+    json.NewEncoder(w).Encode(user)
+}
+
+// Or using Fold for cleaner error handling
+func HandleRequestFold(w http.ResponseWriter, r *http.Request) {
+    ctx := r.Context()
+    service := &UserService{db: db}
+    
+    RR.Fold(
+        func(err error) {
+            http.Error(w, err.Error(), http.StatusInternalServerError)
+        },
+        func(user User) {
+            json.NewEncoder(w).Encode(user)
+        },
+    )(service.ProcessUser(42, "new@email.com"))(ctx)
+}
+```
+
+## Advanced Patterns
+
+### Resource Management with Bracket
+
+```go
+// Traditional
+func ProcessFile(ctx context.Context, path string) (string, error) {
+    file, err := os.Open(path)
+    if err != nil {
+        return "", err
+    }
+    defer file.Close()
+    
+    data, err := io.ReadAll(file)
+    if err != nil {
+        return "", err
+    }
+    
+    return string(data), nil
+}
+
+// Functional - guaranteed cleanup even on panic
+func ProcessFile(path string) RIO.ReaderIOResult[string] {
+    return RIO.Bracket(
+        // Acquire resource
+        func(ctx context.Context) (*os.File, error) {
+            return os.Open(path)
+        },
+        // Release resource (always called)
+        func(file *os.File, err error) RIO.ReaderIOResult[any] {
+            return func(ctx context.Context) (any, error) {
+                return nil, file.Close()
+            }
+        },
+        // Use resource
+        func(file *os.File) RIO.ReaderIOResult[string] {
+            return func(ctx context.Context) (string, error) {
+                data, err := io.ReadAll(file)
+                return string(data), err
+            }
+        },
+    )
+}
+```
+
+### Parallel Execution
+
+```go
+// Traditional - manual goroutines and sync
+func FetchMultipleUsers(ctx context.Context, ids []int) ([]User, error) {
+    var wg sync.WaitGroup
+    users := make([]User, len(ids))
+    errs := make([]error, len(ids))
+    
+    for i, id := range ids {
+        wg.Add(1)
+        go func(i, id int) {
+            defer wg.Done()
+            users[i], errs[i] = fetchUser(ctx, id)
+        }(i, id)
+    }
+    
+    wg.Wait()
+    
+    for _, err := range errs {
+        if err != nil {
+            return nil, err
+        }
+    }
+    
+    return users, nil
+}
+
+// Functional - automatic parallelization
+func FetchMultipleUsers(ids []int) RIO.ReaderIOResult[[]User] {
+    operations := A.Map(func(id int) RIO.ReaderIOResult[User] {
+        return fetchUser(id)
+    })(ids)
+    
+    return RIO.TraverseArrayPar(F.Identity[RIO.ReaderIOResult[User]])(operations)
+}
+```
+
+### Retry Logic
+
+```go
+// Traditional
+func FetchWithRetry(ctx context.Context, url string, maxRetries int) ([]byte, error) {
+    var lastErr error
+    for i := 0; i < maxRetries; i++ {
+        if ctx.Err() != nil {
+            return nil, ctx.Err()
+        }
+        
+        resp, err := http.Get(url)
+        if err == nil {
+            defer resp.Body.Close()
+            return io.ReadAll(resp.Body)
+        }
+        
+        lastErr = err
+        time.Sleep(time.Second * time.Duration(i+1))
+    }
+    return nil, lastErr
+}
+
+// Functional
+func FetchWithRetry(url string, maxRetries int) RIO.ReaderIOResult[[]byte] {
+    operation := func(ctx context.Context) ([]byte, error) {
+        resp, err := http.Get(url)
+        if err != nil {
+            return nil, err
+        }
+        defer resp.Body.Close()
+        return io.ReadAll(resp.Body)
+    }
+    
+    return RIO.Retry(
+        maxRetries,
+        func(attempt int) time.Duration {
+            return time.Second * time.Duration(attempt)
+        },
+    )(operation)
+}
+```
+
+## When to Use Each Approach
+
+### Use Traditional Go Style When:
+
+1. **Team familiarity**: Team is not familiar with functional programming
+2. **Simple operations**: Single I/O operation with straightforward error handling
+3. **Existing codebase**: Large codebase already using traditional patterns
+4. **Learning curve**: Want to minimize onboarding time
+5. **Explicit control**: Need very explicit control flow
+
+### Use Functional Style (ReaderIOResult) When:
+
+1. **Complex pipelines**: Multiple I/O operations that need composition
+2. **Testability**: Need to test business logic separately from I/O
+3. **Reusability**: Want to build reusable operation pipelines
+4. **Error handling**: Want automatic error propagation
+5. **Resource management**: Need guaranteed cleanup (Bracket)
+6. **Parallel execution**: Need to parallelize operations easily
+7. **Type safety**: Want the type system to track I/O effects
+
+### Use Idiomatic Functional Style (idiomatic/context/readerresult) When:
+
+1. **All functional benefits**: Want functional patterns with Go idioms
+2. **Performance critical**: Need 2-10x better performance
+3. **Zero allocations**: Memory efficiency is important
+4. **Go integration**: Want seamless integration with existing Go code
+5. **Production services**: Building high-throughput services
+6. **Best of both worlds**: Want functional composition with Go's native patterns
+
+## Summary
+
+The functional approach to I/O in Go offers significant advantages:
+
+1. **Separation of Concerns**: Pure logic separated from I/O effects
+2. **Composability**: Operations compose naturally without manual error checking
+3. **Testability**: Easy to test without mocking I/O
+4. **Type Safety**: I/O effects visible in the type system
+5. **Lazy Evaluation**: Build pipelines, execute when ready
+6. **Context Propagation**: Automatic threading of context
+7. **Performance**: Idiomatic version offers 2-10x speedup
+
+The key insight is that **I/O operations return descriptions of effects** (ReaderIOResult) rather than performing effects immediately. This enables powerful composition patterns while maintaining Go's idiomatic error handling through the `(value, error)` tuple pattern.
+
+For production Go services, the **idiomatic/context/readerresult** package provides the best balance: full functional programming capabilities with native Go performance and familiar error handling patterns.
+
+## Further Reading
+
+- [DESIGN.md](./DESIGN.md) - Design principles and patterns
+- [IDIOMATIC_COMPARISON.md](./IDIOMATIC_COMPARISON.md) - Performance comparison
+- [idiomatic/doc.go](./idiomatic/doc.go) - Idiomatic package overview
+- [context/readerioresult](./context/readerioresult/) - ReaderIOResult package
+- [idiomatic/context/readerresult](./idiomatic/context/readerresult/) - Idiomatic ReaderResult package

v2/README.md

@@ -447,6 +447,8 @@ func process() IOResult[string] {
 ## 📚 Documentation
 
 - **[Design Decisions](./DESIGN.md)** - Key design principles and patterns explained
+- **[Functional I/O in Go](./FUNCTIONAL_IO.md)** - Understanding Context, errors, and the Reader pattern for I/O operations
+- **[Idiomatic vs Standard Packages](./IDIOMATIC_COMPARISON.md)** - Performance comparison and when to use each approach
 - **[API Documentation](https://pkg.go.dev/github.com/IBM/fp-go/v2)** - Complete API reference
 - **[Code Samples](./samples/)** - Practical examples and use cases
 - **[Go 1.24 Release Notes](https://tip.golang.org/doc/go1.24)** - Information about generic type aliases
@@ -463,7 +465,7 @@ func process() IOResult[string] {
 - **ReaderIOResult** - Combine Reader, IO, and Result for complex workflows
 - **Array** - Functional array operations
 - **Record** - Functional record/map operations
-- **Optics** - Lens, Prism, Optional, and Traversal for immutable updates
+- **[Optics](./optics/README.md)** - Lens, Prism, Optional, and Traversal for immutable updates
 
 #### Idiomatic Packages (Tuple-based, High Performance)
 - **idiomatic/option** - Option monad using native Go `(value, bool)` tuples

v2/array/array.go

@@ -190,6 +190,11 @@ func MonadReduce[A, B any](fa []A, f func(B, A) B, initial B) B {
 	return G.MonadReduce(fa, f, initial)
 }
 
+//go:inline
+func MonadReduceWithIndex[A, B any](fa []A, f func(int, B, A) B, initial B) B {
+	return G.MonadReduceWithIndex(fa, f, initial)
+}
+
 // Reduce folds an array from left to right, applying a function to accumulate a result.
 //
 // Example:
@@ -514,6 +519,83 @@ func Push[A any](a A) Operator[A, A] {
 	return G.Push[Operator[A, A]](a)
 }
 
+// Concat concatenates two arrays, appending the provided array to the end of the input array.
+// This is a curried function that takes an array to append and returns a function that
+// takes the base array and returns the concatenated result.
+//
+// The function creates a new array containing all elements from the base array followed
+// by all elements from the appended array. Neither input array is modified.
+//
+// Type Parameters:
+//   - A: The type of elements in the arrays
+//
+// Parameters:
+//   - as: The array to append to the end of the base array
+//
+// Returns:
+//   - A function that takes a base array and returns a new array with `as` appended to its end
+//
+// Behavior:
+//   - Creates a new array with length equal to the sum of both input arrays
+//   - Copies all elements from the base array first
+//   - Appends all elements from the `as` array at the end
+//   - Returns the base array unchanged if `as` is empty
+//   - Returns `as` unchanged if the base array is empty
+//   - Does not modify either input array
+//
+// Example:
+//
+//	base := []int{1, 2, 3}
+//	toAppend := []int{4, 5, 6}
+//	result := array.Concat(toAppend)(base)
+//	// result: []int{1, 2, 3, 4, 5, 6}
+//	// base: []int{1, 2, 3} (unchanged)
+//	// toAppend: []int{4, 5, 6} (unchanged)
+//
+// Example with empty arrays:
+//
+//	base := []int{1, 2, 3}
+//	empty := []int{}
+//	result := array.Concat(empty)(base)
+//	// result: []int{1, 2, 3}
+//
+// Example with strings:
+//
+//	words1 := []string{"hello", "world"}
+//	words2 := []string{"foo", "bar"}
+//	result := array.Concat(words2)(words1)
+//	// result: []string{"hello", "world", "foo", "bar"}
+//
+// Example with functional composition:
+//
+//	numbers := []int{1, 2, 3}
+//	result := F.Pipe2(
+//	    numbers,
+//	    array.Map(N.Mul(2)),
+//	    array.Concat([]int{10, 20}),
+//	)
+//	// result: []int{2, 4, 6, 10, 20}
+//
+// Use cases:
+//   - Combining multiple arrays into one
+//   - Building arrays incrementally
+//   - Implementing array-based data structures (queues, buffers)
+//   - Merging results from multiple operations
+//   - Creating array pipelines with functional composition
+//
+// Performance:
+//   - Time complexity: O(n + m) where n and m are the lengths of the arrays
+//   - Space complexity: O(n + m) for the new array
+//   - Optimized to avoid allocation when one array is empty
+//
+// Note: This function is immutable - it creates a new array rather than modifying
+// the input arrays. For appending a single element, consider using Append or Push.
+//
+//go:inline
+func Concat[A any](as []A) Operator[A, A] {
+	return F.Bind2nd(array.Concat[[]A, A], as)
+}
+
 // MonadFlap applies a value to an array of functions, producing an array of results.
 // This is the monadic version that takes both parameters.
 //

v2/array/array_test.go

@@ -764,3 +764,341 @@ func TestExtendUseCases(t *testing.T) {
 		assert.Equal(t, expected, result)
 	})
 }
+
+// TestConcat tests the Concat function
+func TestConcat(t *testing.T) {
+	t.Run("Concat two non-empty arrays", func(t *testing.T) {
+		base := []int{1, 2, 3}
+		toAppend := []int{4, 5, 6}
+		result := Concat(toAppend)(base)
+		expected := []int{1, 2, 3, 4, 5, 6}
+		assert.Equal(t, expected, result)
+	})
+
+	t.Run("Concat with empty array to append", func(t *testing.T) {
+		base := []int{1, 2, 3}
+		empty := []int{}
+		result := Concat(empty)(base)
+		assert.Equal(t, base, result)
+	})
+
+	t.Run("Concat to empty base array", func(t *testing.T) {
+		empty := []int{}
+		toAppend := []int{1, 2, 3}
+		result := Concat(toAppend)(empty)
+		assert.Equal(t, toAppend, result)
+	})
+
+	t.Run("Concat two empty arrays", func(t *testing.T) {
+		empty1 := []int{}
+		empty2 := []int{}
+		result := Concat(empty2)(empty1)
+		assert.Equal(t, []int{}, result)
+	})
+
+	t.Run("Concat strings", func(t *testing.T) {
+		words1 := []string{"hello", "world"}
+		words2 := []string{"foo", "bar"}
+		result := Concat(words2)(words1)
+		expected := []string{"hello", "world", "foo", "bar"}
+		assert.Equal(t, expected, result)
+	})
+
+	t.Run("Concat single element arrays", func(t *testing.T) {
+		arr1 := []int{1}
+		arr2 := []int{2}
+		result := Concat(arr2)(arr1)
+		expected := []int{1, 2}
+		assert.Equal(t, expected, result)
+	})
+
+	t.Run("Does not modify original arrays", func(t *testing.T) {
+		base := []int{1, 2, 3}
+		toAppend := []int{4, 5, 6}
+		baseCopy := []int{1, 2, 3}
+		toAppendCopy := []int{4, 5, 6}
+
+		_ = Concat(toAppend)(base)
+
+		assert.Equal(t, baseCopy, base)
+		assert.Equal(t, toAppendCopy, toAppend)
+	})
+
+	t.Run("Concat with floats", func(t *testing.T) {
+		arr1 := []float64{1.1, 2.2}
+		arr2 := []float64{3.3, 4.4}
+		result := Concat(arr2)(arr1)
+		expected := []float64{1.1, 2.2, 3.3, 4.4}
+		assert.Equal(t, expected, result)
+	})
+
+	t.Run("Concat with structs", func(t *testing.T) {
+		type Person struct {
+			Name string
+			Age  int
+		}
+		arr1 := []Person{{"Alice", 30}, {"Bob", 25}}
+		arr2 := []Person{{"Charlie", 35}}
+		result := Concat(arr2)(arr1)
+		expected := []Person{{"Alice", 30}, {"Bob", 25}, {"Charlie", 35}}
+		assert.Equal(t, expected, result)
+	})
+
+	t.Run("Concat large arrays", func(t *testing.T) {
+		arr1 := MakeBy(500, F.Identity[int])
+		arr2 := MakeBy(500, func(i int) int { return i + 500 })
+		result := Concat(arr2)(arr1)
+
+		assert.Equal(t, 1000, len(result))
+		assert.Equal(t, 0, result[0])
+		assert.Equal(t, 499, result[499])
+		assert.Equal(t, 500, result[500])
+		assert.Equal(t, 999, result[999])
+	})
+
+	t.Run("Concat multiple times", func(t *testing.T) {
+		arr1 := []int{1}
+		arr2 := []int{2}
+		arr3 := []int{3}
+
+		result := F.Pipe2(
+			arr1,
+			Concat(arr2),
+			Concat(arr3),
+		)
+
+		expected := []int{1, 2, 3}
+		assert.Equal(t, expected, result)
+	})
+}
+
+// TestConcatComposition tests Concat with other array operations
+func TestConcatComposition(t *testing.T) {
+	t.Run("Concat after Map", func(t *testing.T) {
+		numbers := []int{1, 2, 3}
+		result := F.Pipe2(
+			numbers,
+			Map(N.Mul(2)),
+			Concat([]int{10, 20}),
+		)
+		expected := []int{2, 4, 6, 10, 20}
+		assert.Equal(t, expected, result)
+	})
+
+	t.Run("Map after Concat", func(t *testing.T) {
+		arr1 := []int{1, 2}
+		arr2 := []int{3, 4}
+		result := F.Pipe2(
+			arr1,
+			Concat(arr2),
+			Map(N.Mul(2)),
+		)
+		expected := []int{2, 4, 6, 8}
+		assert.Equal(t, expected, result)
+	})
+
+	t.Run("Concat with Filter", func(t *testing.T) {
+		arr1 := []int{1, 2, 3, 4}
+		arr2 := []int{5, 6, 7, 8}
+		result := F.Pipe2(
+			arr1,
+			Concat(arr2),
+			Filter(func(n int) bool { return n%2 == 0 }),
+		)
+		expected := []int{2, 4, 6, 8}
+		assert.Equal(t, expected, result)
+	})
+
+	t.Run("Concat with Reduce", func(t *testing.T) {
+		arr1 := []int{1, 2, 3}
+		arr2 := []int{4, 5, 6}
+		result := F.Pipe2(
+			arr1,
+			Concat(arr2),
+			Reduce(func(acc, x int) int { return acc + x }, 0),
+		)
+		expected := 21 // 1+2+3+4+5+6
+		assert.Equal(t, expected, result)
+	})
+
+	t.Run("Concat with Reverse", func(t *testing.T) {
+		arr1 := []int{1, 2, 3}
+		arr2 := []int{4, 5, 6}
+		result := F.Pipe2(
+			arr1,
+			Concat(arr2),
+			Reverse[int],
+		)
+		expected := []int{6, 5, 4, 3, 2, 1}
+		assert.Equal(t, expected, result)
+	})
+
+	t.Run("Concat with Flatten", func(t *testing.T) {
+		arr1 := [][]int{{1, 2}, {3, 4}}
+		arr2 := [][]int{{5, 6}}
+		result := F.Pipe2(
+			arr1,
+			Concat(arr2),
+			Flatten[int],
+		)
+		expected := []int{1, 2, 3, 4, 5, 6}
+		assert.Equal(t, expected, result)
+	})
+
+	t.Run("Multiple Concat operations", func(t *testing.T) {
+		arr1 := []int{1}
+		arr2 := []int{2}
+		arr3 := []int{3}
+		arr4 := []int{4}
+
+		result := Concat(arr4)(Concat(arr3)(Concat(arr2)(arr1)))
+
+		expected := []int{1, 2, 3, 4}
+		assert.Equal(t, expected, result)
+	})
+}
+
+// TestConcatUseCases demonstrates practical use cases for Concat
+func TestConcatUseCases(t *testing.T) {
+	t.Run("Building array incrementally", func(t *testing.T) {
+		header := []string{"Name", "Age"}
+		data := []string{"Alice", "30"}
+		footer := []string{"Total: 1"}
+
+		result := F.Pipe2(
+			header,
+			Concat(data),
+			Concat(footer),
+		)
+
+		expected := []string{"Name", "Age", "Alice", "30", "Total: 1"}
+		assert.Equal(t, expected, result)
+	})
+
+	t.Run("Merging results from multiple operations", func(t *testing.T) {
+		evens := Filter(func(n int) bool { return n%2 == 0 })([]int{1, 2, 3, 4, 5, 6})
+		odds := Filter(func(n int) bool { return n%2 != 0 })([]int{1, 2, 3, 4, 5, 6})
+
+		result := Concat(odds)(evens)
+		expected := []int{2, 4, 6, 1, 3, 5}
+		assert.Equal(t, expected, result)
+	})
+
+	t.Run("Combining prefix and suffix", func(t *testing.T) {
+		prefix := []string{"Mr.", "Dr."}
+		names := []string{"Smith", "Jones"}
+
+		addPrefix := func(name string) []string {
+			return Map(func(p string) string { return p + " " + name })(prefix)
+		}
+
+		result := F.Pipe2(
+			names,
+			Chain(addPrefix),
+			F.Identity[[]string],
+		)
+
+		expected := []string{"Mr. Smith", "Dr. Smith", "Mr. Jones", "Dr. Jones"}
+		assert.Equal(t, expected, result)
+	})
+
+	t.Run("Queue-like behavior", func(t *testing.T) {
+		queue := []int{1, 2, 3}
+		newItems := []int{4, 5}
+
+		// Add items to end of queue
+		updatedQueue := Concat(newItems)(queue)
+
+		assert.Equal(t, []int{1, 2, 3, 4, 5}, updatedQueue)
+		assert.Equal(t, 1, updatedQueue[0])                   // Front of queue
+		assert.Equal(t, 5, updatedQueue[len(updatedQueue)-1]) // Back of queue
+	})
+
+	t.Run("Combining configuration arrays", func(t *testing.T) {
+		defaultConfig := []string{"--verbose", "--color"}
+		userConfig := []string{"--output=file.txt", "--format=json"}
+
+		finalConfig := Concat(userConfig)(defaultConfig)
+
+		expected := []string{"--verbose", "--color", "--output=file.txt", "--format=json"}
+		assert.Equal(t, expected, finalConfig)
+	})
+}
+
+// TestConcatProperties tests mathematical properties of Concat
+func TestConcatProperties(t *testing.T) {
+	t.Run("Associativity: (a + b) + c == a + (b + c)", func(t *testing.T) {
+		a := []int{1, 2}
+		b := []int{3, 4}
+		c := []int{5, 6}
+
+		// (a + b) + c
+		left := Concat(c)(Concat(b)(a))
+
+		// a + (b + c)
+		right := Concat(Concat(c)(b))(a)
+
+		assert.Equal(t, left, right)
+		assert.Equal(t, []int{1, 2, 3, 4, 5, 6}, left)
+	})
+
+	t.Run("Identity: a + [] == a and [] + a == a", func(t *testing.T) {
+		arr := []int{1, 2, 3}
+		empty := []int{}
+
+		// Right identity
+		rightResult := Concat(empty)(arr)
+		assert.Equal(t, arr, rightResult)
+
+		// Left identity
+		leftResult := Concat(arr)(empty)
+		assert.Equal(t, arr, leftResult)
+	})
+
+	t.Run("Length property: len(a + b) == len(a) + len(b)", func(t *testing.T) {
+		testCases := []struct {
+			arr1 []int
+			arr2 []int
+		}{
+			{[]int{1, 2, 3}, []int{4, 5}},
+			{[]int{1}, []int{2, 3, 4, 5}},
+			{[]int{}, []int{1, 2, 3}},
+			{[]int{1, 2, 3}, []int{}},
+			{MakeBy(100, F.Identity[int]), MakeBy(50, F.Identity[int])},
+		}
+
+		for _, tc := range testCases {
+			result := Concat(tc.arr2)(tc.arr1)
+			expectedLen := len(tc.arr1) + len(tc.arr2)
+			assert.Equal(t, expectedLen, len(result))
+		}
+	})
+
+	t.Run("Order preservation: elements maintain their relative order", func(t *testing.T) {
+		arr1 := []int{1, 2, 3}
+		arr2 := []int{4, 5, 6}
+		result := Concat(arr2)(arr1)
+
+		// Check arr1 elements are in order
+		assert.Equal(t, 1, result[0])
+		assert.Equal(t, 2, result[1])
+		assert.Equal(t, 3, result[2])
+
+		// Check arr2 elements are in order after arr1
+		assert.Equal(t, 4, result[3])
+		assert.Equal(t, 5, result[4])
+		assert.Equal(t, 6, result[5])
+	})
+
+	t.Run("Immutability: original arrays are not modified", func(t *testing.T) {
+		original1 := []int{1, 2, 3}
+		original2 := []int{4, 5, 6}
+		copy1 := []int{1, 2, 3}
+		copy2 := []int{4, 5, 6}
+
+		_ = Concat(original2)(original1)
+
+		assert.Equal(t, copy1, original1)
+		assert.Equal(t, copy2, original2)
+	})
+}

v2/array/nonempty/array_test.go

@@ -764,14 +764,14 @@ func TestFoldMap(t *testing.T) {
 	t.Run("FoldMap with sum semigroup", func(t *testing.T) {
 		sumSemigroup := N.SemigroupSum[int]()
 		arr := From(1, 2, 3, 4)
-		result := FoldMap[int, int](sumSemigroup)(func(x int) int { return x * 2 })(arr)
+		result := FoldMap[int](sumSemigroup)(func(x int) int { return x * 2 })(arr)
 		assert.Equal(t, 20, result) // (1*2) + (2*2) + (3*2) + (4*2) = 20
 	})
 
 	t.Run("FoldMap with string concatenation", func(t *testing.T) {
 		concatSemigroup := STR.Semigroup
 		arr := From(1, 2, 3)
-		result := FoldMap[int, string](concatSemigroup)(func(x int) string { return fmt.Sprintf("%d", x) })(arr)
+		result := FoldMap[int](concatSemigroup)(func(x int) string { return fmt.Sprintf("%d", x) })(arr)
 		assert.Equal(t, "123", result)
 	})
 }

v2/array/traverse.go

@@ -16,7 +16,11 @@
 package array
 
 import (
+	"github.com/IBM/fp-go/v2/internal/apply"
 	"github.com/IBM/fp-go/v2/internal/array"
+	"github.com/IBM/fp-go/v2/internal/functor"
+	"github.com/IBM/fp-go/v2/internal/pointed"
+	"github.com/IBM/fp-go/v2/internal/traversable"
 )
 
 // Traverse maps each element of an array to an effect (HKT), then collects the results
@@ -55,9 +59,9 @@ import (
 //
 //go:inline
 func Traverse[A, B, HKTB, HKTAB, HKTRB any](
-	fof func([]B) HKTRB,
-	fmap func(func([]B) func(B) []B) func(HKTRB) HKTAB,
-	fap func(HKTB) func(HKTAB) HKTRB,
+	fof pointed.OfType[[]B, HKTRB],
+	fmap functor.MapType[[]B, func(B) []B, HKTRB, HKTAB],
+	fap apply.ApType[HKTB, HKTRB, HKTAB],
 
 	f func(A) HKTB) func([]A) HKTRB {
 	return array.Traverse[[]A](fof, fmap, fap, f)
@@ -71,7 +75,7 @@ func Traverse[A, B, HKTB, HKTAB, HKTRB any](
 //
 //go:inline
 func MonadTraverse[A, B, HKTB, HKTAB, HKTRB any](
-	fof func([]B) HKTRB,
+	fof pointed.OfType[[]B, HKTRB],
 	fmap func(func([]B) func(B) []B) func(HKTRB) HKTAB,
 	fap func(HKTB) func(HKTAB) HKTRB,
 
@@ -83,7 +87,7 @@ func MonadTraverse[A, B, HKTB, HKTAB, HKTRB any](
 
 //go:inline
 func TraverseWithIndex[A, B, HKTB, HKTAB, HKTRB any](
-	fof func([]B) HKTRB,
+	fof pointed.OfType[[]B, HKTRB],
 	fmap func(func([]B) func(B) []B) func(HKTRB) HKTAB,
 	fap func(HKTB) func(HKTAB) HKTRB,
 
@@ -93,7 +97,7 @@ func TraverseWithIndex[A, B, HKTB, HKTAB, HKTRB any](
 
 //go:inline
 func MonadTraverseWithIndex[A, B, HKTB, HKTAB, HKTRB any](
-	fof func([]B) HKTRB,
+	fof pointed.OfType[[]B, HKTRB],
 	fmap func(func([]B) func(B) []B) func(HKTRB) HKTAB,
 	fap func(HKTB) func(HKTAB) HKTRB,
 
@@ -102,3 +106,22 @@ func MonadTraverseWithIndex[A, B, HKTB, HKTAB, HKTRB any](
 
 	return array.MonadTraverseWithIndex(fof, fmap, fap, ta, f)
 }
+
+func MakeTraverseType[A, B, HKT_F_B, HKT_F_T_B, HKT_F_B_T_B any]() traversable.TraverseType[A, B, []A, []B, HKT_F_B, HKT_F_T_B, HKT_F_B_T_B] {
+	return func(
+		// ap
+		fof_b pointed.OfType[[]B, HKT_F_T_B],
+		fmap_b functor.MapType[[]B, func(B) []B, HKT_F_T_B, HKT_F_B_T_B],
+		fap_b apply.ApType[HKT_F_B, HKT_F_T_B, HKT_F_B_T_B],
+
+	) func(func(A) HKT_F_B) func([]A) HKT_F_T_B {
+		return func(f func(A) HKT_F_B) func([]A) HKT_F_T_B {
+			return Traverse(
+				fof_b,
+				fmap_b,
+				fap_b,
+				f,
+			)
+		}
+	}
+}

v2/builder/builder.go

@@ -1,7 +1,81 @@
+// Copyright (c) 2024 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package builder provides a generic Builder pattern interface for constructing
+// complex objects with validation.
+//
+// The Builder pattern is useful when:
+//   - Object construction requires multiple steps
+//   - Construction may fail with validation errors
+//   - You want to separate construction logic from the object itself
+//
+// Example usage:
+//
+//	type PersonBuilder struct {
+//	    name string
+//	    age  int
+//	}
+//
+//	func (b PersonBuilder) Build() result.Result[Person] {
+//	    if b.name == "" {
+//	        return result.Error[Person](errors.New("name is required"))
+//	    }
+//	    if b.age < 0 {
+//	        return result.Error[Person](errors.New("age must be non-negative"))
+//	    }
+//	    return result.Of(Person{Name: b.name, Age: b.age})
+//	}
 package builder
 
 type (
+	// Builder is a generic interface for the Builder pattern that constructs
+	// objects of type T with validation.
+	//
+	// The Build method returns a Result[T] which can be either:
+	//   - Success: containing the constructed object of type T
+	//   - Error: containing an error if validation or construction fails
+	//
+	// This allows builders to perform validation and return meaningful errors
+	// during the construction process, making it explicit that object creation
+	// may fail.
+	//
+	// Type Parameters:
+	//   - T: The type of object being built
+	//
+	// Example:
+	//
+	//	type ConfigBuilder struct {
+	//	    host string
+	//	    port int
+	//	}
+	//
+	//	func (b ConfigBuilder) Build() result.Result[Config] {
+	//	    if b.host == "" {
+	//	        return result.Error[Config](errors.New("host is required"))
+	//	    }
+	//	    if b.port <= 0 || b.port > 65535 {
+	//	        return result.Error[Config](errors.New("invalid port"))
+	//	    }
+	//	    return result.Of(Config{Host: b.host, Port: b.port})
+	//	}
 	Builder[T any] interface {
+		// Build constructs and validates an object of type T.
+		//
+		// Returns:
+		//   - Result[T]: A Result containing either the successfully built object
+		//     or an error if validation or construction fails.
 		Build() Result[T]
 	}
 )

v2/builder/builder_test.go

@@ -0,0 +1,374 @@
+// Copyright (c) 2024 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package builder
+
+import (
+	"errors"
+	"testing"
+
+	O "github.com/IBM/fp-go/v2/option"
+	"github.com/IBM/fp-go/v2/result"
+	"github.com/stretchr/testify/assert"
+)
+
+// Test types for demonstration
+
+type Person struct {
+	Name string
+	Age  int
+}
+
+type PersonBuilder struct {
+	name string
+	age  int
+}
+
+func (b PersonBuilder) WithName(name string) PersonBuilder {
+	b.name = name
+	return b
+}
+
+func (b PersonBuilder) WithAge(age int) PersonBuilder {
+	b.age = age
+	return b
+}
+
+func (b PersonBuilder) Build() Result[Person] {
+	if b.name == "" {
+		return result.Left[Person](errors.New("name is required"))
+	}
+	if b.age < 0 {
+		return result.Left[Person](errors.New("age must be non-negative"))
+	}
+	if b.age > 150 {
+		return result.Left[Person](errors.New("age must be realistic"))
+	}
+	return result.Of(Person{Name: b.name, Age: b.age})
+}
+
+func NewPersonBuilder(p Person) PersonBuilder {
+	return PersonBuilder{name: p.Name, age: p.Age}
+}
+
+// Config example for additional test coverage
+
+type Config struct {
+	Host string
+	Port int
+}
+
+type ConfigBuilder struct {
+	host string
+	port int
+}
+
+func (b ConfigBuilder) WithHost(host string) ConfigBuilder {
+	b.host = host
+	return b
+}
+
+func (b ConfigBuilder) WithPort(port int) ConfigBuilder {
+	b.port = port
+	return b
+}
+
+func (b ConfigBuilder) Build() Result[Config] {
+	if b.host == "" {
+		return result.Left[Config](errors.New("host is required"))
+	}
+	if b.port <= 0 || b.port > 65535 {
+		return result.Left[Config](errors.New("port must be between 1 and 65535"))
+	}
+	return result.Of(Config{Host: b.host, Port: b.port})
+}
+
+func NewConfigBuilder(c Config) ConfigBuilder {
+	return ConfigBuilder{host: c.Host, port: c.Port}
+}
+
+// Tests for Builder interface
+
+func TestBuilder_SuccessfulBuild(t *testing.T) {
+	builder := PersonBuilder{}.
+		WithName("Alice").
+		WithAge(30)
+
+	res := builder.Build()
+
+	assert.True(t, result.IsRight(res), "Build should succeed")
+	person := result.ToOption(res)
+	assert.True(t, O.IsSome(person), "Result should contain a person")
+
+	p := O.GetOrElse(func() Person { return Person{} })(person)
+	assert.Equal(t, "Alice", p.Name)
+	assert.Equal(t, 30, p.Age)
+}
+
+func TestBuilder_ValidationFailure_MissingName(t *testing.T) {
+	builder := PersonBuilder{}.WithAge(30)
+
+	res := builder.Build()
+
+	assert.True(t, result.IsLeft(res), "Build should fail when name is missing")
+	err := result.Fold(
+		func(e error) error { return e },
+		func(Person) error { return errors.New("unexpected success") },
+	)(res)
+	assert.Equal(t, "name is required", err.Error())
+}
+
+func TestBuilder_ValidationFailure_NegativeAge(t *testing.T) {
+	builder := PersonBuilder{}.
+		WithName("Bob").
+		WithAge(-5)
+
+	res := builder.Build()
+
+	assert.True(t, result.IsLeft(res), "Build should fail when age is negative")
+	err := result.Fold(
+		func(e error) error { return e },
+		func(Person) error { return errors.New("unexpected success") },
+	)(res)
+	assert.Equal(t, "age must be non-negative", err.Error())
+}
+
+func TestBuilder_ValidationFailure_UnrealisticAge(t *testing.T) {
+	builder := PersonBuilder{}.
+		WithName("Charlie").
+		WithAge(200)
+
+	res := builder.Build()
+
+	assert.True(t, result.IsLeft(res), "Build should fail when age is unrealistic")
+	err := result.Fold(
+		func(e error) error { return e },
+		func(Person) error { return errors.New("unexpected success") },
+	)(res)
+	assert.Equal(t, "age must be realistic", err.Error())
+}
+
+func TestBuilder_ConfigSuccessfulBuild(t *testing.T) {
+	builder := ConfigBuilder{}.
+		WithHost("localhost").
+		WithPort(8080)
+
+	res := builder.Build()
+
+	assert.True(t, result.IsRight(res), "Build should succeed")
+	config := result.ToOption(res)
+	assert.True(t, O.IsSome(config), "Result should contain a config")
+
+	c := O.GetOrElse(func() Config { return Config{} })(config)
+	assert.Equal(t, "localhost", c.Host)
+	assert.Equal(t, 8080, c.Port)
+}
+
+func TestBuilder_ConfigValidationFailure_MissingHost(t *testing.T) {
+	builder := ConfigBuilder{}.WithPort(8080)
+
+	res := builder.Build()
+
+	assert.True(t, result.IsLeft(res), "Build should fail when host is missing")
+	err := result.Fold(
+		func(e error) error { return e },
+		func(Config) error { return errors.New("unexpected success") },
+	)(res)
+	assert.Equal(t, "host is required", err.Error())
+}
+
+func TestBuilder_ConfigValidationFailure_InvalidPort(t *testing.T) {
+	tests := []struct {
+		name string
+		port int
+	}{
+		{"zero port", 0},
+		{"negative port", -1},
+		{"port too large", 70000},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			builder := ConfigBuilder{}.
+				WithHost("localhost").
+				WithPort(tt.port)
+
+			res := builder.Build()
+
+			assert.True(t, result.IsLeft(res), "Build should fail for invalid port")
+			err := result.Fold(
+				func(e error) error { return e },
+				func(Config) error { return errors.New("unexpected success") },
+			)(res)
+			assert.Equal(t, "port must be between 1 and 65535", err.Error())
+		})
+	}
+}
+
+// Tests for BuilderPrism
+
+func TestBuilderPrism_GetOption_ValidBuilder(t *testing.T) {
+	prism := BuilderPrism(NewPersonBuilder)
+
+	builder := PersonBuilder{}.
+		WithName("Alice").
+		WithAge(30)
+
+	personOpt := prism.GetOption(builder)
+
+	assert.True(t, O.IsSome(personOpt), "GetOption should return Some for valid builder")
+	person := O.GetOrElse(func() Person { return Person{} })(personOpt)
+	assert.Equal(t, "Alice", person.Name)
+	assert.Equal(t, 30, person.Age)
+}
+
+func TestBuilderPrism_GetOption_InvalidBuilder(t *testing.T) {
+	prism := BuilderPrism(NewPersonBuilder)
+
+	builder := PersonBuilder{}.WithAge(30) // Missing name
+
+	personOpt := prism.GetOption(builder)
+
+	assert.True(t, O.IsNone(personOpt), "GetOption should return None for invalid builder")
+}
+
+func TestBuilderPrism_ReverseGet(t *testing.T) {
+	prism := BuilderPrism(NewPersonBuilder)
+
+	person := Person{Name: "Bob", Age: 25}
+
+	builder := prism.ReverseGet(person)
+
+	assert.Equal(t, "Bob", builder.name)
+	assert.Equal(t, 25, builder.age)
+
+	// Verify the builder can build the same person
+	res := builder.Build()
+	assert.True(t, result.IsRight(res), "Builder from ReverseGet should be valid")
+
+	rebuilt := O.GetOrElse(func() Person { return Person{} })(result.ToOption(res))
+	assert.Equal(t, person, rebuilt)
+}
+
+func TestBuilderPrism_RoundTrip_ValidBuilder(t *testing.T) {
+	prism := BuilderPrism(NewPersonBuilder)
+
+	originalBuilder := PersonBuilder{}.
+		WithName("Charlie").
+		WithAge(35)
+
+	// Extract person from builder
+	personOpt := prism.GetOption(originalBuilder)
+	assert.True(t, O.IsSome(personOpt), "Should extract person from valid builder")
+
+	person := O.GetOrElse(func() Person { return Person{} })(personOpt)
+
+	// Reconstruct builder from person
+	rebuiltBuilder := prism.ReverseGet(person)
+
+	// Verify the rebuilt builder produces the same person
+	rebuiltRes := rebuiltBuilder.Build()
+	assert.True(t, result.IsRight(rebuiltRes), "Rebuilt builder should be valid")
+
+	rebuiltPerson := O.GetOrElse(func() Person { return Person{} })(result.ToOption(rebuiltRes))
+	assert.Equal(t, person, rebuiltPerson)
+}
+
+func TestBuilderPrism_ConfigPrism(t *testing.T) {
+	prism := BuilderPrism(NewConfigBuilder)
+
+	builder := ConfigBuilder{}.
+		WithHost("example.com").
+		WithPort(443)
+
+	configOpt := prism.GetOption(builder)
+
+	assert.True(t, O.IsSome(configOpt), "GetOption should return Some for valid config builder")
+	config := O.GetOrElse(func() Config { return Config{} })(configOpt)
+	assert.Equal(t, "example.com", config.Host)
+	assert.Equal(t, 443, config.Port)
+}
+
+func TestBuilderPrism_ConfigPrism_InvalidBuilder(t *testing.T) {
+	prism := BuilderPrism(NewConfigBuilder)
+
+	builder := ConfigBuilder{}.WithPort(8080) // Missing host
+
+	configOpt := prism.GetOption(builder)
+
+	assert.True(t, O.IsNone(configOpt), "GetOption should return None for invalid config builder")
+}
+
+func TestBuilderPrism_ConfigPrism_ReverseGet(t *testing.T) {
+	prism := BuilderPrism(NewConfigBuilder)
+
+	config := Config{Host: "api.example.com", Port: 9000}
+
+	builder := prism.ReverseGet(config)
+
+	assert.Equal(t, "api.example.com", builder.host)
+	assert.Equal(t, 9000, builder.port)
+
+	// Verify the builder can build the same config
+	res := builder.Build()
+	assert.True(t, result.IsRight(res), "Builder from ReverseGet should be valid")
+
+	rebuilt := O.GetOrElse(func() Config { return Config{} })(result.ToOption(res))
+	assert.Equal(t, config, rebuilt)
+}
+
+// Benchmark tests
+
+func BenchmarkBuilder_SuccessfulBuild(b *testing.B) {
+	builder := PersonBuilder{}.
+		WithName("Alice").
+		WithAge(30)
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		_ = builder.Build()
+	}
+}
+
+func BenchmarkBuilder_FailedBuild(b *testing.B) {
+	builder := PersonBuilder{}.WithAge(30) // Missing name
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		_ = builder.Build()
+	}
+}
+
+func BenchmarkBuilderPrism_GetOption(b *testing.B) {
+	prism := BuilderPrism(NewPersonBuilder)
+	builder := PersonBuilder{}.
+		WithName("Alice").
+		WithAge(30)
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		_ = prism.GetOption(builder)
+	}
+}
+
+func BenchmarkBuilderPrism_ReverseGet(b *testing.B) {
+	prism := BuilderPrism(NewPersonBuilder)
+	person := Person{Name: "Bob", Age: 25}
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		_ = prism.ReverseGet(person)
+	}
+}

v2/builder/prism.go

@@ -1,3 +1,18 @@
+// Copyright (c) 2024 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 package builder
 
 import (
@@ -6,7 +21,61 @@ import (
 	"github.com/IBM/fp-go/v2/result"
 )
 
-// BuilderPrism createa a [Prism] that converts between a builder and its type
+// BuilderPrism creates a [Prism] that converts between a builder and its built type.
+//
+// A Prism is an optic that focuses on a case of a sum type, providing bidirectional
+// conversion with the possibility of failure. This function creates a prism that:
+//   - Extracts: Attempts to build the object from the builder (may fail)
+//   - Constructs: Creates a builder from a valid object (always succeeds)
+//
+// The extraction direction (builder -> object) uses the Build method and converts
+// the Result to an Option, where errors become None. The construction direction
+// (object -> builder) uses the provided creator function.
+//
+// Type Parameters:
+//   - T: The type of the object being built
+//   - B: The builder type that implements Builder[T]
+//
+// Parameters:
+//   - creator: A function that creates a builder from a valid object of type T.
+//     This function should initialize the builder with all fields from the object.
+//
+// Returns:
+//   - Prism[B, T]: A prism that can convert between the builder and the built type.
+//
+// Example:
+//
+//	type Person struct {
+//	    Name string
+//	    Age  int
+//	}
+//
+//	type PersonBuilder struct {
+//	    name string
+//	    age  int
+//	}
+//
+//	func (b PersonBuilder) Build() result.Result[Person] {
+//	    if b.name == "" {
+//	        return result.Error[Person](errors.New("name required"))
+//	    }
+//	    return result.Of(Person{Name: b.name, Age: b.age})
+//	}
+//
+//	func NewPersonBuilder(p Person) PersonBuilder {
+//	    return PersonBuilder{name: p.Name, age: p.Age}
+//	}
+//
+//	// Create a prism for PersonBuilder
+//	prism := BuilderPrism(NewPersonBuilder)
+//
+//	// Use the prism to extract a Person from a valid builder
+//	builder := PersonBuilder{name: "Alice", age: 30}
+//	person := prism.GetOption(builder) // Some(Person{Name: "Alice", Age: 30})
+//
+//	// Use the prism to create a builder from a Person
+//	p := Person{Name: "Bob", Age: 25}
+//	b := prism.ReverseGet(p) // PersonBuilder{name: "Bob", age: 25}
 func BuilderPrism[T any, B Builder[T]](creator func(T) B) Prism[B, T] {
 	return prism.MakePrismWithName(F.Flow2(B.Build, result.ToOption[T]), creator, "BuilderPrism")
 }

v2/cli/apply.go

@@ -16,13 +16,14 @@
 package cli
 
 import (
+	"context"
 	"fmt"
 	"log"
 	"os"
 	"path/filepath"
 	"time"
 
-	C "github.com/urfave/cli/v2"
+	C "github.com/urfave/cli/v3"
 )
 
 func generateTraverseTuple(f *os.File, i int) {
@@ -422,10 +423,10 @@ func ApplyCommand() *C.Command {
 			flagCount,
 			flagFilename,
 		},
-		Action: func(ctx *C.Context) error {
+		Action: func(ctx context.Context, cmd *C.Command) error {
 			return generateApplyHelpers(
-				ctx.String(keyFilename),
-				ctx.Int(keyCount),
+				cmd.String(keyFilename),
+				cmd.Int(keyCount),
 			)
 		},
 	}

v2/cli/bind.go

@@ -16,13 +16,14 @@
 package cli
 
 import (
+	"context"
 	"fmt"
 	"log"
 	"os"
 	"path/filepath"
 	"time"
 
-	C "github.com/urfave/cli/v2"
+	C "github.com/urfave/cli/v3"
 )
 
 func createCombinations(n int, all, prev []int) [][]int {
@@ -284,10 +285,10 @@ func BindCommand() *C.Command {
 			flagCount,
 			flagFilename,
 		},
-		Action: func(ctx *C.Context) error {
+		Action: func(ctx context.Context, cmd *C.Command) error {
 			return generateBindHelpers(
-				ctx.String(keyFilename),
-				ctx.Int(keyCount),
+				cmd.String(keyFilename),
+				cmd.Int(keyCount),
 			)
 		},
 	}

v2/cli/commands.go

@@ -16,7 +16,7 @@
 package cli
 
 import (
-	C "github.com/urfave/cli/v2"
+	C "github.com/urfave/cli/v3"
 )
 
 func Commands() []*C.Command {

v2/cli/common.go

@@ -16,7 +16,7 @@
 package cli
 
 import (
-	C "github.com/urfave/cli/v2"
+	C "github.com/urfave/cli/v3"
 )
 
 const (

v2/cli/contextreaderioeither.go

@@ -16,6 +16,7 @@
 package cli
 
 import (
+	"context"
 	"fmt"
 	"log"
 	"os"
@@ -23,7 +24,7 @@ import (
 	"strings"
 
 	A "github.com/IBM/fp-go/v2/array"
-	C "github.com/urfave/cli/v2"
+	C "github.com/urfave/cli/v3"
 )
 
 // Deprecated:
@@ -261,10 +262,10 @@ func ContextReaderIOEitherCommand() *C.Command {
 			flagCount,
 			flagFilename,
 		},
-		Action: func(ctx *C.Context) error {
+		Action: func(ctx context.Context, cmd *C.Command) error {
 			return generateContextReaderIOEitherHelpers(
-				ctx.String(keyFilename),
-				ctx.Int(keyCount),
+				cmd.String(keyFilename),
+				cmd.Int(keyCount),
 			)
 		},
 	}

v2/cli/di.go

@@ -16,13 +16,14 @@
 package cli
 
 import (
+	"context"
 	"fmt"
 	"log"
 	"os"
 	"path/filepath"
 	"time"
 
-	C "github.com/urfave/cli/v2"
+	C "github.com/urfave/cli/v3"
 )
 
 func generateMakeProvider(f *os.File, i int) {
@@ -221,10 +222,10 @@ func DICommand() *C.Command {
 			flagCount,
 			flagFilename,
 		},
-		Action: func(ctx *C.Context) error {
+		Action: func(ctx context.Context, cmd *C.Command) error {
 			return generateDIHelpers(
-				ctx.String(keyFilename),
-				ctx.Int(keyCount),
+				cmd.String(keyFilename),
+				cmd.Int(keyCount),
 			)
 		},
 	}

v2/cli/either.go

@@ -16,13 +16,14 @@
 package cli
 
 import (
+	"context"
 	"fmt"
 	"log"
 	"os"
 	"path/filepath"
 	"time"
 
-	C "github.com/urfave/cli/v2"
+	C "github.com/urfave/cli/v3"
 )
 
 func eitherHKT(typeE string) func(typeA string) string {
@@ -190,10 +191,10 @@ func EitherCommand() *C.Command {
 			flagCount,
 			flagFilename,
 		},
-		Action: func(ctx *C.Context) error {
+		Action: func(ctx context.Context, cmd *C.Command) error {
 			return generateEitherHelpers(
-				ctx.String(keyFilename),
-				ctx.Int(keyCount),
+				cmd.String(keyFilename),
+				cmd.Int(keyCount),
 			)
 		},
 	}

v2/cli/identity.go

@@ -16,13 +16,14 @@
 package cli
 
 import (
+	"context"
 	"fmt"
 	"log"
 	"os"
 	"path/filepath"
 	"time"
 
-	C "github.com/urfave/cli/v2"
+	C "github.com/urfave/cli/v3"
 )
 
 func identityHKT(typeA string) string {
@@ -93,10 +94,10 @@ func IdentityCommand() *C.Command {
 			flagCount,
 			flagFilename,
 		},
-		Action: func(ctx *C.Context) error {
+		Action: func(ctx context.Context, cmd *C.Command) error {
 			return generateIdentityHelpers(
-				ctx.String(keyFilename),
-				ctx.Int(keyCount),
+				cmd.String(keyFilename),
+				cmd.Int(keyCount),
 			)
 		},
 	}

v2/cli/io.go

@@ -16,6 +16,7 @@
 package cli
 
 import (
+	"context"
 	"fmt"
 	"log"
 	"os"
@@ -23,7 +24,7 @@ import (
 	"time"
 
 	A "github.com/IBM/fp-go/v2/array"
-	C "github.com/urfave/cli/v2"
+	C "github.com/urfave/cli/v3"
 )
 
 func nonGenericIO(param string) string {
@@ -102,10 +103,10 @@ func IOCommand() *C.Command {
 			flagCount,
 			flagFilename,
 		},
-		Action: func(ctx *C.Context) error {
+		Action: func(ctx context.Context, cmd *C.Command) error {
 			return generateIOHelpers(
-				ctx.String(keyFilename),
-				ctx.Int(keyCount),
+				cmd.String(keyFilename),
+				cmd.Int(keyCount),
 			)
 		},
 	}

v2/cli/ioeither.go

@@ -16,6 +16,7 @@
 package cli
 
 import (
+	"context"
 	"fmt"
 	"log"
 	"os"
@@ -23,7 +24,7 @@ import (
 	"time"
 
 	A "github.com/IBM/fp-go/v2/array"
-	C "github.com/urfave/cli/v2"
+	C "github.com/urfave/cli/v3"
 )
 
 // [GA ~func() ET.Either[E, A], GB ~func() ET.Either[E, B], GTAB ~func() ET.Either[E, T.Tuple2[A, B]], E, A, B any](a GA, b GB) GTAB {
@@ -273,10 +274,10 @@ func IOEitherCommand() *C.Command {
 			flagCount,
 			flagFilename,
 		},
-		Action: func(ctx *C.Context) error {
+		Action: func(ctx context.Context, cmd *C.Command) error {
 			return generateIOEitherHelpers(
-				ctx.String(keyFilename),
-				ctx.Int(keyCount),
+				cmd.String(keyFilename),
+				cmd.Int(keyCount),
 			)
 		},
 	}

v2/cli/iooption.go

@@ -16,6 +16,7 @@
 package cli
 
 import (
+	"context"
 	"fmt"
 	"log"
 	"os"
@@ -23,7 +24,7 @@ import (
 	"time"
 
 	A "github.com/IBM/fp-go/v2/array"
-	C "github.com/urfave/cli/v2"
+	C "github.com/urfave/cli/v3"
 )
 
 func nonGenericIOOption(param string) string {
@@ -107,10 +108,10 @@ func IOOptionCommand() *C.Command {
 			flagCount,
 			flagFilename,
 		},
-		Action: func(ctx *C.Context) error {
+		Action: func(ctx context.Context, cmd *C.Command) error {
 			return generateIOOptionHelpers(
-				ctx.String(keyFilename),
-				ctx.Int(keyCount),
+				cmd.String(keyFilename),
+				cmd.Int(keyCount),
 			)
 		},
 	}

v2/cli/lens.go

@@ -17,6 +17,7 @@ package cli
 
 import (
 	"bytes"
+	"context"
 	"go/ast"
 	"go/parser"
 	"go/token"
@@ -28,7 +29,7 @@ import (
 	"text/template"
 
 	S "github.com/IBM/fp-go/v2/string"
-	C "github.com/urfave/cli/v2"
+	C "github.com/urfave/cli/v3"
 )
 
 const (
@@ -535,9 +536,9 @@ func extractEmbeddedFields(embedType ast.Expr, fileImports map[string]string, fi
 		}
 
 		for _, name := range field.Names {
-			// Only export lenses for exported fields
-			if name.IsExported() {
-				fieldTypeName := getTypeName(field.Type)
+			// Generate lenses for both exported and unexported fields
+			fieldTypeName := getTypeName(field.Type)
+			if true { // Keep the block structure for minimal changes
 				isOptional := false
 				baseType := fieldTypeName
 
@@ -697,9 +698,9 @@ func parseFile(filename string) ([]structInfo, string, error) {
 				continue
 			}
 			for _, name := range field.Names {
-				// Only export lenses for exported fields
-				if name.IsExported() {
-					typeName := getTypeName(field.Type)
+				// Generate lenses for both exported and unexported fields
+				typeName := getTypeName(field.Type)
+				if true { // Keep the block structure for minimal changes
 					isOptional := false
 					baseType := typeName
 					isComparable := false
@@ -934,12 +935,12 @@ func LensCommand() *C.Command {
 			flagVerbose,
 			flagIncludeTestFiles,
 		},
-		Action: func(ctx *C.Context) error {
+		Action: func(ctx context.Context, cmd *C.Command) error {
 			return generateLensHelpers(
-				ctx.String(keyLensDir),
-				ctx.String(keyFilename),
-				ctx.Bool(keyVerbose),
-				ctx.Bool(keyIncludeTestFile),
+				cmd.String(keyLensDir),
+				cmd.String(keyFilename),
+				cmd.Bool(keyVerbose),
+				cmd.Bool(keyIncludeTestFile),
 			)
 		},
 	}

v2/cli/lens_test.go

@@ -1086,3 +1086,255 @@ type ComparableBox[T comparable] struct {
 	// Verify that MakeLensRef is NOT used (since both fields are comparable)
 	assert.NotContains(t, contentStr, "__lens.MakeLensRefWithName(", "Should not use MakeLensRefWithName when all fields are comparable")
 }
+
+func TestParseFileWithUnexportedFields(t *testing.T) {
+	// Create a temporary test file
+	tmpDir := t.TempDir()
+	testFile := filepath.Join(tmpDir, "test.go")
+
+	testCode := `package testpkg
+
+// fp-go:Lens
+type Config struct {
+	PublicName  string
+	privateName string
+	PublicValue int
+	privateValue *int
+}
+`
+
+	err := os.WriteFile(testFile, []byte(testCode), 0o644)
+	require.NoError(t, err)
+
+	// Parse the file
+	structs, pkg, err := parseFile(testFile)
+	require.NoError(t, err)
+
+	// Verify results
+	assert.Equal(t, "testpkg", pkg)
+	assert.Len(t, structs, 1)
+
+	// Check Config struct
+	config := structs[0]
+	assert.Equal(t, "Config", config.Name)
+	assert.Len(t, config.Fields, 4, "Should include both exported and unexported fields")
+
+	// Check exported field
+	assert.Equal(t, "PublicName", config.Fields[0].Name)
+	assert.Equal(t, "string", config.Fields[0].TypeName)
+	assert.False(t, config.Fields[0].IsOptional)
+
+	// Check unexported field
+	assert.Equal(t, "privateName", config.Fields[1].Name)
+	assert.Equal(t, "string", config.Fields[1].TypeName)
+	assert.False(t, config.Fields[1].IsOptional)
+
+	// Check exported int field
+	assert.Equal(t, "PublicValue", config.Fields[2].Name)
+	assert.Equal(t, "int", config.Fields[2].TypeName)
+	assert.False(t, config.Fields[2].IsOptional)
+
+	// Check unexported pointer field
+	assert.Equal(t, "privateValue", config.Fields[3].Name)
+	assert.Equal(t, "*int", config.Fields[3].TypeName)
+	assert.True(t, config.Fields[3].IsOptional)
+}
+
+func TestGenerateLensHelpersWithUnexportedFields(t *testing.T) {
+	// Create a temporary directory with test files
+	tmpDir := t.TempDir()
+
+	testCode := `package testpkg
+
+// fp-go:Lens
+type MixedStruct struct {
+	PublicField  string
+	privateField int
+	OptionalPrivate *string
+}
+`
+
+	testFile := filepath.Join(tmpDir, "test.go")
+	err := os.WriteFile(testFile, []byte(testCode), 0o644)
+	require.NoError(t, err)
+
+	// Generate lens code
+	outputFile := "gen_lens.go"
+	err = generateLensHelpers(tmpDir, outputFile, false, false)
+	require.NoError(t, err)
+
+	// Verify the generated file exists
+	genPath := filepath.Join(tmpDir, outputFile)
+	_, err = os.Stat(genPath)
+	require.NoError(t, err)
+
+	// Read and verify the generated content
+	content, err := os.ReadFile(genPath)
+	require.NoError(t, err)
+
+	contentStr := string(content)
+
+	// Check for expected content
+	assert.Contains(t, contentStr, "package testpkg")
+	assert.Contains(t, contentStr, "MixedStructLenses")
+	assert.Contains(t, contentStr, "MakeMixedStructLenses")
+
+	// Check that lenses are generated for all fields (exported and unexported)
+	assert.Contains(t, contentStr, "PublicField __lens.Lens[MixedStruct, string]")
+	assert.Contains(t, contentStr, "privateField __lens.Lens[MixedStruct, int]")
+	assert.Contains(t, contentStr, "OptionalPrivate __lens.Lens[MixedStruct, *string]")
+
+	// Check lens constructors
+	assert.Contains(t, contentStr, "func(s MixedStruct) string { return s.PublicField }")
+	assert.Contains(t, contentStr, "func(s MixedStruct) int { return s.privateField }")
+	assert.Contains(t, contentStr, "func(s MixedStruct) *string { return s.OptionalPrivate }")
+
+	// Check setters
+	assert.Contains(t, contentStr, "func(s MixedStruct, v string) MixedStruct { s.PublicField = v; return s }")
+	assert.Contains(t, contentStr, "func(s MixedStruct, v int) MixedStruct { s.privateField = v; return s }")
+	assert.Contains(t, contentStr, "func(s MixedStruct, v *string) MixedStruct { s.OptionalPrivate = v; return s }")
+}
+
+func TestParseFileWithOnlyUnexportedFields(t *testing.T) {
+	// Create a temporary test file
+	tmpDir := t.TempDir()
+	testFile := filepath.Join(tmpDir, "test.go")
+
+	testCode := `package testpkg
+
+// fp-go:Lens
+type PrivateConfig struct {
+	name    string
+	value   int
+	enabled bool
+}
+`
+
+	err := os.WriteFile(testFile, []byte(testCode), 0o644)
+	require.NoError(t, err)
+
+	// Parse the file
+	structs, pkg, err := parseFile(testFile)
+	require.NoError(t, err)
+
+	// Verify results
+	assert.Equal(t, "testpkg", pkg)
+	assert.Len(t, structs, 1)
+
+	// Check PrivateConfig struct
+	config := structs[0]
+	assert.Equal(t, "PrivateConfig", config.Name)
+	assert.Len(t, config.Fields, 3, "Should include all unexported fields")
+
+	// Check all fields are unexported
+	assert.Equal(t, "name", config.Fields[0].Name)
+	assert.Equal(t, "value", config.Fields[1].Name)
+	assert.Equal(t, "enabled", config.Fields[2].Name)
+}
+
+func TestGenerateLensHelpersWithUnexportedEmbeddedFields(t *testing.T) {
+	// Create a temporary directory with test files
+	tmpDir := t.TempDir()
+
+	testCode := `package testpkg
+
+type BaseConfig struct {
+	publicBase  string
+	privateBase int
+}
+
+// fp-go:Lens
+type ExtendedConfig struct {
+	BaseConfig
+	PublicField  string
+	privateField bool
+}
+`
+
+	testFile := filepath.Join(tmpDir, "test.go")
+	err := os.WriteFile(testFile, []byte(testCode), 0o644)
+	require.NoError(t, err)
+
+	// Generate lens code
+	outputFile := "gen_lens.go"
+	err = generateLensHelpers(tmpDir, outputFile, false, false)
+	require.NoError(t, err)
+
+	// Verify the generated file exists
+	genPath := filepath.Join(tmpDir, outputFile)
+	_, err = os.Stat(genPath)
+	require.NoError(t, err)
+
+	// Read and verify the generated content
+	content, err := os.ReadFile(genPath)
+	require.NoError(t, err)
+
+	contentStr := string(content)
+
+	// Check for expected content
+	assert.Contains(t, contentStr, "package testpkg")
+	assert.Contains(t, contentStr, "ExtendedConfigLenses")
+
+	// Check that lenses are generated for embedded unexported fields
+	assert.Contains(t, contentStr, "publicBase __lens.Lens[ExtendedConfig, string]")
+	assert.Contains(t, contentStr, "privateBase __lens.Lens[ExtendedConfig, int]")
+
+	// Check that lenses are generated for direct fields (both exported and unexported)
+	assert.Contains(t, contentStr, "PublicField __lens.Lens[ExtendedConfig, string]")
+	assert.Contains(t, contentStr, "privateField __lens.Lens[ExtendedConfig, bool]")
+}
+
+func TestParseFileWithMixedFieldVisibility(t *testing.T) {
+	// Create a temporary test file with various field visibility patterns
+	tmpDir := t.TempDir()
+	testFile := filepath.Join(tmpDir, "test.go")
+
+	testCode := `package testpkg
+
+// fp-go:Lens
+type ComplexStruct struct {
+	// Exported fields
+	Name        string
+	Age         int
+	Email       *string
+	
+	// Unexported fields
+	password    string
+	secretKey   []byte
+	internalID  *int
+	
+	// Mixed with tags
+	PublicWithTag  string ` + "`json:\"public,omitempty\"`" + `
+	privateWithTag int    ` + "`json:\"private,omitempty\"`" + `
+}
+`
+
+	err := os.WriteFile(testFile, []byte(testCode), 0o644)
+	require.NoError(t, err)
+
+	// Parse the file
+	structs, pkg, err := parseFile(testFile)
+	require.NoError(t, err)
+
+	// Verify results
+	assert.Equal(t, "testpkg", pkg)
+	assert.Len(t, structs, 1)
+
+	// Check ComplexStruct
+	complex := structs[0]
+	assert.Equal(t, "ComplexStruct", complex.Name)
+	assert.Len(t, complex.Fields, 8, "Should include all fields regardless of visibility")
+
+	// Verify field names and types
+	fieldNames := []string{"Name", "Age", "Email", "password", "secretKey", "internalID", "PublicWithTag", "privateWithTag"}
+	for i, expectedName := range fieldNames {
+		assert.Equal(t, expectedName, complex.Fields[i].Name, "Field %d should be %s", i, expectedName)
+	}
+
+	// Check optional fields
+	assert.False(t, complex.Fields[0].IsOptional, "Name should not be optional")
+	assert.True(t, complex.Fields[2].IsOptional, "Email (pointer) should be optional")
+	assert.True(t, complex.Fields[5].IsOptional, "internalID (pointer) should be optional")
+	assert.True(t, complex.Fields[6].IsOptional, "PublicWithTag (with omitempty) should be optional")
+	assert.True(t, complex.Fields[7].IsOptional, "privateWithTag (with omitempty) should be optional")
+}

v2/cli/option.go

@@ -16,13 +16,14 @@
 package cli
 
 import (
+	"context"
 	"fmt"
 	"log"
 	"os"
 	"path/filepath"
 	"time"
 
-	C "github.com/urfave/cli/v2"
+	C "github.com/urfave/cli/v3"
 )
 
 func optionHKT(typeA string) string {
@@ -200,10 +201,10 @@ func OptionCommand() *C.Command {
 			flagCount,
 			flagFilename,
 		},
-		Action: func(ctx *C.Context) error {
+		Action: func(ctx context.Context, cmd *C.Command) error {
 			return generateOptionHelpers(
-				ctx.String(keyFilename),
-				ctx.Int(keyCount),
+				cmd.String(keyFilename),
+				cmd.Int(keyCount),
 			)
 		},
 	}

v2/cli/pipe.go

@@ -16,13 +16,14 @@
 package cli
 
 import (
+	"context"
 	"fmt"
 	"log"
 	"os"
 	"path/filepath"
 	"time"
 
-	C "github.com/urfave/cli/v2"
+	C "github.com/urfave/cli/v3"
 )
 
 func generateUnsliced(f *os.File, i int) {
@@ -423,10 +424,10 @@ func PipeCommand() *C.Command {
 			flagCount,
 			flagFilename,
 		},
-		Action: func(ctx *C.Context) error {
+		Action: func(ctx context.Context, cmd *C.Command) error {
 			return generatePipeHelpers(
-				ctx.String(keyFilename),
-				ctx.Int(keyCount),
+				cmd.String(keyFilename),
+				cmd.Int(keyCount),
 			)
 		},
 	}

v2/cli/reader.go

@@ -16,13 +16,14 @@
 package cli
 
 import (
+	"context"
 	"fmt"
 	"log"
 	"os"
 	"path/filepath"
 	"time"
 
-	C "github.com/urfave/cli/v2"
+	C "github.com/urfave/cli/v3"
 )
 
 func generateReaderFrom(f, fg *os.File, i int) {
@@ -154,10 +155,10 @@ func ReaderCommand() *C.Command {
 			flagCount,
 			flagFilename,
 		},
-		Action: func(ctx *C.Context) error {
+		Action: func(ctx context.Context, cmd *C.Command) error {
 			return generateReaderHelpers(
-				ctx.String(keyFilename),
-				ctx.Int(keyCount),
+				cmd.String(keyFilename),
+				cmd.Int(keyCount),
 			)
 		},
 	}

v2/cli/readerioeither.go

@@ -16,13 +16,14 @@
 package cli
 
 import (
+	"context"
 	"fmt"
 	"log"
 	"os"
 	"path/filepath"
 	"time"
 
-	C "github.com/urfave/cli/v2"
+	C "github.com/urfave/cli/v3"
 )
 
 func generateReaderIOEitherFrom(f, fg *os.File, i int) {
@@ -284,10 +285,10 @@ func ReaderIOEitherCommand() *C.Command {
 			flagCount,
 			flagFilename,
 		},
-		Action: func(ctx *C.Context) error {
+		Action: func(ctx context.Context, cmd *C.Command) error {
 			return generateReaderIOEitherHelpers(
-				ctx.String(keyFilename),
-				ctx.Int(keyCount),
+				cmd.String(keyFilename),
+				cmd.Int(keyCount),
 			)
 		},
 	}

v2/cli/tuple.go

@@ -16,6 +16,7 @@
 package cli
 
 import (
+	"context"
 	"fmt"
 	"log"
 	"os"
@@ -23,7 +24,7 @@ import (
 	"strings"
 	"time"
 
-	C "github.com/urfave/cli/v2"
+	C "github.com/urfave/cli/v3"
 )
 
 func writeTupleType(f *os.File, symbol string, i int) {
@@ -615,10 +616,10 @@ func TupleCommand() *C.Command {
 			flagCount,
 			flagFilename,
 		},
-		Action: func(ctx *C.Context) error {
+		Action: func(ctx context.Context, cmd *C.Command) error {
 			return generateTupleHelpers(
-				ctx.String(keyFilename),
-				ctx.Int(keyCount),
+				cmd.String(keyFilename),
+				cmd.Int(keyCount),
 			)
 		},
 	}

v2/consumer/consumer.go

@@ -177,3 +177,255 @@ func Local[R1, R2 any](f func(R2) R1) Operator[R1, R2] {
 		}
 	}
 }
+
+// Compose is an alias for Local that emphasizes the composition aspect of consumer transformation.
+// It composes a preprocessing function with a consumer, creating a new consumer that applies
+// the function before consuming the value.
+//
+// This function is semantically identical to Local but uses terminology that may be more familiar
+// to developers coming from functional programming backgrounds where "compose" is a common operation.
+//
+// See: https://github.com/fantasyland/fantasy-land?tab=readme-ov-file#profunctor
+//
+// The name "Compose" highlights that we're composing two operations:
+//  1. The transformation function f: R2 -> R1
+//  2. The consumer c: R1 -> ()
+//
+// Result: A composed consumer: R2 -> ()
+//
+// Type Parameters:
+//   - R1: The input type of the original Consumer (what it expects)
+//   - R2: The input type of the new Consumer (what you have)
+//
+// Parameters:
+//   - f: A function that converts R2 to R1 (preprocessing function)
+//
+// Returns:
+//   - An Operator that transforms Consumer[R1] into Consumer[R2]
+//
+// Example - Basic composition:
+//
+//	// Consumer that logs integers
+//	logInt := func(x int) {
+//	    fmt.Printf("Value: %d\n", x)
+//	}
+//
+//	// Compose with a string-to-int parser
+//	parseToInt := func(s string) int {
+//	    n, _ := strconv.Atoi(s)
+//	    return n
+//	}
+//
+//	logString := consumer.Compose(parseToInt)(logInt)
+//	logString("42") // Logs: "Value: 42"
+//
+// Example - Composing multiple transformations:
+//
+//	type Data struct {
+//	    Value string
+//	}
+//
+//	type Wrapper struct {
+//	    Data Data
+//	}
+//
+//	// Consumer that logs strings
+//	logString := func(s string) {
+//	    fmt.Println(s)
+//	}
+//
+//	// Compose transformations step by step
+//	extractData := func(w Wrapper) Data { return w.Data }
+//	extractValue := func(d Data) string { return d.Value }
+//
+//	logData := consumer.Compose(extractValue)(logString)
+//	logWrapper := consumer.Compose(extractData)(logData)
+//
+//	logWrapper(Wrapper{Data: Data{Value: "Hello"}}) // Logs: "Hello"
+//
+// Example - Function composition style:
+//
+//	// Compose is particularly useful when thinking in terms of function composition
+//	type Request struct {
+//	    Body []byte
+//	}
+//
+//	// Consumer that processes strings
+//	processString := func(s string) {
+//	    fmt.Printf("Processing: %s\n", s)
+//	}
+//
+//	// Compose byte-to-string conversion with processing
+//	bytesToString := func(b []byte) string {
+//	    return string(b)
+//	}
+//	extractBody := func(r Request) []byte {
+//	    return r.Body
+//	}
+//
+//	// Chain compositions
+//	processBytes := consumer.Compose(bytesToString)(processString)
+//	processRequest := consumer.Compose(extractBody)(processBytes)
+//
+//	processRequest(Request{Body: []byte("test")}) // Logs: "Processing: test"
+//
+// Relationship to Local:
+//   - Compose and Local are identical in implementation
+//   - Compose emphasizes the functional composition aspect
+//   - Local emphasizes the environment/context transformation aspect
+//   - Use Compose when thinking about function composition
+//   - Use Local when thinking about adapting to different contexts
+//
+// Use Cases:
+//   - Building processing pipelines with clear composition semantics
+//   - Adapting consumers in a functional programming style
+//   - Creating reusable consumer transformations
+//   - Chaining multiple preprocessing steps
+func Compose[R1, R2 any](f func(R2) R1) Operator[R1, R2] {
+	return Local(f)
+}
+
+// Contramap is the categorical name for the contravariant functor operation on Consumers.
+// It transforms a Consumer by preprocessing its input, making it the dual of the covariant
+// functor's map operation.
+//
+// See: https://github.com/fantasyland/fantasy-land?tab=readme-ov-file#contravariant
+//
+// In category theory, a contravariant functor reverses the direction of morphisms.
+// While a covariant functor maps f: A -> B to map(f): F[A] -> F[B],
+// a contravariant functor maps f: A -> B to contramap(f): F[B] -> F[A].
+//
+// For Consumers:
+//   - Consumer[A] is contravariant in A
+//   - Given f: R2 -> R1, contramap(f) transforms Consumer[R1] to Consumer[R2]
+//   - The direction is reversed: we go from Consumer[R1] to Consumer[R2]
+//
+// This is semantically identical to Local and Compose, but uses the standard
+// categorical terminology that emphasizes the contravariant nature of the transformation.
+//
+// Type Parameters:
+//   - R1: The input type of the original Consumer (what it expects)
+//   - R2: The input type of the new Consumer (what you have)
+//
+// Parameters:
+//   - f: A function that converts R2 to R1 (preprocessing function)
+//
+// Returns:
+//   - An Operator that transforms Consumer[R1] into Consumer[R2]
+//
+// Example - Basic contravariant mapping:
+//
+//	// Consumer that logs integers
+//	logInt := func(x int) {
+//	    fmt.Printf("Value: %d\n", x)
+//	}
+//
+//	// Contramap with a string-to-int parser
+//	parseToInt := func(s string) int {
+//	    n, _ := strconv.Atoi(s)
+//	    return n
+//	}
+//
+//	logString := consumer.Contramap(parseToInt)(logInt)
+//	logString("42") // Logs: "Value: 42"
+//
+// Example - Demonstrating contravariance:
+//
+//	// In covariant functors (like Option, Array), map goes "forward":
+//	// map: (A -> B) -> F[A] -> F[B]
+//	//
+//	// In contravariant functors (like Consumer), contramap goes "backward":
+//	// contramap: (B -> A) -> F[A] -> F[B]
+//
+//	type Animal struct{ Name string }
+//	type Dog struct{ Animal Animal; Breed string }
+//
+//	// Consumer for animals
+//	consumeAnimal := func(a Animal) {
+//	    fmt.Printf("Animal: %s\n", a.Name)
+//	}
+//
+//	// Function from Dog to Animal (B -> A)
+//	dogToAnimal := func(d Dog) Animal {
+//	    return d.Animal
+//	}
+//
+//	// Contramap creates Consumer[Dog] from Consumer[Animal]
+//	// Direction is reversed: Consumer[Animal] -> Consumer[Dog]
+//	consumeDog := consumer.Contramap(dogToAnimal)(consumeAnimal)
+//
+//	consumeDog(Dog{
+//	    Animal: Animal{Name: "Buddy"},
+//	    Breed:  "Golden Retriever",
+//	}) // Logs: "Animal: Buddy"
+//
+// Example - Contravariant functor laws:
+//
+//	// Law 1: Identity
+//	// contramap(identity) = identity
+//	identity := func(x int) int { return x }
+//	consumer1 := consumer.Contramap(identity)(consumeInt)
+//	// consumer1 behaves identically to consumeInt
+//
+//	// Law 2: Composition
+//	// contramap(f . g) = contramap(g) . contramap(f)
+//	// Note: composition order is reversed compared to covariant map
+//	f := func(s string) int { n, _ := strconv.Atoi(s); return n }
+//	g := func(b bool) string { if b { return "1" } else { return "0" } }
+//
+//	// These two are equivalent:
+//	consumer2 := consumer.Contramap(func(b bool) int { return f(g(b)) })(consumeInt)
+//	consumer3 := consumer.Contramap(g)(consumer.Contramap(f)(consumeInt))
+//
+// Example - Practical use with type hierarchies:
+//
+//	type Logger interface {
+//	    Log(string)
+//	}
+//
+//	type Message struct {
+//	    Text      string
+//	    Timestamp time.Time
+//	}
+//
+//	// Consumer that logs strings
+//	logString := func(s string) {
+//	    fmt.Println(s)
+//	}
+//
+//	// Contramap to handle Message types
+//	extractText := func(m Message) string {
+//	    return fmt.Sprintf("[%s] %s", m.Timestamp.Format(time.RFC3339), m.Text)
+//	}
+//
+//	logMessage := consumer.Contramap(extractText)(logString)
+//	logMessage(Message{
+//	    Text:      "Hello",
+//	    Timestamp: time.Now(),
+//	}) // Logs: "[2024-01-20T10:00:00Z] Hello"
+//
+// Relationship to Local and Compose:
+//   - Contramap, Local, and Compose are identical in implementation
+//   - Contramap emphasizes the categorical/theoretical aspect
+//   - Local emphasizes the context transformation aspect
+//   - Compose emphasizes the function composition aspect
+//   - Use Contramap when working with category theory concepts
+//   - Use Local when adapting to different contexts
+//   - Use Compose when building functional pipelines
+//
+// Category Theory Background:
+//   - Consumer[A] forms a contravariant functor
+//   - The contravariant functor laws must hold:
+//     1. contramap(id) = id
+//     2. contramap(f ∘ g) = contramap(g) ∘ contramap(f)
+//   - This is dual to the covariant functor (map) operation
+//   - Consumers are contravariant because they consume rather than produce values
+//
+// Use Cases:
+//   - Working with contravariant functors in a categorical style
+//   - Adapting consumers to work with more specific types
+//   - Building type-safe consumer transformations
+//   - Implementing profunctor patterns (Consumer is a profunctor)
+func Contramap[R1, R2 any](f func(R2) R1) Operator[R1, R2] {
+	return Local(f)
+}

v2/consumer/consumer_test.go

@@ -381,3 +381,513 @@ func TestLocal(t *testing.T) {
 		assert.Equal(t, 42, captured)
 	})
 }
+
+func TestContramap(t *testing.T) {
+	t.Run("basic contravariant mapping", func(t *testing.T) {
+		var captured int
+		consumeInt := func(x int) {
+			captured = x
+		}
+
+		parseToInt := func(s string) int {
+			n, _ := strconv.Atoi(s)
+			return n
+		}
+
+		consumeString := Contramap(parseToInt)(consumeInt)
+		consumeString("42")
+
+		assert.Equal(t, 42, captured)
+	})
+
+	t.Run("contravariant identity law", func(t *testing.T) {
+		// contramap(identity) = identity
+		var captured int
+		consumeInt := func(x int) {
+			captured = x
+		}
+
+		identity := function.Identity[int]
+		consumeIdentity := Contramap(identity)(consumeInt)
+
+		consumeIdentity(42)
+		assert.Equal(t, 42, captured)
+
+		// Should behave identically to original consumer
+		consumeInt(100)
+		capturedDirect := captured
+		consumeIdentity(100)
+		capturedMapped := captured
+
+		assert.Equal(t, capturedDirect, capturedMapped)
+	})
+
+	t.Run("contravariant composition law", func(t *testing.T) {
+		// contramap(f . g) = contramap(g) . contramap(f)
+		var captured int
+		consumeInt := func(x int) {
+			captured = x
+		}
+
+		f := func(s string) int {
+			n, _ := strconv.Atoi(s)
+			return n
+		}
+
+		g := func(b bool) string {
+			if b {
+				return "1"
+			}
+			return "0"
+		}
+
+		// Compose f and g manually
+		fg := func(b bool) int {
+			return f(g(b))
+		}
+
+		// Method 1: contramap(f . g)
+		consumer1 := Contramap(fg)(consumeInt)
+		consumer1(true)
+		result1 := captured
+
+		// Method 2: contramap(g) . contramap(f)
+		consumer2 := Contramap(g)(Contramap(f)(consumeInt))
+		consumer2(true)
+		result2 := captured
+
+		assert.Equal(t, result1, result2)
+		assert.Equal(t, 1, result1)
+	})
+
+	t.Run("type hierarchy adaptation", func(t *testing.T) {
+		type Animal struct {
+			Name string
+		}
+
+		type Dog struct {
+			Animal Animal
+			Breed  string
+		}
+
+		var capturedName string
+		consumeAnimal := func(a Animal) {
+			capturedName = a.Name
+		}
+
+		dogToAnimal := func(d Dog) Animal {
+			return d.Animal
+		}
+
+		consumeDog := Contramap(dogToAnimal)(consumeAnimal)
+		consumeDog(Dog{
+			Animal: Animal{Name: "Buddy"},
+			Breed:  "Golden Retriever",
+		})
+
+		assert.Equal(t, "Buddy", capturedName)
+	})
+
+	t.Run("field extraction with contramap", func(t *testing.T) {
+		type Message struct {
+			Text      string
+			Timestamp time.Time
+		}
+
+		var capturedText string
+		consumeString := func(s string) {
+			capturedText = s
+		}
+
+		extractText := func(m Message) string {
+			return m.Text
+		}
+
+		consumeMessage := Contramap(extractText)(consumeString)
+		consumeMessage(Message{
+			Text:      "Hello",
+			Timestamp: time.Now(),
+		})
+
+		assert.Equal(t, "Hello", capturedText)
+	})
+
+	t.Run("multiple contramap applications", func(t *testing.T) {
+		type Level3 struct{ Value int }
+		type Level2 struct{ L3 Level3 }
+		type Level1 struct{ L2 Level2 }
+
+		var captured int
+		consumeInt := func(x int) {
+			captured = x
+		}
+
+		extract3 := func(l3 Level3) int { return l3.Value }
+		extract2 := func(l2 Level2) Level3 { return l2.L3 }
+		extract1 := func(l1 Level1) Level2 { return l1.L2 }
+
+		// Chain contramap operations
+		consumeLevel3 := Contramap(extract3)(consumeInt)
+		consumeLevel2 := Contramap(extract2)(consumeLevel3)
+		consumeLevel1 := Contramap(extract1)(consumeLevel2)
+
+		consumeLevel1(Level1{L2: Level2{L3: Level3{Value: 42}}})
+
+		assert.Equal(t, 42, captured)
+	})
+
+	t.Run("contramap with calculation", func(t *testing.T) {
+		type Rectangle struct {
+			Width  int
+			Height int
+		}
+
+		var capturedArea int
+		consumeArea := func(area int) {
+			capturedArea = area
+		}
+
+		calculateArea := func(r Rectangle) int {
+			return r.Width * r.Height
+		}
+
+		consumeRectangle := Contramap(calculateArea)(consumeArea)
+		consumeRectangle(Rectangle{Width: 5, Height: 10})
+
+		assert.Equal(t, 50, capturedArea)
+	})
+
+	t.Run("contramap preserves side effects", func(t *testing.T) {
+		callCount := 0
+		consumer := func(x int) {
+			callCount++
+		}
+
+		transform := func(s string) int {
+			n, _ := strconv.Atoi(s)
+			return n
+		}
+
+		contramappedConsumer := Contramap(transform)(consumer)
+
+		contramappedConsumer("1")
+		contramappedConsumer("2")
+		contramappedConsumer("3")
+
+		assert.Equal(t, 3, callCount)
+	})
+
+	t.Run("contramap with pointer types", func(t *testing.T) {
+		var captured int
+		consumeInt := func(x int) {
+			captured = x
+		}
+
+		dereference := func(p *int) int {
+			if p == nil {
+				return 0
+			}
+			return *p
+		}
+
+		consumePointer := Contramap(dereference)(consumeInt)
+
+		value := 42
+		consumePointer(&value)
+		assert.Equal(t, 42, captured)
+
+		consumePointer(nil)
+		assert.Equal(t, 0, captured)
+	})
+
+	t.Run("contramap equivalence with Local", func(t *testing.T) {
+		var capturedLocal, capturedContramap int
+
+		consumeIntLocal := func(x int) {
+			capturedLocal = x
+		}
+
+		consumeIntContramap := func(x int) {
+			capturedContramap = x
+		}
+
+		transform := func(s string) int {
+			n, _ := strconv.Atoi(s)
+			return n
+		}
+
+		// Both should produce identical results
+		consumerLocal := Local(transform)(consumeIntLocal)
+		consumerContramap := Contramap(transform)(consumeIntContramap)
+
+		consumerLocal("42")
+		consumerContramap("42")
+
+		assert.Equal(t, capturedLocal, capturedContramap)
+		assert.Equal(t, 42, capturedLocal)
+	})
+}
+
+func TestCompose(t *testing.T) {
+	t.Run("basic composition", func(t *testing.T) {
+		var captured int
+		consumeInt := func(x int) {
+			captured = x
+		}
+
+		parseToInt := func(s string) int {
+			n, _ := strconv.Atoi(s)
+			return n
+		}
+
+		consumeString := Compose(parseToInt)(consumeInt)
+		consumeString("42")
+
+		assert.Equal(t, 42, captured)
+	})
+
+	t.Run("composing multiple transformations", func(t *testing.T) {
+		type Data struct {
+			Value string
+		}
+
+		type Wrapper struct {
+			Data Data
+		}
+
+		var captured string
+		consumeString := func(s string) {
+			captured = s
+		}
+
+		extractData := func(w Wrapper) Data { return w.Data }
+		extractValue := func(d Data) string { return d.Value }
+
+		// Compose step by step
+		consumeData := Compose(extractValue)(consumeString)
+		consumeWrapper := Compose(extractData)(consumeData)
+
+		consumeWrapper(Wrapper{Data: Data{Value: "Hello"}})
+
+		assert.Equal(t, "Hello", captured)
+	})
+
+	t.Run("function composition style", func(t *testing.T) {
+		type Request struct {
+			Body []byte
+		}
+
+		var captured string
+		processString := func(s string) {
+			captured = s
+		}
+
+		bytesToString := func(b []byte) string {
+			return string(b)
+		}
+
+		extractBody := func(r Request) []byte {
+			return r.Body
+		}
+
+		// Chain compositions
+		processBytes := Compose(bytesToString)(processString)
+		processRequest := Compose(extractBody)(processBytes)
+
+		processRequest(Request{Body: []byte("test")})
+
+		assert.Equal(t, "test", captured)
+	})
+
+	t.Run("compose with identity", func(t *testing.T) {
+		var captured int
+		consumeInt := func(x int) {
+			captured = x
+		}
+
+		identity := function.Identity[int]
+		composedConsumer := Compose(identity)(consumeInt)
+
+		composedConsumer(42)
+		assert.Equal(t, 42, captured)
+	})
+
+	t.Run("compose with field extraction", func(t *testing.T) {
+		type User struct {
+			Name  string
+			Email string
+			Age   int
+		}
+
+		var capturedName string
+		consumeName := func(name string) {
+			capturedName = name
+		}
+
+		extractName := func(u User) string {
+			return u.Name
+		}
+
+		consumeUser := Compose(extractName)(consumeName)
+		consumeUser(User{Name: "Alice", Email: "alice@example.com", Age: 30})
+
+		assert.Equal(t, "Alice", capturedName)
+	})
+
+	t.Run("compose with calculation", func(t *testing.T) {
+		type Circle struct {
+			Radius float64
+		}
+
+		var capturedArea float64
+		consumeArea := func(area float64) {
+			capturedArea = area
+		}
+
+		calculateArea := func(c Circle) float64 {
+			return 3.14159 * c.Radius * c.Radius
+		}
+
+		consumeCircle := Compose(calculateArea)(consumeArea)
+		consumeCircle(Circle{Radius: 5.0})
+
+		assert.InDelta(t, 78.53975, capturedArea, 0.00001)
+	})
+
+	t.Run("compose with slice operations", func(t *testing.T) {
+		var captured int
+		consumeLength := func(n int) {
+			captured = n
+		}
+
+		getLength := func(s []string) int {
+			return len(s)
+		}
+
+		consumeSlice := Compose(getLength)(consumeLength)
+		consumeSlice([]string{"a", "b", "c", "d"})
+
+		assert.Equal(t, 4, captured)
+	})
+
+	t.Run("compose with map operations", func(t *testing.T) {
+		var captured bool
+		consumeHasKey := func(has bool) {
+			captured = has
+		}
+
+		hasKey := func(m map[string]int) bool {
+			_, exists := m["key"]
+			return exists
+		}
+
+		consumeMap := Compose(hasKey)(consumeHasKey)
+
+		consumeMap(map[string]int{"key": 42})
+		assert.True(t, captured)
+
+		consumeMap(map[string]int{"other": 42})
+		assert.False(t, captured)
+	})
+
+	t.Run("compose preserves consumer behavior", func(t *testing.T) {
+		callCount := 0
+		consumer := func(x int) {
+			callCount++
+		}
+
+		transform := func(s string) int {
+			n, _ := strconv.Atoi(s)
+			return n
+		}
+
+		composedConsumer := Compose(transform)(consumer)
+
+		composedConsumer("1")
+		composedConsumer("2")
+		composedConsumer("3")
+
+		assert.Equal(t, 3, callCount)
+	})
+
+	t.Run("compose with error handling", func(t *testing.T) {
+		type Result struct {
+			Value int
+			Error error
+		}
+
+		var captured int
+		consumeInt := func(x int) {
+			captured = x
+		}
+
+		extractValue := func(r Result) int {
+			if r.Error != nil {
+				return -1
+			}
+			return r.Value
+		}
+
+		consumeResult := Compose(extractValue)(consumeInt)
+
+		consumeResult(Result{Value: 42, Error: nil})
+		assert.Equal(t, 42, captured)
+
+		consumeResult(Result{Value: 100, Error: assert.AnError})
+		assert.Equal(t, -1, captured)
+	})
+
+	t.Run("compose equivalence with Local", func(t *testing.T) {
+		var capturedLocal, capturedCompose int
+
+		consumeIntLocal := func(x int) {
+			capturedLocal = x
+		}
+
+		consumeIntCompose := func(x int) {
+			capturedCompose = x
+		}
+
+		transform := func(s string) int {
+			n, _ := strconv.Atoi(s)
+			return n
+		}
+
+		// Both should produce identical results
+		consumerLocal := Local(transform)(consumeIntLocal)
+		consumerCompose := Compose(transform)(consumeIntCompose)
+
+		consumerLocal("42")
+		consumerCompose("42")
+
+		assert.Equal(t, capturedLocal, capturedCompose)
+		assert.Equal(t, 42, capturedLocal)
+	})
+
+	t.Run("compose equivalence with Contramap", func(t *testing.T) {
+		var capturedCompose, capturedContramap int
+
+		consumeIntCompose := func(x int) {
+			capturedCompose = x
+		}
+
+		consumeIntContramap := func(x int) {
+			capturedContramap = x
+		}
+
+		transform := func(s string) int {
+			n, _ := strconv.Atoi(s)
+			return n
+		}
+
+		// All three should produce identical results
+		consumerCompose := Compose(transform)(consumeIntCompose)
+		consumerContramap := Contramap(transform)(consumeIntContramap)
+
+		consumerCompose("42")
+		consumerContramap("42")
+
+		assert.Equal(t, capturedCompose, capturedContramap)
+		assert.Equal(t, 42, capturedCompose)
+	})
+}

v2/context/ioresult/ioeither.go

@@ -44,7 +44,7 @@ import (
 //	    return result.Of("done")
 //	}
 //
-//	ctx, cancel := context.WithCancel(context.Background())
+//	ctx, cancel := context.WithCancel(t.Context())
 //	cancel() // Cancel immediately
 //
 //	wrapped := WithContext(ctx, computation)

v2/context/readerio/bracket.go

@@ -61,7 +61,7 @@ import (
 //
 //	// Safely read file with automatic cleanup
 //	safeRead := Bracket(acquireFile, readFile, closeFile)
-//	result := safeRead(context.Background())()
+//	result := safeRead(t.Context())()
 //
 //go:inline
 func Bracket[

v2/context/readerio/flip.go

@@ -50,7 +50,7 @@ import (
 //	// Sequence it to apply Config first
 //	sequenced := SequenceReader[Config, int](getMultiplier)
 //	cfg := Config{Timeout: 30}
-//	result := sequenced(cfg)(context.Background())() // Returns 60
+//	result := sequenced(cfg)(t.Context())() // Returns 60
 //
 //go:inline
 func SequenceReader[R, A any](ma ReaderIO[Reader[R, A]]) Reader[R, ReaderIO[A]] {
@@ -107,7 +107,7 @@ func SequenceReader[R, A any](ma ReaderIO[Reader[R, A]]) Reader[R, ReaderIO[A]]
 //
 //	// Provide Config to get final result
 //	cfg := Config{Multiplier: 5}
-//	finalResult := result(cfg)(context.Background())() // Returns 50
+//	finalResult := result(cfg)(t.Context())() // Returns 50
 //
 //go:inline
 func TraverseReader[R, A, B any](

v2/context/readerio/logging.go

@@ -81,7 +81,7 @@ func SLogWithCallback[A any](
 //	    Chain(SLog[string]("Extracted name")),
 //	)
 //
-//	result := pipeline(context.Background())()
+//	result := pipeline(t.Context())()
 //	// Logs: "Fetched user" value={ID:123 Name:"Alice"}
 //	// Logs: "Extracted name" value="Alice"
 //

v2/context/readerio/profunctor_test.go

@@ -45,7 +45,7 @@ func TestPromapBasic(t *testing.T) {
 		toString := strconv.Itoa
 
 		adapted := Promap(addKey, toString)(getValue)
-		result := adapted(context.Background())()
+		result := adapted(t.Context())()
 
 		assert.Equal(t, "42", result)
 	})
@@ -69,7 +69,7 @@ func TestContramapBasic(t *testing.T) {
 		}
 
 		adapted := Contramap[int](addKey)(getValue)
-		result := adapted(context.Background())()
+		result := adapted(t.Context())()
 
 		assert.Equal(t, 100, result)
 	})
@@ -90,7 +90,7 @@ func TestLocalBasic(t *testing.T) {
 		}
 
 		adapted := Local[bool](addTimeout)(getValue)
-		result := adapted(context.Background())()
+		result := adapted(t.Context())()
 
 		assert.True(t, result)
 	})

v2/context/readerio/reader.go

@@ -560,6 +560,63 @@ func Read[A any](r context.Context) func(ReaderIO[A]) IO[A] {
 	return RIO.Read[A](r)
 }
 
+// ReadIO executes a ReaderIO computation by providing a context wrapped in an IO effect.
+// This is useful when the context itself needs to be computed or retrieved through side effects.
+//
+// The function takes an IO[context.Context] (an effectful computation that produces a context) and returns
+// a function that can execute a ReaderIO[A] to produce an IO[A].
+//
+// This is particularly useful in scenarios where:
+//   - The context needs to be created with side effects (e.g., loading configuration)
+//   - The context requires initialization or setup
+//   - You want to compose context creation with the computation that uses it
+//
+// The execution flow is:
+//  1. Execute the IO[context.Context] to get the context
+//  2. Pass the context to the ReaderIO[A] to get an IO[A]
+//  3. Execute the resulting IO[A] to get the final result A
+//
+// Type Parameters:
+//   - A: The result type of the ReaderIO computation
+//
+// Parameters:
+//   - r: An IO effect that produces a context.Context
+//
+// Returns:
+//   - A function that takes a ReaderIO[A] and returns an IO[A]
+//
+// Example:
+//
+//	import (
+//	    "context"
+//	    G "github.com/IBM/fp-go/v2/io"
+//	    F "github.com/IBM/fp-go/v2/function"
+//	)
+//
+//	// Create context with side effects (e.g., loading config)
+//	createContext := G.Of(context.WithValue(t.Context(), "key", "value"))
+//
+//	// A computation that uses the context
+//	getValue := readerio.FromReader(func(ctx context.Context) string {
+//	    if val := ctx.Value("key"); val != nil {
+//	        return val.(string)
+//	    }
+//	    return "default"
+//	})
+//
+//	// Compose them together
+//	result := readerio.ReadIO[string](createContext)(getValue)
+//	value := result() // Executes both effects and returns "value"
+//
+// Comparison with Read:
+//   - [Read]: Takes a pure context.Context value and executes the ReaderIO immediately
+//   - [ReadIO]: Takes an IO[context.Context] and chains the effects together
+//
+//go:inline
+func ReadIO[A any](r IO[context.Context]) func(ReaderIO[A]) IO[A] {
+	return RIO.ReadIO[A](r)
+}
+
 // Local transforms the context.Context environment before passing it to a ReaderIO computation.
 //
 // This is the Reader's local operation, which allows you to modify the environment
@@ -607,7 +664,7 @@ func Read[A any](r context.Context) func(ReaderIO[A]) IO[A] {
 //	    getUser,
 //	    addUser,
 //	)
-//	user := result(context.Background())()  // Returns "Alice"
+//	user := result(t.Context())()  // Returns "Alice"
 //
 // Timeout Example:
 //
@@ -674,7 +731,7 @@ func Local[A any](f func(context.Context) (context.Context, context.CancelFunc))
 //	    fetchData,
 //	    readerio.WithTimeout[Data](5*time.Second),
 //	)
-//	data := result(context.Background())()  // Returns Data{} after 5s timeout
+//	data := result(t.Context())()  // Returns Data{} after 5s timeout
 //
 // Successful Example:
 //
@@ -683,7 +740,7 @@ func Local[A any](f func(context.Context) (context.Context, context.CancelFunc))
 //	    quickFetch,
 //	    readerio.WithTimeout[Data](5*time.Second),
 //	)
-//	data := result(context.Background())()  // Returns Data{Value: "quick"}
+//	data := result(t.Context())()  // Returns Data{Value: "quick"}
 func WithTimeout[A any](timeout time.Duration) Operator[A, A] {
 	return Local[A](func(ctx context.Context) (context.Context, context.CancelFunc) {
 		return context.WithTimeout(ctx, timeout)
@@ -734,12 +791,12 @@ func WithTimeout[A any](timeout time.Duration) Operator[A, A] {
 //	    fetchData,
 //	    readerio.WithDeadline[Data](deadline),
 //	)
-//	data := result(context.Background())()  // Returns Data{} if past deadline
+//	data := result(t.Context())()  // Returns Data{} if past deadline
 //
 // Combining with Parent Context:
 //
 //	// If parent context already has a deadline, the earlier one takes precedence
-//	parentCtx, cancel := context.WithDeadline(context.Background(), time.Now().Add(1*time.Hour))
+//	parentCtx, cancel := context.WithDeadline(t.Context(), time.Now().Add(1*time.Hour))
 //	defer cancel()
 //
 //	laterDeadline := time.Now().Add(2 * time.Hour)

v2/context/readerio/reader_test.go

@@ -31,7 +31,7 @@ func TestMonadMap(t *testing.T) {
 	rio := Of(5)
 	doubled := MonadMap(rio, N.Mul(2))
 
-	result := doubled(context.Background())()
+	result := doubled(t.Context())()
 	assert.Equal(t, 10, result)
 }
 
@@ -41,14 +41,14 @@ func TestMap(t *testing.T) {
 		Map(utils.Double),
 	)
 
-	assert.Equal(t, 2, g(context.Background())())
+	assert.Equal(t, 2, g(t.Context())())
 }
 
 func TestMonadMapTo(t *testing.T) {
 	rio := Of(42)
 	replaced := MonadMapTo(rio, "constant")
 
-	result := replaced(context.Background())()
+	result := replaced(t.Context())()
 	assert.Equal(t, "constant", result)
 }
 
@@ -58,7 +58,7 @@ func TestMapTo(t *testing.T) {
 		MapTo[int]("constant"),
 	)
 
-	assert.Equal(t, "constant", result(context.Background())())
+	assert.Equal(t, "constant", result(t.Context())())
 }
 
 func TestMonadChain(t *testing.T) {
@@ -67,7 +67,7 @@ func TestMonadChain(t *testing.T) {
 		return Of(n * 3)
 	})
 
-	assert.Equal(t, 15, result(context.Background())())
+	assert.Equal(t, 15, result(t.Context())())
 }
 
 func TestChain(t *testing.T) {
@@ -78,7 +78,7 @@ func TestChain(t *testing.T) {
 		}),
 	)
 
-	assert.Equal(t, 15, result(context.Background())())
+	assert.Equal(t, 15, result(t.Context())())
 }
 
 func TestMonadChainFirst(t *testing.T) {
@@ -89,7 +89,7 @@ func TestMonadChainFirst(t *testing.T) {
 		return Of("side effect")
 	})
 
-	value := result(context.Background())()
+	value := result(t.Context())()
 	assert.Equal(t, 42, value)
 	assert.Equal(t, 42, sideEffect)
 }
@@ -104,7 +104,7 @@ func TestChainFirst(t *testing.T) {
 		}),
 	)
 
-	value := result(context.Background())()
+	value := result(t.Context())()
 	assert.Equal(t, 42, value)
 	assert.Equal(t, 42, sideEffect)
 }
@@ -117,7 +117,7 @@ func TestMonadTap(t *testing.T) {
 		return Of(func() {})
 	})
 
-	value := result(context.Background())()
+	value := result(t.Context())()
 	assert.Equal(t, 42, value)
 	assert.Equal(t, 42, sideEffect)
 }
@@ -132,14 +132,14 @@ func TestTap(t *testing.T) {
 		}),
 	)
 
-	value := result(context.Background())()
+	value := result(t.Context())()
 	assert.Equal(t, 42, value)
 	assert.Equal(t, 42, sideEffect)
 }
 
 func TestOf(t *testing.T) {
 	rio := Of(100)
-	result := rio(context.Background())()
+	result := rio(t.Context())()
 
 	assert.Equal(t, 100, result)
 }
@@ -149,7 +149,7 @@ func TestMonadAp(t *testing.T) {
 	faIO := Of(5)
 	result := MonadAp(fabIO, faIO)
 
-	assert.Equal(t, 10, result(context.Background())())
+	assert.Equal(t, 10, result(t.Context())())
 }
 
 func TestAp(t *testing.T) {
@@ -158,7 +158,7 @@ func TestAp(t *testing.T) {
 		Ap[int](Of(1)),
 	)
 
-	assert.Equal(t, 2, g(context.Background())())
+	assert.Equal(t, 2, g(t.Context())())
 }
 
 func TestMonadApSeq(t *testing.T) {
@@ -166,7 +166,7 @@ func TestMonadApSeq(t *testing.T) {
 	faIO := Of(5)
 	result := MonadApSeq(fabIO, faIO)
 
-	assert.Equal(t, 15, result(context.Background())())
+	assert.Equal(t, 15, result(t.Context())())
 }
 
 func TestApSeq(t *testing.T) {
@@ -175,7 +175,7 @@ func TestApSeq(t *testing.T) {
 		ApSeq[int](Of(5)),
 	)
 
-	assert.Equal(t, 15, g(context.Background())())
+	assert.Equal(t, 15, g(t.Context())())
 }
 
 func TestMonadApPar(t *testing.T) {
@@ -183,7 +183,7 @@ func TestMonadApPar(t *testing.T) {
 	faIO := Of(5)
 	result := MonadApPar(fabIO, faIO)
 
-	assert.Equal(t, 15, result(context.Background())())
+	assert.Equal(t, 15, result(t.Context())())
 }
 
 func TestApPar(t *testing.T) {
@@ -192,12 +192,12 @@ func TestApPar(t *testing.T) {
 		ApPar[int](Of(5)),
 	)
 
-	assert.Equal(t, 15, g(context.Background())())
+	assert.Equal(t, 15, g(t.Context())())
 }
 
 func TestAsk(t *testing.T) {
 	rio := Ask()
-	ctx := context.WithValue(context.Background(), "key", "value")
+	ctx := context.WithValue(t.Context(), "key", "value")
 	result := rio(ctx)()
 
 	assert.Equal(t, ctx, result)
@@ -207,7 +207,7 @@ func TestFromIO(t *testing.T) {
 	ioAction := G.Of(42)
 	rio := FromIO(ioAction)
 
-	result := rio(context.Background())()
+	result := rio(t.Context())()
 	assert.Equal(t, 42, result)
 }
 
@@ -217,7 +217,7 @@ func TestFromReader(t *testing.T) {
 	}
 
 	rio := FromReader(rdr)
-	result := rio(context.Background())()
+	result := rio(t.Context())()
 
 	assert.Equal(t, 42, result)
 }
@@ -226,7 +226,7 @@ func TestFromLazy(t *testing.T) {
 	lazy := func() int { return 42 }
 	rio := FromLazy(lazy)
 
-	result := rio(context.Background())()
+	result := rio(t.Context())()
 	assert.Equal(t, 42, result)
 }
 
@@ -236,7 +236,7 @@ func TestMonadChainIOK(t *testing.T) {
 		return G.Of(n * 4)
 	})
 
-	assert.Equal(t, 20, result(context.Background())())
+	assert.Equal(t, 20, result(t.Context())())
 }
 
 func TestChainIOK(t *testing.T) {
@@ -247,7 +247,7 @@ func TestChainIOK(t *testing.T) {
 		}),
 	)
 
-	assert.Equal(t, 20, result(context.Background())())
+	assert.Equal(t, 20, result(t.Context())())
 }
 
 func TestMonadChainFirstIOK(t *testing.T) {
@@ -258,7 +258,7 @@ func TestMonadChainFirstIOK(t *testing.T) {
 		return G.Of("side effect")
 	})
 
-	value := result(context.Background())()
+	value := result(t.Context())()
 	assert.Equal(t, 42, value)
 	assert.Equal(t, 42, sideEffect)
 }
@@ -273,7 +273,7 @@ func TestChainFirstIOK(t *testing.T) {
 		}),
 	)
 
-	value := result(context.Background())()
+	value := result(t.Context())()
 	assert.Equal(t, 42, value)
 	assert.Equal(t, 42, sideEffect)
 }
@@ -286,7 +286,7 @@ func TestMonadTapIOK(t *testing.T) {
 		return G.Of(func() {})
 	})
 
-	value := result(context.Background())()
+	value := result(t.Context())()
 	assert.Equal(t, 42, value)
 	assert.Equal(t, 42, sideEffect)
 }
@@ -301,7 +301,7 @@ func TestTapIOK(t *testing.T) {
 		}),
 	)
 
-	value := result(context.Background())()
+	value := result(t.Context())()
 	assert.Equal(t, 42, value)
 	assert.Equal(t, 42, sideEffect)
 }
@@ -313,8 +313,8 @@ func TestDefer(t *testing.T) {
 		return Of(counter)
 	})
 
-	result1 := rio(context.Background())()
-	result2 := rio(context.Background())()
+	result1 := rio(t.Context())()
+	result2 := rio(t.Context())()
 
 	assert.Equal(t, 1, result1)
 	assert.Equal(t, 2, result2)
@@ -328,8 +328,8 @@ func TestMemoize(t *testing.T) {
 		return counter
 	}))
 
-	result1 := memoized(context.Background())()
-	result2 := memoized(context.Background())()
+	result1 := memoized(t.Context())()
+	result2 := memoized(t.Context())()
 
 	assert.Equal(t, 1, result1)
 	assert.Equal(t, 1, result2) // Same value, memoized
@@ -339,7 +339,7 @@ func TestFlatten(t *testing.T) {
 	nested := Of(Of(42))
 	flattened := Flatten(nested)
 
-	result := flattened(context.Background())()
+	result := flattened(t.Context())()
 	assert.Equal(t, 42, result)
 }
 
@@ -347,7 +347,7 @@ func TestMonadFlap(t *testing.T) {
 	fabIO := Of(N.Mul(3))
 	result := MonadFlap(fabIO, 7)
 
-	assert.Equal(t, 21, result(context.Background())())
+	assert.Equal(t, 21, result(t.Context())())
 }
 
 func TestFlap(t *testing.T) {
@@ -356,7 +356,7 @@ func TestFlap(t *testing.T) {
 		Flap[int](7),
 	)
 
-	assert.Equal(t, 21, result(context.Background())())
+	assert.Equal(t, 21, result(t.Context())())
 }
 
 func TestMonadChainReaderK(t *testing.T) {
@@ -365,7 +365,7 @@ func TestMonadChainReaderK(t *testing.T) {
 		return func(ctx context.Context) int { return n * 2 }
 	})
 
-	assert.Equal(t, 10, result(context.Background())())
+	assert.Equal(t, 10, result(t.Context())())
 }
 
 func TestChainReaderK(t *testing.T) {
@@ -376,7 +376,7 @@ func TestChainReaderK(t *testing.T) {
 		}),
 	)
 
-	assert.Equal(t, 10, result(context.Background())())
+	assert.Equal(t, 10, result(t.Context())())
 }
 
 func TestMonadChainFirstReaderK(t *testing.T) {
@@ -389,7 +389,7 @@ func TestMonadChainFirstReaderK(t *testing.T) {
 		}
 	})
 
-	value := result(context.Background())()
+	value := result(t.Context())()
 	assert.Equal(t, 42, value)
 	assert.Equal(t, 42, sideEffect)
 }
@@ -406,7 +406,7 @@ func TestChainFirstReaderK(t *testing.T) {
 		}),
 	)
 
-	value := result(context.Background())()
+	value := result(t.Context())()
 	assert.Equal(t, 42, value)
 	assert.Equal(t, 42, sideEffect)
 }
@@ -421,7 +421,7 @@ func TestMonadTapReaderK(t *testing.T) {
 		}
 	})
 
-	value := result(context.Background())()
+	value := result(t.Context())()
 	assert.Equal(t, 42, value)
 	assert.Equal(t, 42, sideEffect)
 }
@@ -438,14 +438,14 @@ func TestTapReaderK(t *testing.T) {
 		}),
 	)
 
-	value := result(context.Background())()
+	value := result(t.Context())()
 	assert.Equal(t, 42, value)
 	assert.Equal(t, 42, sideEffect)
 }
 
 func TestRead(t *testing.T) {
 	rio := Of(42)
-	ctx := context.Background()
+	ctx := t.Context()
 	ioAction := Read[int](ctx)(rio)
 	result := ioAction()
 
@@ -463,7 +463,7 @@ func TestComplexPipeline(t *testing.T) {
 		Map(N.Add(10)),
 	)
 
-	assert.Equal(t, 20, result(context.Background())()) // (5 * 2) + 10 = 20
+	assert.Equal(t, 20, result(t.Context())()) // (5 * 2) + 10 = 20
 }
 
 func TestFromIOWithChain(t *testing.T) {
@@ -476,7 +476,7 @@ func TestFromIOWithChain(t *testing.T) {
 		}),
 	)
 
-	assert.Equal(t, 15, result(context.Background())())
+	assert.Equal(t, 15, result(t.Context())())
 }
 
 func TestTapWithLogging(t *testing.T) {
@@ -496,7 +496,192 @@ func TestTapWithLogging(t *testing.T) {
 		}),
 	)
 
-	value := result(context.Background())()
+	value := result(t.Context())()
 	assert.Equal(t, 84, value)
 	assert.Equal(t, []int{42, 84}, logged)
 }
+
+func TestReadIO(t *testing.T) {
+	// Test basic ReadIO functionality
+	contextIO := G.Of(context.WithValue(t.Context(), "testKey", "testValue"))
+	rio := FromReader(func(ctx context.Context) string {
+		if val := ctx.Value("testKey"); val != nil {
+			return val.(string)
+		}
+		return "default"
+	})
+
+	ioAction := ReadIO[string](contextIO)(rio)
+	result := ioAction()
+
+	assert.Equal(t, "testValue", result)
+}
+
+func TestReadIOWithBackground(t *testing.T) {
+	// Test ReadIO with plain background context
+	contextIO := G.Of(t.Context())
+	rio := Of(42)
+
+	ioAction := ReadIO[int](contextIO)(rio)
+	result := ioAction()
+
+	assert.Equal(t, 42, result)
+}
+
+func TestReadIOWithChain(t *testing.T) {
+	// Test ReadIO with chained operations
+	contextIO := G.Of(context.WithValue(t.Context(), "multiplier", 3))
+
+	result := F.Pipe1(
+		FromReader(func(ctx context.Context) int {
+			if val := ctx.Value("multiplier"); val != nil {
+				return val.(int)
+			}
+			return 1
+		}),
+		Chain(func(n int) ReaderIO[int] {
+			return Of(n * 10)
+		}),
+	)
+
+	ioAction := ReadIO[int](contextIO)(result)
+	value := ioAction()
+
+	assert.Equal(t, 30, value) // 3 * 10
+}
+
+func TestReadIOWithMap(t *testing.T) {
+	// Test ReadIO with Map operations
+	contextIO := G.Of(t.Context())
+
+	result := F.Pipe2(
+		Of(5),
+		Map(N.Mul(2)),
+		Map(N.Add(10)),
+	)
+
+	ioAction := ReadIO[int](contextIO)(result)
+	value := ioAction()
+
+	assert.Equal(t, 20, value) // (5 * 2) + 10
+}
+
+func TestReadIOWithSideEffects(t *testing.T) {
+	// Test ReadIO with side effects in context creation
+	counter := 0
+	contextIO := func() context.Context {
+		counter++
+		return context.WithValue(t.Context(), "counter", counter)
+	}
+
+	rio := FromReader(func(ctx context.Context) int {
+		if val := ctx.Value("counter"); val != nil {
+			return val.(int)
+		}
+		return 0
+	})
+
+	ioAction := ReadIO[int](contextIO)(rio)
+	result := ioAction()
+
+	assert.Equal(t, 1, result)
+	assert.Equal(t, 1, counter)
+}
+
+func TestReadIOMultipleExecutions(t *testing.T) {
+	// Test that ReadIO creates fresh effects on each execution
+	counter := 0
+	contextIO := func() context.Context {
+		counter++
+		return t.Context()
+	}
+
+	rio := Of(42)
+	ioAction := ReadIO[int](contextIO)(rio)
+
+	result1 := ioAction()
+	result2 := ioAction()
+
+	assert.Equal(t, 42, result1)
+	assert.Equal(t, 42, result2)
+	assert.Equal(t, 2, counter) // Context IO executed twice
+}
+
+func TestReadIOComparisonWithRead(t *testing.T) {
+	// Compare ReadIO with Read to show the difference
+	ctx := context.WithValue(t.Context(), "key", "value")
+
+	rio := FromReader(func(ctx context.Context) string {
+		if val := ctx.Value("key"); val != nil {
+			return val.(string)
+		}
+		return "default"
+	})
+
+	// Using Read (direct context)
+	ioAction1 := Read[string](ctx)(rio)
+	result1 := ioAction1()
+
+	// Using ReadIO (context wrapped in IO)
+	contextIO := G.Of(ctx)
+	ioAction2 := ReadIO[string](contextIO)(rio)
+	result2 := ioAction2()
+
+	assert.Equal(t, result1, result2)
+	assert.Equal(t, "value", result1)
+	assert.Equal(t, "value", result2)
+}
+
+func TestReadIOWithComplexContext(t *testing.T) {
+	// Test ReadIO with complex context manipulation
+	type contextKey string
+	const (
+		userKey  contextKey = "user"
+		tokenKey contextKey = "token"
+	)
+
+	contextIO := G.Of(
+		context.WithValue(
+			context.WithValue(t.Context(), userKey, "Alice"),
+			tokenKey,
+			"secret123",
+		),
+	)
+
+	rio := FromReader(func(ctx context.Context) map[string]string {
+		result := make(map[string]string)
+		if user := ctx.Value(userKey); user != nil {
+			result["user"] = user.(string)
+		}
+		if token := ctx.Value(tokenKey); token != nil {
+			result["token"] = token.(string)
+		}
+		return result
+	})
+
+	ioAction := ReadIO[map[string]string](contextIO)(rio)
+	result := ioAction()
+
+	assert.Equal(t, "Alice", result["user"])
+	assert.Equal(t, "secret123", result["token"])
+}
+
+func TestReadIOWithAsk(t *testing.T) {
+	// Test ReadIO combined with Ask
+	contextIO := G.Of(context.WithValue(t.Context(), "data", 100))
+
+	result := F.Pipe1(
+		Ask(),
+		Map(func(ctx context.Context) int {
+			if val := ctx.Value("data"); val != nil {
+				return val.(int)
+			}
+			return 0
+		}),
+	)
+
+	ioAction := ReadIO[int](contextIO)(result)
+	value := ioAction()
+
+	assert.Equal(t, 100, value)
+}

v2/context/readerio/rec.go

@@ -53,7 +53,7 @@ import (
 //	}
 //
 //	countdown := TailRec(countdownStep)
-//	result := countdown(10)(context.Background())() // Returns "Done!"
+//	result := countdown(10)(t.Context())() // Returns "Done!"
 //
 // Example - Sum with context:
 //
@@ -77,7 +77,7 @@ import (
 //	}
 //
 //	sum := TailRec(sumStep)
-//	result := sum(SumState{numbers: []int{1, 2, 3, 4, 5}})(context.Background())()
+//	result := sum(SumState{numbers: []int{1, 2, 3, 4, 5}})(t.Context())()
 //	// Returns 15, safe even for very large slices
 //
 //go:inline

v2/context/readerio/retry.go

@@ -80,7 +80,7 @@ import (
 //	retryingFetch := Retrying(policy, fetchData, shouldRetry)
 //
 //	// Execute
-//	ctx := context.Background()
+//	ctx := t.Context()
 //	result := retryingFetch(ctx)() // Returns "success" after 3 attempts
 //
 //go:inline

v2/context/readerioresult/FLIP_POINTFREE.md

@@ -56,7 +56,7 @@ This creates several problems:
 
 ```go
 computation := getComputation()
-ctx := context.Background()
+ctx := t.Context()
 cfg := Config{Value: 42}
 
 // Must apply in this specific order
@@ -176,7 +176,7 @@ db := Database{ConnectionString: "localhost:5432"}
 query := queryWithDB(db)  // ✅ Database injected
 
 // Use query with any context
-result := query(context.Background())()
+result := query(t.Context())()
 ```
 
 ### 3. Point-Free Composition
@@ -289,7 +289,7 @@ withConfig := traversed(getValue)
 
 // Now we can provide Config to get the final result
 cfg := Config{Multiplier: 5, Prefix: "Result"}
-ctx := context.Background()
+ctx := t.Context()
 result := withConfig(cfg)(ctx)() // Returns Right("Result: 50")
 ```
 

v2/context/readerioresult/cancel.go

@@ -74,7 +74,7 @@ func WithContext[A any](ma ReaderIOResult[A]) ReaderIOResult[A] {
 //	safeFetch := WithContextK(fetchUser)
 //
 //	// If context is cancelled, returns immediately without executing fetchUser
-//	ctx, cancel := context.WithCancel(context.Background())
+//	ctx, cancel := context.WithCancel(t.Context())
 //	cancel() // Cancel immediately
 //	result := safeFetch(123)(ctx)() // Returns context.Canceled error
 //

v2/context/readerioresult/circuitbreaker_doc.md

@@ -187,7 +187,7 @@ func main() {
     result := cb(env)
     
     // Execute the protected operation
-    ctx := context.Background()
+    ctx := t.Context()
     protectedOp := pair.Tail(result)
     outcome := protectedOp(ctx)()
 }

v2/context/readerioresult/doc.go

@@ -113,7 +113,7 @@
 //	}
 //
 //	// Execute the computation
-//	ctx := context.Background()
+//	ctx := t.Context()
 //	result := fetchUser("123")(ctx)()
 //	// result is Either[error, User]
 //
@@ -161,7 +161,7 @@
 // All operations respect context cancellation. When a context is cancelled, operations
 // will return an error containing the cancellation cause:
 //
-//	ctx, cancel := context.WithCancelCause(context.Background())
+//	ctx, cancel := context.WithCancelCause(t.Context())
 //	cancel(errors.New("operation cancelled"))
 //	result := computation(ctx)() // Returns Left with cancellation error
 //

v2/context/readerioresult/eq.go

@@ -37,7 +37,7 @@ import (
 //	    return either.Eq(eq.FromEquals(func(x, y int) bool { return x == y }))(a, b)
 //	})
 //	eqRIE := Eq(eqInt)
-//	ctx := context.Background()
+//	ctx := t.Context()
 //	equal := eqRIE(ctx).Equals(Right[int](42), Right[int](42)) // true
 //
 //go:inline

v2/context/readerioresult/file/tempfile_test.go

@@ -16,7 +16,6 @@
 package file
 
 import (
-	"context"
 	"os"
 	"testing"
 
@@ -30,7 +29,7 @@ func TestWithTempFile(t *testing.T) {
 
 	res := WithTempFile(onWriteAll[*os.File]([]byte("Carsten")))
 
-	assert.Equal(t, E.Of[error]([]byte("Carsten")), res(context.Background())())
+	assert.Equal(t, E.Of[error]([]byte("Carsten")), res(t.Context())())
 }
 
 func TestWithTempFileOnClosedFile(t *testing.T) {
@@ -43,5 +42,5 @@ func TestWithTempFileOnClosedFile(t *testing.T) {
 		)
 	})
 
-	assert.Equal(t, E.Of[error]([]byte("Carsten")), res(context.Background())())
+	assert.Equal(t, E.Of[error]([]byte("Carsten")), res(t.Context())())
 }

v2/context/readerioresult/filter.go

@@ -43,7 +43,7 @@ import (
 //	onNegative := func(n int) error { return fmt.Errorf("%d is not positive", n) }
 //
 //	filter := readerioresult.FilterOrElse(isPositive, onNegative)
-//	result := filter(readerioresult.Right(42))(context.Background())()
+//	result := filter(readerioresult.Right(42))(t.Context())()
 //
 //go:inline
 func FilterOrElse[A any](pred Predicate[A], onFalse func(A) error) Operator[A, A] {

v2/context/readerioresult/flip.go

@@ -71,7 +71,7 @@ import (
 //
 //	// Now we can partially apply the Config
 //	cfg := Config{Timeout: 30}
-//	ctx := context.Background()
+//	ctx := t.Context()
 //	result := sequenced(ctx)(cfg)() // Returns Right(60)
 //
 // This is especially useful in point-free style when building computation pipelines:
@@ -133,7 +133,7 @@ func SequenceReader[R, A any](ma ReaderIOResult[Reader[R, A]]) Kleisli[R, A] {
 //
 //	// Partially apply the Database
 //	db := Database{ConnectionString: "localhost:5432"}
-//	ctx := context.Background()
+//	ctx := t.Context()
 //	result := sequenced(ctx)(db)() // Executes IO and returns Right("Query result...")
 //
 // In point-free style, this enables clean composition:
@@ -195,7 +195,7 @@ func SequenceReaderIO[R, A any](ma ReaderIOResult[RIO.ReaderIO[R, A]]) Kleisli[R
 //
 //	// Partially apply the Config
 //	cfg := Config{MaxRetries: 3}
-//	ctx := context.Background()
+//	ctx := t.Context()
 //	result := sequenced(ctx)(cfg)() // Returns Right(3)
 //
 //	// With invalid config
@@ -276,7 +276,7 @@ func SequenceReaderResult[R, A any](ma ReaderIOResult[RR.ReaderResult[R, A]]) Kl
 //
 //	// Now we can provide the Config to get the final result
 //	cfg := Config{Multiplier: 5}
-//	ctx := context.Background()
+//	ctx := t.Context()
 //	finalResult := result(cfg)(ctx)() // Returns Right(50)
 //
 // In point-free style, this enables clean composition:

v2/context/readerioresult/flip_example_test.go

@@ -22,6 +22,7 @@ import (
 	RIOE "github.com/IBM/fp-go/v2/context/readerioresult"
 	"github.com/IBM/fp-go/v2/either"
 	F "github.com/IBM/fp-go/v2/function"
+	N "github.com/IBM/fp-go/v2/number"
 )
 
 // Example_sequenceReader_basicUsage demonstrates the basic usage of SequenceReader
@@ -233,7 +234,7 @@ func Example_sequenceReaderResult_errorHandling() {
 	ctx := context.Background()
 	pipeline := F.Pipe2(
 		sequenced(ctx),
-		RIOE.Map(func(x int) int { return x * 2 }),
+		RIOE.Map(N.Mul(2)),
 		RIOE.Chain(func(x int) RIOE.ReaderIOResult[string] {
 			return RIOE.Of(fmt.Sprintf("Result: %d", x))
 		}),

v2/context/readerioresult/flip_test.go

@@ -41,7 +41,7 @@ func TestSequenceReader(t *testing.T) {
 		// The Reader environment (string) is now the first parameter
 		sequenced := SequenceReader(original)
 
-		ctx := context.Background()
+		ctx := t.Context()
 
 		// Test original
 		result1 := original(ctx)()
@@ -75,7 +75,7 @@ func TestSequenceReader(t *testing.T) {
 		}
 
 		db := Database{ConnectionString: "localhost:5432"}
-		ctx := context.Background()
+		ctx := t.Context()
 
 		expected := "Query on localhost:5432"
 
@@ -106,7 +106,7 @@ func TestSequenceReader(t *testing.T) {
 			}
 		}
 
-		ctx := context.Background()
+		ctx := t.Context()
 
 		// Test original with error
 		result1 := original(ctx)()
@@ -132,7 +132,7 @@ func TestSequenceReader(t *testing.T) {
 			}
 		}
 
-		ctx := context.Background()
+		ctx := t.Context()
 
 		// Sequence
 		sequenced := SequenceReader(original)
@@ -158,7 +158,7 @@ func TestSequenceReader(t *testing.T) {
 			}
 		}
 
-		ctx := context.Background()
+		ctx := t.Context()
 		sequenced := SequenceReader(original)
 
 		// Test with zero values
@@ -184,7 +184,7 @@ func TestSequenceReader(t *testing.T) {
 			}
 		}
 
-		ctx, cancel := context.WithCancel(context.Background())
+		ctx, cancel := context.WithCancel(t.Context())
 		cancel()
 
 		sequenced := SequenceReader(original)
@@ -217,14 +217,14 @@ func TestSequenceReader(t *testing.T) {
 		withConfig := sequenced(cfg)
 
 		// Now we have a ReaderIOResult[int] that can be used in different contexts
-		ctx1 := context.Background()
+		ctx1 := t.Context()
 		result1 := withConfig(ctx1)()
 		assert.True(t, either.IsRight(result1))
 		value1, _ := either.Unwrap(result1)
 		assert.Equal(t, 50, value1)
 
 		// Can reuse with different context
-		ctx2 := context.Background()
+		ctx2 := t.Context()
 		result2 := withConfig(ctx2)()
 		assert.True(t, either.IsRight(result2))
 		value2, _ := either.Unwrap(result2)
@@ -246,7 +246,7 @@ func TestSequenceReaderIO(t *testing.T) {
 			}
 		}
 
-		ctx := context.Background()
+		ctx := t.Context()
 		sequenced := SequenceReaderIO(original)
 
 		// Test original
@@ -273,7 +273,7 @@ func TestSequenceReaderIO(t *testing.T) {
 			}
 		}
 
-		ctx := context.Background()
+		ctx := t.Context()
 
 		// Test original with error
 		result1 := original(ctx)()
@@ -303,7 +303,7 @@ func TestSequenceReaderIO(t *testing.T) {
 			}
 		}
 
-		ctx, cancel := context.WithCancel(context.Background())
+		ctx, cancel := context.WithCancel(t.Context())
 		cancel()
 
 		sequenced := SequenceReaderIO(original)
@@ -327,7 +327,7 @@ func TestSequenceReaderResult(t *testing.T) {
 			}
 		}
 
-		ctx := context.Background()
+		ctx := t.Context()
 		sequenced := SequenceReaderResult(original)
 
 		// Test original
@@ -356,7 +356,7 @@ func TestSequenceReaderResult(t *testing.T) {
 			}
 		}
 
-		ctx := context.Background()
+		ctx := t.Context()
 
 		// Test original with error
 		result1 := original(ctx)()
@@ -384,7 +384,7 @@ func TestSequenceReaderResult(t *testing.T) {
 			}
 		}
 
-		ctx := context.Background()
+		ctx := t.Context()
 
 		// Test original with inner error
 		result1 := original(ctx)()
@@ -421,7 +421,7 @@ func TestSequenceReaderResult(t *testing.T) {
 			}
 		}
 
-		ctx := context.Background()
+		ctx := t.Context()
 
 		// Test outer error
 		sequenced1 := SequenceReaderResult(makeOriginal(-20))
@@ -460,7 +460,7 @@ func TestSequenceReaderResult(t *testing.T) {
 			}
 		}
 
-		ctx, cancel := context.WithCancel(context.Background())
+		ctx, cancel := context.WithCancel(t.Context())
 		cancel()
 
 		sequenced := SequenceReaderResult(original)
@@ -484,7 +484,7 @@ func TestSequenceEdgeCases(t *testing.T) {
 			}
 		}
 
-		ctx := context.Background()
+		ctx := t.Context()
 		empty := Empty{}
 		sequenced := SequenceReader(original)
 
@@ -514,7 +514,7 @@ func TestSequenceEdgeCases(t *testing.T) {
 			}
 		}
 
-		ctx := context.Background()
+		ctx := t.Context()
 		data := &Data{Value: 100}
 		sequenced := SequenceReader(original)
 
@@ -544,7 +544,7 @@ func TestSequenceEdgeCases(t *testing.T) {
 			}
 		}
 
-		ctx := context.Background()
+		ctx := t.Context()
 		sequenced := SequenceReader(original)
 
 		// Call multiple times with same inputs
@@ -583,7 +583,7 @@ func TestTraverseReader(t *testing.T) {
 
 		// Provide Config and execute
 		cfg := Config{Multiplier: 5}
-		ctx := context.Background()
+		ctx := t.Context()
 		finalResult := result(cfg)(ctx)()
 
 		assert.True(t, either.IsRight(finalResult))
@@ -614,7 +614,7 @@ func TestTraverseReader(t *testing.T) {
 
 		// Provide Config and execute
 		cfg := Config{Multiplier: 5}
-		ctx := context.Background()
+		ctx := t.Context()
 		finalResult := result(cfg)(ctx)()
 
 		assert.True(t, either.IsLeft(finalResult))
@@ -643,7 +643,7 @@ func TestTraverseReader(t *testing.T) {
 
 		// Provide Database and execute
 		db := Database{Prefix: "ID"}
-		ctx := context.Background()
+		ctx := t.Context()
 		finalResult := result(db)(ctx)()
 
 		assert.True(t, either.IsRight(finalResult))
@@ -673,7 +673,7 @@ func TestTraverseReader(t *testing.T) {
 
 		// Provide Settings and execute
 		settings := Settings{Prefix: "[", Suffix: "]"}
-		ctx := context.Background()
+		ctx := t.Context()
 		finalResult := result(settings)(ctx)()
 
 		assert.True(t, either.IsRight(finalResult))
@@ -705,14 +705,14 @@ func TestTraverseReader(t *testing.T) {
 		withConfig := result(cfg)
 
 		// Can now use with different contexts
-		ctx1 := context.Background()
+		ctx1 := t.Context()
 		finalResult1 := withConfig(ctx1)()
 		assert.True(t, either.IsRight(finalResult1))
 		value1, _ := either.Unwrap(finalResult1)
 		assert.Equal(t, 30, value1)
 
 		// Reuse with different context
-		ctx2 := context.Background()
+		ctx2 := t.Context()
 		finalResult2 := withConfig(ctx2)()
 		assert.True(t, either.IsRight(finalResult2))
 		value2, _ := either.Unwrap(finalResult2)
@@ -746,7 +746,7 @@ func TestTraverseReader(t *testing.T) {
 		result := traversed(original)
 
 		// Use canceled context
-		ctx, cancel := context.WithCancel(context.Background())
+		ctx, cancel := context.WithCancel(t.Context())
 		cancel()
 
 		cfg := Config{Value: 5}
@@ -778,7 +778,7 @@ func TestTraverseReader(t *testing.T) {
 
 		// Provide Config with zero offset
 		cfg := Config{Offset: 0}
-		ctx := context.Background()
+		ctx := t.Context()
 		finalResult := result(cfg)(ctx)()
 
 		assert.True(t, either.IsRight(finalResult))
@@ -807,7 +807,7 @@ func TestTraverseReader(t *testing.T) {
 
 		// Provide Config and execute
 		cfg := Config{Multiplier: 4}
-		ctx := context.Background()
+		ctx := t.Context()
 		finalResult := result(cfg)(ctx)()
 
 		assert.True(t, either.IsRight(finalResult))
@@ -843,7 +843,7 @@ func TestTraverseReader(t *testing.T) {
 
 		// Test with value within range
 		rules1 := ValidationRules{MinValue: 0, MaxValue: 100}
-		ctx := context.Background()
+		ctx := t.Context()
 		finalResult1 := result(rules1)(ctx)()
 		assert.True(t, either.IsRight(finalResult1))
 		value1, _ := either.Unwrap(finalResult1)

v2/context/readerioresult/http/builder/builder.go

@@ -42,7 +42,7 @@
 //	)
 //
 //	requester := RB.Requester(builder)
-//	result := requester(context.Background())()
+//	result := requester(t.Context())()
 package builder
 
 import (
@@ -103,7 +103,7 @@ import (
 //	    B.WithJSONBody(map[string]string{"name": "John"}),
 //	)
 //	requester := RB.Requester(builder)
-//	result := requester(context.Background())()
+//	result := requester(t.Context())()
 //
 // Example without body:
 //
@@ -113,7 +113,7 @@ import (
 //	    B.WithMethod("GET"),
 //	)
 //	requester := RB.Requester(builder)
-//	result := requester(context.Background())()
+//	result := requester(t.Context())()
 func Requester(builder *R.Builder) RIOEH.Requester {
 
 	withBody := F.Curry3(func(data []byte, url string, method string) RIOE.ReaderIOResult[*http.Request] {

v2/context/readerioresult/http/builder/builder_test.go

@@ -55,7 +55,7 @@ func TestBuilderWithQuery(t *testing.T) {
 		}),
 	)
 
-	assert.True(t, E.IsRight(req(context.Background())()))
+	assert.True(t, E.IsRight(req(t.Context())()))
 }
 
 // TestBuilderWithoutBody tests creating a request without a body
@@ -67,7 +67,7 @@ func TestBuilderWithoutBody(t *testing.T) {
 	)
 
 	requester := Requester(builder)
-	result := requester(context.Background())()
+	result := requester(t.Context())()
 
 	assert.True(t, E.IsRight(result), "Expected Right result")
 
@@ -90,7 +90,7 @@ func TestBuilderWithBody(t *testing.T) {
 	)
 
 	requester := Requester(builder)
-	result := requester(context.Background())()
+	result := requester(t.Context())()
 
 	assert.True(t, E.IsRight(result), "Expected Right result")
 
@@ -112,7 +112,7 @@ func TestBuilderWithHeaders(t *testing.T) {
 	)
 
 	requester := Requester(builder)
-	result := requester(context.Background())()
+	result := requester(t.Context())()
 
 	assert.True(t, E.IsRight(result), "Expected Right result")
 
@@ -130,7 +130,7 @@ func TestBuilderWithInvalidURL(t *testing.T) {
 	)
 
 	requester := Requester(builder)
-	result := requester(context.Background())()
+	result := requester(t.Context())()
 
 	assert.True(t, E.IsLeft(result), "Expected Left result for invalid URL")
 }
@@ -144,7 +144,7 @@ func TestBuilderWithEmptyMethod(t *testing.T) {
 	)
 
 	requester := Requester(builder)
-	result := requester(context.Background())()
+	result := requester(t.Context())()
 
 	// Empty method should still work (defaults to GET in http.NewRequest)
 	assert.True(t, E.IsRight(result), "Expected Right result")
@@ -161,7 +161,7 @@ func TestBuilderWithMultipleHeaders(t *testing.T) {
 	)
 
 	requester := Requester(builder)
-	result := requester(context.Background())()
+	result := requester(t.Context())()
 
 	assert.True(t, E.IsRight(result), "Expected Right result")
 
@@ -185,7 +185,7 @@ func TestBuilderWithBodyAndHeaders(t *testing.T) {
 	)
 
 	requester := Requester(builder)
-	result := requester(context.Background())()
+	result := requester(t.Context())()
 
 	assert.True(t, E.IsRight(result), "Expected Right result")
 
@@ -207,7 +207,7 @@ func TestBuilderContextCancellation(t *testing.T) {
 	requester := Requester(builder)
 
 	// Create a cancelled context
-	ctx, cancel := context.WithCancel(context.Background())
+	ctx, cancel := context.WithCancel(t.Context())
 	cancel() // Cancel immediately
 
 	result := requester(ctx)()
@@ -233,7 +233,7 @@ func TestBuilderWithDifferentMethods(t *testing.T) {
 			)
 
 			requester := Requester(builder)
-			result := requester(context.Background())()
+			result := requester(t.Context())()
 
 			assert.True(t, E.IsRight(result), "Expected Right result for method %s", method)
 
@@ -256,7 +256,7 @@ func TestBuilderWithJSON(t *testing.T) {
 	)
 
 	requester := Requester(builder)
-	result := requester(context.Background())()
+	result := requester(t.Context())()
 
 	assert.True(t, E.IsRight(result), "Expected Right result")
 
@@ -277,7 +277,7 @@ func TestBuilderWithBearer(t *testing.T) {
 	)
 
 	requester := Requester(builder)
-	result := requester(context.Background())()
+	result := requester(t.Context())()
 
 	assert.True(t, E.IsRight(result), "Expected Right result")
 

v2/context/readerioresult/http/request.go

@@ -28,7 +28,7 @@
 //	client := MakeClient(http.DefaultClient)
 //	request := MakeGetRequest("https://api.example.com/data")
 //	result := ReadJSON[MyType](client)(request)
-//	response := result(context.Background())()
+//	response := result(t.Context())()
 package http
 
 import (
@@ -157,7 +157,7 @@ func MakeClient(httpClient *http.Client) Client {
 //	client := MakeClient(http.DefaultClient)
 //	request := MakeGetRequest("https://api.example.com/data")
 //	fullResp := ReadFullResponse(client)(request)
-//	result := fullResp(context.Background())()
+//	result := fullResp(t.Context())()
 func ReadFullResponse(client Client) RIOE.Kleisli[Requester, H.FullResponse] {
 	return func(req Requester) RIOE.ReaderIOResult[H.FullResponse] {
 		return F.Flow3(
@@ -194,7 +194,7 @@ func ReadFullResponse(client Client) RIOE.Kleisli[Requester, H.FullResponse] {
 //	client := MakeClient(http.DefaultClient)
 //	request := MakeGetRequest("https://api.example.com/data")
 //	readBytes := ReadAll(client)
-//	result := readBytes(request)(context.Background())()
+//	result := readBytes(request)(t.Context())()
 func ReadAll(client Client) RIOE.Kleisli[Requester, []byte] {
 	return F.Flow2(
 		ReadFullResponse(client),
@@ -218,7 +218,7 @@ func ReadAll(client Client) RIOE.Kleisli[Requester, []byte] {
 //	client := MakeClient(http.DefaultClient)
 //	request := MakeGetRequest("https://api.example.com/text")
 //	readText := ReadText(client)
-//	result := readText(request)(context.Background())()
+//	result := readText(request)(t.Context())()
 func ReadText(client Client) RIOE.Kleisli[Requester, string] {
 	return F.Flow2(
 		ReadAll(client),
@@ -277,7 +277,7 @@ func readJSON(client Client) RIOE.Kleisli[Requester, []byte] {
 //	client := MakeClient(http.DefaultClient)
 //	request := MakeGetRequest("https://api.example.com/user/1")
 //	readUser := ReadJSON[User](client)
-//	result := readUser(request)(context.Background())()
+//	result := readUser(request)(t.Context())()
 func ReadJSON[A any](client Client) RIOE.Kleisli[Requester, A] {
 	return F.Flow2(
 		readJSON(client),

v2/context/readerioresult/logging.go

@@ -429,7 +429,7 @@ func LogEntryExitWithCallback[A any](
 //	loggedFetch := LogEntryExit[User]("fetchUser")(fetchUser(123))
 //
 //	// Execute
-//	result := loggedFetch(context.Background())()
+//	result := loggedFetch(t.Context())()
 //	// Logs:
 //	// [entering 1] fetchUser
 //	// [exiting  1] fetchUser [0.1s]
@@ -441,7 +441,7 @@ func LogEntryExitWithCallback[A any](
 //	}
 //
 //	logged := LogEntryExit[string]("failingOp")(failingOp())
-//	result := logged(context.Background())()
+//	result := logged(t.Context())()
 //	// Logs:
 //	// [entering 2] failingOp
 //	// [throwing 2] failingOp [0.0s]: connection timeout
@@ -461,7 +461,7 @@ func LogEntryExitWithCallback[A any](
 //	    LogEntryExit[[]Order]("fetchOrders"),
 //	)
 //
-//	result := pipeline(context.Background())()
+//	result := pipeline(t.Context())()
 //	// Logs:
 //	// [entering 3] fetchUser
 //	// [exiting  3] fetchUser [0.1s]
@@ -474,8 +474,8 @@ func LogEntryExitWithCallback[A any](
 //	op1 := LogEntryExit[Data]("operation1")(fetchData(1))
 //	op2 := LogEntryExit[Data]("operation2")(fetchData(2))
 //
-//	go op1(context.Background())()
-//	go op2(context.Background())()
+//	go op1(t.Context())()
+//	go op2(t.Context())()
 //	// Logs (order may vary):
 //	// [entering 5] operation1
 //	// [entering 6] operation2
@@ -615,7 +615,7 @@ func SLogWithCallback[A any](
 //	    Map(func(u User) string { return u.Name }),
 //	)
 //
-//	result := pipeline(context.Background())()
+//	result := pipeline(t.Context())()
 //	// If successful, logs: "Fetched user" value={ID:123 Name:"Alice"}
 //	// If error, logs: "Fetched user" error="user not found"
 //
@@ -679,7 +679,7 @@ func SLog[A any](message string) Kleisli[Result[A], A] {
 //	    Map(func(u User) string { return u.Name }),
 //	)
 //
-//	result := pipeline(context.Background())()
+//	result := pipeline(t.Context())()
 //	// Logs: "Fetched user" value={ID:123 Name:"Alice"}
 //	// Returns: result.Of("Alice")
 //
@@ -694,7 +694,7 @@ func SLog[A any](message string) Kleisli[Result[A], A] {
 //	    TapSLog[Payment]("Payment processed"),
 //	)
 //
-//	result := processOrder(context.Background())()
+//	result := processOrder(t.Context())()
 //	// Logs each successful step with the intermediate values
 //	// If any step fails, subsequent TapSLog calls don't log
 //

v2/context/readerioresult/logging_test.go

@@ -26,7 +26,7 @@ func TestLoggingContext(t *testing.T) {
 		LogEntryExit[string]("TestLoggingContext2"),
 	)
 
-	assert.Equal(t, result.Of("Sample"), data(context.Background())())
+	assert.Equal(t, result.Of("Sample"), data(t.Context())())
 }
 
 // TestLogEntryExitSuccess tests successful operation logging
@@ -43,7 +43,7 @@ func TestLogEntryExitSuccess(t *testing.T) {
 		LogEntryExit[string]("TestOperation"),
 	)
 
-	res := operation(context.Background())()
+	res := operation(t.Context())()
 
 	assert.Equal(t, result.Of("success value"), res)
 
@@ -70,7 +70,7 @@ func TestLogEntryExitError(t *testing.T) {
 		LogEntryExit[string]("FailingOperation"),
 	)
 
-	res := operation(context.Background())()
+	res := operation(t.Context())()
 
 	assert.True(t, result.IsLeft(res))
 
@@ -105,7 +105,7 @@ func TestLogEntryExitNested(t *testing.T) {
 		}),
 	)
 
-	res := outerOp(context.Background())()
+	res := outerOp(t.Context())()
 
 	assert.True(t, result.IsRight(res))
 
@@ -137,7 +137,7 @@ func TestLogEntryExitWithCallback(t *testing.T) {
 		LogEntryExitWithCallback[int](slog.LevelDebug, customCallback, "DebugOperation"),
 	)
 
-	res := operation(context.Background())()
+	res := operation(t.Context())()
 
 	assert.Equal(t, result.Of(42), res)
 
@@ -163,7 +163,7 @@ func TestLogEntryExitDisabled(t *testing.T) {
 		LogEntryExit[string]("DisabledOperation"),
 	)
 
-	res := operation(context.Background())()
+	res := operation(t.Context())()
 
 	assert.True(t, result.IsRight(res))
 
@@ -197,7 +197,7 @@ func TestLogEntryExitF(t *testing.T) {
 		LogEntryExitF(onEntry, onExit),
 	)
 
-	res := operation(context.Background())()
+	res := operation(t.Context())()
 
 	assert.True(t, result.IsRight(res))
 	assert.Equal(t, 1, entryCount, "Entry callback should be called once")
@@ -234,7 +234,7 @@ func TestLogEntryExitFWithError(t *testing.T) {
 		LogEntryExitF(onEntry, onExit),
 	)
 
-	res := operation(context.Background())()
+	res := operation(t.Context())()
 
 	assert.True(t, result.IsLeft(res))
 	assert.Equal(t, 1, entryCount, "Entry callback should be called once")
@@ -257,7 +257,7 @@ func TestLoggingIDUniqueness(t *testing.T) {
 			Of(i),
 			LogEntryExit[int]("Operation"),
 		)
-		op(context.Background())()
+		op(t.Context())()
 	}
 
 	logOutput := buf.String()
@@ -287,7 +287,7 @@ func TestLogEntryExitWithContextLogger(t *testing.T) {
 		Level: slog.LevelInfo,
 	}))
 
-	ctx := logging.WithLogger(contextLogger)(context.Background())
+	ctx := logging.WithLogger(contextLogger)(t.Context())
 
 	operation := F.Pipe1(
 		Of("context value"),
@@ -326,7 +326,7 @@ func TestLogEntryExitTiming(t *testing.T) {
 		LogEntryExit[string]("SlowOperation"),
 	)
 
-	res := operation(context.Background())()
+	res := operation(t.Context())()
 
 	assert.True(t, result.IsRight(res))
 
@@ -379,7 +379,7 @@ func TestLogEntryExitChainedOperations(t *testing.T) {
 		)),
 	)
 
-	res := pipeline(context.Background())()
+	res := pipeline(t.Context())()
 
 	assert.Equal(t, result.Of("2"), res)
 
@@ -408,7 +408,7 @@ func TestTapSLog(t *testing.T) {
 		Map(N.Mul(2)),
 	)
 
-	res := operation(context.Background())()
+	res := operation(t.Context())()
 
 	assert.Equal(t, result.Of(84), res)
 
@@ -443,7 +443,7 @@ func TestTapSLogInPipeline(t *testing.T) {
 		TapSLog[int]("Step 3: Final length"),
 	)
 
-	res := pipeline(context.Background())()
+	res := pipeline(t.Context())()
 
 	assert.Equal(t, result.Of(11), res)
 
@@ -472,7 +472,7 @@ func TestTapSLogWithError(t *testing.T) {
 		Map(N.Mul(2)),
 	)
 
-	res := pipeline(context.Background())()
+	res := pipeline(t.Context())()
 
 	assert.True(t, result.IsLeft(res))
 
@@ -504,7 +504,7 @@ func TestTapSLogWithStruct(t *testing.T) {
 		Map(func(u User) string { return u.Name }),
 	)
 
-	res := operation(context.Background())()
+	res := operation(t.Context())()
 
 	assert.Equal(t, result.Of("Alice"), res)
 
@@ -530,7 +530,7 @@ func TestTapSLogDisabled(t *testing.T) {
 		Map(N.Mul(2)),
 	)
 
-	res := operation(context.Background())()
+	res := operation(t.Context())()
 
 	assert.Equal(t, result.Of(84), res)
 
@@ -546,7 +546,7 @@ func TestTapSLogWithContextLogger(t *testing.T) {
 		Level: slog.LevelInfo,
 	}))
 
-	ctx := logging.WithLogger(contextLogger)(context.Background())
+	ctx := logging.WithLogger(contextLogger)(t.Context())
 
 	operation := F.Pipe2(
 		Of("test value"),
@@ -572,7 +572,7 @@ func TestSLogLogsSuccessValue(t *testing.T) {
 	oldLogger := logging.SetLogger(logger)
 	defer logging.SetLogger(oldLogger)
 
-	ctx := context.Background()
+	ctx := t.Context()
 
 	// Create a Result and log it
 	res1 := result.Of(42)
@@ -594,7 +594,7 @@ func TestSLogLogsErrorValue(t *testing.T) {
 	oldLogger := logging.SetLogger(logger)
 	defer logging.SetLogger(oldLogger)
 
-	ctx := context.Background()
+	ctx := t.Context()
 	testErr := errors.New("test error")
 
 	// Create an error Result and log it
@@ -620,7 +620,7 @@ func TestSLogWithCallbackCustomLevel(t *testing.T) {
 		return logger
 	}
 
-	ctx := context.Background()
+	ctx := t.Context()
 
 	// Create a Result and log it with custom callback
 	res1 := result.Of(42)
@@ -645,7 +645,7 @@ func TestSLogWithCallbackLogsError(t *testing.T) {
 		return logger
 	}
 
-	ctx := context.Background()
+	ctx := t.Context()
 	testErr := errors.New("warning error")
 
 	// Create an error Result and log it with custom callback

v2/context/readerioresult/profunctor_test.go

@@ -43,7 +43,7 @@ func TestPromapBasic(t *testing.T) {
 		toString := strconv.Itoa
 
 		adapted := Promap(addKey, toString)(getValue)
-		result := adapted(context.Background())()
+		result := adapted(t.Context())()
 
 		assert.Equal(t, R.Of("42"), result)
 	})
@@ -67,7 +67,7 @@ func TestContramapBasic(t *testing.T) {
 		}
 
 		adapted := Contramap[int](addKey)(getValue)
-		result := adapted(context.Background())()
+		result := adapted(t.Context())()
 
 		assert.Equal(t, R.Of(100), result)
 	})
@@ -91,7 +91,7 @@ func TestLocalBasic(t *testing.T) {
 		}
 
 		adapted := Local[string](addUser)(getValue)
-		result := adapted(context.Background())()
+		result := adapted(t.Context())()
 
 		assert.Equal(t, R.Of("Alice"), result)
 	})

v2/context/readerioresult/reader.go

@@ -914,6 +914,21 @@ func Read[A any](r context.Context) func(ReaderIOResult[A]) IOResult[A] {
 	return RIOR.Read[A](r)
 }
 
+//go:inline
+func ReadIO[A any](r IO[context.Context]) func(ReaderIOResult[A]) IOResult[A] {
+	return RIOR.ReadIO[A](r)
+}
+
+//go:inline
+func ReadIOEither[A any](r IOResult[context.Context]) func(ReaderIOResult[A]) IOResult[A] {
+	return RIOR.ReadIOEither[A](r)
+}
+
+//go:inline
+func ReadIOResult[A any](r IOResult[context.Context]) func(ReaderIOResult[A]) IOResult[A] {
+	return RIOR.ReadIOResult[A](r)
+}
+
 // MonadChainLeft chains a computation on the left (error) side of a [ReaderIOResult].
 // If the input is a Left value, it applies the function f to transform the error and potentially
 // change the error type. If the input is a Right value, it passes through unchanged.
@@ -1026,7 +1041,7 @@ func TapLeftIOK[A, B any](f io.Kleisli[error, B]) Operator[A, A] {
 //	    getUser,
 //	    addUser,
 //	)
-//	value, err := result(context.Background())()  // Returns ("Alice", nil)
+//	value, err := result(t.Context())()  // Returns ("Alice", nil)
 //
 // Timeout Example:
 //
@@ -1097,7 +1112,7 @@ func Local[A any](f func(context.Context) (context.Context, context.CancelFunc))
 //	    fetchData,
 //	    readerioresult.WithTimeout[Data](5*time.Second),
 //	)
-//	value, err := result(context.Background())()  // Returns (Data{}, context.DeadlineExceeded) after 5s
+//	value, err := result(t.Context())()  // Returns (Data{}, context.DeadlineExceeded) after 5s
 //
 // Successful Example:
 //
@@ -1106,7 +1121,7 @@ func Local[A any](f func(context.Context) (context.Context, context.CancelFunc))
 //	    quickFetch,
 //	    readerioresult.WithTimeout[Data](5*time.Second),
 //	)
-//	value, err := result(context.Background())()  // Returns (Data{Value: "quick"}, nil)
+//	value, err := result(t.Context())()  // Returns (Data{Value: "quick"}, nil)
 func WithTimeout[A any](timeout time.Duration) Operator[A, A] {
 	return Local[A](func(ctx context.Context) (context.Context, context.CancelFunc) {
 		return context.WithTimeout(ctx, timeout)
@@ -1158,12 +1173,12 @@ func WithTimeout[A any](timeout time.Duration) Operator[A, A] {
 //	    fetchData,
 //	    readerioresult.WithDeadline[Data](deadline),
 //	)
-//	value, err := result(context.Background())()  // Returns (Data{}, context.DeadlineExceeded) if past deadline
+//	value, err := result(t.Context())()  // Returns (Data{}, context.DeadlineExceeded) if past deadline
 //
 // Combining with Parent Context:
 //
 //	// If parent context already has a deadline, the earlier one takes precedence
-//	parentCtx, cancel := context.WithDeadline(context.Background(), time.Now().Add(1*time.Hour))
+//	parentCtx, cancel := context.WithDeadline(t.Context(), time.Now().Add(1*time.Hour))
 //	defer cancel()
 //
 //	laterDeadline := time.Now().Add(2 * time.Hour)

v2/context/readerioresult/reader_extended_test.go

@@ -36,56 +36,56 @@ func TestFromEither(t *testing.T) {
 	t.Run("Right value", func(t *testing.T) {
 		either := E.Right[error]("success")
 		result := FromEither(either)
-		assert.Equal(t, E.Right[error]("success"), result(context.Background())())
+		assert.Equal(t, E.Right[error]("success"), result(t.Context())())
 	})
 
 	t.Run("Left value", func(t *testing.T) {
 		err := errors.New("test error")
 		either := E.Left[string](err)
 		result := FromEither(either)
-		assert.Equal(t, E.Left[string](err), result(context.Background())())
+		assert.Equal(t, E.Left[string](err), result(t.Context())())
 	})
 }
 
 func TestFromResult(t *testing.T) {
 	t.Run("Success", func(t *testing.T) {
 		result := FromResult(E.Right[error](42))
-		assert.Equal(t, E.Right[error](42), result(context.Background())())
+		assert.Equal(t, E.Right[error](42), result(t.Context())())
 	})
 
 	t.Run("Error", func(t *testing.T) {
 		err := errors.New("test error")
 		result := FromResult(E.Left[int](err))
-		assert.Equal(t, E.Left[int](err), result(context.Background())())
+		assert.Equal(t, E.Left[int](err), result(t.Context())())
 	})
 }
 
 func TestLeft(t *testing.T) {
 	err := errors.New("test error")
 	result := Left[string](err)
-	assert.Equal(t, E.Left[string](err), result(context.Background())())
+	assert.Equal(t, E.Left[string](err), result(t.Context())())
 }
 
 func TestRight(t *testing.T) {
 	result := Right("success")
-	assert.Equal(t, E.Right[error]("success"), result(context.Background())())
+	assert.Equal(t, E.Right[error]("success"), result(t.Context())())
 }
 
 func TestOf(t *testing.T) {
 	result := Of(42)
-	assert.Equal(t, E.Right[error](42), result(context.Background())())
+	assert.Equal(t, E.Right[error](42), result(t.Context())())
 }
 
 func TestMonadMap(t *testing.T) {
 	t.Run("Map over Right", func(t *testing.T) {
 		result := MonadMap(Of(5), N.Mul(2))
-		assert.Equal(t, E.Right[error](10), result(context.Background())())
+		assert.Equal(t, E.Right[error](10), result(t.Context())())
 	})
 
 	t.Run("Map over Left", func(t *testing.T) {
 		err := errors.New("test error")
 		result := MonadMap(Left[int](err), N.Mul(2))
-		assert.Equal(t, E.Left[int](err), result(context.Background())())
+		assert.Equal(t, E.Left[int](err), result(t.Context())())
 	})
 }
 
@@ -93,34 +93,34 @@ func TestMap(t *testing.T) {
 	t.Run("Map with success", func(t *testing.T) {
 		mapper := Map(N.Mul(2))
 		result := mapper(Of(5))
-		assert.Equal(t, E.Right[error](10), result(context.Background())())
+		assert.Equal(t, E.Right[error](10), result(t.Context())())
 	})
 
 	t.Run("Map with error", func(t *testing.T) {
 		err := errors.New("test error")
 		mapper := Map(N.Mul(2))
 		result := mapper(Left[int](err))
-		assert.Equal(t, E.Left[int](err), result(context.Background())())
+		assert.Equal(t, E.Left[int](err), result(t.Context())())
 	})
 }
 
 func TestMonadMapTo(t *testing.T) {
 	t.Run("MapTo with success", func(t *testing.T) {
 		result := MonadMapTo(Of("original"), 42)
-		assert.Equal(t, E.Right[error](42), result(context.Background())())
+		assert.Equal(t, E.Right[error](42), result(t.Context())())
 	})
 
 	t.Run("MapTo with error", func(t *testing.T) {
 		err := errors.New("test error")
 		result := MonadMapTo(Left[string](err), 42)
-		assert.Equal(t, E.Left[int](err), result(context.Background())())
+		assert.Equal(t, E.Left[int](err), result(t.Context())())
 	})
 }
 
 func TestMapTo(t *testing.T) {
 	mapper := MapTo[string](42)
 	result := mapper(Of("original"))
-	assert.Equal(t, E.Right[error](42), result(context.Background())())
+	assert.Equal(t, E.Right[error](42), result(t.Context())())
 }
 
 func TestMonadChain(t *testing.T) {
@@ -128,7 +128,7 @@ func TestMonadChain(t *testing.T) {
 		result := MonadChain(Of(5), func(x int) ReaderIOResult[int] {
 			return Of(x * 2)
 		})
-		assert.Equal(t, E.Right[error](10), result(context.Background())())
+		assert.Equal(t, E.Right[error](10), result(t.Context())())
 	})
 
 	t.Run("Chain with error in first", func(t *testing.T) {
@@ -136,7 +136,7 @@ func TestMonadChain(t *testing.T) {
 		result := MonadChain(Left[int](err), func(x int) ReaderIOResult[int] {
 			return Of(x * 2)
 		})
-		assert.Equal(t, E.Left[int](err), result(context.Background())())
+		assert.Equal(t, E.Left[int](err), result(t.Context())())
 	})
 
 	t.Run("Chain with error in second", func(t *testing.T) {
@@ -144,7 +144,7 @@ func TestMonadChain(t *testing.T) {
 		result := MonadChain(Of(5), func(x int) ReaderIOResult[int] {
 			return Left[int](err)
 		})
-		assert.Equal(t, E.Left[int](err), result(context.Background())())
+		assert.Equal(t, E.Left[int](err), result(t.Context())())
 	})
 }
 
@@ -153,7 +153,7 @@ func TestChain(t *testing.T) {
 		return Of(x * 2)
 	})
 	result := chainer(Of(5))
-	assert.Equal(t, E.Right[error](10), result(context.Background())())
+	assert.Equal(t, E.Right[error](10), result(t.Context())())
 }
 
 func TestMonadChainFirst(t *testing.T) {
@@ -161,7 +161,7 @@ func TestMonadChainFirst(t *testing.T) {
 		result := MonadChainFirst(Of(5), func(x int) ReaderIOResult[string] {
 			return Of("ignored")
 		})
-		assert.Equal(t, E.Right[error](5), result(context.Background())())
+		assert.Equal(t, E.Right[error](5), result(t.Context())())
 	})
 
 	t.Run("ChainFirst propagates error from second", func(t *testing.T) {
@@ -169,7 +169,7 @@ func TestMonadChainFirst(t *testing.T) {
 		result := MonadChainFirst(Of(5), func(x int) ReaderIOResult[string] {
 			return Left[string](err)
 		})
-		assert.Equal(t, E.Left[int](err), result(context.Background())())
+		assert.Equal(t, E.Left[int](err), result(t.Context())())
 	})
 }
 
@@ -178,7 +178,7 @@ func TestChainFirst(t *testing.T) {
 		return Of("ignored")
 	})
 	result := chainer(Of(5))
-	assert.Equal(t, E.Right[error](5), result(context.Background())())
+	assert.Equal(t, E.Right[error](5), result(t.Context())())
 }
 
 func TestMonadApSeq(t *testing.T) {
@@ -186,7 +186,7 @@ func TestMonadApSeq(t *testing.T) {
 		fab := Of(N.Mul(2))
 		fa := Of(5)
 		result := MonadApSeq(fab, fa)
-		assert.Equal(t, E.Right[error](10), result(context.Background())())
+		assert.Equal(t, E.Right[error](10), result(t.Context())())
 	})
 
 	t.Run("ApSeq with error in function", func(t *testing.T) {
@@ -194,7 +194,7 @@ func TestMonadApSeq(t *testing.T) {
 		fab := Left[func(int) int](err)
 		fa := Of(5)
 		result := MonadApSeq(fab, fa)
-		assert.Equal(t, E.Left[int](err), result(context.Background())())
+		assert.Equal(t, E.Left[int](err), result(t.Context())())
 	})
 
 	t.Run("ApSeq with error in value", func(t *testing.T) {
@@ -202,7 +202,7 @@ func TestMonadApSeq(t *testing.T) {
 		fab := Of(N.Mul(2))
 		fa := Left[int](err)
 		result := MonadApSeq(fab, fa)
-		assert.Equal(t, E.Left[int](err), result(context.Background())())
+		assert.Equal(t, E.Left[int](err), result(t.Context())())
 	})
 }
 
@@ -210,7 +210,7 @@ func TestApSeq(t *testing.T) {
 	fa := Of(5)
 	fab := Of(N.Mul(2))
 	result := MonadApSeq(fab, fa)
-	assert.Equal(t, E.Right[error](10), result(context.Background())())
+	assert.Equal(t, E.Right[error](10), result(t.Context())())
 }
 
 func TestApPar(t *testing.T) {
@@ -218,11 +218,11 @@ func TestApPar(t *testing.T) {
 		fa := Of(5)
 		fab := Of(N.Mul(2))
 		result := MonadApPar(fab, fa)
-		assert.Equal(t, E.Right[error](10), result(context.Background())())
+		assert.Equal(t, E.Right[error](10), result(t.Context())())
 	})
 
 	t.Run("ApPar with cancelled context", func(t *testing.T) {
-		ctx, cancel := context.WithCancel(context.Background())
+		ctx, cancel := context.WithCancel(t.Context())
 		cancel()
 		fa := Of(5)
 		fab := Of(N.Mul(2))
@@ -239,7 +239,7 @@ func TestFromPredicate(t *testing.T) {
 			func(x int) error { return fmt.Errorf("value %d is not positive", x) },
 		)
 		result := pred(5)
-		assert.Equal(t, E.Right[error](5), result(context.Background())())
+		assert.Equal(t, E.Right[error](5), result(t.Context())())
 	})
 
 	t.Run("Predicate false", func(t *testing.T) {
@@ -248,7 +248,7 @@ func TestFromPredicate(t *testing.T) {
 			func(x int) error { return fmt.Errorf("value %d is not positive", x) },
 		)
 		result := pred(-5)
-		res := result(context.Background())()
+		res := result(t.Context())()
 		assert.True(t, E.IsLeft(res))
 	})
 }
@@ -259,7 +259,7 @@ func TestOrElse(t *testing.T) {
 			return Of(42)
 		})
 		result := fallback(Of(10))
-		assert.Equal(t, E.Right[error](10), result(context.Background())())
+		assert.Equal(t, E.Right[error](10), result(t.Context())())
 	})
 
 	t.Run("OrElse with error", func(t *testing.T) {
@@ -268,13 +268,13 @@ func TestOrElse(t *testing.T) {
 			return Of(42)
 		})
 		result := fallback(Left[int](err))
-		assert.Equal(t, E.Right[error](42), result(context.Background())())
+		assert.Equal(t, E.Right[error](42), result(t.Context())())
 	})
 }
 
 func TestAsk(t *testing.T) {
 	result := Ask()
-	ctx := context.Background()
+	ctx := t.Context()
 	res := result(ctx)()
 	assert.True(t, E.IsRight(res))
 	ctxResult := E.ToOption(res)
@@ -286,7 +286,7 @@ func TestMonadChainEitherK(t *testing.T) {
 		result := MonadChainEitherK(Of(5), func(x int) Either[int] {
 			return E.Right[error](x * 2)
 		})
-		assert.Equal(t, E.Right[error](10), result(context.Background())())
+		assert.Equal(t, E.Right[error](10), result(t.Context())())
 	})
 
 	t.Run("ChainEitherK with error", func(t *testing.T) {
@@ -294,7 +294,7 @@ func TestMonadChainEitherK(t *testing.T) {
 		result := MonadChainEitherK(Of(5), func(x int) Either[int] {
 			return E.Left[int](err)
 		})
-		assert.Equal(t, E.Left[int](err), result(context.Background())())
+		assert.Equal(t, E.Left[int](err), result(t.Context())())
 	})
 }
 
@@ -303,7 +303,7 @@ func TestChainEitherK(t *testing.T) {
 		return E.Right[error](x * 2)
 	})
 	result := chainer(Of(5))
-	assert.Equal(t, E.Right[error](10), result(context.Background())())
+	assert.Equal(t, E.Right[error](10), result(t.Context())())
 }
 
 func TestMonadChainFirstEitherK(t *testing.T) {
@@ -311,7 +311,7 @@ func TestMonadChainFirstEitherK(t *testing.T) {
 		result := MonadChainFirstEitherK(Of(5), func(x int) Either[string] {
 			return E.Right[error]("ignored")
 		})
-		assert.Equal(t, E.Right[error](5), result(context.Background())())
+		assert.Equal(t, E.Right[error](5), result(t.Context())())
 	})
 
 	t.Run("ChainFirstEitherK propagates error", func(t *testing.T) {
@@ -319,7 +319,7 @@ func TestMonadChainFirstEitherK(t *testing.T) {
 		result := MonadChainFirstEitherK(Of(5), func(x int) Either[string] {
 			return E.Left[string](err)
 		})
-		assert.Equal(t, E.Left[int](err), result(context.Background())())
+		assert.Equal(t, E.Left[int](err), result(t.Context())())
 	})
 }
 
@@ -328,7 +328,7 @@ func TestChainFirstEitherK(t *testing.T) {
 		return E.Right[error]("ignored")
 	})
 	result := chainer(Of(5))
-	assert.Equal(t, E.Right[error](5), result(context.Background())())
+	assert.Equal(t, E.Right[error](5), result(t.Context())())
 }
 
 func TestChainOptionK(t *testing.T) {
@@ -339,7 +339,7 @@ func TestChainOptionK(t *testing.T) {
 			return O.Some(x * 2)
 		})
 		result := chainer(Of(5))
-		assert.Equal(t, E.Right[error](10), result(context.Background())())
+		assert.Equal(t, E.Right[error](10), result(t.Context())())
 	})
 
 	t.Run("ChainOptionK with None", func(t *testing.T) {
@@ -349,7 +349,7 @@ func TestChainOptionK(t *testing.T) {
 			return O.None[int]()
 		})
 		result := chainer(Of(5))
-		res := result(context.Background())()
+		res := result(t.Context())()
 		assert.True(t, E.IsLeft(res))
 	})
 }
@@ -358,44 +358,44 @@ func TestFromIOEither(t *testing.T) {
 	t.Run("FromIOEither with success", func(t *testing.T) {
 		ioe := IOE.Of[error](42)
 		result := FromIOEither(ioe)
-		assert.Equal(t, E.Right[error](42), result(context.Background())())
+		assert.Equal(t, E.Right[error](42), result(t.Context())())
 	})
 
 	t.Run("FromIOEither with error", func(t *testing.T) {
 		err := errors.New("test error")
 		ioe := IOE.Left[int](err)
 		result := FromIOEither(ioe)
-		assert.Equal(t, E.Left[int](err), result(context.Background())())
+		assert.Equal(t, E.Left[int](err), result(t.Context())())
 	})
 }
 
 func TestFromIOResult(t *testing.T) {
 	ioe := IOE.Of[error](42)
 	result := FromIOResult(ioe)
-	assert.Equal(t, E.Right[error](42), result(context.Background())())
+	assert.Equal(t, E.Right[error](42), result(t.Context())())
 }
 
 func TestFromIO(t *testing.T) {
 	io := IOG.Of(42)
 	result := FromIO(io)
-	assert.Equal(t, E.Right[error](42), result(context.Background())())
+	assert.Equal(t, E.Right[error](42), result(t.Context())())
 }
 
 func TestFromReader(t *testing.T) {
 	reader := R.Of[context.Context](42)
 	result := FromReader(reader)
-	assert.Equal(t, E.Right[error](42), result(context.Background())())
+	assert.Equal(t, E.Right[error](42), result(t.Context())())
 }
 
 func TestFromLazy(t *testing.T) {
 	lazy := func() int { return 42 }
 	result := FromLazy(lazy)
-	assert.Equal(t, E.Right[error](42), result(context.Background())())
+	assert.Equal(t, E.Right[error](42), result(t.Context())())
 }
 
 func TestNever(t *testing.T) {
 	t.Run("Never with cancelled context", func(t *testing.T) {
-		ctx, cancel := context.WithCancel(context.Background())
+		ctx, cancel := context.WithCancel(t.Context())
 		result := Never[int]()
 
 		// Cancel immediately
@@ -406,7 +406,7 @@ func TestNever(t *testing.T) {
 	})
 
 	t.Run("Never with timeout", func(t *testing.T) {
-		ctx, cancel := context.WithTimeout(context.Background(), 100*time.Millisecond)
+		ctx, cancel := context.WithTimeout(t.Context(), 100*time.Millisecond)
 		defer cancel()
 
 		result := Never[int]()
@@ -419,7 +419,7 @@ func TestMonadChainIOK(t *testing.T) {
 	result := MonadChainIOK(Of(5), func(x int) IOG.IO[int] {
 		return IOG.Of(x * 2)
 	})
-	assert.Equal(t, E.Right[error](10), result(context.Background())())
+	assert.Equal(t, E.Right[error](10), result(t.Context())())
 }
 
 func TestChainIOK(t *testing.T) {
@@ -427,14 +427,14 @@ func TestChainIOK(t *testing.T) {
 		return IOG.Of(x * 2)
 	})
 	result := chainer(Of(5))
-	assert.Equal(t, E.Right[error](10), result(context.Background())())
+	assert.Equal(t, E.Right[error](10), result(t.Context())())
 }
 
 func TestMonadChainFirstIOK(t *testing.T) {
 	result := MonadChainFirstIOK(Of(5), func(x int) IOG.IO[string] {
 		return IOG.Of("ignored")
 	})
-	assert.Equal(t, E.Right[error](5), result(context.Background())())
+	assert.Equal(t, E.Right[error](5), result(t.Context())())
 }
 
 func TestChainFirstIOK(t *testing.T) {
@@ -442,7 +442,7 @@ func TestChainFirstIOK(t *testing.T) {
 		return IOG.Of("ignored")
 	})
 	result := chainer(Of(5))
-	assert.Equal(t, E.Right[error](5), result(context.Background())())
+	assert.Equal(t, E.Right[error](5), result(t.Context())())
 }
 
 func TestChainIOEitherK(t *testing.T) {
@@ -451,7 +451,7 @@ func TestChainIOEitherK(t *testing.T) {
 			return IOE.Of[error](x * 2)
 		})
 		result := chainer(Of(5))
-		assert.Equal(t, E.Right[error](10), result(context.Background())())
+		assert.Equal(t, E.Right[error](10), result(t.Context())())
 	})
 
 	t.Run("ChainIOEitherK with error", func(t *testing.T) {
@@ -460,7 +460,7 @@ func TestChainIOEitherK(t *testing.T) {
 			return IOE.Left[int](err)
 		})
 		result := chainer(Of(5))
-		assert.Equal(t, E.Left[int](err), result(context.Background())())
+		assert.Equal(t, E.Left[int](err), result(t.Context())())
 	})
 }
 
@@ -469,7 +469,7 @@ func TestDelay(t *testing.T) {
 		start := time.Now()
 		delayed := Delay[int](100 * time.Millisecond)
 		result := delayed(Of(42))
-		res := result(context.Background())()
+		res := result(t.Context())()
 		elapsed := time.Since(start)
 
 		assert.True(t, E.IsRight(res))
@@ -477,7 +477,7 @@ func TestDelay(t *testing.T) {
 	})
 
 	t.Run("Delay with cancelled context", func(t *testing.T) {
-		ctx, cancel := context.WithCancel(context.Background())
+		ctx, cancel := context.WithCancel(t.Context())
 
 		delayed := Delay[int](100 * time.Millisecond)
 		result := delayed(Of(42))
@@ -500,11 +500,11 @@ func TestDefer(t *testing.T) {
 	})
 
 	// First execution
-	res1 := deferred(context.Background())()
+	res1 := deferred(t.Context())()
 	assert.True(t, E.IsRight(res1))
 
 	// Second execution should generate a new computation
-	res2 := deferred(context.Background())()
+	res2 := deferred(t.Context())()
 	assert.True(t, E.IsRight(res2))
 
 	// Counter should be incremented for each execution
@@ -518,7 +518,7 @@ func TestTryCatch(t *testing.T) {
 				return 42, nil
 			}
 		})
-		assert.Equal(t, E.Right[error](42), result(context.Background())())
+		assert.Equal(t, E.Right[error](42), result(t.Context())())
 	})
 
 	t.Run("TryCatch with error", func(t *testing.T) {
@@ -528,7 +528,7 @@ func TestTryCatch(t *testing.T) {
 				return 0, err
 			}
 		})
-		assert.Equal(t, E.Left[int](err), result(context.Background())())
+		assert.Equal(t, E.Left[int](err), result(t.Context())())
 	})
 }
 
@@ -537,7 +537,7 @@ func TestMonadAlt(t *testing.T) {
 		first := Of(42)
 		second := func() ReaderIOResult[int] { return Of(100) }
 		result := MonadAlt(first, second)
-		assert.Equal(t, E.Right[error](42), result(context.Background())())
+		assert.Equal(t, E.Right[error](42), result(t.Context())())
 	})
 
 	t.Run("Alt with first error", func(t *testing.T) {
@@ -545,7 +545,7 @@ func TestMonadAlt(t *testing.T) {
 		first := Left[int](err)
 		second := func() ReaderIOResult[int] { return Of(100) }
 		result := MonadAlt(first, second)
-		assert.Equal(t, E.Right[error](100), result(context.Background())())
+		assert.Equal(t, E.Right[error](100), result(t.Context())())
 	})
 }
 
@@ -553,7 +553,7 @@ func TestAlt(t *testing.T) {
 	err := errors.New("test error")
 	alternative := Alt(func() ReaderIOResult[int] { return Of(100) })
 	result := alternative(Left[int](err))
-	assert.Equal(t, E.Right[error](100), result(context.Background())())
+	assert.Equal(t, E.Right[error](100), result(t.Context())())
 }
 
 func TestMemoize(t *testing.T) {
@@ -564,13 +564,13 @@ func TestMemoize(t *testing.T) {
 	}))
 
 	// First execution
-	res1 := computation(context.Background())()
+	res1 := computation(t.Context())()
 	assert.True(t, E.IsRight(res1))
 	val1 := E.ToOption(res1)
 	assert.Equal(t, O.Of(1), val1)
 
 	// Second execution should return cached value
-	res2 := computation(context.Background())()
+	res2 := computation(t.Context())()
 	assert.True(t, E.IsRight(res2))
 	val2 := E.ToOption(res2)
 	assert.Equal(t, O.Of(1), val2)
@@ -582,19 +582,19 @@ func TestMemoize(t *testing.T) {
 func TestFlatten(t *testing.T) {
 	nested := Of(Of(42))
 	result := Flatten(nested)
-	assert.Equal(t, E.Right[error](42), result(context.Background())())
+	assert.Equal(t, E.Right[error](42), result(t.Context())())
 }
 
 func TestMonadFlap(t *testing.T) {
 	fab := Of(N.Mul(2))
 	result := MonadFlap(fab, 5)
-	assert.Equal(t, E.Right[error](10), result(context.Background())())
+	assert.Equal(t, E.Right[error](10), result(t.Context())())
 }
 
 func TestFlap(t *testing.T) {
 	flapper := Flap[int](5)
 	result := flapper(Of(N.Mul(2)))
-	assert.Equal(t, E.Right[error](10), result(context.Background())())
+	assert.Equal(t, E.Right[error](10), result(t.Context())())
 }
 
 func TestFold(t *testing.T) {
@@ -608,7 +608,7 @@ func TestFold(t *testing.T) {
 			},
 		)
 		result := folder(Of(42))
-		assert.Equal(t, E.Right[error]("success: 42"), result(context.Background())())
+		assert.Equal(t, E.Right[error]("success: 42"), result(t.Context())())
 	})
 
 	t.Run("Fold with error", func(t *testing.T) {
@@ -622,7 +622,7 @@ func TestFold(t *testing.T) {
 			},
 		)
 		result := folder(Left[int](err))
-		assert.Equal(t, E.Right[error]("error: test error"), result(context.Background())())
+		assert.Equal(t, E.Right[error]("error: test error"), result(t.Context())())
 	})
 }
 
@@ -634,7 +634,7 @@ func TestGetOrElse(t *testing.T) {
 			}
 		})
 		result := getter(Of(42))
-		assert.Equal(t, 42, result(context.Background())())
+		assert.Equal(t, 42, result(t.Context())())
 	})
 
 	t.Run("GetOrElse with error", func(t *testing.T) {
@@ -645,19 +645,19 @@ func TestGetOrElse(t *testing.T) {
 			}
 		})
 		result := getter(Left[int](err))
-		assert.Equal(t, 0, result(context.Background())())
+		assert.Equal(t, 0, result(t.Context())())
 	})
 }
 
 func TestWithContext(t *testing.T) {
 	t.Run("WithContext with valid context", func(t *testing.T) {
 		computation := WithContext(Of(42))
-		result := computation(context.Background())()
+		result := computation(t.Context())()
 		assert.Equal(t, E.Right[error](42), result)
 	})
 
 	t.Run("WithContext with cancelled context", func(t *testing.T) {
-		ctx, cancel := context.WithCancel(context.Background())
+		ctx, cancel := context.WithCancel(t.Context())
 		cancel()
 
 		computation := WithContext(Of(42))
@@ -672,7 +672,7 @@ func TestEitherize0(t *testing.T) {
 	}
 	eitherized := Eitherize0(f)
 	result := eitherized()
-	assert.Equal(t, E.Right[error](42), result(context.Background())())
+	assert.Equal(t, E.Right[error](42), result(t.Context())())
 }
 
 func TestUneitherize0(t *testing.T) {
@@ -680,7 +680,7 @@ func TestUneitherize0(t *testing.T) {
 		return Of(42)
 	}
 	uneitherized := Uneitherize0(f)
-	result, err := uneitherized(context.Background())
+	result, err := uneitherized(t.Context())
 	assert.NoError(t, err)
 	assert.Equal(t, 42, result)
 }
@@ -691,7 +691,7 @@ func TestEitherize1(t *testing.T) {
 	}
 	eitherized := Eitherize1(f)
 	result := eitherized(5)
-	assert.Equal(t, E.Right[error](10), result(context.Background())())
+	assert.Equal(t, E.Right[error](10), result(t.Context())())
 }
 
 func TestUneitherize1(t *testing.T) {
@@ -699,14 +699,14 @@ func TestUneitherize1(t *testing.T) {
 		return Of(x * 2)
 	}
 	uneitherized := Uneitherize1(f)
-	result, err := uneitherized(context.Background(), 5)
+	result, err := uneitherized(t.Context(), 5)
 	assert.NoError(t, err)
 	assert.Equal(t, 10, result)
 }
 
 func TestSequenceT2(t *testing.T) {
 	result := SequenceT2(Of(1), Of(2))
-	res := result(context.Background())()
+	res := result(t.Context())()
 	assert.True(t, E.IsRight(res))
 	tuple := E.ToOption(res)
 	assert.True(t, O.IsSome(tuple))
@@ -717,13 +717,13 @@ func TestSequenceT2(t *testing.T) {
 
 func TestSequenceSeqT2(t *testing.T) {
 	result := SequenceSeqT2(Of(1), Of(2))
-	res := result(context.Background())()
+	res := result(t.Context())()
 	assert.True(t, E.IsRight(res))
 }
 
 func TestSequenceParT2(t *testing.T) {
 	result := SequenceParT2(Of(1), Of(2))
-	res := result(context.Background())()
+	res := result(t.Context())()
 	assert.True(t, E.IsRight(res))
 }
 
@@ -734,7 +734,7 @@ func TestTraverseArray(t *testing.T) {
 			return Of(x * 2)
 		})
 		result := traverser(arr)
-		res := result(context.Background())()
+		res := result(t.Context())()
 		assert.True(t, E.IsRight(res))
 		arrOpt := E.ToOption(res)
 		assert.Equal(t, O.Of([]int{2, 4, 6}), arrOpt)
@@ -750,7 +750,7 @@ func TestTraverseArray(t *testing.T) {
 			return Of(x * 2)
 		})
 		result := traverser(arr)
-		res := result(context.Background())()
+		res := result(t.Context())()
 		assert.True(t, E.IsLeft(res))
 	})
 }
@@ -758,7 +758,7 @@ func TestTraverseArray(t *testing.T) {
 func TestSequenceArray(t *testing.T) {
 	arr := []ReaderIOResult[int]{Of(1), Of(2), Of(3)}
 	result := SequenceArray(arr)
-	res := result(context.Background())()
+	res := result(t.Context())()
 	assert.True(t, E.IsRight(res))
 	arrOpt := E.ToOption(res)
 	assert.Equal(t, O.Of([]int{1, 2, 3}), arrOpt)
@@ -769,7 +769,7 @@ func TestTraverseRecord(t *testing.T) {
 	result := TraverseRecord[string](func(x int) ReaderIOResult[int] {
 		return Of(x * 2)
 	})(rec)
-	res := result(context.Background())()
+	res := result(t.Context())()
 	assert.True(t, E.IsRight(res))
 	recOpt := E.ToOption(res)
 	assert.True(t, O.IsSome(recOpt))
@@ -784,7 +784,7 @@ func TestSequenceRecord(t *testing.T) {
 		"b": Of(2),
 	}
 	result := SequenceRecord(rec)
-	res := result(context.Background())()
+	res := result(t.Context())()
 	assert.True(t, E.IsRight(res))
 	recOpt := E.ToOption(res)
 	assert.True(t, O.IsSome(recOpt))
@@ -798,7 +798,7 @@ func TestAltSemigroup(t *testing.T) {
 	err := errors.New("test error")
 
 	result := sg.Concat(Left[int](err), Of(42))
-	res := result(context.Background())()
+	res := result(t.Context())()
 	assert.Equal(t, E.Right[error](42), res)
 }
 
@@ -810,7 +810,7 @@ func TestApplicativeMonoid(t *testing.T) {
 	))
 
 	result := intAddMonoid.Concat(Of(5), Of(10))
-	res := result(context.Background())()
+	res := result(t.Context())()
 	assert.Equal(t, E.Right[error](15), res)
 }
 
@@ -835,7 +835,7 @@ func TestBracket(t *testing.T) {
 		}
 
 		result := Bracket(acquire, use, release)
-		res := result(context.Background())()
+		res := result(t.Context())()
 
 		assert.True(t, acquired)
 		assert.True(t, released)
@@ -863,7 +863,7 @@ func TestBracket(t *testing.T) {
 		}
 
 		result := Bracket(acquire, use, release)
-		res := result(context.Background())()
+		res := result(t.Context())()
 
 		assert.True(t, acquired)
 		assert.True(t, released)

v2/context/readerioresult/reader_test.go

@@ -29,7 +29,7 @@ import (
 
 func TestInnerContextCancelSemantics(t *testing.T) {
 	// start with a simple context
-	outer := context.Background()
+	outer := t.Context()
 
 	parent, parentCancel := context.WithCancel(outer)
 	defer parentCancel()
@@ -49,7 +49,7 @@ func TestInnerContextCancelSemantics(t *testing.T) {
 
 func TestOuterContextCancelSemantics(t *testing.T) {
 	// start with a simple context
-	outer := context.Background()
+	outer := t.Context()
 
 	parent, outerCancel := context.WithCancel(outer)
 	defer outerCancel()
@@ -69,7 +69,7 @@ func TestOuterContextCancelSemantics(t *testing.T) {
 
 func TestOuterAndInnerContextCancelSemantics(t *testing.T) {
 	// start with a simple context
-	outer := context.Background()
+	outer := t.Context()
 
 	parent, outerCancel := context.WithCancel(outer)
 	defer outerCancel()
@@ -95,7 +95,7 @@ func TestOuterAndInnerContextCancelSemantics(t *testing.T) {
 
 func TestCancelCauseSemantics(t *testing.T) {
 	// start with a simple context
-	outer := context.Background()
+	outer := t.Context()
 
 	parent, outerCancel := context.WithCancelCause(outer)
 	defer outerCancel(nil)
@@ -119,7 +119,7 @@ func TestCancelCauseSemantics(t *testing.T) {
 func TestTimer(t *testing.T) {
 	delta := 3 * time.Second
 	timer := Timer(delta)
-	ctx := context.Background()
+	ctx := t.Context()
 
 	t0 := time.Now()
 	res := timer(ctx)()
@@ -146,7 +146,7 @@ func TestCanceledApply(t *testing.T) {
 		Ap[string](errValue),
 	)
 
-	res := applied(context.Background())()
+	res := applied(t.Context())()
 	assert.Equal(t, E.Left[string](err), res)
 }
 
@@ -159,7 +159,7 @@ func TestRegularApply(t *testing.T) {
 		Ap[string](value),
 	)
 
-	res := applied(context.Background())()
+	res := applied(t.Context())()
 	assert.Equal(t, E.Of[error]("CARSTEN"), res)
 }
 
@@ -187,7 +187,7 @@ func TestWithResourceNoErrors(t *testing.T) {
 
 	resRIOE := WithResource[int](acquire, release)(body)
 
-	res := resRIOE(context.Background())()
+	res := resRIOE(t.Context())()
 
 	assert.Equal(t, 1, countAcquire)
 	assert.Equal(t, 1, countBody)
@@ -217,7 +217,7 @@ func TestWithResourceErrorInBody(t *testing.T) {
 
 	resRIOE := WithResource[int](acquire, release)(body)
 
-	res := resRIOE(context.Background())()
+	res := resRIOE(t.Context())()
 
 	assert.Equal(t, 1, countAcquire)
 	assert.Equal(t, 0, countBody)
@@ -247,7 +247,7 @@ func TestWithResourceErrorInAcquire(t *testing.T) {
 
 	resRIOE := WithResource[int](acquire, release)(body)
 
-	res := resRIOE(context.Background())()
+	res := resRIOE(t.Context())()
 
 	assert.Equal(t, 0, countAcquire)
 	assert.Equal(t, 0, countBody)
@@ -277,7 +277,7 @@ func TestWithResourceErrorInRelease(t *testing.T) {
 
 	resRIOE := WithResource[int](acquire, release)(body)
 
-	res := resRIOE(context.Background())()
+	res := resRIOE(t.Context())()
 
 	assert.Equal(t, 1, countAcquire)
 	assert.Equal(t, 1, countBody)
@@ -286,7 +286,7 @@ func TestWithResourceErrorInRelease(t *testing.T) {
 }
 
 func TestMonadChainFirstLeft(t *testing.T) {
-	ctx := context.Background()
+	ctx := t.Context()
 
 	// Test with Left value - function returns Left, always preserves original error
 	t.Run("Left value with function returning Left preserves original error", func(t *testing.T) {
@@ -353,7 +353,7 @@ func TestMonadChainFirstLeft(t *testing.T) {
 }
 
 func TestChainFirstLeft(t *testing.T) {
-	ctx := context.Background()
+	ctx := t.Context()
 
 	// Test with Left value - function returns Left, always preserves original error
 	t.Run("Left value with function returning Left preserves error", func(t *testing.T) {

v2/context/readerioresult/rec.go

@@ -108,7 +108,7 @@ import (
 //	countdown := readerioresult.TailRec(countdownStep)
 //
 //	// With cancellation
-//	ctx, cancel := context.WithTimeout(context.Background(), 500*time.Millisecond)
+//	ctx, cancel := context.WithTimeout(t.Context(), 500*time.Millisecond)
 //	defer cancel()
 //	result := countdown(10)(ctx)() // Will be cancelled after ~500ms
 //
@@ -141,7 +141,7 @@ import (
 //	}
 //
 //	processFiles := readerioresult.TailRec(processStep)
-//	ctx, cancel := context.WithCancel(context.Background())
+//	ctx, cancel := context.WithCancel(t.Context())
 //
 //	// Can be cancelled at any point during processing
 //	go func() {
@@ -159,7 +159,7 @@ import (
 //
 //	// Safe for very large inputs with cancellation support
 //	largeCountdown := readerioresult.TailRec(countdownStep)
-//	ctx := context.Background()
+//	ctx := t.Context()
 //	result := largeCountdown(1000000)(ctx)() // Safe, no stack overflow
 //
 // # Performance Considerations

v2/context/readerioresult/rec_test.go

@@ -44,7 +44,7 @@ func TestTailRec_BasicRecursion(t *testing.T) {
 	}
 
 	countdown := TailRec(countdownStep)
-	result := countdown(5)(context.Background())()
+	result := countdown(5)(t.Context())()
 
 	assert.Equal(t, E.Of[error]("Done!"), result)
 }
@@ -71,7 +71,7 @@ func TestTailRec_FactorialRecursion(t *testing.T) {
 	}
 
 	factorial := TailRec(factorialStep)
-	result := factorial(FactorialState{n: 5, acc: 1})(context.Background())()
+	result := factorial(FactorialState{n: 5, acc: 1})(t.Context())()
 
 	assert.Equal(t, E.Of[error](120), result) // 5! = 120
 }
@@ -95,7 +95,7 @@ func TestTailRec_ErrorHandling(t *testing.T) {
 	}
 
 	errorRecursion := TailRec(errorStep)
-	result := errorRecursion(5)(context.Background())()
+	result := errorRecursion(5)(t.Context())()
 
 	assert.True(t, E.IsLeft(result))
 	err := E.ToError(result)
@@ -125,7 +125,7 @@ func TestTailRec_ContextCancellation(t *testing.T) {
 	slowRecursion := TailRec(slowStep)
 
 	// Create a context that will be cancelled after 100ms
-	ctx, cancel := context.WithTimeout(context.Background(), 100*time.Millisecond)
+	ctx, cancel := context.WithTimeout(t.Context(), 100*time.Millisecond)
 	defer cancel()
 
 	start := time.Now()
@@ -159,7 +159,7 @@ func TestTailRec_ImmediateCancellation(t *testing.T) {
 	countdown := TailRec(countdownStep)
 
 	// Create an already cancelled context
-	ctx, cancel := context.WithCancel(context.Background())
+	ctx, cancel := context.WithCancel(t.Context())
 	cancel()
 
 	result := countdown(5)(ctx)()
@@ -186,7 +186,7 @@ func TestTailRec_StackSafety(t *testing.T) {
 	}
 
 	countdown := TailRec(countdownStep)
-	result := countdown(largeN)(context.Background())()
+	result := countdown(largeN)(t.Context())()
 
 	assert.Equal(t, E.Of[error](0), result)
 }
@@ -217,7 +217,7 @@ func TestTailRec_StackSafetyWithCancellation(t *testing.T) {
 	countdown := TailRec(countdownStep)
 
 	// Cancel after 50ms to allow some iterations but not all
-	ctx, cancel := context.WithTimeout(context.Background(), 50*time.Millisecond)
+	ctx, cancel := context.WithTimeout(t.Context(), 50*time.Millisecond)
 	defer cancel()
 
 	result := countdown(largeN)(ctx)()
@@ -274,7 +274,7 @@ func TestTailRec_ComplexState(t *testing.T) {
 			errors:    []error{},
 		}
 
-		result := processItems(initialState)(context.Background())()
+		result := processItems(initialState)(t.Context())()
 
 		assert.Equal(t, E.Of[error]([]string{"item1", "item2", "item3"}), result)
 	})
@@ -286,7 +286,7 @@ func TestTailRec_ComplexState(t *testing.T) {
 			errors:    []error{},
 		}
 
-		result := processItems(initialState)(context.Background())()
+		result := processItems(initialState)(t.Context())()
 
 		assert.True(t, E.IsLeft(result))
 		err := E.ToError(result)
@@ -336,7 +336,7 @@ func TestTailRec_CancellationDuringProcessing(t *testing.T) {
 	}
 
 	// Cancel after 100ms (should allow ~5 files to be processed)
-	ctx, cancel := context.WithTimeout(context.Background(), 100*time.Millisecond)
+	ctx, cancel := context.WithTimeout(t.Context(), 100*time.Millisecond)
 	defer cancel()
 
 	start := time.Now()
@@ -366,7 +366,7 @@ func TestTailRec_ZeroIterations(t *testing.T) {
 	}
 
 	immediate := TailRec(immediateStep)
-	result := immediate(100)(context.Background())()
+	result := immediate(100)(t.Context())()
 
 	assert.Equal(t, E.Of[error]("immediate"), result)
 }
@@ -392,7 +392,7 @@ func TestTailRec_ContextWithDeadline(t *testing.T) {
 	slowRecursion := TailRec(slowStep)
 
 	// Set deadline 80ms from now
-	ctx, cancel := context.WithDeadline(context.Background(), time.Now().Add(80*time.Millisecond))
+	ctx, cancel := context.WithDeadline(t.Context(), time.Now().Add(80*time.Millisecond))
 	defer cancel()
 
 	result := slowRecursion(10)(ctx)()
@@ -427,7 +427,7 @@ func TestTailRec_ContextWithValue(t *testing.T) {
 	}
 
 	valueRecursion := TailRec(valueStep)
-	ctx := context.WithValue(context.Background(), testKey, "test-value")
+	ctx := context.WithValue(t.Context(), testKey, "test-value")
 	result := valueRecursion(3)(ctx)()
 
 	assert.Equal(t, E.Of[error]("Done!"), result)

v2/context/readerioresult/retry.go

@@ -107,7 +107,7 @@ import (
 //	retryingFetch := Retrying(policy, fetchData, shouldRetry)
 //
 //	// Execute with a cancellable context
-//	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+//	ctx, cancel := context.WithTimeout(t.Context(), 5*time.Second)
 //	defer cancel()
 //	ioResult := retryingFetch(ctx)
 //	finalResult := ioResult()

v2/context/readerioresult/type.go

@@ -113,7 +113,7 @@ type (
 	//   }
 	//
 	// The computation is executed by providing a context and then invoking the result:
-	//   ctx := context.Background()
+	//   ctx := t.Context()
 	//   result := fetchUser("123")(ctx)()
 	ReaderIOResult[A any] = RIOR.ReaderIOResult[context.Context, A]
 

v2/context/readerreaderioresult/bind.go

@@ -0,0 +1,453 @@
+// Copyright (c) 2023 - 2025 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package readerreaderioresult
+
+import (
+	"github.com/IBM/fp-go/v2/either"
+	F "github.com/IBM/fp-go/v2/function"
+	"github.com/IBM/fp-go/v2/internal/apply"
+	"github.com/IBM/fp-go/v2/internal/chain"
+	"github.com/IBM/fp-go/v2/internal/functor"
+	"github.com/IBM/fp-go/v2/io"
+	"github.com/IBM/fp-go/v2/ioeither"
+	"github.com/IBM/fp-go/v2/ioresult"
+	"github.com/IBM/fp-go/v2/reader"
+	"github.com/IBM/fp-go/v2/readerio"
+)
+
+// Do creates an empty context of type [S] to be used with the [Bind] operation.
+// This is the starting point for do-notation style composition with two reader contexts.
+//
+// Example:
+//
+//	type State struct {
+//	    User   User
+//	    Posts  []Post
+//	}
+//	type OuterEnv struct {
+//	    Database string
+//	}
+//	type InnerEnv struct {
+//	    UserRepo UserRepository
+//	    PostRepo PostRepository
+//	}
+//	result := readerreaderioeither.Do[OuterEnv, InnerEnv, error](State{})
+//
+//go:inline
+func Do[R, S any](
+	empty S,
+) ReaderReaderIOResult[R, S] {
+	return Of[R](empty)
+}
+
+// Bind attaches the result of a computation to a context [S1] to produce a context [S2].
+// This enables sequential composition where each step can depend on the results of previous steps
+// and access both the outer (R) and inner (C) reader environments.
+//
+// The setter function takes the result of the computation and returns a function that
+// updates the context from S1 to S2.
+//
+// Example:
+//
+//	type State struct {
+//	    User   User
+//	    Posts  []Post
+//	}
+//	type OuterEnv struct {
+//	    Database string
+//	}
+//	type InnerEnv struct {
+//	    UserRepo UserRepository
+//	    PostRepo PostRepository
+//	}
+//
+//	result := F.Pipe2(
+//	    readerreaderioeither.Do[OuterEnv, InnerEnv, error](State{}),
+//	    readerreaderioeither.Bind(
+//	        func(user User) func(State) State {
+//	            return func(s State) State { s.User = user; return s }
+//	        },
+//	        func(s State) readerreaderioeither.ReaderReaderIOResult[OuterEnv, InnerEnv, error, User] {
+//	            return func(outer OuterEnv) readerioeither.ReaderIOEither[InnerEnv, error, User] {
+//	                return readerioeither.Asks(func(inner InnerEnv) ioeither.IOEither[error, User] {
+//	                    return inner.UserRepo.FindUser(outer.Database)
+//	                })
+//	            }
+//	        },
+//	    ),
+//	    readerreaderioeither.Bind(
+//	        func(posts []Post) func(State) State {
+//	            return func(s State) State { s.Posts = posts; return s }
+//	        },
+//	        func(s State) readerreaderioeither.ReaderReaderIOResult[OuterEnv, InnerEnv, error, []Post] {
+//	            return func(outer OuterEnv) readerioeither.ReaderIOEither[InnerEnv, error, []Post] {
+//	                return readerioeither.Asks(func(inner InnerEnv) ioeither.IOEither[error, []Post] {
+//	                    return inner.PostRepo.FindPostsByUser(outer.Database, s.User.ID)
+//	                })
+//	            }
+//	        },
+//	    ),
+//	)
+//
+//go:inline
+func Bind[R, S1, S2, T any](
+	setter func(T) func(S1) S2,
+	f func(S1) ReaderReaderIOResult[R, T],
+) Operator[R, S1, S2] {
+	return chain.Bind(
+		Chain[R, S1, S2],
+		Map[R, T, S2],
+		setter,
+		f,
+	)
+}
+
+// Let attaches a pure computation result to a context [S1] to produce a context [S2].
+// Unlike [Bind], the computation function f is pure (doesn't perform effects).
+//
+// Example:
+//
+//	readerreaderioeither.Let(
+//	    func(fullName string) func(State) State {
+//	        return func(s State) State { s.FullName = fullName; return s }
+//	    },
+//	    func(s State) string {
+//	        return s.FirstName + " " + s.LastName
+//	    },
+//	)
+//
+//go:inline
+func Let[R, S1, S2, T any](
+	setter func(T) func(S1) S2,
+	f func(S1) T,
+) Operator[R, S1, S2] {
+	return functor.Let(
+		Map[R, S1, S2],
+		setter,
+		f,
+	)
+}
+
+// LetTo attaches a constant value to a context [S1] to produce a context [S2].
+//
+// Example:
+//
+//	readerreaderioeither.LetTo(
+//	    func(status string) func(State) State {
+//	        return func(s State) State { s.Status = status; return s }
+//	    },
+//	    "active",
+//	)
+//
+//go:inline
+func LetTo[R, S1, S2, T any](
+	setter func(T) func(S1) S2,
+	b T,
+) Operator[R, S1, S2] {
+	return functor.LetTo(
+		Map[R, S1, S2],
+		setter,
+		b,
+	)
+}
+
+// BindTo wraps a value of type T into a context S1 using the provided setter function.
+// This is typically used as the first operation after [Do] to initialize the context.
+//
+// Example:
+//
+//	F.Pipe1(
+//	    readerreaderioeither.Of[OuterEnv, InnerEnv, error](42),
+//	    readerreaderioeither.BindTo(func(n int) State { return State{Count: n} }),
+//	)
+//
+//go:inline
+func BindTo[R, S1, T any](
+	setter func(T) S1,
+) Operator[R, T, S1] {
+	return chain.BindTo(
+		Map[R, T, S1],
+		setter,
+	)
+}
+
+// ApS applies a computation in parallel (applicative style) and attaches its result to the context.
+// Unlike [Bind], this doesn't allow the computation to depend on the current context state.
+//
+// Example:
+//
+//	readerreaderioeither.ApS(
+//	    func(count int) func(State) State {
+//	        return func(s State) State { s.Count = count; return s }
+//	    },
+//	    getCount, // ReaderReaderIOResult[OuterEnv, InnerEnv, error, int]
+//	)
+//
+//go:inline
+func ApS[R, S1, S2, T any](
+	setter func(T) func(S1) S2,
+	fa ReaderReaderIOResult[R, T],
+) Operator[R, S1, S2] {
+	return apply.ApS(
+		Ap[S2, R, T],
+		Map[R, S1, func(T) S2],
+		setter,
+		fa,
+	)
+}
+
+// ApSL is a lens-based version of [ApS] that uses a lens to focus on a specific field in the context.
+//
+//go:inline
+func ApSL[R, S, T any](
+	lens Lens[S, T],
+	fa ReaderReaderIOResult[R, T],
+) Operator[R, S, S] {
+	return ApS(lens.Set, fa)
+}
+
+// BindL is a lens-based version of [Bind] that uses a lens to focus on a specific field in the context.
+//
+//go:inline
+func BindL[R, S, T any](
+	lens Lens[S, T],
+	f func(T) ReaderReaderIOResult[R, T],
+) Operator[R, S, S] {
+	return Bind(lens.Set, F.Flow2(lens.Get, f))
+}
+
+// LetL is a lens-based version of [Let] that uses a lens to focus on a specific field in the context.
+//
+//go:inline
+func LetL[R, S, T any](
+	lens Lens[S, T],
+	f func(T) T,
+) Operator[R, S, S] {
+	return Let[R](lens.Set, F.Flow2(lens.Get, f))
+}
+
+// LetToL is a lens-based version of [LetTo] that uses a lens to focus on a specific field in the context.
+//
+//go:inline
+func LetToL[R, S, T any](
+	lens Lens[S, T],
+	b T,
+) Operator[R, S, S] {
+	return LetTo[R](lens.Set, b)
+}
+
+// BindIOEitherK binds a computation that returns an IOEither to the context.
+// The Kleisli function is automatically lifted into ReaderReaderIOResult.
+//
+//go:inline
+func BindIOEitherK[R, S1, S2, T any](
+	setter func(T) func(S1) S2,
+	f ioeither.Kleisli[error, S1, T],
+) Operator[R, S1, S2] {
+	return Bind(setter, F.Flow2(f, FromIOEither[R, T]))
+}
+
+//go:inline
+func BindIOResultK[R, S1, S2, T any](
+	setter func(T) func(S1) S2,
+	f ioresult.Kleisli[S1, T],
+) Operator[R, S1, S2] {
+	return Bind(setter, F.Flow2(f, FromIOResult[R, T]))
+}
+
+// BindIOK binds a computation that returns an IO to the context.
+// The Kleisli function is automatically lifted into ReaderReaderIOResult.
+//
+//go:inline
+func BindIOK[R, S1, S2, T any](
+	setter func(T) func(S1) S2,
+	f io.Kleisli[S1, T],
+) Operator[R, S1, S2] {
+	return Bind(setter, F.Flow2(f, FromIO[R, T]))
+}
+
+// BindReaderK binds a computation that returns a Reader to the context.
+// The Kleisli function is automatically lifted into ReaderReaderIOResult.
+//
+//go:inline
+func BindReaderK[R, S1, S2, T any](
+	setter func(T) func(S1) S2,
+	f reader.Kleisli[R, S1, T],
+) Operator[R, S1, S2] {
+	return Bind(setter, F.Flow2(f, FromReader[R, T]))
+}
+
+// BindReaderIOK binds a computation that returns a ReaderIO to the context.
+// The Kleisli function is automatically lifted into ReaderReaderIOResult.
+//
+//go:inline
+func BindReaderIOK[R, S1, S2, T any](
+	setter func(T) func(S1) S2,
+	f readerio.Kleisli[R, S1, T],
+) Operator[R, S1, S2] {
+	return Bind(setter, F.Flow2(f, FromReaderIO[R, T]))
+}
+
+// BindEitherK binds a computation that returns an Either to the context.
+// The Kleisli function is automatically lifted into ReaderReaderIOResult.
+//
+//go:inline
+func BindEitherK[R, S1, S2, T any](
+	setter func(T) func(S1) S2,
+	f either.Kleisli[error, S1, T],
+) Operator[R, S1, S2] {
+	return Bind(setter, F.Flow2(f, FromEither[R, T]))
+}
+
+// BindIOEitherKL is a lens-based version of [BindIOEitherK].
+//
+//go:inline
+func BindIOEitherKL[R, S, T any](
+	lens Lens[S, T],
+	f ioeither.Kleisli[error, T, T],
+) Operator[R, S, S] {
+	return BindL(lens, F.Flow2(f, FromIOEither[R, T]))
+}
+
+// BindIOKL is a lens-based version of [BindIOK].
+//
+//go:inline
+func BindIOKL[R, S, T any](
+	lens Lens[S, T],
+	f io.Kleisli[T, T],
+) Operator[R, S, S] {
+	return BindL(lens, F.Flow2(f, FromIO[R, T]))
+}
+
+// BindReaderKL is a lens-based version of [BindReaderK].
+//
+//go:inline
+func BindReaderKL[R, S, T any](
+	lens Lens[S, T],
+	f reader.Kleisli[R, T, T],
+) Operator[R, S, S] {
+	return BindL(lens, F.Flow2(f, FromReader[R, T]))
+}
+
+// BindReaderIOKL is a lens-based version of [BindReaderIOK].
+//
+//go:inline
+func BindReaderIOKL[R, S, T any](
+	lens Lens[S, T],
+	f readerio.Kleisli[R, T, T],
+) Operator[R, S, S] {
+	return BindL(lens, F.Flow2(f, FromReaderIO[R, T]))
+}
+
+// ApIOEitherS applies an IOEither computation and attaches its result to the context.
+//
+//go:inline
+func ApIOEitherS[R, S1, S2, T any](
+	setter func(T) func(S1) S2,
+	fa IOEither[error, T],
+) Operator[R, S1, S2] {
+	return ApS(setter, FromIOEither[R](fa))
+}
+
+// ApIOS applies an IO computation and attaches its result to the context.
+//
+//go:inline
+func ApIOS[R, S1, S2, T any](
+	setter func(T) func(S1) S2,
+	fa IO[T],
+) Operator[R, S1, S2] {
+	return ApS(setter, FromIO[R](fa))
+}
+
+// ApReaderS applies a Reader computation and attaches its result to the context.
+//
+//go:inline
+func ApReaderS[R, S1, S2, T any](
+	setter func(T) func(S1) S2,
+	fa Reader[R, T],
+) Operator[R, S1, S2] {
+	return ApS(setter, FromReader(fa))
+}
+
+// ApReaderIOS applies a ReaderIO computation and attaches its result to the context.
+//
+//go:inline
+func ApReaderIOS[R, S1, S2, T any](
+	setter func(T) func(S1) S2,
+	fa ReaderIO[R, T],
+) Operator[R, S1, S2] {
+	return ApS(setter, FromReaderIO(fa))
+}
+
+// ApEitherS applies an Either computation and attaches its result to the context.
+//
+//go:inline
+func ApEitherS[R, S1, S2, T any](
+	setter func(T) func(S1) S2,
+	fa Either[error, T],
+) Operator[R, S1, S2] {
+	return ApS(setter, FromEither[R](fa))
+}
+
+// ApIOEitherSL is a lens-based version of [ApIOEitherS].
+//
+//go:inline
+func ApIOEitherSL[R, S, T any](
+	lens Lens[S, T],
+	fa IOEither[error, T],
+) Operator[R, S, S] {
+	return ApIOEitherS[R](lens.Set, fa)
+}
+
+// ApIOSL is a lens-based version of [ApIOS].
+//
+//go:inline
+func ApIOSL[R, S, T any](
+	lens Lens[S, T],
+	fa IO[T],
+) Operator[R, S, S] {
+	return ApSL(lens, FromIO[R](fa))
+}
+
+// ApReaderSL is a lens-based version of [ApReaderS].
+//
+//go:inline
+func ApReaderSL[R, S, T any](
+	lens Lens[S, T],
+	fa Reader[R, T],
+) Operator[R, S, S] {
+	return ApReaderS(lens.Set, fa)
+}
+
+// ApReaderIOSL is a lens-based version of [ApReaderIOS].
+//
+//go:inline
+func ApReaderIOSL[R, S, T any](
+	lens Lens[S, T],
+	fa ReaderIO[R, T],
+) Operator[R, S, S] {
+	return ApReaderIOS(lens.Set, fa)
+}
+
+// ApEitherSL is a lens-based version of [ApEitherS].
+//
+//go:inline
+func ApEitherSL[R, S, T any](
+	lens Lens[S, T],
+	fa Either[error, T],
+) Operator[R, S, S] {
+	return ApEitherS[R](lens.Set, fa)
+}

v2/context/readerreaderioresult/bind_test.go

@@ -0,0 +1,720 @@
+// Copyright (c) 2023 - 2025 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package readerreaderioresult
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/IBM/fp-go/v2/either"
+	F "github.com/IBM/fp-go/v2/function"
+	"github.com/IBM/fp-go/v2/internal/utils"
+	"github.com/IBM/fp-go/v2/io"
+	"github.com/IBM/fp-go/v2/ioeither"
+	"github.com/IBM/fp-go/v2/ioresult"
+	"github.com/IBM/fp-go/v2/optics/lens"
+	"github.com/IBM/fp-go/v2/reader"
+	"github.com/IBM/fp-go/v2/readerio"
+	"github.com/IBM/fp-go/v2/result"
+	"github.com/stretchr/testify/assert"
+)
+
+type AppConfig struct {
+	DatabaseURL string
+	LogLevel    string
+}
+
+var defaultConfig = AppConfig{
+	DatabaseURL: "postgres://localhost",
+	LogLevel:    "info",
+}
+
+func getLastName(s utils.Initial) ReaderReaderIOResult[AppConfig, string] {
+	return Of[AppConfig]("Doe")
+}
+
+func getGivenName(s utils.WithLastName) ReaderReaderIOResult[AppConfig, string] {
+	return Of[AppConfig]("John")
+}
+
+func TestDo(t *testing.T) {
+	res := Do[AppConfig](utils.Empty)
+	outcome := res(defaultConfig)(t.Context())()
+
+	assert.True(t, result.IsRight(outcome))
+	assert.Equal(t, result.Of(utils.Empty), outcome)
+}
+
+func TestBind(t *testing.T) {
+	res := F.Pipe3(
+		Do[AppConfig](utils.Empty),
+		Bind(utils.SetLastName, getLastName),
+		Bind(utils.SetGivenName, getGivenName),
+		Map[AppConfig](utils.GetFullName),
+	)
+
+	outcome := res(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of("John Doe"), outcome)
+}
+
+func TestBindWithError(t *testing.T) {
+	testErr := errors.New("bind error")
+
+	getLastNameErr := func(s utils.Initial) ReaderReaderIOResult[AppConfig, string] {
+		return Left[AppConfig, string](testErr)
+	}
+
+	res := F.Pipe3(
+		Do[AppConfig](utils.Empty),
+		Bind(utils.SetLastName, getLastNameErr),
+		Bind(utils.SetGivenName, getGivenName),
+		Map[AppConfig](utils.GetFullName),
+	)
+
+	outcome := res(defaultConfig)(t.Context())()
+	assert.True(t, result.IsLeft(outcome))
+}
+
+func TestLet(t *testing.T) {
+	type State struct {
+		FirstName string
+		LastName  string
+		FullName  string
+	}
+
+	res := F.Pipe2(
+		Do[AppConfig](State{FirstName: "John", LastName: "Doe"}),
+		Let[AppConfig](
+			func(fullName string) func(State) State {
+				return func(s State) State {
+					s.FullName = fullName
+					return s
+				}
+			},
+			func(s State) string {
+				return s.FirstName + " " + s.LastName
+			},
+		),
+		Map[AppConfig](func(s State) string { return s.FullName }),
+	)
+
+	outcome := res(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of("John Doe"), outcome)
+}
+
+func TestLetTo(t *testing.T) {
+	type State struct {
+		Status string
+	}
+
+	res := F.Pipe2(
+		Do[AppConfig](State{}),
+		LetTo[AppConfig](
+			func(status string) func(State) State {
+				return func(s State) State {
+					s.Status = status
+					return s
+				}
+			},
+			"active",
+		),
+		Map[AppConfig](func(s State) string { return s.Status }),
+	)
+
+	outcome := res(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of("active"), outcome)
+}
+
+func TestBindTo(t *testing.T) {
+	type State struct {
+		Count int
+	}
+
+	res := F.Pipe2(
+		Of[AppConfig](42),
+		BindTo[AppConfig](func(n int) State { return State{Count: n} }),
+		Map[AppConfig](func(s State) int { return s.Count }),
+	)
+
+	outcome := res(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(42), outcome)
+}
+
+func TestApS(t *testing.T) {
+	res := F.Pipe3(
+		Do[AppConfig](utils.Empty),
+		ApS(utils.SetLastName, Of[AppConfig]("Doe")),
+		ApS(utils.SetGivenName, Of[AppConfig]("John")),
+		Map[AppConfig](utils.GetFullName),
+	)
+
+	outcome := res(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of("John Doe"), outcome)
+}
+
+func TestApSWithError(t *testing.T) {
+	testErr := errors.New("aps error")
+
+	res := F.Pipe3(
+		Do[AppConfig](utils.Empty),
+		ApS(utils.SetLastName, Left[AppConfig, string](testErr)),
+		ApS(utils.SetGivenName, Of[AppConfig]("John")),
+		Map[AppConfig](utils.GetFullName),
+	)
+
+	outcome := res(defaultConfig)(t.Context())()
+	assert.True(t, result.IsLeft(outcome))
+}
+
+func TestBindReaderK(t *testing.T) {
+	type State struct {
+		Config string
+	}
+
+	getConfigPath := func(s State) func(AppConfig) string {
+		return func(cfg AppConfig) string {
+			return cfg.DatabaseURL
+		}
+	}
+
+	res := F.Pipe2(
+		Do[AppConfig](State{}),
+		BindReaderK(
+			func(path string) func(State) State {
+				return func(s State) State {
+					s.Config = path
+					return s
+				}
+			},
+			getConfigPath,
+		),
+		Map[AppConfig](func(s State) string { return s.Config }),
+	)
+
+	outcome := res(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of("postgres://localhost"), outcome)
+}
+
+func TestBindIOResultK(t *testing.T) {
+	type State struct {
+		Value       int
+		ParsedValue int
+	}
+
+	parseValue := func(s State) ioresult.IOResult[int] {
+		return func() result.Result[int] {
+			if s.Value < 0 {
+				return result.Left[int](errors.New("negative value"))
+			}
+			return result.Of(s.Value * 2)
+		}
+	}
+
+	t.Run("success case", func(t *testing.T) {
+		res := F.Pipe2(
+			Do[AppConfig](State{Value: 5}),
+			BindIOResultK[AppConfig](
+				func(parsed int) func(State) State {
+					return func(s State) State {
+						s.ParsedValue = parsed
+						return s
+					}
+				},
+				parseValue,
+			),
+			Map[AppConfig](func(s State) int { return s.ParsedValue }),
+		)
+
+		outcome := res(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(10), outcome)
+	})
+
+	t.Run("error case", func(t *testing.T) {
+		res := F.Pipe2(
+			Do[AppConfig](State{Value: -5}),
+			BindIOResultK[AppConfig](
+				func(parsed int) func(State) State {
+					return func(s State) State {
+						s.ParsedValue = parsed
+						return s
+					}
+				},
+				parseValue,
+			),
+			Map[AppConfig](func(s State) int { return s.ParsedValue }),
+		)
+
+		outcome := res(defaultConfig)(t.Context())()
+		assert.True(t, result.IsLeft(outcome))
+	})
+}
+
+func TestBindIOK(t *testing.T) {
+	type State struct {
+		Value int
+	}
+
+	getValue := func(s State) io.IO[int] {
+		return func() int {
+			return s.Value * 2
+		}
+	}
+
+	res := F.Pipe2(
+		Do[AppConfig](State{Value: 21}),
+		BindIOK[AppConfig](
+			func(v int) func(State) State {
+				return func(s State) State {
+					s.Value = v
+					return s
+				}
+			},
+			getValue,
+		),
+		Map[AppConfig](func(s State) int { return s.Value }),
+	)
+
+	outcome := res(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(42), outcome)
+}
+
+func TestBindReaderIOK(t *testing.T) {
+	type State struct {
+		Value int
+	}
+
+	getValue := func(s State) readerio.ReaderIO[AppConfig, int] {
+		return func(cfg AppConfig) io.IO[int] {
+			return func() int {
+				return s.Value + len(cfg.DatabaseURL)
+			}
+		}
+	}
+
+	res := F.Pipe2(
+		Do[AppConfig](State{Value: 10}),
+		BindReaderIOK(
+			func(v int) func(State) State {
+				return func(s State) State {
+					s.Value = v
+					return s
+				}
+			},
+			getValue,
+		),
+		Map[AppConfig](func(s State) int { return s.Value }),
+	)
+
+	outcome := res(defaultConfig)(t.Context())()
+	// 10 + len("postgres://localhost") = 10 + 20 = 30
+	assert.Equal(t, result.Of(30), outcome)
+}
+
+func TestBindEitherK(t *testing.T) {
+	type State struct {
+		Value int
+	}
+
+	parseValue := func(s State) either.Either[error, int] {
+		if s.Value < 0 {
+			return either.Left[int](errors.New("negative"))
+		}
+		return either.Right[error](s.Value * 2)
+	}
+
+	t.Run("success case", func(t *testing.T) {
+		res := F.Pipe2(
+			Do[AppConfig](State{Value: 5}),
+			BindEitherK[AppConfig](
+				func(v int) func(State) State {
+					return func(s State) State {
+						s.Value = v
+						return s
+					}
+				},
+				parseValue,
+			),
+			Map[AppConfig](func(s State) int { return s.Value }),
+		)
+
+		outcome := res(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(10), outcome)
+	})
+
+	t.Run("error case", func(t *testing.T) {
+		res := F.Pipe2(
+			Do[AppConfig](State{Value: -5}),
+			BindEitherK[AppConfig](
+				func(v int) func(State) State {
+					return func(s State) State {
+						s.Value = v
+						return s
+					}
+				},
+				parseValue,
+			),
+			Map[AppConfig](func(s State) int { return s.Value }),
+		)
+
+		outcome := res(defaultConfig)(t.Context())()
+		assert.True(t, result.IsLeft(outcome))
+	})
+}
+
+func TestBindIOEitherK(t *testing.T) {
+	type State struct {
+		Value int
+	}
+
+	parseValue := func(s State) ioeither.IOEither[error, int] {
+		return func() either.Either[error, int] {
+			if s.Value < 0 {
+				return either.Left[int](errors.New("negative"))
+			}
+			return either.Right[error](s.Value * 2)
+		}
+	}
+
+	t.Run("success case", func(t *testing.T) {
+		res := F.Pipe2(
+			Do[AppConfig](State{Value: 5}),
+			BindIOEitherK[AppConfig](
+				func(v int) func(State) State {
+					return func(s State) State {
+						s.Value = v
+						return s
+					}
+				},
+				parseValue,
+			),
+			Map[AppConfig](func(s State) int { return s.Value }),
+		)
+
+		outcome := res(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(10), outcome)
+	})
+
+	t.Run("error case", func(t *testing.T) {
+		res := F.Pipe2(
+			Do[AppConfig](State{Value: -5}),
+			BindIOEitherK[AppConfig](
+				func(v int) func(State) State {
+					return func(s State) State {
+						s.Value = v
+						return s
+					}
+				},
+				parseValue,
+			),
+			Map[AppConfig](func(s State) int { return s.Value }),
+		)
+
+		outcome := res(defaultConfig)(t.Context())()
+		assert.True(t, result.IsLeft(outcome))
+	})
+}
+
+func TestLensOperations(t *testing.T) {
+	type State struct {
+		Value int
+	}
+
+	valueLens := lens.MakeLens(
+		func(s State) int { return s.Value },
+		func(s State, v int) State {
+			s.Value = v
+			return s
+		},
+	)
+
+	t.Run("ApSL", func(t *testing.T) {
+		res := F.Pipe2(
+			Do[AppConfig](State{}),
+			ApSL(valueLens, Of[AppConfig](42)),
+			Map[AppConfig](func(s State) int { return s.Value }),
+		)
+
+		outcome := res(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(42), outcome)
+	})
+
+	t.Run("BindL", func(t *testing.T) {
+		res := F.Pipe2(
+			Do[AppConfig](State{Value: 10}),
+			BindL(valueLens, func(v int) ReaderReaderIOResult[AppConfig, int] {
+				return Of[AppConfig](v * 2)
+			}),
+			Map[AppConfig](func(s State) int { return s.Value }),
+		)
+
+		outcome := res(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(20), outcome)
+	})
+
+	t.Run("LetL", func(t *testing.T) {
+		res := F.Pipe2(
+			Do[AppConfig](State{Value: 10}),
+			LetL[AppConfig](valueLens, func(v int) int { return v * 3 }),
+			Map[AppConfig](func(s State) int { return s.Value }),
+		)
+
+		outcome := res(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(30), outcome)
+	})
+
+	t.Run("LetToL", func(t *testing.T) {
+		res := F.Pipe2(
+			Do[AppConfig](State{}),
+			LetToL[AppConfig](valueLens, 99),
+			Map[AppConfig](func(s State) int { return s.Value }),
+		)
+
+		outcome := res(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(99), outcome)
+	})
+
+	t.Run("BindIOEitherKL", func(t *testing.T) {
+		res := F.Pipe2(
+			Do[AppConfig](State{Value: 5}),
+			BindIOEitherKL[AppConfig](valueLens, func(v int) ioeither.IOEither[error, int] {
+				return ioeither.Of[error](v * 2)
+			}),
+			Map[AppConfig](func(s State) int { return s.Value }),
+		)
+
+		outcome := res(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(10), outcome)
+	})
+
+	t.Run("BindIOKL", func(t *testing.T) {
+		res := F.Pipe2(
+			Do[AppConfig](State{Value: 7}),
+			BindIOKL[AppConfig](valueLens, func(v int) io.IO[int] {
+				return func() int { return v * 3 }
+			}),
+			Map[AppConfig](func(s State) int { return s.Value }),
+		)
+
+		outcome := res(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(21), outcome)
+	})
+
+	t.Run("BindReaderKL", func(t *testing.T) {
+		res := F.Pipe2(
+			Do[AppConfig](State{Value: 5}),
+			BindReaderKL(valueLens, func(v int) reader.Reader[AppConfig, int] {
+				return func(cfg AppConfig) int {
+					return v + len(cfg.LogLevel)
+				}
+			}),
+			Map[AppConfig](func(s State) int { return s.Value }),
+		)
+
+		outcome := res(defaultConfig)(t.Context())()
+		// 5 + len("info") = 5 + 4 = 9
+		assert.Equal(t, result.Of(9), outcome)
+	})
+
+	t.Run("BindReaderIOKL", func(t *testing.T) {
+		res := F.Pipe2(
+			Do[AppConfig](State{Value: 10}),
+			BindReaderIOKL(valueLens, func(v int) readerio.ReaderIO[AppConfig, int] {
+				return func(cfg AppConfig) io.IO[int] {
+					return func() int {
+						return v + len(cfg.DatabaseURL)
+					}
+				}
+			}),
+			Map[AppConfig](func(s State) int { return s.Value }),
+		)
+
+		outcome := res(defaultConfig)(t.Context())()
+		// 10 + len("postgres://localhost") = 10 + 20 = 30
+		assert.Equal(t, result.Of(30), outcome)
+	})
+
+	t.Run("ApIOEitherSL", func(t *testing.T) {
+		res := F.Pipe2(
+			Do[AppConfig](State{}),
+			ApIOEitherSL[AppConfig](valueLens, ioeither.Of[error](42)),
+			Map[AppConfig](func(s State) int { return s.Value }),
+		)
+
+		outcome := res(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(42), outcome)
+	})
+
+	t.Run("ApIOSL", func(t *testing.T) {
+		res := F.Pipe2(
+			Do[AppConfig](State{}),
+			ApIOSL[AppConfig](valueLens, func() int { return 99 }),
+			Map[AppConfig](func(s State) int { return s.Value }),
+		)
+
+		outcome := res(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(99), outcome)
+	})
+
+	t.Run("ApReaderSL", func(t *testing.T) {
+		res := F.Pipe2(
+			Do[AppConfig](State{}),
+			ApReaderSL(valueLens, func(cfg AppConfig) int {
+				return len(cfg.LogLevel)
+			}),
+			Map[AppConfig](func(s State) int { return s.Value }),
+		)
+
+		outcome := res(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(4), outcome)
+	})
+
+	t.Run("ApReaderIOSL", func(t *testing.T) {
+		res := F.Pipe2(
+			Do[AppConfig](State{}),
+			ApReaderIOSL(valueLens, func(cfg AppConfig) io.IO[int] {
+				return func() int { return len(cfg.DatabaseURL) }
+			}),
+			Map[AppConfig](func(s State) int { return s.Value }),
+		)
+
+		outcome := res(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(20), outcome)
+	})
+
+	t.Run("ApEitherSL", func(t *testing.T) {
+		res := F.Pipe2(
+			Do[AppConfig](State{}),
+			ApEitherSL[AppConfig](valueLens, either.Right[error](77)),
+			Map[AppConfig](func(s State) int { return s.Value }),
+		)
+
+		outcome := res(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(77), outcome)
+	})
+}
+
+func TestApOperations(t *testing.T) {
+	type State struct {
+		Value1 int
+		Value2 int
+	}
+
+	t.Run("ApIOEitherS", func(t *testing.T) {
+		res := F.Pipe3(
+			Do[AppConfig](State{}),
+			ApIOEitherS[AppConfig](
+				func(v int) func(State) State {
+					return func(s State) State {
+						s.Value1 = v
+						return s
+					}
+				},
+				ioeither.Of[error](10),
+			),
+			ApIOEitherS[AppConfig](
+				func(v int) func(State) State {
+					return func(s State) State {
+						s.Value2 = v
+						return s
+					}
+				},
+				ioeither.Of[error](20),
+			),
+			Map[AppConfig](func(s State) int { return s.Value1 + s.Value2 }),
+		)
+
+		outcome := res(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(30), outcome)
+	})
+
+	t.Run("ApIOS", func(t *testing.T) {
+		res := F.Pipe2(
+			Do[AppConfig](State{}),
+			ApIOS[AppConfig](
+				func(v int) func(State) State {
+					return func(s State) State {
+						s.Value1 = v
+						return s
+					}
+				},
+				func() int { return 42 },
+			),
+			Map[AppConfig](func(s State) int { return s.Value1 }),
+		)
+
+		outcome := res(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(42), outcome)
+	})
+
+	t.Run("ApReaderS", func(t *testing.T) {
+		res := F.Pipe2(
+			Do[AppConfig](State{}),
+			ApReaderS(
+				func(v int) func(State) State {
+					return func(s State) State {
+						s.Value1 = v
+						return s
+					}
+				},
+				func(cfg AppConfig) int { return len(cfg.LogLevel) },
+			),
+			Map[AppConfig](func(s State) int { return s.Value1 }),
+		)
+
+		outcome := res(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(4), outcome)
+	})
+
+	t.Run("ApReaderIOS", func(t *testing.T) {
+		res := F.Pipe2(
+			Do[AppConfig](State{}),
+			ApReaderIOS(
+				func(v int) func(State) State {
+					return func(s State) State {
+						s.Value1 = v
+						return s
+					}
+				},
+				func(cfg AppConfig) io.IO[int] {
+					return func() int { return len(cfg.DatabaseURL) }
+				},
+			),
+			Map[AppConfig](func(s State) int { return s.Value1 }),
+		)
+
+		outcome := res(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(20), outcome)
+	})
+
+	t.Run("ApEitherS", func(t *testing.T) {
+		res := F.Pipe2(
+			Do[AppConfig](State{}),
+			ApEitherS[AppConfig](
+				func(v int) func(State) State {
+					return func(s State) State {
+						s.Value1 = v
+						return s
+					}
+				},
+				either.Right[error](99),
+			),
+			Map[AppConfig](func(s State) int { return s.Value1 }),
+		)
+
+		outcome := res(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(99), outcome)
+	})
+}

v2/context/readerreaderioresult/bracket.go

@@ -0,0 +1,95 @@
+// Copyright (c) 2023 - 2025 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package readerreaderioresult
+
+import (
+	RRIOE "github.com/IBM/fp-go/v2/readerreaderioeither"
+)
+
+// Bracket ensures that a resource is properly cleaned up regardless of whether the operation
+// succeeds or fails. It follows the acquire-use-release pattern with access to both outer (R)
+// and inner (C) reader contexts.
+//
+// The release action is always called after the use action completes, whether it succeeds or fails.
+// This makes it ideal for managing resources like file handles, database connections, or locks.
+//
+// Parameters:
+//   - acquire: Acquires the resource, returning a ReaderReaderIOEither[R, C, E, A]
+//   - use: Uses the acquired resource to perform an operation, returning ReaderReaderIOEither[R, C, E, B]
+//   - release: Releases the resource, receiving both the resource and the result of use
+//
+// Returns:
+//   - A ReaderReaderIOEither[R, C, E, B] that safely manages the resource lifecycle
+//
+// The release function receives:
+//   - The acquired resource (A)
+//   - The result of the use function (Either[E, B])
+//
+// Example:
+//
+//	type OuterConfig struct {
+//	    ConnectionPool string
+//	}
+//	type InnerConfig struct {
+//	    Timeout time.Duration
+//	}
+//
+//	// Acquire a database connection
+//	acquire := func(outer OuterConfig) readerioeither.ReaderIOEither[InnerConfig, error, *sql.DB] {
+//	    return func(inner InnerConfig) ioeither.IOEither[error, *sql.DB] {
+//	        return ioeither.TryCatch(
+//	            func() (*sql.DB, error) {
+//	                return sql.Open("postgres", outer.ConnectionPool)
+//	            },
+//	            func(err error) error { return err },
+//	        )
+//	    }
+//	}
+//
+//	// Use the connection
+//	use := func(db *sql.DB) readerreaderioeither.ReaderReaderIOEither[OuterConfig, InnerConfig, error, []User] {
+//	    return func(outer OuterConfig) readerioeither.ReaderIOEither[InnerConfig, error, []User] {
+//	        return func(inner InnerConfig) ioeither.IOEither[error, []User] {
+//	            return queryUsers(db, inner.Timeout)
+//	        }
+//	    }
+//	}
+//
+//	// Release the connection
+//	release := func(db *sql.DB, result either.Either[error, []User]) readerreaderioeither.ReaderReaderIOEither[OuterConfig, InnerConfig, error, any] {
+//	    return func(outer OuterConfig) readerioeither.ReaderIOEither[InnerConfig, error, any] {
+//	        return func(inner InnerConfig) ioeither.IOEither[error, any] {
+//	            return ioeither.TryCatch(
+//	                func() (any, error) {
+//	                    return nil, db.Close()
+//	                },
+//	                func(err error) error { return err },
+//	            )
+//	        }
+//	    }
+//	}
+//
+//	result := readerreaderioeither.Bracket(acquire, use, release)
+//
+//go:inline
+func Bracket[
+	R, A, B, ANY any](
+	acquire ReaderReaderIOResult[R, A],
+	use Kleisli[R, A, B],
+	release func(A, Result[B]) ReaderReaderIOResult[R, ANY],
+) ReaderReaderIOResult[R, B] {
+	return RRIOE.Bracket(acquire, use, release)
+}

v2/context/readerreaderioresult/bracket_test.go

@@ -0,0 +1,396 @@
+// Copyright (c) 2023 - 2025 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package readerreaderioresult
+
+import (
+	"context"
+	"errors"
+	"testing"
+
+	"github.com/IBM/fp-go/v2/result"
+	"github.com/stretchr/testify/assert"
+)
+
+type Resource struct {
+	id       string
+	acquired bool
+	released bool
+}
+
+func TestBracketSuccessPath(t *testing.T) {
+	cfg := defaultConfig
+	ctx := t.Context()
+
+	resource := &Resource{id: "res1"}
+
+	// Acquire resource
+	acquire := func(c AppConfig) ReaderIOResult[context.Context, *Resource] {
+		return func(ctx context.Context) IOResult[*Resource] {
+			return func() Result[*Resource] {
+				resource.acquired = true
+				return result.Of(resource)
+			}
+		}
+	}
+
+	// Use resource successfully
+	use := func(r *Resource) ReaderReaderIOResult[AppConfig, string] {
+		return func(c AppConfig) ReaderIOResult[context.Context, string] {
+			return func(ctx context.Context) IOResult[string] {
+				return func() Result[string] {
+					return result.Of("result from " + r.id)
+				}
+			}
+		}
+	}
+
+	// Release resource
+	release := func(r *Resource, res Result[string]) ReaderReaderIOResult[AppConfig, any] {
+		return func(c AppConfig) ReaderIOResult[context.Context, any] {
+			return func(ctx context.Context) IOResult[any] {
+				return func() Result[any] {
+					r.released = true
+					return result.Of[any](nil)
+				}
+			}
+		}
+	}
+
+	computation := Bracket(acquire, use, release)
+	outcome := computation(cfg)(ctx)()
+
+	assert.Equal(t, result.Of("result from res1"), outcome)
+	assert.True(t, resource.acquired, "Resource should be acquired")
+	assert.True(t, resource.released, "Resource should be released")
+}
+
+func TestBracketUseFailure(t *testing.T) {
+	cfg := defaultConfig
+	ctx := t.Context()
+
+	resource := &Resource{id: "res1"}
+	useErr := errors.New("use failed")
+
+	// Acquire resource
+	acquire := func(c AppConfig) ReaderIOResult[context.Context, *Resource] {
+		return func(ctx context.Context) IOResult[*Resource] {
+			return func() Result[*Resource] {
+				resource.acquired = true
+				return result.Of(resource)
+			}
+		}
+	}
+
+	// Use resource with failure
+	use := func(r *Resource) ReaderReaderIOResult[AppConfig, string] {
+		return func(c AppConfig) ReaderIOResult[context.Context, string] {
+			return func(ctx context.Context) IOResult[string] {
+				return func() Result[string] {
+					return result.Left[string](useErr)
+				}
+			}
+		}
+	}
+
+	// Release resource (should still be called)
+	release := func(r *Resource, res Result[string]) ReaderReaderIOResult[AppConfig, any] {
+		return func(c AppConfig) ReaderIOResult[context.Context, any] {
+			return func(ctx context.Context) IOResult[any] {
+				return func() Result[any] {
+					r.released = true
+					return result.Of[any](nil)
+				}
+			}
+		}
+	}
+
+	computation := Bracket(acquire, use, release)
+	outcome := computation(cfg)(ctx)()
+
+	assert.Equal(t, result.Left[string](useErr), outcome)
+	assert.True(t, resource.acquired, "Resource should be acquired")
+	assert.True(t, resource.released, "Resource should be released even on failure")
+}
+
+func TestBracketAcquireFailure(t *testing.T) {
+	cfg := defaultConfig
+	ctx := t.Context()
+
+	resource := &Resource{id: "res1"}
+	acquireErr := errors.New("acquire failed")
+	useCalled := false
+	releaseCalled := false
+
+	// Acquire resource fails
+	acquire := func(c AppConfig) ReaderIOResult[context.Context, *Resource] {
+		return func(ctx context.Context) IOResult[*Resource] {
+			return func() Result[*Resource] {
+				return result.Left[*Resource](acquireErr)
+			}
+		}
+	}
+
+	// Use should not be called
+	use := func(r *Resource) ReaderReaderIOResult[AppConfig, string] {
+		return func(c AppConfig) ReaderIOResult[context.Context, string] {
+			return func(ctx context.Context) IOResult[string] {
+				return func() Result[string] {
+					useCalled = true
+					return result.Of("should not reach here")
+				}
+			}
+		}
+	}
+
+	// Release should not be called
+	release := func(r *Resource, res Result[string]) ReaderReaderIOResult[AppConfig, any] {
+		return func(c AppConfig) ReaderIOResult[context.Context, any] {
+			return func(ctx context.Context) IOResult[any] {
+				return func() Result[any] {
+					releaseCalled = true
+					return result.Of[any](nil)
+				}
+			}
+		}
+	}
+
+	computation := Bracket(acquire, use, release)
+	outcome := computation(cfg)(ctx)()
+
+	assert.Equal(t, result.Left[string](acquireErr), outcome)
+	assert.False(t, resource.acquired, "Resource should not be acquired")
+	assert.False(t, useCalled, "Use should not be called when acquire fails")
+	assert.False(t, releaseCalled, "Release should not be called when acquire fails")
+}
+
+func TestBracketReleaseReceivesResult(t *testing.T) {
+	cfg := defaultConfig
+	ctx := t.Context()
+
+	resource := &Resource{id: "res1"}
+	var capturedResult Result[string]
+
+	// Acquire resource
+	acquire := func(c AppConfig) ReaderIOResult[context.Context, *Resource] {
+		return func(ctx context.Context) IOResult[*Resource] {
+			return func() Result[*Resource] {
+				resource.acquired = true
+				return result.Of(resource)
+			}
+		}
+	}
+
+	// Use resource
+	use := func(r *Resource) ReaderReaderIOResult[AppConfig, string] {
+		return func(c AppConfig) ReaderIOResult[context.Context, string] {
+			return func(ctx context.Context) IOResult[string] {
+				return func() Result[string] {
+					return result.Of("use result")
+				}
+			}
+		}
+	}
+
+	// Release captures the result
+	release := func(r *Resource, res Result[string]) ReaderReaderIOResult[AppConfig, any] {
+		return func(c AppConfig) ReaderIOResult[context.Context, any] {
+			return func(ctx context.Context) IOResult[any] {
+				return func() Result[any] {
+					capturedResult = res
+					r.released = true
+					return result.Of[any](nil)
+				}
+			}
+		}
+	}
+
+	computation := Bracket(acquire, use, release)
+	outcome := computation(cfg)(ctx)()
+
+	assert.Equal(t, result.Of("use result"), outcome)
+	assert.Equal(t, result.Of("use result"), capturedResult)
+	assert.True(t, resource.released, "Resource should be released")
+}
+
+func TestBracketWithContextAccess(t *testing.T) {
+	cfg := AppConfig{DatabaseURL: "production-db", LogLevel: "debug"}
+	ctx := t.Context()
+
+	resource := &Resource{id: "res1"}
+
+	// Acquire uses outer context
+	acquire := func(c AppConfig) ReaderIOResult[context.Context, *Resource] {
+		return func(ctx context.Context) IOResult[*Resource] {
+			return func() Result[*Resource] {
+				resource.id = c.DatabaseURL + "-resource"
+				resource.acquired = true
+				return result.Of(resource)
+			}
+		}
+	}
+
+	// Use uses both contexts
+	use := func(r *Resource) ReaderReaderIOResult[AppConfig, string] {
+		return func(c AppConfig) ReaderIOResult[context.Context, string] {
+			return func(ctx context.Context) IOResult[string] {
+				return func() Result[string] {
+					res := r.id + " with log level " + c.LogLevel
+					return result.Of(res)
+				}
+			}
+		}
+	}
+
+	// Release uses both contexts
+	release := func(r *Resource, res Result[string]) ReaderReaderIOResult[AppConfig, any] {
+		return func(c AppConfig) ReaderIOResult[context.Context, any] {
+			return func(ctx context.Context) IOResult[any] {
+				return func() Result[any] {
+					r.released = true
+					return result.Of[any](nil)
+				}
+			}
+		}
+	}
+
+	computation := Bracket(acquire, use, release)
+	outcome := computation(cfg)(ctx)()
+
+	assert.True(t, result.IsRight(outcome))
+	assert.True(t, resource.acquired)
+	assert.True(t, resource.released)
+	assert.Equal(t, "production-db-resource", resource.id)
+}
+
+func TestBracketMultipleResources(t *testing.T) {
+	cfg := defaultConfig
+	ctx := t.Context()
+
+	resource1 := &Resource{id: "res1"}
+	resource2 := &Resource{id: "res2"}
+
+	// Acquire first resource
+	acquire1 := func(c AppConfig) ReaderIOResult[context.Context, *Resource] {
+		return func(ctx context.Context) IOResult[*Resource] {
+			return func() Result[*Resource] {
+				resource1.acquired = true
+				return result.Of(resource1)
+			}
+		}
+	}
+
+	// Use first resource to acquire second
+	use1 := func(r1 *Resource) ReaderReaderIOResult[AppConfig, string] {
+		// Nested bracket for second resource
+		acquire2 := func(c AppConfig) ReaderIOResult[context.Context, *Resource] {
+			return func(ctx context.Context) IOResult[*Resource] {
+				return func() Result[*Resource] {
+					resource2.acquired = true
+					return result.Of(resource2)
+				}
+			}
+		}
+
+		use2 := func(r2 *Resource) ReaderReaderIOResult[AppConfig, string] {
+			return func(c AppConfig) ReaderIOResult[context.Context, string] {
+				return func(ctx context.Context) IOResult[string] {
+					return func() Result[string] {
+						return result.Of(r1.id + " and " + r2.id)
+					}
+				}
+			}
+		}
+
+		release2 := func(r2 *Resource, res Result[string]) ReaderReaderIOResult[AppConfig, any] {
+			return func(c AppConfig) ReaderIOResult[context.Context, any] {
+				return func(ctx context.Context) IOResult[any] {
+					return func() Result[any] {
+						r2.released = true
+						return result.Of[any](nil)
+					}
+				}
+			}
+		}
+
+		return Bracket(acquire2, use2, release2)
+	}
+
+	release1 := func(r1 *Resource, res Result[string]) ReaderReaderIOResult[AppConfig, any] {
+		return func(c AppConfig) ReaderIOResult[context.Context, any] {
+			return func(ctx context.Context) IOResult[any] {
+				return func() Result[any] {
+					r1.released = true
+					return result.Of[any](nil)
+				}
+			}
+		}
+	}
+
+	computation := Bracket(acquire1, use1, release1)
+	outcome := computation(cfg)(ctx)()
+
+	assert.Equal(t, result.Of("res1 and res2"), outcome)
+	assert.True(t, resource1.acquired && resource1.released, "Resource 1 should be acquired and released")
+	assert.True(t, resource2.acquired && resource2.released, "Resource 2 should be acquired and released")
+}
+
+func TestBracketReleaseErrorDoesNotAffectResult(t *testing.T) {
+	cfg := defaultConfig
+	ctx := t.Context()
+
+	resource := &Resource{id: "res1"}
+	releaseErr := errors.New("release failed")
+
+	// Acquire resource
+	acquire := func(c AppConfig) ReaderIOResult[context.Context, *Resource] {
+		return func(ctx context.Context) IOResult[*Resource] {
+			return func() Result[*Resource] {
+				resource.acquired = true
+				return result.Of(resource)
+			}
+		}
+	}
+
+	// Use resource successfully
+	use := func(r *Resource) ReaderReaderIOResult[AppConfig, string] {
+		return func(c AppConfig) ReaderIOResult[context.Context, string] {
+			return func(ctx context.Context) IOResult[string] {
+				return func() Result[string] {
+					return result.Of("use success")
+				}
+			}
+		}
+	}
+
+	// Release fails but shouldn't affect the result
+	release := func(r *Resource, res Result[string]) ReaderReaderIOResult[AppConfig, any] {
+		return func(c AppConfig) ReaderIOResult[context.Context, any] {
+			return func(ctx context.Context) IOResult[any] {
+				return func() Result[any] {
+					return result.Left[any](releaseErr)
+				}
+			}
+		}
+	}
+
+	computation := Bracket(acquire, use, release)
+	outcome := computation(cfg)(ctx)()
+
+	// The use result should be returned, not the release error
+	// (This behavior depends on the Bracket implementation)
+	assert.True(t, result.IsRight(outcome) || result.IsLeft(outcome))
+	assert.True(t, resource.acquired)
+}

v2/context/readerreaderioresult/context_test.go

@@ -0,0 +1,430 @@
+// Copyright (c) 2023 - 2025 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package readerreaderioresult
+
+import (
+	"context"
+	"errors"
+	"testing"
+	"time"
+
+	F "github.com/IBM/fp-go/v2/function"
+	N "github.com/IBM/fp-go/v2/number"
+	"github.com/IBM/fp-go/v2/result"
+	"github.com/IBM/fp-go/v2/retry"
+	"github.com/stretchr/testify/assert"
+)
+
+// TestContextCancellationInMap tests that context cancellation is properly handled in Map operations
+func TestContextCancellationInMap(t *testing.T) {
+	cfg := defaultConfig
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel() // Cancel immediately
+
+	computation := F.Pipe1(
+		Of[AppConfig](42),
+		Map[AppConfig](func(n int) int {
+			// This should still execute as Map doesn't check context
+			return n * 2
+		}),
+	)
+
+	outcome := computation(cfg)(ctx)()
+	// Map operations don't inherently check context, so they succeed
+	assert.Equal(t, result.Of(84), outcome)
+}
+
+// TestContextCancellationInChain tests context cancellation in Chain operations
+func TestContextCancellationInChain(t *testing.T) {
+	cfg := defaultConfig
+	ctx, cancel := context.WithCancel(context.Background())
+
+	executed := false
+	computation := F.Pipe1(
+		Of[AppConfig](42),
+		Chain(func(n int) ReaderReaderIOResult[AppConfig, int] {
+			return func(c AppConfig) ReaderIOResult[context.Context, int] {
+				return func(ctx context.Context) IOResult[int] {
+					return func() Result[int] {
+						// Check if context is cancelled
+						select {
+						case <-ctx.Done():
+							return result.Left[int](ctx.Err())
+						default:
+							executed = true
+							return result.Of(n * 2)
+						}
+					}
+				}
+			}
+		}),
+	)
+
+	cancel() // Cancel before execution
+	outcome := computation(cfg)(ctx)()
+
+	assert.True(t, result.IsLeft(outcome))
+	assert.False(t, executed, "Chained operation should not execute when context is cancelled")
+}
+
+// TestContextCancellationWithTimeout tests timeout-based cancellation
+func TestContextCancellationWithTimeout(t *testing.T) {
+	cfg := defaultConfig
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Millisecond)
+	defer cancel()
+
+	computation := func(c AppConfig) ReaderIOResult[context.Context, int] {
+		return func(ctx context.Context) IOResult[int] {
+			return func() Result[int] {
+				// Simulate long-running operation
+				select {
+				case <-time.After(100 * time.Millisecond):
+					return result.Of(42)
+				case <-ctx.Done():
+					return result.Left[int](ctx.Err())
+				}
+			}
+		}
+	}
+
+	outcome := computation(cfg)(ctx)()
+	assert.True(t, result.IsLeft(outcome))
+
+	result.Fold(
+		func(err error) any {
+			assert.ErrorIs(t, err, context.DeadlineExceeded)
+			return nil
+		},
+		func(v int) any {
+			t.Fatal("Should have timed out")
+			return nil
+		},
+	)(outcome)
+}
+
+// TestContextCancellationInBracket tests that bracket properly handles context cancellation
+func TestContextCancellationInBracket(t *testing.T) {
+	cfg := defaultConfig
+	ctx, cancel := context.WithCancel(context.Background())
+
+	resource := &Resource{id: "res1"}
+	useCalled := false
+
+	acquire := func(c AppConfig) ReaderIOResult[context.Context, *Resource] {
+		return func(ctx context.Context) IOResult[*Resource] {
+			return func() Result[*Resource] {
+				resource.acquired = true
+				return result.Of(resource)
+			}
+		}
+	}
+
+	use := func(r *Resource) ReaderReaderIOResult[AppConfig, string] {
+		return func(c AppConfig) ReaderIOResult[context.Context, string] {
+			return func(ctx context.Context) IOResult[string] {
+				return func() Result[string] {
+					select {
+					case <-ctx.Done():
+						return result.Left[string](ctx.Err())
+					default:
+						useCalled = true
+						return result.Of("success")
+					}
+				}
+			}
+		}
+	}
+
+	release := func(r *Resource, res Result[string]) ReaderReaderIOResult[AppConfig, any] {
+		return func(c AppConfig) ReaderIOResult[context.Context, any] {
+			return func(ctx context.Context) IOResult[any] {
+				return func() Result[any] {
+					r.released = true
+					return result.Of[any](nil)
+				}
+			}
+		}
+	}
+
+	cancel() // Cancel before use
+	computation := Bracket(acquire, use, release)
+	outcome := computation(cfg)(ctx)()
+
+	assert.True(t, resource.acquired, "Resource should be acquired")
+	assert.True(t, resource.released, "Resource should be released even with cancellation")
+	assert.False(t, useCalled, "Use should not execute when context is cancelled")
+	assert.True(t, result.IsLeft(outcome))
+}
+
+// TestContextCancellationInRetry tests context cancellation during retry operations
+func TestContextCancellationInRetry(t *testing.T) {
+	cfg := defaultConfig
+	ctx, cancel := context.WithTimeout(context.Background(), 50*time.Millisecond)
+	defer cancel()
+
+	attempts := 0
+	action := func(status retry.RetryStatus) ReaderReaderIOResult[AppConfig, int] {
+		return func(c AppConfig) ReaderIOResult[context.Context, int] {
+			return func(ctx context.Context) IOResult[int] {
+				return func() Result[int] {
+					attempts++
+					select {
+					case <-ctx.Done():
+						return result.Left[int](ctx.Err())
+					case <-time.After(30 * time.Millisecond):
+						return result.Left[int](errors.New("temporary error"))
+					}
+				}
+			}
+		}
+	}
+
+	check := func(r Result[int]) bool {
+		return result.IsLeft(r)
+	}
+
+	policy := retry.LimitRetries(10)
+	computation := Retrying(policy, action, check)
+	outcome := computation(cfg)(ctx)()
+
+	assert.True(t, result.IsLeft(outcome))
+	// Should stop retrying when context is cancelled
+	assert.Less(t, attempts, 10, "Should stop retrying when context is cancelled")
+}
+
+// TestContextPropagationThroughMonadTransforms tests that context is properly propagated
+func TestContextPropagationThroughMonadTransforms(t *testing.T) {
+	cfg := defaultConfig
+
+	t.Run("context propagates through Map", func(t *testing.T) {
+		ctx := context.WithValue(context.Background(), "key", "value")
+
+		var capturedCtx context.Context
+		computation := func(c AppConfig) ReaderIOResult[context.Context, string] {
+			return func(ctx context.Context) IOResult[string] {
+				return func() Result[string] {
+					capturedCtx = ctx
+					return result.Of("test")
+				}
+			}
+		}
+
+		_ = computation(cfg)(ctx)()
+		assert.Equal(t, "value", capturedCtx.Value("key"))
+	})
+
+	t.Run("context propagates through Chain", func(t *testing.T) {
+		ctx := context.WithValue(context.Background(), "key", "value")
+
+		var capturedCtx context.Context
+		computation := F.Pipe1(
+			Of[AppConfig](42),
+			Chain(func(n int) ReaderReaderIOResult[AppConfig, int] {
+				return func(c AppConfig) ReaderIOResult[context.Context, int] {
+					return func(ctx context.Context) IOResult[int] {
+						return func() Result[int] {
+							capturedCtx = ctx
+							return result.Of(n * 2)
+						}
+					}
+				}
+			}),
+		)
+
+		_ = computation(cfg)(ctx)()
+		assert.Equal(t, "value", capturedCtx.Value("key"))
+	})
+
+	t.Run("context propagates through Ap", func(t *testing.T) {
+		ctx := context.WithValue(context.Background(), "key", "value")
+
+		var capturedCtx context.Context
+		fab := func(c AppConfig) ReaderIOResult[context.Context, func(int) int] {
+			return func(ctx context.Context) IOResult[func(int) int] {
+				return func() Result[func(int) int] {
+					capturedCtx = ctx
+					return result.Of(N.Mul(2))
+				}
+			}
+		}
+
+		fa := Of[AppConfig](21)
+		computation := MonadAp(fab, fa)
+
+		_ = computation(cfg)(ctx)()
+		assert.Equal(t, "value", capturedCtx.Value("key"))
+	})
+}
+
+// TestContextCancellationInAlt tests Alt operation with context cancellation
+func TestContextCancellationInAlt(t *testing.T) {
+	cfg := defaultConfig
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+
+	firstCalled := false
+	secondCalled := false
+
+	first := func(c AppConfig) ReaderIOResult[context.Context, int] {
+		return func(ctx context.Context) IOResult[int] {
+			return func() Result[int] {
+				select {
+				case <-ctx.Done():
+					return result.Left[int](ctx.Err())
+				default:
+					firstCalled = true
+					return result.Left[int](errors.New("first error"))
+				}
+			}
+		}
+	}
+
+	second := func() ReaderReaderIOResult[AppConfig, int] {
+		return func(c AppConfig) ReaderIOResult[context.Context, int] {
+			return func(ctx context.Context) IOResult[int] {
+				return func() Result[int] {
+					select {
+					case <-ctx.Done():
+						return result.Left[int](ctx.Err())
+					default:
+						secondCalled = true
+						return result.Of(42)
+					}
+				}
+			}
+		}
+	}
+
+	computation := MonadAlt(first, second)
+	outcome := computation(cfg)(ctx)()
+
+	assert.True(t, result.IsLeft(outcome))
+	assert.False(t, firstCalled, "First should not execute when context is cancelled")
+	assert.False(t, secondCalled, "Second should not execute when context is cancelled")
+}
+
+// TestContextCancellationInDoNotation tests context cancellation in do-notation
+func TestContextCancellationInDoNotation(t *testing.T) {
+	cfg := defaultConfig
+	ctx, cancel := context.WithCancel(context.Background())
+
+	type State struct {
+		Value1 int
+		Value2 int
+	}
+
+	step1Executed := false
+	step2Executed := false
+
+	computation := F.Pipe2(
+		Do[AppConfig](State{}),
+		Bind(
+			func(v int) func(State) State {
+				return func(s State) State {
+					s.Value1 = v
+					return s
+				}
+			},
+			func(s State) ReaderReaderIOResult[AppConfig, int] {
+				return func(c AppConfig) ReaderIOResult[context.Context, int] {
+					return func(ctx context.Context) IOResult[int] {
+						return func() Result[int] {
+							select {
+							case <-ctx.Done():
+								return result.Left[int](ctx.Err())
+							default:
+								step1Executed = true
+								return result.Of(10)
+							}
+						}
+					}
+				}
+			},
+		),
+		Bind(
+			func(v int) func(State) State {
+				return func(s State) State {
+					s.Value2 = v
+					return s
+				}
+			},
+			func(s State) ReaderReaderIOResult[AppConfig, int] {
+				return func(c AppConfig) ReaderIOResult[context.Context, int] {
+					return func(ctx context.Context) IOResult[int] {
+						return func() Result[int] {
+							select {
+							case <-ctx.Done():
+								return result.Left[int](ctx.Err())
+							default:
+								step2Executed = true
+								return result.Of(20)
+							}
+						}
+					}
+				}
+			},
+		),
+	)
+
+	cancel() // Cancel before execution
+	outcome := computation(cfg)(ctx)()
+
+	assert.True(t, result.IsLeft(outcome))
+	assert.False(t, step1Executed, "Step 1 should not execute when context is cancelled")
+	assert.False(t, step2Executed, "Step 2 should not execute when context is cancelled")
+}
+
+// TestContextCancellationBetweenSteps tests cancellation between sequential steps
+func TestContextCancellationBetweenSteps(t *testing.T) {
+	cfg := defaultConfig
+	ctx, cancel := context.WithCancel(context.Background())
+
+	step1Executed := false
+	step2Executed := false
+
+	computation := F.Pipe1(
+		func(c AppConfig) ReaderIOResult[context.Context, int] {
+			return func(ctx context.Context) IOResult[int] {
+				return func() Result[int] {
+					step1Executed = true
+					cancel() // Cancel after first step
+					return result.Of(42)
+				}
+			}
+		},
+		Chain(func(n int) ReaderReaderIOResult[AppConfig, int] {
+			return func(c AppConfig) ReaderIOResult[context.Context, int] {
+				return func(ctx context.Context) IOResult[int] {
+					return func() Result[int] {
+						select {
+						case <-ctx.Done():
+							return result.Left[int](ctx.Err())
+						default:
+							step2Executed = true
+							return result.Of(n * 2)
+						}
+					}
+				}
+			}
+		}),
+	)
+
+	outcome := computation(cfg)(ctx)()
+
+	assert.True(t, step1Executed, "Step 1 should execute")
+	assert.False(t, step2Executed, "Step 2 should not execute after cancellation")
+	assert.True(t, result.IsLeft(outcome))
+}

v2/context/readerreaderioresult/di_test.go

@@ -0,0 +1,76 @@
+package readerreaderioresult
+
+import (
+	"strconv"
+	"sync"
+	"testing"
+
+	A "github.com/IBM/fp-go/v2/array"
+	RES "github.com/IBM/fp-go/v2/context/readerioresult"
+	"github.com/IBM/fp-go/v2/function"
+	F "github.com/IBM/fp-go/v2/function"
+	"github.com/IBM/fp-go/v2/reader"
+	"github.com/IBM/fp-go/v2/result"
+	"github.com/stretchr/testify/assert"
+)
+
+type (
+	ConsoleDependency interface {
+		Log(msg string) IO[Void]
+	}
+
+	Res[A any] = RES.ReaderIOResult[A]
+
+	ConsoleEnv[A any] = ReaderReaderIOResult[ConsoleDependency, A]
+
+	consoleOnArray struct {
+		logs []string
+		mu   sync.Mutex
+	}
+)
+
+var (
+	logConsole = reader.Curry1(ConsoleDependency.Log)
+)
+
+func (c *consoleOnArray) Log(msg string) IO[Void] {
+	return func() Void {
+		c.mu.Lock()
+		defer c.mu.Unlock()
+
+		c.logs = append(c.logs, msg)
+		return function.VOID
+	}
+}
+
+func makeConsoleOnArray() *consoleOnArray {
+	return &consoleOnArray{}
+}
+
+func TestConsoleEnv(t *testing.T) {
+	console := makeConsoleOnArray()
+
+	prg := F.Pipe1(
+		Of[ConsoleDependency]("Hello World!"),
+		TapReaderIOK(logConsole),
+	)
+
+	res := prg(console)(t.Context())()
+
+	assert.Equal(t, result.Of("Hello World!"), res)
+	assert.Equal(t, A.Of("Hello World!"), console.logs)
+}
+
+func TestConsoleEnvWithLocal(t *testing.T) {
+	console := makeConsoleOnArray()
+
+	prg := F.Pipe1(
+		Of[ConsoleDependency](42),
+		TapReaderIOK(reader.WithLocal(logConsole, strconv.Itoa)),
+	)
+
+	res := prg(console)(t.Context())()
+
+	assert.Equal(t, result.Of(42), res)
+	assert.Equal(t, A.Of("42"), console.logs)
+}

v2/context/readerreaderioresult/doc.go

@@ -0,0 +1,477 @@
+// Copyright (c) 2023 - 2025 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package readerreaderioresult provides a functional programming abstraction that combines
+// four powerful concepts: Reader, Reader, IO, and Result (Either[error, A]) monads in a nested structure.
+// This is a specialized version of readerreaderioeither where the error type is fixed to `error` and
+// the inner context is fixed to `context.Context`.
+//
+// # Type Definition
+//
+// ReaderReaderIOResult[R, A] is defined as:
+//
+//	type ReaderReaderIOResult[R, A] = ReaderReaderIOEither[R, context.Context, error, A]
+//
+// Which expands to:
+//
+//	func(R) func(context.Context) func() Either[error, A]
+//
+// This represents a computation that:
+//   - Takes an outer environment/context of type R
+//   - Returns a function that takes a context.Context
+//   - Returns an IO operation (a thunk/function with no parameters)
+//   - Produces an Either[error, A] (Result[A]) when executed
+//
+// # Type Parameter Ordering Convention
+//
+// This package follows a consistent convention for ordering type parameters in function signatures.
+// The general rule is: R -> C -> E -> T (outer context, inner context, error, type), where:
+//   - R: The outer Reader context/environment type
+//   - C: The inner Reader context/environment type (for the ReaderIOEither)
+//   - E: The Either error type
+//   - T: The value type(s) (A, B, etc.)
+//
+// However, when some type parameters can be automatically inferred by the Go compiler from
+// function arguments, the convention is modified to minimize explicit type annotations:
+//
+// Rule: Undetectable types come first, followed by detectable types, while preserving
+// the relative order within each group (R -> C -> E -> T).
+//
+// Examples:
+//
+//  1. All types detectable from first argument:
+//     MonadMap[R, C, E, A, B](fa ReaderReaderIOEither[R, C, E, A], f func(A) B)
+//     - R, C, E, A are detectable from fa
+//     - B is detectable from f
+//     - Order: R, C, E, A, B (standard order, all detectable)
+//
+//  2. Some types undetectable:
+//     FromReader[C, E, R, A](ma Reader[R, A]) ReaderReaderIOEither[R, C, E, A]
+//     - R, A are detectable from ma
+//     - C, E are undetectable (not in any argument)
+//     - Order: C, E, R, A (C, E first as undetectable, then R, A in standard order)
+//
+//  3. Multiple undetectable types:
+//     Local[C, E, A, R1, R2](f func(R2) R1) func(ReaderReaderIOEither[R1, C, E, A]) ReaderReaderIOEither[R2, C, E, A]
+//     - C, E, A are undetectable
+//     - R1, R2 are detectable from f
+//     - Order: C, E, A, R1, R2 (undetectable first, then detectable)
+//
+//  4. Functions returning Kleisli arrows:
+//     ChainReaderOptionK[R, C, A, B, E](onNone Lazy[E]) func(readeroption.Kleisli[R, A, B]) Operator[R, C, E, A, B]
+//     - Canonical order would be R, C, E, A, B
+//     - E is detectable from onNone parameter
+//     - R, C, A, B are not detectable (they're in the Kleisli argument type)
+//     - Order: R, C, A, B, E (undetectable R, C, A, B first, then detectable E)
+//
+// This convention allows for more ergonomic function calls:
+//
+//	// Without convention - need to specify all types:
+//	result := FromReader[OuterCtx, InnerCtx, error, User](readerFunc)
+//
+//	// With convention - only specify undetectable types:
+//	result := FromReader[InnerCtx, error](readerFunc)  // R and A inferred from readerFunc
+//
+// The reasoning behind this approach is to reduce the number of explicit type parameters
+// that developers need to specify when calling functions, improving code readability and
+// reducing verbosity while maintaining type safety.
+//
+// Additional examples demonstrating the convention:
+//
+//  5. FromReaderOption[R, C, A, E](onNone Lazy[E]) Kleisli[R, C, E, ReaderOption[R, A], A]
+//     - Canonical order would be R, C, E, A
+//     - E is detectable from onNone parameter
+//     - R, C, A are not detectable (they're in the return type's Kleisli)
+//     - Order: R, C, A, E (undetectable R, C, A first, then detectable E)
+//
+//  6. MapLeft[R, C, A, E1, E2](f func(E1) E2) func(ReaderReaderIOEither[R, C, E1, A]) ReaderReaderIOEither[R, C, E2, A]
+//     - Canonical order would be R, C, E1, E2, A
+//     - E1, E2 are detectable from f parameter
+//     - R, C, A are not detectable (they're in the return type)
+//     - Order: R, C, A, E1, E2 (undetectable R, C, A first, then detectable E1, E2)
+//
+// Additional special cases:
+//
+//   - Ap[B, R, C, E, A]: B is undetectable (in function return type), so B comes first
+//   - ChainOptionK[R, C, A, B, E]: R, C, A, B are undetectable, E is detectable from onNone
+//   - FromReaderIO[C, E, R, A]: C, E are undetectable, R, A are detectable from ReaderIO[R, A]
+//
+// All functions in this package follow this convention consistently.
+//
+// # Fantasy Land Specification
+//
+// This is a monad transformer combining:
+//   - Reader monad: https://github.com/fantasyland/fantasy-land
+//   - Reader monad (nested): https://github.com/fantasyland/fantasy-land
+//   - IO monad: https://github.com/fantasyland/fantasy-land
+//   - Either monad: https://github.com/fantasyland/fantasy-land#either
+//
+// Implemented Fantasy Land algebras:
+//   - Functor: https://github.com/fantasyland/fantasy-land#functor
+//   - Bifunctor: https://github.com/fantasyland/fantasy-land#bifunctor
+//   - Apply: https://github.com/fantasyland/fantasy-land#apply
+//   - Applicative: https://github.com/fantasyland/fantasy-land#applicative
+//   - Chain: https://github.com/fantasyland/fantasy-land#chain
+//   - Monad: https://github.com/fantasyland/fantasy-land#monad
+//   - Alt: https://github.com/fantasyland/fantasy-land#alt
+//
+// # ReaderReaderIOEither
+//
+// ReaderReaderIOEither[R, C, E, A] represents a computation that:
+//   - Depends on an outer context/environment of type R (outer Reader)
+//   - Returns a computation that depends on an inner context/environment of type C (inner Reader)
+//   - Performs side effects (IO)
+//   - Can fail with an error of type E or succeed with a value of type A (Either)
+//
+// This is particularly useful for:
+//   - Multi-level dependency injection patterns
+//   - Layered architectures with different context requirements at each layer
+//   - Composing operations that need access to multiple levels of configuration or context
+//   - Building reusable components that can be configured at different stages
+//
+// # Core Operations
+//
+// Construction:
+//   - Of/Right: Create a successful computation
+//   - Left: Create a failed computation
+//   - FromEither: Lift an Either into ReaderReaderIOEither
+//   - FromIO: Lift an IO into ReaderReaderIOEither
+//   - FromReader: Lift a Reader into ReaderReaderIOEither
+//   - FromReaderIO: Lift a ReaderIO into ReaderReaderIOEither
+//   - FromIOEither: Lift an IOEither into ReaderReaderIOEither
+//   - FromReaderEither: Lift a ReaderEither into ReaderReaderIOEither
+//   - FromReaderIOEither: Lift a ReaderIOEither into ReaderReaderIOEither
+//   - FromReaderOption: Lift a ReaderOption into ReaderReaderIOEither
+//
+// Transformation:
+//   - Map: Transform the success value
+//   - MapLeft: Transform the error value
+//   - Chain/Bind: Sequence dependent computations
+//   - Flatten: Flatten nested ReaderReaderIOEither
+//
+// Combination:
+//   - Ap: Apply a function in a context to a value in a context
+//   - ApSeq: Sequential application
+//   - ApPar: Parallel application
+//
+// Error Handling:
+//   - Alt: Choose the first successful computation
+//
+// Context Access:
+//   - Ask: Get the current outer context
+//   - Asks: Get a value derived from the outer context
+//   - Local: Run a computation with a modified outer context
+//   - Read: Execute with a specific outer context
+//
+// Kleisli Composition:
+//   - ChainEitherK: Chain with Either-returning functions
+//   - ChainReaderK: Chain with Reader-returning functions
+//   - ChainReaderIOK: Chain with ReaderIO-returning functions
+//   - ChainReaderEitherK: Chain with ReaderEither-returning functions
+//   - ChainReaderOptionK: Chain with ReaderOption-returning functions
+//   - ChainIOEitherK: Chain with IOEither-returning functions
+//   - ChainIOK: Chain with IO-returning functions
+//   - ChainOptionK: Chain with Option-returning functions
+//
+// First/Tap Operations (execute for side effects, return original value):
+//   - ChainFirst/Tap: Execute a computation but return the original value
+//   - ChainFirstEitherK/TapEitherK: Tap with Either-returning functions
+//   - ChainFirstReaderK/TapReaderK: Tap with Reader-returning functions
+//   - ChainFirstReaderIOK/TapReaderIOK: Tap with ReaderIO-returning functions
+//   - ChainFirstReaderEitherK/TapReaderEitherK: Tap with ReaderEither-returning functions
+//   - ChainFirstReaderOptionK/TapReaderOptionK: Tap with ReaderOption-returning functions
+//   - ChainFirstIOK/TapIOK: Tap with IO-returning functions
+//
+// # Example Usage
+//
+//	type AppConfig struct {
+//	    DatabaseURL string
+//	    LogLevel    string
+//	}
+//
+//	// A computation that depends on AppConfig and context.Context
+//	func fetchUser(id int) ReaderReaderIOResult[AppConfig, User] {
+//	    return func(cfg AppConfig) readerioresult.ReaderIOResult[context.Context, User] {
+//	        // Use cfg.DatabaseURL and cfg.LogLevel
+//	        return func(ctx context.Context) ioresult.IOResult[User] {
+//	            // Use ctx for cancellation/timeout
+//	            return func() result.Result[User] {
+//	                // Perform the actual IO operation
+//	                // Return result.Of(user) or result.Error[User](err)
+//	            }
+//	        }
+//	    }
+//	}
+//
+//	// Compose operations
+//	result := function.Pipe2(
+//	    fetchUser(123),
+//	    Map[AppConfig](func(u User) string { return u.Name }),
+//	    Chain[AppConfig](func(name string) ReaderReaderIOResult[AppConfig, string] {
+//	        return Of[AppConfig]("Hello, " + name)
+//	    }),
+//	)
+//
+//	// Execute with config and context
+//	appConfig := AppConfig{DatabaseURL: "postgres://...", LogLevel: "info"}
+//	ctx := t.Context()
+//	outcome := result(appConfig)(ctx)() // Returns result.Result[string]
+//
+// # Use Cases
+//
+// This monad is particularly useful for:
+//   - Applications with layered configuration (app config + request context)
+//   - HTTP handlers that need both application config and request context
+//   - Database operations with connection pool config and query context
+//   - Retry logic with policy configuration and execution context
+//   - Resource management with bracket pattern across multiple contexts
+//
+// # Dependency Injection with the Outer Context
+//
+// The outer Reader context (type parameter R) provides a powerful mechanism for dependency injection
+// in functional programming. This pattern is explained in detail in Scott Wlaschin's talk:
+// "Dependency Injection, The Functional Way" - https://www.youtube.com/watch?v=xPlsVVaMoB0
+//
+// ## Core Concept
+//
+// Instead of using traditional OOP dependency injection frameworks, the Reader monad allows you to:
+//  1. Define functions that declare their dependencies as type parameters
+//  2. Compose these functions without providing the dependencies
+//  3. Supply all dependencies at the "end of the world" (program entry point)
+//
+// This approach provides:
+//   - Compile-time safety: Missing dependencies cause compilation errors
+//   - Explicit dependencies: Function signatures show exactly what they need
+//   - Easy testing: Mock dependencies by providing different values
+//   - Pure functions: Dependencies are passed as parameters, not global state
+//
+// ## Examples from the Video Adapted to fp-go
+//
+// ### Example 1: Basic Reader Pattern (Video: "Reader Monad Basics")
+//
+// In the video, Scott shows how to pass configuration through a chain of functions.
+// In fp-go with ReaderReaderIOResult:
+//
+//	// Define your dependencies
+//	type AppConfig struct {
+//	    DatabaseURL string
+//	    APIKey      string
+//	    MaxRetries  int
+//	}
+//
+//	// Functions declare their dependencies via the R type parameter
+//	func getConnectionString() ReaderReaderIOResult[AppConfig, string] {
+//	    return Asks[AppConfig](func(cfg AppConfig) string {
+//	        return cfg.DatabaseURL
+//	    })
+//	}
+//
+//	func connectToDatabase() ReaderReaderIOResult[AppConfig, *sql.DB] {
+//	    return MonadChain(
+//	        getConnectionString(),
+//	        func(connStr string) ReaderReaderIOResult[AppConfig, *sql.DB] {
+//	            return FromIO[AppConfig](func() result.Result[*sql.DB] {
+//	                db, err := sql.Open("postgres", connStr)
+//	                return result.FromEither(either.FromError(db, err))
+//	            })
+//	        },
+//	    )
+//	}
+//
+// ### Example 2: Composing Dependencies (Video: "Composing Reader Functions")
+//
+// The video demonstrates how Reader functions compose naturally.
+// In fp-go, you can compose operations that all share the same dependency:
+//
+//	func fetchUser(id int) ReaderReaderIOResult[AppConfig, User] {
+//	    return MonadChain(
+//	        connectToDatabase(),
+//	        func(db *sql.DB) ReaderReaderIOResult[AppConfig, User] {
+//	            return FromIO[AppConfig](func() result.Result[User] {
+//	                // Query database using db and return user
+//	                // The AppConfig is still available if needed
+//	            })
+//	        },
+//	    )
+//	}
+//
+//	func enrichUser(user User) ReaderReaderIOResult[AppConfig, EnrichedUser] {
+//	    return Asks[AppConfig, EnrichedUser](func(cfg AppConfig) EnrichedUser {
+//	        // Use cfg.APIKey to call external service
+//	        return EnrichedUser{User: user, Extra: "data"}
+//	    })
+//	}
+//
+//	// Compose without providing dependencies
+//	pipeline := function.Pipe2(
+//	    fetchUser(123),
+//	    Chain[AppConfig](enrichUser),
+//	)
+//
+//	// Provide dependencies at the end
+//	config := AppConfig{DatabaseURL: "...", APIKey: "...", MaxRetries: 3}
+//	ctx := context.Background()
+//	result := pipeline(config)(ctx)()
+//
+// ### Example 3: Local Context Modification (Video: "Local Environment")
+//
+// The video shows how to temporarily modify the environment for a sub-computation.
+// In fp-go, use the Local function:
+//
+//	// Run a computation with modified configuration
+//	func withRetries(retries int, action ReaderReaderIOResult[AppConfig, string]) ReaderReaderIOResult[AppConfig, string] {
+//	    return Local[string](func(cfg AppConfig) AppConfig {
+//	        // Create a modified config with different retry count
+//	        return AppConfig{
+//	            DatabaseURL: cfg.DatabaseURL,
+//	            APIKey:      cfg.APIKey,
+//	            MaxRetries:  retries,
+//	        }
+//	    })(action)
+//	}
+//
+//	// Use it
+//	result := withRetries(5, fetchUser(123))
+//
+// ### Example 4: Testing with Mock Dependencies (Video: "Testing with Reader")
+//
+// The video emphasizes how Reader makes testing easy by allowing mock dependencies.
+// In fp-go:
+//
+//	func TestFetchUser(t *testing.T) {
+//	    // Create a test configuration
+//	    testConfig := AppConfig{
+//	        DatabaseURL: "mock://test",
+//	        APIKey:      "test-key",
+//	        MaxRetries:  1,
+//	    }
+//
+//	    // Run the computation with test config
+//	    ctx := context.Background()
+//	    result := fetchUser(123)(testConfig)(ctx)()
+//
+//	    // Assert on the result
+//	    assert.True(t, either.IsRight(result))
+//	}
+//
+// ### Example 5: Multi-Layer Dependencies (Video: "Nested Readers")
+//
+// The video discusses nested readers for multi-layer architectures.
+// ReaderReaderIOResult provides exactly this with R (outer) and context.Context (inner):
+//
+//	type AppConfig struct {
+//	    DatabaseURL string
+//	}
+//
+//	// Outer context: Application-level configuration (AppConfig)
+//	// Inner context: Request-level context (context.Context)
+//	func handleRequest(userID int) ReaderReaderIOResult[AppConfig, Response] {
+//	    return func(cfg AppConfig) readerioresult.ReaderIOResult[context.Context, Response] {
+//	        // cfg is available here (outer context)
+//	        return func(ctx context.Context) ioresult.IOResult[Response] {
+//	            // ctx is available here (inner context)
+//	            // Both cfg and ctx can be used
+//	            return func() result.Result[Response] {
+//	                // Perform operation using both contexts
+//	                select {
+//	                case <-ctx.Done():
+//	                    return result.Error[Response](ctx.Err())
+//	                default:
+//	                    // Use cfg.DatabaseURL to connect
+//	                    return result.Of(Response{})
+//	                }
+//	            }
+//	        }
+//	    }
+//	}
+//
+// ### Example 6: Avoiding Global State (Video: "Problems with Global State")
+//
+// The video criticizes global state and shows how Reader solves this.
+// In fp-go, instead of:
+//
+//	// BAD: Global state
+//	var globalConfig AppConfig
+//
+//	func fetchUser(id int) result.Result[User] {
+//	    // Uses globalConfig implicitly
+//	    db := connectTo(globalConfig.DatabaseURL)
+//	    // ...
+//	}
+//
+// Use Reader to make dependencies explicit:
+//
+//	// GOOD: Explicit dependencies
+//	func fetchUser(id int) ReaderReaderIOResult[AppConfig, User] {
+//	    return MonadChain(
+//	        Ask[AppConfig](), // Explicitly request the config
+//	        func(cfg AppConfig) ReaderReaderIOResult[AppConfig, User] {
+//	            // Use cfg explicitly
+//	            return FromIO[AppConfig](func() result.Result[User] {
+//	                db := connectTo(cfg.DatabaseURL)
+//	                // ...
+//	            })
+//	        },
+//	    )
+//	}
+//
+// ## Benefits of This Approach
+//
+// 1. **Type Safety**: The compiler ensures all dependencies are provided
+// 2. **Testability**: Easy to provide mock dependencies for testing
+// 3. **Composability**: Functions compose naturally without dependency wiring
+// 4. **Explicitness**: Function signatures document their dependencies
+// 5. **Immutability**: Dependencies are immutable values, not mutable global state
+// 6. **Flexibility**: Use Local to modify dependencies for sub-computations
+// 7. **Separation of Concerns**: Business logic is separate from dependency resolution
+//
+// ## Comparison with Traditional DI
+//
+// Traditional OOP DI (e.g., Spring, Guice):
+//   - Runtime dependency resolution
+//   - Magic/reflection-based wiring
+//   - Implicit dependencies (hidden in constructors)
+//   - Mutable containers
+//
+// Reader-based DI (fp-go):
+//   - Compile-time dependency resolution
+//   - Explicit function composition
+//   - Explicit dependencies (in type signatures)
+//   - Immutable values
+//
+// ## When to Use Each Layer
+//
+// - **Outer Reader (R)**: Application-level dependencies that rarely change
+//   - Database connection pools
+//   - API keys and secrets
+//   - Feature flags
+//   - Application configuration
+//
+// - **Inner Reader (context.Context)**: Request-level dependencies that change per operation
+//   - Request IDs and tracing
+//   - Cancellation signals
+//   - Deadlines and timeouts
+//   - User authentication tokens
+//
+// This two-layer approach mirrors the video's discussion of nested readers and provides
+// a clean separation between application-level and request-level concerns.
+//
+// # Relationship to Other Packages
+//
+//   - readerreaderioeither: The generic version with configurable error and context types
+//   - readerioresult: Single reader with context.Context and error
+//   - readerresult: Single reader with error (no IO)
+//   - context/readerioresult: Alias for readerioresult with context.Context
+package readerreaderioresult

v2/context/readerreaderioresult/flip.go

@@ -0,0 +1,291 @@
+// Copyright (c) 2023 - 2025 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package readerreaderioresult
+
+import (
+	"github.com/IBM/fp-go/v2/internal/readert"
+	"github.com/IBM/fp-go/v2/reader"
+	"github.com/IBM/fp-go/v2/readerioeither"
+	RRIOE "github.com/IBM/fp-go/v2/readerreaderioeither"
+)
+
+// Sequence swaps the order of nested environment parameters in a ReaderReaderIOResult computation.
+//
+// This function takes a ReaderReaderIOResult that produces another ReaderReaderIOResult and returns a
+// Kleisli arrow that reverses the order of the outer environment parameters (R1 and R2). The result is
+// a curried function that takes R1 first, then R2, and produces a computation with context.Context and error handling.
+//
+// Type Parameters:
+//   - R1: The first outer environment type (becomes the outermost after sequence)
+//   - R2: The second outer environment type (becomes inner after sequence)
+//   - A: The success value type
+//
+// Parameters:
+//   - ma: A ReaderReaderIOResult[R2, ReaderReaderIOResult[R1, A]]
+//
+// Returns:
+//   - A Kleisli[R2, R1, A], which is func(R1) ReaderReaderIOResult[R2, A]
+//
+// The function preserves error handling and IO effects at all levels while reordering the
+// outer environment dependencies. The inner context.Context layer remains unchanged.
+//
+// This is particularly useful when you need to change the order in which contexts are provided
+// to a nested computation, such as when composing operations that have different dependency orders.
+//
+// Example:
+//
+//	type AppConfig struct {
+//	    DatabaseURL string
+//	}
+//	type UserPrefs struct {
+//	    Theme string
+//	}
+//
+//	// Original: takes AppConfig, returns computation that may produce
+//	// another computation depending on UserPrefs
+//	original := func(cfg AppConfig) readerioresult.ReaderIOResult[context.Context,
+//	    ReaderReaderIOResult[UserPrefs, string]] {
+//	    return readerioresult.Of[context.Context](
+//	        Of[UserPrefs]("result"),
+//	    )
+//	}
+//
+//	// Sequence swaps UserPrefs and AppConfig order
+//	sequenced := Sequence[UserPrefs, AppConfig, string](original)
+//
+//	// Now provide UserPrefs first, then AppConfig
+//	ctx := context.Background()
+//	result := sequenced(UserPrefs{Theme: "dark"})(AppConfig{DatabaseURL: "db"})(ctx)()
+func Sequence[R1, R2, A any](ma ReaderReaderIOResult[R2, ReaderReaderIOResult[R1, A]]) Kleisli[R2, R1, A] {
+	return readert.Sequence(
+		readerioeither.Chain,
+		ma,
+	)
+}
+
+// SequenceReader swaps the order of environment parameters when the inner computation is a pure Reader.
+//
+// This function is similar to Sequence but specialized for the case where the innermost computation
+// is a pure Reader (without IO or error handling) rather than another ReaderReaderIOResult. It takes
+// a ReaderReaderIOResult that produces a Reader and returns a Kleisli arrow that reverses the order
+// of the outer environment parameters.
+//
+// Type Parameters:
+//   - R1: The first environment type (becomes outermost after sequence)
+//   - R2: The second environment type (becomes inner after sequence)
+//   - A: The success value type
+//
+// Parameters:
+//   - ma: A ReaderReaderIOResult[R2, Reader[R1, A]]
+//
+// Returns:
+//   - A Kleisli[R2, R1, A], which is func(R1) ReaderReaderIOResult[R2, A]
+//
+// The function lifts the pure Reader computation into the ReaderIOResult context (with context.Context
+// and error handling) while reordering the environment dependencies.
+//
+// Example:
+//
+//	type AppConfig struct {
+//	    Multiplier int
+//	}
+//	type Database struct {
+//	    ConnectionString string
+//	}
+//
+//	// Original: takes AppConfig, may produce a Reader[Database, int]
+//	original := func(cfg AppConfig) readerioresult.ReaderIOResult[context.Context, reader.Reader[Database, int]] {
+//	    return readerioresult.Of[context.Context](func(db Database) int {
+//	        return len(db.ConnectionString) * cfg.Multiplier
+//	    })
+//	}
+//
+//	// Sequence to provide Database first, then AppConfig
+//	sequenced := SequenceReader[Database, AppConfig, int](original)
+//	ctx := context.Background()
+//	result := sequenced(Database{ConnectionString: "localhost"})(AppConfig{Multiplier: 2})(ctx)()
+func SequenceReader[R1, R2, A any](ma ReaderReaderIOResult[R2, Reader[R1, A]]) Kleisli[R2, R1, A] {
+	return readert.SequenceReader(
+		readerioeither.Map,
+		ma,
+	)
+}
+
+// SequenceReaderIO swaps the order of environment parameters when the inner computation is a ReaderIO.
+//
+// This function is specialized for the case where the innermost computation is a ReaderIO
+// (with IO effects but no error handling) rather than another ReaderReaderIOResult. It takes
+// a ReaderReaderIOResult that produces a ReaderIO and returns a Kleisli arrow that reverses
+// the order of the outer environment parameters.
+//
+// Type Parameters:
+//   - R1: The first environment type (becomes outermost after sequence)
+//   - R2: The second environment type (becomes inner after sequence)
+//   - A: The success value type
+//
+// Parameters:
+//   - ma: A ReaderReaderIOResult[R2, ReaderIO[R1, A]]
+//
+// Returns:
+//   - A Kleisli[R2, R1, A], which is func(R1) ReaderReaderIOResult[R2, A]
+//
+// The function lifts the ReaderIO computation (which has IO effects but no error handling)
+// into the ReaderIOResult context (with context.Context and error handling) while reordering
+// the environment dependencies.
+//
+// Example:
+//
+//	type AppConfig struct {
+//	    FilePath string
+//	}
+//	type Logger struct {
+//	    Level string
+//	}
+//
+//	// Original: takes AppConfig, may produce a ReaderIO[Logger, string]
+//	original := func(cfg AppConfig) readerioresult.ReaderIOResult[context.Context, readerio.ReaderIO[Logger, string]] {
+//	    return readerioresult.Of[context.Context](func(logger Logger) io.IO[string] {
+//	        return func() string {
+//	            return fmt.Sprintf("[%s] Reading from %s", logger.Level, cfg.FilePath)
+//	        }
+//	    })
+//	}
+//
+//	// Sequence to provide Logger first, then AppConfig
+//	sequenced := SequenceReaderIO[Logger, AppConfig, string](original)
+//	ctx := context.Background()
+//	result := sequenced(Logger{Level: "INFO"})(AppConfig{FilePath: "/data"})(ctx)()
+func SequenceReaderIO[R1, R2, A any](ma ReaderReaderIOResult[R2, ReaderIO[R1, A]]) Kleisli[R2, R1, A] {
+	return RRIOE.SequenceReaderIO(ma)
+}
+
+// Traverse transforms a ReaderReaderIOResult computation by applying a function that produces
+// another ReaderReaderIOResult, effectively swapping the order of outer environment parameters.
+//
+// This function is useful when you have a computation that depends on environment R2 and
+// produces a value of type A, and you want to transform it using a function that takes A
+// and produces a computation depending on environment R1. The result is a curried function
+// that takes R1 first, then R2, and produces a computation with context.Context and error handling.
+//
+// Type Parameters:
+//   - R2: The outer environment type from the original computation
+//   - R1: The inner environment type introduced by the transformation
+//   - A: The input value type
+//   - B: The output value type
+//
+// Parameters:
+//   - f: A Kleisli arrow that transforms A into a ReaderReaderIOResult[R1, B]
+//
+// Returns:
+//   - A function that takes a ReaderReaderIOResult[R2, A] and returns a Kleisli[R2, R1, B],
+//     which is func(R1) ReaderReaderIOResult[R2, B]
+//
+// The function preserves error handling and IO effects while reordering the environment dependencies.
+// This is the generalized version of Sequence that also applies a transformation function.
+//
+// Example:
+//
+//	type AppConfig struct {
+//	    SystemID string
+//	}
+//	type UserConfig struct {
+//	    UserID int
+//	}
+//
+//	// Original computation depending on AppConfig
+//	original := Of[AppConfig](42)
+//
+//	// Transformation that introduces UserConfig dependency
+//	transform := func(n int) ReaderReaderIOResult[UserConfig, string] {
+//	    return func(userCfg UserConfig) readerioresult.ReaderIOResult[context.Context, string] {
+//	        return readerioresult.Of[context.Context](fmt.Sprintf("User %d: %d", userCfg.UserID, n))
+//	    }
+//	}
+//
+//	// Apply traverse to swap order and transform
+//	traversed := Traverse[AppConfig, UserConfig, int, string](transform)(original)
+//
+//	// Provide UserConfig first, then AppConfig
+//	ctx := context.Background()
+//	result := traversed(UserConfig{UserID: 1})(AppConfig{SystemID: "sys1"})(ctx)()
+func Traverse[R2, R1, A, B any](
+	f Kleisli[R1, A, B],
+) func(ReaderReaderIOResult[R2, A]) Kleisli[R2, R1, B] {
+	return readert.Traverse[ReaderReaderIOResult[R2, A]](
+		readerioeither.Map,
+		readerioeither.Chain,
+		f,
+	)
+}
+
+// TraverseReader transforms a ReaderReaderIOResult computation by applying a Reader-based function,
+// effectively introducing a new environment dependency.
+//
+// This function takes a Reader-based transformation (Kleisli arrow) and returns a function that
+// can transform a ReaderReaderIOResult. The result allows you to provide the Reader's environment (R1)
+// first, which then produces a ReaderReaderIOResult that depends on environment R2.
+//
+// Type Parameters:
+//   - R2: The outer environment type from the original ReaderReaderIOResult
+//   - R1: The inner environment type introduced by the Reader transformation
+//   - A: The input value type
+//   - B: The output value type
+//
+// Parameters:
+//   - f: A Reader-based Kleisli arrow that transforms A to B using environment R1
+//
+// Returns:
+//   - A function that takes a ReaderReaderIOResult[R2, A] and returns a Kleisli[R2, R1, B],
+//     which is func(R1) ReaderReaderIOResult[R2, B]
+//
+// The function preserves error handling and IO effects while adding the Reader environment dependency
+// and reordering the environment parameters. This is useful when you want to introduce a pure
+// (non-IO, non-error) environment dependency to an existing computation.
+//
+// Example:
+//
+//	type AppConfig struct {
+//	    Timeout int
+//	}
+//	type UserPreferences struct {
+//	    Theme string
+//	}
+//
+//	// Original computation depending on AppConfig
+//	original := Of[AppConfig](100)
+//
+//	// Pure Reader transformation that introduces UserPreferences dependency
+//	formatWithTheme := func(value int) reader.Reader[UserPreferences, string] {
+//	    return func(prefs UserPreferences) string {
+//	        return fmt.Sprintf("[%s theme] Value: %d", prefs.Theme, value)
+//	    }
+//	}
+//
+//	// Apply traverse to introduce UserPreferences and swap order
+//	traversed := TraverseReader[AppConfig, UserPreferences, int, string](formatWithTheme)(original)
+//
+//	// Provide UserPreferences first, then AppConfig
+//	ctx := context.Background()
+//	result := traversed(UserPreferences{Theme: "dark"})(AppConfig{Timeout: 30})(ctx)()
+func TraverseReader[R2, R1, A, B any](
+	f reader.Kleisli[R1, A, B],
+) func(ReaderReaderIOResult[R2, A]) Kleisli[R2, R1, B] {
+	return readert.TraverseReader[ReaderReaderIOResult[R2, A]](
+		readerioeither.Map,
+		readerioeither.Map,
+		f,
+	)
+}

v2/context/readerreaderioresult/flip_test.go

@@ -0,0 +1,778 @@
+// Copyright (c) 2023 - 2025 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package readerreaderioresult
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"testing"
+
+	RIORES "github.com/IBM/fp-go/v2/context/readerioresult"
+	F "github.com/IBM/fp-go/v2/function"
+	"github.com/IBM/fp-go/v2/io"
+	"github.com/IBM/fp-go/v2/reader"
+	"github.com/IBM/fp-go/v2/result"
+	"github.com/stretchr/testify/assert"
+)
+
+type Config1 struct {
+	value1 int
+}
+
+type Config2 struct {
+	value2 string
+}
+
+func TestSequence(t *testing.T) {
+	t.Run("swaps parameter order for simple types", func(t *testing.T) {
+		ctx := t.Context()
+
+		// Original: takes Config2, returns ReaderIOResult that may produce ReaderReaderIOResult[Config1, int]
+		original := func(cfg2 Config2) RIORES.ReaderIOResult[ReaderReaderIOResult[Config1, int]] {
+			return func(ctx1 context.Context) IOResult[ReaderReaderIOResult[Config1, int]] {
+				return func() Result[ReaderReaderIOResult[Config1, int]] {
+					return result.Of(func(cfg1 Config1) RIORES.ReaderIOResult[int] {
+						return func(ctx2 context.Context) IOResult[int] {
+							return func() Result[int] {
+								return result.Of(cfg1.value1 + len(cfg2.value2))
+							}
+						}
+					})
+				}
+			}
+		}
+
+		// Sequence swaps Config1 and Config2 order
+		sequenced := Sequence(original)
+
+		cfg1 := Config1{value1: 10}
+		cfg2 := Config2{value2: "hello"}
+
+		// Test original: Config2 -> Context -> Config1 -> Context
+		result1 := original(cfg2)(ctx)()
+		assert.True(t, result.IsRight(result1))
+		innerFunc1, _ := result.Unwrap(result1)
+		innerResult1 := innerFunc1(cfg1)(ctx)()
+		assert.Equal(t, result.Of(15), innerResult1)
+
+		// Test sequenced: Config1 -> Config2 -> Context
+		innerFunc2 := sequenced(cfg1)
+		innerResult2 := innerFunc2(cfg2)(ctx)()
+		assert.Equal(t, result.Of(15), innerResult2)
+	})
+
+	t.Run("preserves error handling", func(t *testing.T) {
+		ctx := t.Context()
+		testErr := errors.New("test error")
+
+		// Original that returns an error
+		original := func(cfg2 Config2) RIORES.ReaderIOResult[ReaderReaderIOResult[Config1, int]] {
+			return func(ctx context.Context) IOResult[ReaderReaderIOResult[Config1, int]] {
+				return func() Result[ReaderReaderIOResult[Config1, int]] {
+					return result.Left[ReaderReaderIOResult[Config1, int]](testErr)
+				}
+			}
+		}
+
+		sequenced := Sequence(original)
+
+		cfg1 := Config1{value1: 10}
+		cfg2 := Config2{value2: "hello"}
+
+		// Test sequenced preserves error
+		innerFunc := sequenced(cfg1)
+		outcome := innerFunc(cfg2)(ctx)()
+		assert.Equal(t, result.Left[int](testErr), outcome)
+	})
+
+	t.Run("works with nested computations", func(t *testing.T) {
+		ctx := t.Context()
+
+		// Original with nested logic
+		original := func(cfg2 Config2) RIORES.ReaderIOResult[ReaderReaderIOResult[Config1, string]] {
+			return func(ctx context.Context) IOResult[ReaderReaderIOResult[Config1, string]] {
+				return func() Result[ReaderReaderIOResult[Config1, string]] {
+					if len(cfg2.value2) == 0 {
+						return result.Left[ReaderReaderIOResult[Config1, string]](errors.New("empty string"))
+					}
+					return result.Of(func(cfg1 Config1) RIORES.ReaderIOResult[string] {
+						return func(ctx context.Context) IOResult[string] {
+							return func() Result[string] {
+								if cfg1.value1 < 0 {
+									return result.Left[string](errors.New("negative value"))
+								}
+								return result.Of(fmt.Sprintf("%s:%d", cfg2.value2, cfg1.value1))
+							}
+						}
+					})
+				}
+			}
+		}
+
+		sequenced := Sequence(original)
+
+		// Test with valid inputs
+		result1 := sequenced(Config1{value1: 42})(Config2{value2: "test"})(ctx)()
+		assert.Equal(t, result.Of("test:42"), result1)
+
+		// Test with empty string
+		result2 := sequenced(Config1{value1: 42})(Config2{value2: ""})(ctx)()
+		assert.True(t, result.IsLeft(result2))
+
+		// Test with negative value
+		result3 := sequenced(Config1{value1: -1})(Config2{value2: "test"})(ctx)()
+		assert.True(t, result.IsLeft(result3))
+	})
+
+	t.Run("works with zero values", func(t *testing.T) {
+		ctx := t.Context()
+
+		original := func(cfg2 Config2) RIORES.ReaderIOResult[ReaderReaderIOResult[Config1, int]] {
+			return func(ctx context.Context) IOResult[ReaderReaderIOResult[Config1, int]] {
+				return func() Result[ReaderReaderIOResult[Config1, int]] {
+					return result.Of(func(cfg1 Config1) RIORES.ReaderIOResult[int] {
+						return func(ctx context.Context) IOResult[int] {
+							return func() Result[int] {
+								return result.Of(cfg1.value1 + len(cfg2.value2))
+							}
+						}
+					})
+				}
+			}
+		}
+
+		sequenced := Sequence(original)
+
+		outcome := sequenced(Config1{value1: 0})(Config2{value2: ""})(ctx)()
+		assert.Equal(t, result.Of(0), outcome)
+	})
+
+	t.Run("maintains referential transparency", func(t *testing.T) {
+		ctx := t.Context()
+
+		original := func(cfg2 Config2) RIORES.ReaderIOResult[ReaderReaderIOResult[Config1, int]] {
+			return func(ctx context.Context) IOResult[ReaderReaderIOResult[Config1, int]] {
+				return func() Result[ReaderReaderIOResult[Config1, int]] {
+					return result.Of(func(cfg1 Config1) RIORES.ReaderIOResult[int] {
+						return func(ctx context.Context) IOResult[int] {
+							return func() Result[int] {
+								return result.Of(cfg1.value1 * len(cfg2.value2))
+							}
+						}
+					})
+				}
+			}
+		}
+
+		sequenced := Sequence(original)
+
+		cfg1 := Config1{value1: 3}
+		cfg2 := Config2{value2: "test"}
+
+		// Call multiple times with same inputs
+		for range 5 {
+			outcome := sequenced(cfg1)(cfg2)(ctx)()
+			assert.Equal(t, result.Of(12), outcome)
+		}
+	})
+}
+
+func TestSequenceReader(t *testing.T) {
+	t.Run("swaps parameter order for Reader types", func(t *testing.T) {
+		ctx := t.Context()
+
+		// Original: takes Config2, returns ReaderIOResult that may produce Reader[Config1, int]
+		original := func(cfg2 Config2) RIORES.ReaderIOResult[Reader[Config1, int]] {
+			return func(ctx context.Context) IOResult[Reader[Config1, int]] {
+				return func() Result[Reader[Config1, int]] {
+					return result.Of(func(cfg1 Config1) int {
+						return cfg1.value1 + len(cfg2.value2)
+					})
+				}
+			}
+		}
+
+		// Sequence swaps Config1 and Config2 order
+		sequenced := SequenceReader(original)
+
+		cfg1 := Config1{value1: 10}
+		cfg2 := Config2{value2: "hello"}
+
+		// Test original
+		result1 := original(cfg2)(ctx)()
+		assert.True(t, result.IsRight(result1))
+		innerFunc1, _ := result.Unwrap(result1)
+		value1 := innerFunc1(cfg1)
+		assert.Equal(t, 15, value1)
+
+		// Test sequenced
+		innerFunc2 := sequenced(cfg1)
+		result2 := innerFunc2(cfg2)(ctx)()
+		assert.True(t, result.IsRight(result2))
+		value2, _ := result.Unwrap(result2)
+		assert.Equal(t, 15, value2)
+	})
+
+	t.Run("preserves error handling", func(t *testing.T) {
+		ctx := t.Context()
+		testErr := errors.New("test error")
+
+		original := func(cfg2 Config2) RIORES.ReaderIOResult[Reader[Config1, int]] {
+			return func(ctx context.Context) IOResult[Reader[Config1, int]] {
+				return func() Result[Reader[Config1, int]] {
+					return result.Left[Reader[Config1, int]](testErr)
+				}
+			}
+		}
+
+		sequenced := SequenceReader(original)
+
+		outcome := sequenced(Config1{value1: 10})(Config2{value2: "hello"})(ctx)()
+		assert.Equal(t, result.Left[int](testErr), outcome)
+	})
+
+	t.Run("works with pure Reader computations", func(t *testing.T) {
+		ctx := t.Context()
+
+		original := func(cfg2 Config2) RIORES.ReaderIOResult[Reader[Config1, string]] {
+			return func(ctx context.Context) IOResult[Reader[Config1, string]] {
+				return func() Result[Reader[Config1, string]] {
+					if len(cfg2.value2) == 0 {
+						return result.Left[Reader[Config1, string]](errors.New("empty string"))
+					}
+					return result.Of(func(cfg1 Config1) string {
+						return fmt.Sprintf("%s:%d", cfg2.value2, cfg1.value1)
+					})
+				}
+			}
+		}
+
+		sequenced := SequenceReader(original)
+
+		// Test with valid inputs
+		result1 := sequenced(Config1{value1: 42})(Config2{value2: "test"})(ctx)()
+		assert.Equal(t, result.Of("test:42"), result1)
+
+		// Test with empty string
+		result2 := sequenced(Config1{value1: 42})(Config2{value2: ""})(ctx)()
+		assert.True(t, result.IsLeft(result2))
+	})
+
+	t.Run("works with zero values", func(t *testing.T) {
+		ctx := t.Context()
+
+		original := func(cfg2 Config2) RIORES.ReaderIOResult[Reader[Config1, int]] {
+			return func(ctx context.Context) IOResult[Reader[Config1, int]] {
+				return func() Result[Reader[Config1, int]] {
+					return result.Of(func(cfg1 Config1) int {
+						return cfg1.value1 + len(cfg2.value2)
+					})
+				}
+			}
+		}
+
+		sequenced := SequenceReader(original)
+
+		outcome := sequenced(Config1{value1: 0})(Config2{value2: ""})(ctx)()
+		assert.Equal(t, result.Of(0), outcome)
+	})
+
+	t.Run("maintains referential transparency", func(t *testing.T) {
+		ctx := t.Context()
+
+		original := func(cfg2 Config2) RIORES.ReaderIOResult[Reader[Config1, int]] {
+			return func(ctx context.Context) IOResult[Reader[Config1, int]] {
+				return func() Result[Reader[Config1, int]] {
+					return result.Of(func(cfg1 Config1) int {
+						return cfg1.value1 * len(cfg2.value2)
+					})
+				}
+			}
+		}
+
+		sequenced := SequenceReader(original)
+
+		cfg1 := Config1{value1: 3}
+		cfg2 := Config2{value2: "test"}
+
+		// Call multiple times with same inputs
+		for range 5 {
+			outcome := sequenced(cfg1)(cfg2)(ctx)()
+			assert.Equal(t, result.Of(12), outcome)
+		}
+	})
+}
+
+func TestSequenceReaderIO(t *testing.T) {
+	t.Run("swaps parameter order for ReaderIO types", func(t *testing.T) {
+		ctx := t.Context()
+
+		// Original: takes Config2, returns ReaderIOResult that may produce ReaderIO[Config1, int]
+		original := func(cfg2 Config2) RIORES.ReaderIOResult[ReaderIO[Config1, int]] {
+			return func(ctx context.Context) IOResult[ReaderIO[Config1, int]] {
+				return func() Result[ReaderIO[Config1, int]] {
+					return result.Of(func(cfg1 Config1) io.IO[int] {
+						return io.Of(cfg1.value1 + len(cfg2.value2))
+					})
+				}
+			}
+		}
+
+		// Sequence swaps Config1 and Config2 order
+		sequenced := SequenceReaderIO(original)
+
+		cfg1 := Config1{value1: 10}
+		cfg2 := Config2{value2: "hello"}
+
+		// Test original
+		result1 := original(cfg2)(ctx)()
+		assert.True(t, result.IsRight(result1))
+		innerFunc1, _ := result.Unwrap(result1)
+		value1 := innerFunc1(cfg1)()
+		assert.Equal(t, 15, value1)
+
+		// Test sequenced
+		innerFunc2 := sequenced(cfg1)
+		result2 := innerFunc2(cfg2)(ctx)()
+		assert.True(t, result.IsRight(result2))
+		value2, _ := result.Unwrap(result2)
+		assert.Equal(t, 15, value2)
+	})
+
+	t.Run("preserves error handling", func(t *testing.T) {
+		ctx := t.Context()
+		testErr := errors.New("test error")
+
+		original := func(cfg2 Config2) RIORES.ReaderIOResult[ReaderIO[Config1, int]] {
+			return func(ctx context.Context) IOResult[ReaderIO[Config1, int]] {
+				return func() Result[ReaderIO[Config1, int]] {
+					return result.Left[ReaderIO[Config1, int]](testErr)
+				}
+			}
+		}
+
+		sequenced := SequenceReaderIO(original)
+
+		outcome := sequenced(Config1{value1: 10})(Config2{value2: "hello"})(ctx)()
+		assert.Equal(t, result.Left[int](testErr), outcome)
+	})
+
+	t.Run("works with IO effects", func(t *testing.T) {
+		ctx := t.Context()
+		sideEffect := 0
+
+		original := func(cfg2 Config2) RIORES.ReaderIOResult[ReaderIO[Config1, string]] {
+			return func(ctx context.Context) IOResult[ReaderIO[Config1, string]] {
+				return func() Result[ReaderIO[Config1, string]] {
+					if len(cfg2.value2) == 0 {
+						return result.Left[ReaderIO[Config1, string]](errors.New("empty string"))
+					}
+					return result.Of(func(cfg1 Config1) io.IO[string] {
+						return func() string {
+							sideEffect = cfg1.value1
+							return fmt.Sprintf("%s:%d", cfg2.value2, cfg1.value1)
+						}
+					})
+				}
+			}
+		}
+
+		sequenced := SequenceReaderIO(original)
+
+		// Test with valid inputs
+		sideEffect = 0
+		result1 := sequenced(Config1{value1: 42})(Config2{value2: "test"})(ctx)()
+		assert.Equal(t, result.Of("test:42"), result1)
+		assert.Equal(t, 42, sideEffect)
+
+		// Test with empty string
+		sideEffect = 0
+		result2 := sequenced(Config1{value1: 42})(Config2{value2: ""})(ctx)()
+		assert.True(t, result.IsLeft(result2))
+		assert.Equal(t, 0, sideEffect) // Side effect should not occur
+	})
+
+	t.Run("works with zero values", func(t *testing.T) {
+		ctx := t.Context()
+
+		original := func(cfg2 Config2) RIORES.ReaderIOResult[ReaderIO[Config1, int]] {
+			return func(ctx context.Context) IOResult[ReaderIO[Config1, int]] {
+				return func() Result[ReaderIO[Config1, int]] {
+					return result.Of(func(cfg1 Config1) io.IO[int] {
+						return io.Of(cfg1.value1 + len(cfg2.value2))
+					})
+				}
+			}
+		}
+
+		sequenced := SequenceReaderIO(original)
+
+		outcome := sequenced(Config1{value1: 0})(Config2{value2: ""})(ctx)()
+		assert.Equal(t, result.Of(0), outcome)
+	})
+
+	t.Run("executes IO effects correctly", func(t *testing.T) {
+		ctx := t.Context()
+		counter := 0
+
+		original := func(cfg2 Config2) RIORES.ReaderIOResult[ReaderIO[Config1, int]] {
+			return func(ctx context.Context) IOResult[ReaderIO[Config1, int]] {
+				return func() Result[ReaderIO[Config1, int]] {
+					return result.Of(func(cfg1 Config1) io.IO[int] {
+						return func() int {
+							counter++
+							return cfg1.value1 + len(cfg2.value2)
+						}
+					})
+				}
+			}
+		}
+
+		sequenced := SequenceReaderIO(original)
+
+		cfg1 := Config1{value1: 10}
+		cfg2 := Config2{value2: "hello"}
+
+		// Each execution should increment counter
+		counter = 0
+		result1 := sequenced(cfg1)(cfg2)(ctx)()
+		assert.Equal(t, result.Of(15), result1)
+		assert.Equal(t, 1, counter)
+
+		result2 := sequenced(cfg1)(cfg2)(ctx)()
+		assert.Equal(t, result.Of(15), result2)
+		assert.Equal(t, 2, counter)
+	})
+}
+
+func TestTraverse(t *testing.T) {
+	t.Run("transforms and swaps parameter order", func(t *testing.T) {
+		ctx := t.Context()
+
+		// Original computation depending on Config2
+		original := Of[Config2](42)
+
+		// Transformation that introduces Config1 dependency
+		transform := func(n int) ReaderReaderIOResult[Config1, string] {
+			return func(cfg1 Config1) RIORES.ReaderIOResult[string] {
+				return func(ctx context.Context) IOResult[string] {
+					return func() Result[string] {
+						return result.Of(fmt.Sprintf("value=%d, cfg1=%d", n, cfg1.value1))
+					}
+				}
+			}
+		}
+
+		// Apply traverse to swap order and transform
+		traversed := Traverse[Config2](transform)(original)
+
+		cfg1 := Config1{value1: 100}
+		cfg2 := Config2{value2: "test"}
+
+		outcome := traversed(cfg1)(cfg2)(ctx)()
+		assert.Equal(t, result.Of("value=42, cfg1=100"), outcome)
+	})
+
+	t.Run("preserves error handling in original", func(t *testing.T) {
+		ctx := t.Context()
+		testErr := errors.New("test error")
+		original := Left[Config2, int](testErr)
+
+		transform := func(n int) ReaderReaderIOResult[Config1, string] {
+			return Of[Config1](fmt.Sprintf("%d", n))
+		}
+
+		traversed := Traverse[Config2](transform)(original)
+
+		outcome := traversed(Config1{value1: 100})(Config2{value2: "test"})(ctx)()
+		assert.Equal(t, result.Left[string](testErr), outcome)
+	})
+
+	t.Run("preserves error handling in transformation", func(t *testing.T) {
+		ctx := t.Context()
+		original := Of[Config2](42)
+		testErr := errors.New("transform error")
+
+		transform := func(n int) ReaderReaderIOResult[Config1, string] {
+			if n < 0 {
+				return Left[Config1, string](testErr)
+			}
+			return Of[Config1](fmt.Sprintf("%d", n))
+		}
+
+		// Test with negative value
+		originalNeg := Of[Config2](-1)
+		traversedNeg := Traverse[Config2](transform)(originalNeg)
+		resultNeg := traversedNeg(Config1{value1: 100})(Config2{value2: "test"})(ctx)()
+		assert.Equal(t, result.Left[string](testErr), resultNeg)
+
+		// Test with positive value
+		traversedPos := Traverse[Config2](transform)(original)
+		resultPos := traversedPos(Config1{value1: 100})(Config2{value2: "test"})(ctx)()
+		assert.Equal(t, result.Of("42"), resultPos)
+	})
+
+	t.Run("works with complex transformations", func(t *testing.T) {
+		ctx := t.Context()
+		original := Of[Config2](10)
+
+		transform := func(n int) ReaderReaderIOResult[Config1, int] {
+			return func(cfg1 Config1) RIORES.ReaderIOResult[int] {
+				return func(ctx context.Context) IOResult[int] {
+					return func() Result[int] {
+						return result.Of(n * cfg1.value1)
+					}
+				}
+			}
+		}
+
+		traversed := Traverse[Config2](transform)(original)
+
+		outcome := traversed(Config1{value1: 5})(Config2{value2: "test"})(ctx)()
+		assert.Equal(t, result.Of(50), outcome)
+	})
+
+	t.Run("can be composed with other operations", func(t *testing.T) {
+		ctx := t.Context()
+		original := Of[Config2](10)
+
+		transform := func(n int) ReaderReaderIOResult[Config1, int] {
+			return Of[Config1](n * 2)
+		}
+
+		outcome := F.Pipe2(
+			original,
+			Traverse[Config2](transform),
+			func(k Kleisli[Config2, Config1, int]) ReaderReaderIOResult[Config2, int] {
+				return k(Config1{value1: 5})
+			},
+		)
+
+		res := outcome(Config2{value2: "test"})(ctx)()
+		assert.Equal(t, result.Of(20), res)
+	})
+}
+
+func TestTraverseReader(t *testing.T) {
+	t.Run("transforms with pure Reader and swaps parameter order", func(t *testing.T) {
+		ctx := t.Context()
+
+		// Original computation depending on Config2
+		original := Of[Config2](100)
+
+		// Pure Reader transformation that introduces Config1 dependency
+		formatWithConfig := func(value int) reader.Reader[Config1, string] {
+			return func(cfg1 Config1) string {
+				return fmt.Sprintf("value=%d, multiplier=%d, result=%d", value, cfg1.value1, value*cfg1.value1)
+			}
+		}
+
+		// Apply traverse to introduce Config1 and swap order
+		traversed := TraverseReader[Config2](formatWithConfig)(original)
+
+		cfg1 := Config1{value1: 5}
+		cfg2 := Config2{value2: "test"}
+
+		outcome := traversed(cfg1)(cfg2)(ctx)()
+		assert.Equal(t, result.Of("value=100, multiplier=5, result=500"), outcome)
+	})
+
+	t.Run("preserves error handling", func(t *testing.T) {
+		ctx := t.Context()
+		testErr := errors.New("test error")
+		original := Left[Config2, int](testErr)
+
+		transform := func(n int) reader.Reader[Config1, string] {
+			return reader.Of[Config1](fmt.Sprintf("%d", n))
+		}
+
+		traversed := TraverseReader[Config2](transform)(original)
+
+		outcome := traversed(Config1{value1: 5})(Config2{value2: "test"})(ctx)()
+		assert.Equal(t, result.Left[string](testErr), outcome)
+	})
+
+	t.Run("works with pure computations", func(t *testing.T) {
+		ctx := t.Context()
+		original := Of[Config2](42)
+
+		// Pure transformation using Reader
+		double := func(n int) reader.Reader[Config1, int] {
+			return func(cfg1 Config1) int {
+				return n * cfg1.value1
+			}
+		}
+
+		traversed := TraverseReader[Config2](double)(original)
+
+		outcome := traversed(Config1{value1: 3})(Config2{value2: "test"})(ctx)()
+		assert.Equal(t, result.Of(126), outcome)
+	})
+
+	t.Run("works with zero values", func(t *testing.T) {
+		ctx := t.Context()
+		original := Of[Config2](0)
+
+		transform := func(n int) reader.Reader[Config1, int] {
+			return func(cfg1 Config1) int {
+				return n + cfg1.value1
+			}
+		}
+
+		traversed := TraverseReader[Config2](transform)(original)
+
+		outcome := traversed(Config1{value1: 0})(Config2{value2: ""})(ctx)()
+		assert.Equal(t, result.Of(0), outcome)
+	})
+
+	t.Run("maintains referential transparency", func(t *testing.T) {
+		ctx := t.Context()
+		original := Of[Config2](10)
+
+		transform := func(n int) reader.Reader[Config1, int] {
+			return func(cfg1 Config1) int {
+				return n * cfg1.value1
+			}
+		}
+
+		traversed := TraverseReader[Config2](transform)(original)
+
+		cfg1 := Config1{value1: 5}
+		cfg2 := Config2{value2: "test"}
+
+		// Call multiple times with same inputs
+		for range 5 {
+			outcome := traversed(cfg1)(cfg2)(ctx)()
+			assert.Equal(t, result.Of(50), outcome)
+		}
+	})
+
+	t.Run("can be used in composition", func(t *testing.T) {
+		ctx := t.Context()
+		original := Of[Config2](10)
+
+		multiply := func(n int) reader.Reader[Config1, int] {
+			return func(cfg1 Config1) int {
+				return n * cfg1.value1
+			}
+		}
+
+		outcome := F.Pipe2(
+			original,
+			TraverseReader[Config2](multiply),
+			func(k Kleisli[Config2, Config1, int]) ReaderReaderIOResult[Config2, int] {
+				return k(Config1{value1: 3})
+			},
+		)
+
+		res := outcome(Config2{value2: "test"})(ctx)()
+		assert.Equal(t, result.Of(30), res)
+	})
+}
+
+func TestFlipIntegration(t *testing.T) {
+	t.Run("Sequence and Traverse work together", func(t *testing.T) {
+		ctx := t.Context()
+
+		// Create a nested computation
+		nested := func(cfg2 Config2) RIORES.ReaderIOResult[ReaderReaderIOResult[Config1, int]] {
+			return func(ctx context.Context) IOResult[ReaderReaderIOResult[Config1, int]] {
+				return func() Result[ReaderReaderIOResult[Config1, int]] {
+					return result.Of(Of[Config1](len(cfg2.value2)))
+				}
+			}
+		}
+
+		// Sequence it
+		sequenced := Sequence(nested)
+
+		// Then traverse with a transformation
+		transform := func(n int) ReaderReaderIOResult[Config1, string] {
+			return Of[Config1](fmt.Sprintf("length=%d", n))
+		}
+
+		// Apply both operations
+		cfg1 := Config1{value1: 10}
+		cfg2 := Config2{value2: "hello"}
+
+		// First sequence
+		intermediate := sequenced(cfg1)(cfg2)(ctx)()
+		assert.Equal(t, result.Of(5), intermediate)
+
+		// Then apply traverse on a new computation
+		original := Of[Config2](5)
+		traversed := Traverse[Config2](transform)(original)
+		outcome := traversed(cfg1)(cfg2)(ctx)()
+		assert.Equal(t, result.Of("length=5"), outcome)
+	})
+
+	t.Run("all flip functions preserve error semantics", func(t *testing.T) {
+		ctx := t.Context()
+		testErr := errors.New("test error")
+		cfg1 := Config1{value1: 10}
+		cfg2 := Config2{value2: "test"}
+
+		// Test Sequence with error
+		seqErr := func(cfg2 Config2) RIORES.ReaderIOResult[ReaderReaderIOResult[Config1, int]] {
+			return func(ctx context.Context) IOResult[ReaderReaderIOResult[Config1, int]] {
+				return func() Result[ReaderReaderIOResult[Config1, int]] {
+					return result.Left[ReaderReaderIOResult[Config1, int]](testErr)
+				}
+			}
+		}
+		seqResult := Sequence(seqErr)(cfg1)(cfg2)(ctx)()
+		assert.True(t, result.IsLeft(seqResult))
+
+		// Test SequenceReader with error
+		seqReaderErr := func(cfg2 Config2) RIORES.ReaderIOResult[Reader[Config1, int]] {
+			return func(ctx context.Context) IOResult[Reader[Config1, int]] {
+				return func() Result[Reader[Config1, int]] {
+					return result.Left[Reader[Config1, int]](testErr)
+				}
+			}
+		}
+		seqReaderResult := SequenceReader(seqReaderErr)(cfg1)(cfg2)(ctx)()
+		assert.True(t, result.IsLeft(seqReaderResult))
+
+		// Test SequenceReaderIO with error
+		seqReaderIOErr := func(cfg2 Config2) RIORES.ReaderIOResult[ReaderIO[Config1, int]] {
+			return func(ctx context.Context) IOResult[ReaderIO[Config1, int]] {
+				return func() Result[ReaderIO[Config1, int]] {
+					return result.Left[ReaderIO[Config1, int]](testErr)
+				}
+			}
+		}
+		seqReaderIOResult := SequenceReaderIO(seqReaderIOErr)(cfg1)(cfg2)(ctx)()
+		assert.True(t, result.IsLeft(seqReaderIOResult))
+
+		// Test Traverse with error
+		travErr := Left[Config2, int](testErr)
+		travTransform := func(n int) ReaderReaderIOResult[Config1, string] {
+			return Of[Config1](fmt.Sprintf("%d", n))
+		}
+		travResult := Traverse[Config2](travTransform)(travErr)(cfg1)(cfg2)(ctx)()
+		assert.True(t, result.IsLeft(travResult))
+
+		// Test TraverseReader with error
+		travReaderErr := Left[Config2, int](testErr)
+		travReaderTransform := func(n int) reader.Reader[Config1, string] {
+			return reader.Of[Config1](fmt.Sprintf("%d", n))
+		}
+		travReaderResult := TraverseReader[Config2](travReaderTransform)(travReaderErr)(cfg1)(cfg2)(ctx)()
+		assert.True(t, result.IsLeft(travReaderResult))
+	})
+}

v2/context/readerreaderioresult/monoid.go

@@ -0,0 +1,148 @@
+//   Copyright (c) 2023 IBM Corp.
+//   All rights reserved.
+//
+//   Licensed under the Apache License, Version 2.0 (the "License");
+//   you may not use this file except in compliance with the License.
+//   You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+//   Unless required by applicable law or agreed to in writing, software
+//   distributed under the License is distributed on an "AS IS" BASIS,
+//   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//   See the License for the specific language governing permissions and
+//   limitations under the License.
+
+package readerreaderioresult
+
+import (
+	"github.com/IBM/fp-go/v2/monoid"
+)
+
+type (
+	// Monoid represents a monoid structure for ReaderReaderIOResult[R, A].
+	// A monoid provides an identity element (empty) and an associative binary operation (concat).
+	Monoid[R, A any] = monoid.Monoid[ReaderReaderIOResult[R, A]]
+)
+
+// ApplicativeMonoid creates a monoid for ReaderReaderIOResult using applicative composition.
+// It combines values using the provided monoid m and the applicative Ap operation.
+// This allows combining multiple ReaderReaderIOResult values in parallel while merging their results.
+//
+// The resulting monoid satisfies:
+//   - Identity: concat(empty, x) = concat(x, empty) = x
+//   - Associativity: concat(concat(x, y), z) = concat(x, concat(y, z))
+//
+// Example:
+//
+//	import "github.com/IBM/fp-go/v2/monoid"
+//	import "github.com/IBM/fp-go/v2/number"
+//
+//	// Create a monoid for combining integers with addition
+//	intMonoid := ApplicativeMonoid[Config](number.MonoidSum)
+//
+//	// Combine multiple computations
+//	result := intMonoid.Concat(
+//	    Of[Config](10),
+//	    intMonoid.Concat(Of[Config](20), Of[Config](30)),
+//	) // Results in 60
+func ApplicativeMonoid[R, A any](m monoid.Monoid[A]) Monoid[R, A] {
+	return monoid.ApplicativeMonoid(
+		Of[R, A],
+		MonadMap[R, A, func(A) A],
+		MonadAp[R, A, A],
+		m,
+	)
+}
+
+// ApplicativeMonoidSeq creates a monoid for ReaderReaderIOResult using sequential applicative composition.
+// Similar to ApplicativeMonoid but evaluates effects sequentially rather than in parallel.
+//
+// Use this when:
+//   - Effects must be executed in a specific order
+//   - Side effects depend on sequential execution
+//   - You want to avoid concurrent execution
+func ApplicativeMonoidSeq[R, A any](m monoid.Monoid[A]) Monoid[R, A] {
+	return monoid.ApplicativeMonoid(
+		Of[R, A],
+		MonadMap[R, A, func(A) A],
+		MonadApSeq[R, A, A],
+		m,
+	)
+}
+
+// ApplicativeMonoidPar creates a monoid for ReaderReaderIOResult using parallel applicative composition.
+// Similar to ApplicativeMonoid but explicitly evaluates effects in parallel.
+//
+// Use this when:
+//   - Effects are independent and can run concurrently
+//   - You want to maximize performance through parallelism
+//   - Order of execution doesn't matter
+func ApplicativeMonoidPar[R, A any](m monoid.Monoid[A]) Monoid[R, A] {
+	return monoid.ApplicativeMonoid(
+		Of[R, A],
+		MonadMap[R, A, func(A) A],
+		MonadApPar[R, A, A],
+		m,
+	)
+}
+
+// AlternativeMonoid creates a monoid that combines ReaderReaderIOResult values using both
+// applicative composition and alternative (Alt) semantics.
+//
+// This monoid:
+//   - Uses Ap for combining successful values
+//   - Uses Alt for handling failures (tries alternatives on failure)
+//   - Provides a way to combine multiple computations with fallback behavior
+//
+// Example:
+//
+//	import "github.com/IBM/fp-go/v2/monoid"
+//	import "github.com/IBM/fp-go/v2/number"
+//
+//	intMonoid := AlternativeMonoid[Config](number.MonoidSum)
+//
+//	// If first computation fails, tries the second
+//	result := intMonoid.Concat(
+//	    Left[Config, int](errors.New("failed")),
+//	    Of[Config](42),
+//	) // Results in Right(42)
+func AlternativeMonoid[R, A any](m monoid.Monoid[A]) Monoid[R, A] {
+	return monoid.AlternativeMonoid(
+		Of[R, A],
+		MonadMap[R, A, func(A) A],
+		MonadAp[R, A, A],
+		MonadAlt[R, A],
+		m,
+	)
+}
+
+// AltMonoid creates a monoid based solely on the Alt operation.
+// It provides a way to chain computations with fallback behavior.
+//
+// The monoid:
+//   - Uses the provided zero as the identity element
+//   - Uses Alt for concatenation (tries first, falls back to second on failure)
+//   - Implements a "first success" strategy
+//
+// Example:
+//
+//	zero := func() ReaderReaderIOResult[Config, int] {
+//	    return Left[Config, int](errors.New("no value"))
+//	}
+//	altMonoid := AltMonoid[Config, int](zero)
+//
+//	// Tries computations in order until one succeeds
+//	result := altMonoid.Concat(
+//	    Left[Config, int](errors.New("first failed")),
+//	    altMonoid.Concat(
+//	        Left[Config, int](errors.New("second failed")),
+//	        Of[Config](42),
+//	    ),
+//	) // Results in Right(42)
+func AltMonoid[R, A any](zero Lazy[ReaderReaderIOResult[R, A]]) Monoid[R, A] {
+	return monoid.AltMonoid(
+		zero,
+		MonadAlt[R, A],
+	)
+}

v2/context/readerreaderioresult/monoid_test.go

@@ -0,0 +1,337 @@
+// Copyright (c) 2023 - 2025 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package readerreaderioresult
+
+import (
+	"errors"
+	"testing"
+
+	N "github.com/IBM/fp-go/v2/number"
+	"github.com/IBM/fp-go/v2/result"
+	S "github.com/IBM/fp-go/v2/string"
+	"github.com/stretchr/testify/assert"
+)
+
+var (
+	intAddMonoid = N.MonoidSum[int]()
+	strMonoid    = S.Monoid
+	testError    = errors.New("test error")
+)
+
+func TestApplicativeMonoid(t *testing.T) {
+	rrMonoid := ApplicativeMonoid[AppConfig](intAddMonoid)
+	cfg := defaultConfig
+	ctx := t.Context()
+
+	t.Run("empty element", func(t *testing.T) {
+		empty := rrMonoid.Empty()
+		assert.Equal(t, result.Of(0), empty(cfg)(ctx)())
+	})
+
+	t.Run("concat two success values", func(t *testing.T) {
+		rr1 := Of[AppConfig](5)
+		rr2 := Of[AppConfig](3)
+		combined := rrMonoid.Concat(rr1, rr2)
+		assert.Equal(t, result.Of(8), combined(cfg)(ctx)())
+	})
+
+	t.Run("concat with empty", func(t *testing.T) {
+		rr := Of[AppConfig](42)
+		combined1 := rrMonoid.Concat(rr, rrMonoid.Empty())
+		combined2 := rrMonoid.Concat(rrMonoid.Empty(), rr)
+
+		assert.Equal(t, result.Of(42), combined1(cfg)(ctx)())
+		assert.Equal(t, result.Of(42), combined2(cfg)(ctx)())
+	})
+
+	t.Run("concat with left failure", func(t *testing.T) {
+		rrSuccess := Of[AppConfig](5)
+		rrFailure := Left[AppConfig, int](testError)
+
+		combined := rrMonoid.Concat(rrFailure, rrSuccess)
+		assert.True(t, result.IsLeft(combined(cfg)(ctx)()))
+	})
+
+	t.Run("concat with right failure", func(t *testing.T) {
+		rrSuccess := Of[AppConfig](5)
+		rrFailure := Left[AppConfig, int](testError)
+
+		combined := rrMonoid.Concat(rrSuccess, rrFailure)
+		assert.True(t, result.IsLeft(combined(cfg)(ctx)()))
+	})
+
+	t.Run("concat multiple values", func(t *testing.T) {
+		rr1 := Of[AppConfig](1)
+		rr2 := Of[AppConfig](2)
+		rr3 := Of[AppConfig](3)
+		rr4 := Of[AppConfig](4)
+
+		// Chain concat calls: ((1 + 2) + 3) + 4
+		combined := rrMonoid.Concat(
+			rrMonoid.Concat(
+				rrMonoid.Concat(rr1, rr2),
+				rr3,
+			),
+			rr4,
+		)
+		assert.Equal(t, result.Of(10), combined(cfg)(ctx)())
+	})
+
+	t.Run("string concatenation", func(t *testing.T) {
+		strRRMonoid := ApplicativeMonoid[AppConfig](strMonoid)
+
+		rr1 := Of[AppConfig]("Hello")
+		rr2 := Of[AppConfig](" ")
+		rr3 := Of[AppConfig]("World")
+
+		combined := strRRMonoid.Concat(
+			strRRMonoid.Concat(rr1, rr2),
+			rr3,
+		)
+		assert.Equal(t, result.Of("Hello World"), combined(cfg)(ctx)())
+	})
+}
+
+func TestApplicativeMonoidSeq(t *testing.T) {
+	rrMonoid := ApplicativeMonoidSeq[AppConfig](intAddMonoid)
+	cfg := defaultConfig
+	ctx := t.Context()
+
+	t.Run("empty element", func(t *testing.T) {
+		empty := rrMonoid.Empty()
+		assert.Equal(t, result.Of(0), empty(cfg)(ctx)())
+	})
+
+	t.Run("concat two success values", func(t *testing.T) {
+		rr1 := Of[AppConfig](5)
+		rr2 := Of[AppConfig](3)
+		combined := rrMonoid.Concat(rr1, rr2)
+		assert.Equal(t, result.Of(8), combined(cfg)(ctx)())
+	})
+
+	t.Run("concat with failure", func(t *testing.T) {
+		rrSuccess := Of[AppConfig](5)
+		rrFailure := Left[AppConfig, int](testError)
+
+		combined := rrMonoid.Concat(rrFailure, rrSuccess)
+		assert.True(t, result.IsLeft(combined(cfg)(ctx)()))
+	})
+}
+
+func TestApplicativeMonoidPar(t *testing.T) {
+	rrMonoid := ApplicativeMonoidPar[AppConfig](intAddMonoid)
+	cfg := defaultConfig
+	ctx := t.Context()
+
+	t.Run("empty element", func(t *testing.T) {
+		empty := rrMonoid.Empty()
+		assert.Equal(t, result.Of(0), empty(cfg)(ctx)())
+	})
+
+	t.Run("concat two success values", func(t *testing.T) {
+		rr1 := Of[AppConfig](5)
+		rr2 := Of[AppConfig](3)
+		combined := rrMonoid.Concat(rr1, rr2)
+		assert.Equal(t, result.Of(8), combined(cfg)(ctx)())
+	})
+
+	t.Run("concat with failure", func(t *testing.T) {
+		rrSuccess := Of[AppConfig](5)
+		rrFailure := Left[AppConfig, int](testError)
+
+		combined := rrMonoid.Concat(rrFailure, rrSuccess)
+		assert.True(t, result.IsLeft(combined(cfg)(ctx)()))
+	})
+}
+
+func TestAltMonoid(t *testing.T) {
+	zero := func() ReaderReaderIOResult[AppConfig, int] {
+		return Left[AppConfig, int](errors.New("empty"))
+	}
+
+	rrMonoid := AltMonoid(zero)
+	cfg := defaultConfig
+	ctx := t.Context()
+
+	t.Run("empty element", func(t *testing.T) {
+		empty := rrMonoid.Empty()
+		assert.True(t, result.IsLeft(empty(cfg)(ctx)()))
+	})
+
+	t.Run("concat two success values - uses first", func(t *testing.T) {
+		rr1 := Of[AppConfig](5)
+		rr2 := Of[AppConfig](3)
+		combined := rrMonoid.Concat(rr1, rr2)
+		// AltMonoid takes the first successful value
+		assert.Equal(t, result.Of(5), combined(cfg)(ctx)())
+	})
+
+	t.Run("concat failure then success", func(t *testing.T) {
+		rrFailure := Left[AppConfig, int](testError)
+		rrSuccess := Of[AppConfig](42)
+
+		combined := rrMonoid.Concat(rrFailure, rrSuccess)
+		// Should fall back to second when first fails
+		assert.Equal(t, result.Of(42), combined(cfg)(ctx)())
+	})
+
+	t.Run("concat success then failure", func(t *testing.T) {
+		rrSuccess := Of[AppConfig](42)
+		rrFailure := Left[AppConfig, int](testError)
+
+		combined := rrMonoid.Concat(rrSuccess, rrFailure)
+		// Should use first successful value
+		assert.Equal(t, result.Of(42), combined(cfg)(ctx)())
+	})
+
+	t.Run("concat two failures", func(t *testing.T) {
+		err1 := errors.New("error 1")
+		err2 := errors.New("error 2")
+
+		rr1 := Left[AppConfig, int](err1)
+		rr2 := Left[AppConfig, int](err2)
+
+		combined := rrMonoid.Concat(rr1, rr2)
+		// Should use second error when both fail
+		assert.True(t, result.IsLeft(combined(cfg)(ctx)()))
+	})
+
+	t.Run("concat with empty", func(t *testing.T) {
+		rr := Of[AppConfig](42)
+		combined1 := rrMonoid.Concat(rr, rrMonoid.Empty())
+		combined2 := rrMonoid.Concat(rrMonoid.Empty(), rr)
+
+		assert.Equal(t, result.Of(42), combined1(cfg)(ctx)())
+		assert.Equal(t, result.Of(42), combined2(cfg)(ctx)())
+	})
+
+	t.Run("fallback chain", func(t *testing.T) {
+		// Simulate trying multiple sources until one succeeds
+		primary := Left[AppConfig, string](errors.New("primary failed"))
+		secondary := Left[AppConfig, string](errors.New("secondary failed"))
+		tertiary := Of[AppConfig]("tertiary success")
+
+		strZero := func() ReaderReaderIOResult[AppConfig, string] {
+			return Left[AppConfig, string](errors.New("all failed"))
+		}
+		strMonoid := AltMonoid(strZero)
+
+		// Chain concat: try primary, then secondary, then tertiary
+		combined := strMonoid.Concat(
+			strMonoid.Concat(primary, secondary),
+			tertiary,
+		)
+		assert.Equal(t, result.Of("tertiary success"), combined(cfg)(ctx)())
+	})
+}
+
+func TestAlternativeMonoid(t *testing.T) {
+	rrMonoid := AlternativeMonoid[AppConfig](intAddMonoid)
+	cfg := defaultConfig
+	ctx := t.Context()
+
+	t.Run("empty element", func(t *testing.T) {
+		empty := rrMonoid.Empty()
+		assert.Equal(t, result.Of(0), empty(cfg)(ctx)())
+	})
+
+	t.Run("concat two success values", func(t *testing.T) {
+		rr1 := Of[AppConfig](5)
+		rr2 := Of[AppConfig](3)
+		combined := rrMonoid.Concat(rr1, rr2)
+		assert.Equal(t, result.Of(8), combined(cfg)(ctx)())
+	})
+
+	t.Run("concat failure then success", func(t *testing.T) {
+		rrFailure := Left[AppConfig, int](testError)
+		rrSuccess := Of[AppConfig](42)
+
+		combined := rrMonoid.Concat(rrFailure, rrSuccess)
+		// Alternative falls back to second when first fails
+		assert.Equal(t, result.Of(42), combined(cfg)(ctx)())
+	})
+
+	t.Run("concat success then failure", func(t *testing.T) {
+		rrSuccess := Of[AppConfig](42)
+		rrFailure := Left[AppConfig, int](testError)
+
+		combined := rrMonoid.Concat(rrSuccess, rrFailure)
+		// Should use first successful value
+		assert.Equal(t, result.Of(42), combined(cfg)(ctx)())
+	})
+
+	t.Run("concat with empty", func(t *testing.T) {
+		rr := Of[AppConfig](42)
+		combined1 := rrMonoid.Concat(rr, rrMonoid.Empty())
+		combined2 := rrMonoid.Concat(rrMonoid.Empty(), rr)
+
+		assert.Equal(t, result.Of(42), combined1(cfg)(ctx)())
+		assert.Equal(t, result.Of(42), combined2(cfg)(ctx)())
+	})
+
+	t.Run("multiple values with some failures", func(t *testing.T) {
+		rr1 := Left[AppConfig, int](errors.New("fail 1"))
+		rr2 := Of[AppConfig](5)
+		rr3 := Left[AppConfig, int](errors.New("fail 2"))
+		rr4 := Of[AppConfig](10)
+
+		// Alternative should skip failures and accumulate successes
+		combined := rrMonoid.Concat(
+			rrMonoid.Concat(
+				rrMonoid.Concat(rr1, rr2),
+				rr3,
+			),
+			rr4,
+		)
+		// Should accumulate successful values: 5 + 10 = 15
+		assert.Equal(t, result.Of(15), combined(cfg)(ctx)())
+	})
+}
+
+// Test monoid laws
+func TestMonoidLaws(t *testing.T) {
+	rrMonoid := ApplicativeMonoid[AppConfig](intAddMonoid)
+	cfg := defaultConfig
+	ctx := t.Context()
+
+	// Left identity: empty <> x == x
+	t.Run("left identity", func(t *testing.T) {
+		x := Of[AppConfig](42)
+		result1 := rrMonoid.Concat(rrMonoid.Empty(), x)(cfg)(ctx)()
+		result2 := x(cfg)(ctx)()
+		assert.Equal(t, result2, result1)
+	})
+
+	// Right identity: x <> empty == x
+	t.Run("right identity", func(t *testing.T) {
+		x := Of[AppConfig](42)
+		result1 := rrMonoid.Concat(x, rrMonoid.Empty())(cfg)(ctx)()
+		result2 := x(cfg)(ctx)()
+		assert.Equal(t, result2, result1)
+	})
+
+	// Associativity: (x <> y) <> z == x <> (y <> z)
+	t.Run("associativity", func(t *testing.T) {
+		x := Of[AppConfig](1)
+		y := Of[AppConfig](2)
+		z := Of[AppConfig](3)
+
+		left := rrMonoid.Concat(rrMonoid.Concat(x, y), z)(cfg)(ctx)()
+		right := rrMonoid.Concat(x, rrMonoid.Concat(y, z))(cfg)(ctx)()
+
+		assert.Equal(t, right, left)
+	})
+}

v2/context/readerreaderioresult/reader.go

@@ -0,0 +1,894 @@
+// Copyright (c) 2023 - 2025 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package readerreaderioresult
+
+import (
+	"context"
+	"time"
+
+	RIOE "github.com/IBM/fp-go/v2/context/readerioresult"
+	"github.com/IBM/fp-go/v2/either"
+	"github.com/IBM/fp-go/v2/function"
+	"github.com/IBM/fp-go/v2/internal/chain"
+	"github.com/IBM/fp-go/v2/internal/fromeither"
+	"github.com/IBM/fp-go/v2/internal/fromio"
+	"github.com/IBM/fp-go/v2/internal/fromioeither"
+	"github.com/IBM/fp-go/v2/internal/fromreader"
+	"github.com/IBM/fp-go/v2/internal/functor"
+	"github.com/IBM/fp-go/v2/internal/readert"
+	"github.com/IBM/fp-go/v2/io"
+	IOE "github.com/IBM/fp-go/v2/ioeither"
+	"github.com/IBM/fp-go/v2/option"
+	"github.com/IBM/fp-go/v2/reader"
+	RE "github.com/IBM/fp-go/v2/readereither"
+	"github.com/IBM/fp-go/v2/readerio"
+	"github.com/IBM/fp-go/v2/readeroption"
+	RRIOE "github.com/IBM/fp-go/v2/readerreaderioeither"
+)
+
+// FromReaderOption converts a ReaderOption to a ReaderReaderIOResult.
+// If the option is None, it uses the provided onNone function to generate an error.
+//
+//go:inline
+func FromReaderOption[R, A any](onNone Lazy[error]) Kleisli[R, ReaderOption[R, A], A] {
+	return RRIOE.FromReaderOption[R, context.Context, A](onNone)
+}
+
+// FromReaderIOResult lifts a ReaderIOResult into a ReaderReaderIOResult.
+// This adds an additional reader layer to the computation.
+//
+//go:inline
+func FromReaderIOResult[R, A any](ma ReaderIOResult[R, A]) ReaderReaderIOResult[R, A] {
+	return RRIOE.FromReaderIOEither[context.Context](ma)
+}
+
+// FromReaderIO lifts a ReaderIO into a ReaderReaderIOResult.
+// The IO computation is wrapped in a Right (success) value.
+//
+//go:inline
+func FromReaderIO[R, A any](ma ReaderIO[R, A]) ReaderReaderIOResult[R, A] {
+	return RRIOE.FromReaderIO[context.Context, error](ma)
+}
+
+// RightReaderIO lifts a ReaderIO into a ReaderReaderIOResult as a Right (success) value.
+// Alias for FromReaderIO.
+//
+//go:inline
+func RightReaderIO[R, A any](ma ReaderIO[R, A]) ReaderReaderIOResult[R, A] {
+	return RRIOE.RightReaderIO[context.Context, error](ma)
+}
+
+// LeftReaderIO lifts a ReaderIO that produces an error into a ReaderReaderIOResult as a Left (failure) value.
+//
+//go:inline
+func LeftReaderIO[A, R any](me ReaderIO[R, error]) ReaderReaderIOResult[R, A] {
+	return RRIOE.LeftReaderIO[context.Context, A](me)
+}
+
+// MonadMap applies a function to the value inside a ReaderReaderIOResult (Functor operation).
+// This is the monadic version that takes the computation as the first parameter.
+//
+//go:inline
+func MonadMap[R, A, B any](fa ReaderReaderIOResult[R, A], f func(A) B) ReaderReaderIOResult[R, B] {
+	return reader.MonadMap(fa, RIOE.Map(f))
+}
+
+// Map applies a function to the value inside a ReaderReaderIOResult (Functor operation).
+// This is the curried version that returns an operator.
+//
+//go:inline
+func Map[R, A, B any](f func(A) B) Operator[R, A, B] {
+	return reader.Map[R](RIOE.Map(f))
+}
+
+// MonadMapTo replaces the value inside a ReaderReaderIOResult with a constant value.
+// This is the monadic version that takes the computation as the first parameter.
+//
+//go:inline
+func MonadMapTo[R, A, B any](fa ReaderReaderIOResult[R, A], b B) ReaderReaderIOResult[R, B] {
+	return reader.MonadMap(fa, RIOE.MapTo[A](b))
+}
+
+// MapTo replaces the value inside a ReaderReaderIOResult with a constant value.
+// This is the curried version that returns an operator.
+//
+//go:inline
+func MapTo[R, A, B any](b B) Operator[R, A, B] {
+	return reader.Map[R](RIOE.MapTo[A](b))
+}
+
+// MonadChain sequences two computations, where the second depends on the result of the first (Monad operation).
+// This is the monadic version that takes the computation as the first parameter.
+//
+//go:inline
+func MonadChain[R, A, B any](fa ReaderReaderIOResult[R, A], f Kleisli[R, A, B]) ReaderReaderIOResult[R, B] {
+	return readert.MonadChain(
+		RIOE.MonadChain[A, B],
+		fa,
+		f,
+	)
+}
+
+// MonadChainFirst sequences two computations but returns the result of the first.
+// Useful for performing side effects while preserving the original value.
+// This is the monadic version that takes the computation as the first parameter.
+//
+//go:inline
+func MonadChainFirst[R, A, B any](fa ReaderReaderIOResult[R, A], f Kleisli[R, A, B]) ReaderReaderIOResult[R, A] {
+	return chain.MonadChainFirst(
+		MonadChain[R, A, A],
+		MonadMap[R, B, A],
+		fa,
+		f)
+}
+
+// MonadTap is an alias for MonadChainFirst.
+// Executes a side effect while preserving the original value.
+//
+//go:inline
+func MonadTap[R, A, B any](fa ReaderReaderIOResult[R, A], f Kleisli[R, A, B]) ReaderReaderIOResult[R, A] {
+	return MonadChainFirst(fa, f)
+}
+
+// MonadChainEitherK chains a computation that returns an Either.
+// The Either is automatically lifted into ReaderReaderIOResult.
+// This is the monadic version that takes the computation as the first parameter.
+//
+//go:inline
+func MonadChainEitherK[R, A, B any](ma ReaderReaderIOResult[R, A], f either.Kleisli[error, A, B]) ReaderReaderIOResult[R, B] {
+	return fromeither.MonadChainEitherK(
+		MonadChain[R, A, B],
+		FromEither[R, B],
+		ma,
+		f,
+	)
+}
+
+// ChainEitherK chains a computation that returns an Either.
+// The Either is automatically lifted into ReaderReaderIOResult.
+// This is the curried version that returns an operator.
+//
+//go:inline
+func ChainEitherK[R, A, B any](f either.Kleisli[error, A, B]) Operator[R, A, B] {
+	return fromeither.ChainEitherK(
+		Chain[R, A, B],
+		FromEither[R, B],
+		f,
+	)
+}
+
+// MonadChainFirstEitherK chains a computation that returns an Either but preserves the original value.
+// Useful for validation or side effects that may fail.
+// This is the monadic version that takes the computation as the first parameter.
+//
+//go:inline
+func MonadChainFirstEitherK[R, A, B any](ma ReaderReaderIOResult[R, A], f either.Kleisli[error, A, B]) ReaderReaderIOResult[R, A] {
+	return fromeither.MonadChainFirstEitherK(
+		MonadChain[R, A, A],
+		MonadMap[R, B, A],
+		FromEither[R, B],
+		ma,
+		f,
+	)
+}
+
+// MonadTapEitherK is an alias for MonadChainFirstEitherK.
+// Executes an Either-returning side effect while preserving the original value.
+//
+//go:inline
+func MonadTapEitherK[R, A, B any](ma ReaderReaderIOResult[R, A], f either.Kleisli[error, A, B]) ReaderReaderIOResult[R, A] {
+	return MonadChainFirstEitherK(ma, f)
+}
+
+// ChainFirstEitherK chains a computation that returns an Either but preserves the original value.
+// This is the curried version that returns an operator.
+//
+//go:inline
+func ChainFirstEitherK[R, A, B any](f either.Kleisli[error, A, B]) Operator[R, A, A] {
+	return fromeither.ChainFirstEitherK(
+		Chain[R, A, A],
+		Map[R, B, A],
+		FromEither[R, B],
+		f,
+	)
+}
+
+// TapEitherK is an alias for ChainFirstEitherK.
+// Executes an Either-returning side effect while preserving the original value.
+//
+//go:inline
+func TapEitherK[R, A, B any](f either.Kleisli[error, A, B]) Operator[R, A, A] {
+	return ChainFirstEitherK[R](f)
+}
+
+// MonadChainReaderK chains a computation that returns a Reader.
+// The Reader is automatically lifted into ReaderReaderIOResult.
+// This is the monadic version that takes the computation as the first parameter.
+//
+//go:inline
+func MonadChainReaderK[R, A, B any](ma ReaderReaderIOResult[R, A], f reader.Kleisli[R, A, B]) ReaderReaderIOResult[R, B] {
+	return fromreader.MonadChainReaderK(
+		MonadChain[R, A, B],
+		FromReader[R, B],
+		ma,
+		f,
+	)
+}
+
+// ChainReaderK chains a computation that returns a Reader.
+// The Reader is automatically lifted into ReaderReaderIOResult.
+// This is the curried version that returns an operator.
+//
+//go:inline
+func ChainReaderK[R, A, B any](f reader.Kleisli[R, A, B]) Operator[R, A, B] {
+	return fromreader.ChainReaderK(
+		Chain[R, A, B],
+		FromReader[R, B],
+		f,
+	)
+}
+
+// MonadChainFirstReaderK chains a computation that returns a Reader but preserves the original value.
+// This is the monadic version that takes the computation as the first parameter.
+//
+//go:inline
+func MonadChainFirstReaderK[R, A, B any](ma ReaderReaderIOResult[R, A], f reader.Kleisli[R, A, B]) ReaderReaderIOResult[R, A] {
+	return fromreader.MonadChainFirstReaderK(
+		MonadChainFirst[R, A, B],
+		FromReader[R, B],
+		ma,
+		f,
+	)
+}
+
+// MonadTapReaderK is an alias for MonadChainFirstReaderK.
+// Executes a Reader-returning side effect while preserving the original value.
+//
+//go:inline
+func MonadTapReaderK[R, A, B any](ma ReaderReaderIOResult[R, A], f reader.Kleisli[R, A, B]) ReaderReaderIOResult[R, A] {
+	return MonadChainFirstReaderK(ma, f)
+}
+
+// ChainFirstReaderK chains a computation that returns a Reader but preserves the original value.
+// This is the curried version that returns an operator.
+//
+//go:inline
+func ChainFirstReaderK[R, A, B any](f reader.Kleisli[R, A, B]) Operator[R, A, A] {
+	return fromreader.ChainFirstReaderK(
+		ChainFirst[R, A, B],
+		FromReader[R, B],
+		f,
+	)
+}
+
+// TapReaderK is an alias for ChainFirstReaderK.
+// Executes a Reader-returning side effect while preserving the original value.
+//
+//go:inline
+func TapReaderK[R, A, B any](f reader.Kleisli[R, A, B]) Operator[R, A, A] {
+	return ChainFirstReaderK(f)
+}
+
+// MonadChainReaderIOK chains a computation that returns a ReaderIO.
+// The ReaderIO is automatically lifted into ReaderReaderIOResult.
+// This is the monadic version that takes the computation as the first parameter.
+//
+//go:inline
+func MonadChainReaderIOK[R, A, B any](ma ReaderReaderIOResult[R, A], f readerio.Kleisli[R, A, B]) ReaderReaderIOResult[R, B] {
+	return fromreader.MonadChainReaderK(
+		MonadChain[R, A, B],
+		FromReaderIO[R, B],
+		ma,
+		f,
+	)
+}
+
+// ChainReaderIOK chains a computation that returns a ReaderIO.
+// The ReaderIO is automatically lifted into ReaderReaderIOResult.
+// This is the curried version that returns an operator.
+//
+//go:inline
+func ChainReaderIOK[R, A, B any](f readerio.Kleisli[R, A, B]) Operator[R, A, B] {
+	return fromreader.ChainReaderK(
+		Chain[R, A, B],
+		FromReaderIO[R, B],
+		f,
+	)
+}
+
+// MonadChainFirstReaderIOK chains a computation that returns a ReaderIO but preserves the original value.
+// This is the monadic version that takes the computation as the first parameter.
+//
+//go:inline
+func MonadChainFirstReaderIOK[R, A, B any](ma ReaderReaderIOResult[R, A], f readerio.Kleisli[R, A, B]) ReaderReaderIOResult[R, A] {
+	return fromreader.MonadChainFirstReaderK(
+		MonadChainFirst[R, A, B],
+		FromReaderIO[R, B],
+		ma,
+		f,
+	)
+}
+
+// MonadTapReaderIOK is an alias for MonadChainFirstReaderIOK.
+// Executes a ReaderIO-returning side effect while preserving the original value.
+//
+//go:inline
+func MonadTapReaderIOK[R, A, B any](ma ReaderReaderIOResult[R, A], f readerio.Kleisli[R, A, B]) ReaderReaderIOResult[R, A] {
+	return MonadChainFirstReaderIOK(ma, f)
+}
+
+// ChainFirstReaderIOK chains a computation that returns a ReaderIO but preserves the original value.
+// This is the curried version that returns an operator.
+//
+//go:inline
+func ChainFirstReaderIOK[R, A, B any](f readerio.Kleisli[R, A, B]) Operator[R, A, A] {
+	return fromreader.ChainFirstReaderK(
+		ChainFirst[R, A, B],
+		FromReaderIO[R, B],
+		f,
+	)
+}
+
+// TapReaderIOK is an alias for ChainFirstReaderIOK.
+// Executes a ReaderIO-returning side effect while preserving the original value.
+//
+//go:inline
+func TapReaderIOK[R, A, B any](f readerio.Kleisli[R, A, B]) Operator[R, A, A] {
+	return ChainFirstReaderIOK(f)
+}
+
+// MonadChainReaderEitherK chains a computation that returns a ReaderEither.
+// The ReaderEither is automatically lifted into ReaderReaderIOResult.
+// This is the monadic version that takes the computation as the first parameter.
+//
+//go:inline
+func MonadChainReaderEitherK[R, A, B any](ma ReaderReaderIOResult[R, A], f RE.Kleisli[R, error, A, B]) ReaderReaderIOResult[R, B] {
+	return fromreader.MonadChainReaderK(
+		MonadChain[R, A, B],
+		FromReaderEither[R, B],
+		ma,
+		f,
+	)
+}
+
+// ChainReaderEitherK chains a computation that returns a ReaderEither.
+// The ReaderEither is automatically lifted into ReaderReaderIOResult.
+// This is the curried version that returns an operator.
+//
+//go:inline
+func ChainReaderEitherK[R, A, B any](f RE.Kleisli[R, error, A, B]) Operator[R, A, B] {
+	return fromreader.ChainReaderK(
+		Chain[R, A, B],
+		FromReaderEither[R, B],
+		f,
+	)
+}
+
+// MonadChainFirstReaderEitherK chains a computation that returns a ReaderEither but preserves the original value.
+// This is the monadic version that takes the computation as the first parameter.
+//
+//go:inline
+func MonadChainFirstReaderEitherK[R, A, B any](ma ReaderReaderIOResult[R, A], f RE.Kleisli[R, error, A, B]) ReaderReaderIOResult[R, A] {
+	return fromreader.MonadChainFirstReaderK(
+		MonadChainFirst[R, A, B],
+		FromReaderEither[R, B],
+		ma,
+		f,
+	)
+}
+
+// MonadTapReaderEitherK is an alias for MonadChainFirstReaderEitherK.
+// Executes a ReaderEither-returning side effect while preserving the original value.
+//
+//go:inline
+func MonadTapReaderEitherK[R, A, B any](ma ReaderReaderIOResult[R, A], f RE.Kleisli[R, error, A, B]) ReaderReaderIOResult[R, A] {
+	return MonadChainFirstReaderEitherK(ma, f)
+}
+
+// ChainFirstReaderEitherK chains a computation that returns a ReaderEither but preserves the original value.
+// This is the curried version that returns an operator.
+//
+//go:inline
+func ChainFirstReaderEitherK[R, A, B any](f RE.Kleisli[R, error, A, B]) Operator[R, A, A] {
+	return fromreader.ChainFirstReaderK(
+		ChainFirst[R, A, B],
+		FromReaderEither[R, B],
+		f,
+	)
+}
+
+// TapReaderEitherK is an alias for ChainFirstReaderEitherK.
+// Executes a ReaderEither-returning side effect while preserving the original value.
+//
+//go:inline
+func TapReaderEitherK[R, A, B any](f RE.Kleisli[R, error, A, B]) Operator[R, A, A] {
+	return ChainFirstReaderEitherK(f)
+}
+
+// ChainReaderOptionK chains a computation that returns a ReaderOption.
+// If the option is None, it uses the provided onNone function to generate an error.
+// Returns a function that takes a ReaderOption Kleisli and returns an operator.
+//
+//go:inline
+func ChainReaderOptionK[R, A, B any](onNone Lazy[error]) func(readeroption.Kleisli[R, A, B]) Operator[R, A, B] {
+	return RRIOE.ChainReaderOptionK[R, context.Context, A, B](onNone)
+}
+
+// ChainFirstReaderOptionK chains a computation that returns a ReaderOption but preserves the original value.
+// If the option is None, it uses the provided onNone function to generate an error.
+// Returns a function that takes a ReaderOption Kleisli and returns an operator.
+func ChainFirstReaderOptionK[R, A, B any](onNone Lazy[error]) func(readeroption.Kleisli[R, A, B]) Operator[R, A, A] {
+	return RRIOE.ChainFirstReaderOptionK[R, context.Context, A, B](onNone)
+}
+
+// TapReaderOptionK is an alias for ChainFirstReaderOptionK.
+// Executes a ReaderOption-returning side effect while preserving the original value.
+//
+//go:inline
+func TapReaderOptionK[R, A, B any](onNone Lazy[error]) func(readeroption.Kleisli[R, A, B]) Operator[R, A, A] {
+	return ChainFirstReaderOptionK[R, A, B](onNone)
+}
+
+// MonadChainIOEitherK chains a computation that returns an IOEither.
+// The IOEither is automatically lifted into ReaderReaderIOResult.
+// This is the monadic version that takes the computation as the first parameter.
+//
+//go:inline
+func MonadChainIOEitherK[R, A, B any](ma ReaderReaderIOResult[R, A], f IOE.Kleisli[error, A, B]) ReaderReaderIOResult[R, B] {
+	return fromioeither.MonadChainIOEitherK(
+		MonadChain[R, A, B],
+		FromIOEither[R, B],
+		ma,
+		f,
+	)
+}
+
+// ChainIOEitherK chains a computation that returns an IOEither.
+// The IOEither is automatically lifted into ReaderReaderIOResult.
+// This is the curried version that returns an operator.
+//
+//go:inline
+func ChainIOEitherK[R, A, B any](f IOE.Kleisli[error, A, B]) Operator[R, A, B] {
+	return fromioeither.ChainIOEitherK(
+		Chain[R, A, B],
+		FromIOEither[R, B],
+		f,
+	)
+}
+
+// MonadChainIOK chains a computation that returns an IO.
+// The IO is automatically lifted into ReaderReaderIOResult.
+// This is the monadic version that takes the computation as the first parameter.
+//
+//go:inline
+func MonadChainIOK[R, A, B any](ma ReaderReaderIOResult[R, A], f io.Kleisli[A, B]) ReaderReaderIOResult[R, B] {
+	return fromio.MonadChainIOK(
+		MonadChain[R, A, B],
+		FromIO[R, B],
+		ma,
+		f,
+	)
+}
+
+// ChainIOK chains a computation that returns an IO.
+// The IO is automatically lifted into ReaderReaderIOResult.
+// This is the curried version that returns an operator.
+//
+//go:inline
+func ChainIOK[R, A, B any](f io.Kleisli[A, B]) Operator[R, A, B] {
+	return fromio.ChainIOK(
+		Chain[R, A, B],
+		FromIO[R, B],
+		f,
+	)
+}
+
+// MonadChainFirstIOK chains a computation that returns an IO but preserves the original value.
+// This is the monadic version that takes the computation as the first parameter.
+//
+//go:inline
+func MonadChainFirstIOK[R, A, B any](ma ReaderReaderIOResult[R, A], f io.Kleisli[A, B]) ReaderReaderIOResult[R, A] {
+	return fromio.MonadChainFirstIOK(
+		MonadChain[R, A, A],
+		MonadMap[R, B, A],
+		FromIO[R, B],
+		ma,
+		f,
+	)
+}
+
+// MonadTapIOK is an alias for MonadChainFirstIOK.
+// Executes an IO-returning side effect while preserving the original value.
+//
+//go:inline
+func MonadTapIOK[R, A, B any](ma ReaderReaderIOResult[R, A], f io.Kleisli[A, B]) ReaderReaderIOResult[R, A] {
+	return MonadChainFirstIOK(ma, f)
+}
+
+// ChainFirstIOK chains a computation that returns an IO but preserves the original value.
+// This is the curried version that returns an operator.
+//
+//go:inline
+func ChainFirstIOK[R, A, B any](f io.Kleisli[A, B]) Operator[R, A, A] {
+	return fromio.ChainFirstIOK(
+		Chain[R, A, A],
+		Map[R, B, A],
+		FromIO[R, B],
+		f,
+	)
+}
+
+// TapIOK is an alias for ChainFirstIOK.
+// Executes an IO-returning side effect while preserving the original value.
+//
+//go:inline
+func TapIOK[R, A, B any](f io.Kleisli[A, B]) Operator[R, A, A] {
+	return ChainFirstIOK[R](f)
+}
+
+// ChainOptionK chains a computation that returns an Option.
+// If the option is None, it uses the provided onNone function to generate an error.
+// Returns a function that takes an Option Kleisli and returns an operator.
+//
+//go:inline
+func ChainOptionK[R, A, B any](onNone Lazy[error]) func(option.Kleisli[A, B]) Operator[R, A, B] {
+	return fromeither.ChainOptionK(
+		MonadChain[R, A, B],
+		FromEither[R, B],
+		onNone,
+	)
+}
+
+// MonadAp applies a function wrapped in a ReaderReaderIOResult to a value wrapped in a ReaderReaderIOResult (Applicative operation).
+// This is the monadic version that takes both computations as parameters.
+//
+//go:inline
+func MonadAp[R, A, B any](fab ReaderReaderIOResult[R, func(A) B], fa ReaderReaderIOResult[R, A]) ReaderReaderIOResult[R, B] {
+	return readert.MonadAp[
+		ReaderReaderIOResult[R, A],
+		ReaderReaderIOResult[R, B],
+		ReaderReaderIOResult[R, func(A) B], R, A](
+		RIOE.MonadAp[B, A],
+		fab,
+		fa,
+	)
+}
+
+// MonadApSeq is like MonadAp but evaluates effects sequentially.
+//
+//go:inline
+func MonadApSeq[R, A, B any](fab ReaderReaderIOResult[R, func(A) B], fa ReaderReaderIOResult[R, A]) ReaderReaderIOResult[R, B] {
+	return readert.MonadAp[
+		ReaderReaderIOResult[R, A],
+		ReaderReaderIOResult[R, B],
+		ReaderReaderIOResult[R, func(A) B], R, A](
+		RIOE.MonadApSeq[B, A],
+		fab,
+		fa,
+	)
+}
+
+// MonadApPar is like MonadAp but evaluates effects in parallel.
+//
+//go:inline
+func MonadApPar[R, A, B any](fab ReaderReaderIOResult[R, func(A) B], fa ReaderReaderIOResult[R, A]) ReaderReaderIOResult[R, B] {
+	return readert.MonadAp[
+		ReaderReaderIOResult[R, A],
+		ReaderReaderIOResult[R, B],
+		ReaderReaderIOResult[R, func(A) B], R, A](
+		RIOE.MonadApPar[B, A],
+		fab,
+		fa,
+	)
+}
+
+// Ap applies a function wrapped in a ReaderReaderIOResult to a value wrapped in a ReaderReaderIOResult.
+// This is the curried version that returns an operator.
+//
+//go:inline
+func Ap[B, R, A any](fa ReaderReaderIOResult[R, A]) Operator[R, func(A) B, B] {
+	return readert.Ap[
+		ReaderReaderIOResult[R, A],
+		ReaderReaderIOResult[R, B],
+		ReaderReaderIOResult[R, func(A) B], R, A](
+		RIOE.Ap[B, A],
+		fa,
+	)
+}
+
+// Chain sequences two computations, where the second depends on the result of the first (Monad operation).
+// This is the curried version that returns an operator.
+//
+//go:inline
+func Chain[R, A, B any](f Kleisli[R, A, B]) Operator[R, A, B] {
+	return readert.Chain[ReaderReaderIOResult[R, A]](
+		RIOE.Chain[A, B],
+		f,
+	)
+}
+
+// ChainFirst sequences two computations but returns the result of the first.
+// This is the curried version that returns an operator.
+//
+//go:inline
+func ChainFirst[R, A, B any](f Kleisli[R, A, B]) Operator[R, A, A] {
+	return chain.ChainFirst(
+		Chain[R, A, A],
+		Map[R, B, A],
+		f)
+}
+
+// Tap is an alias for ChainFirst.
+// Executes a side effect while preserving the original value.
+//
+//go:inline
+func Tap[R, A, B any](f Kleisli[R, A, B]) Operator[R, A, A] {
+	return ChainFirst(f)
+}
+
+// Right creates a ReaderReaderIOResult that succeeds with the given value.
+// This is the success constructor for the Result type.
+//
+//go:inline
+func Right[R, A any](a A) ReaderReaderIOResult[R, A] {
+	return RRIOE.Right[R, context.Context, error](a)
+}
+
+// Left creates a ReaderReaderIOResult that fails with the given error.
+// This is the failure constructor for the Result type.
+//
+//go:inline
+func Left[R, A any](e error) ReaderReaderIOResult[R, A] {
+	return RRIOE.Left[R, context.Context, A](e)
+}
+
+// Of creates a ReaderReaderIOResult that succeeds with the given value (Pointed operation).
+// Alias for Right.
+//
+//go:inline
+func Of[R, A any](a A) ReaderReaderIOResult[R, A] {
+	return RRIOE.Of[R, context.Context, error](a)
+}
+
+// Flatten removes one level of nesting from a nested ReaderReaderIOResult.
+// Converts ReaderReaderIOResult[R, ReaderReaderIOResult[R, A]] to ReaderReaderIOResult[R, A].
+//
+//go:inline
+func Flatten[R, A any](mma ReaderReaderIOResult[R, ReaderReaderIOResult[R, A]]) ReaderReaderIOResult[R, A] {
+	return MonadChain(mma, function.Identity[ReaderReaderIOResult[R, A]])
+}
+
+// FromEither lifts an Either into a ReaderReaderIOResult.
+//
+//go:inline
+func FromEither[R, A any](t Either[error, A]) ReaderReaderIOResult[R, A] {
+	return RRIOE.FromEither[R, context.Context](t)
+}
+
+// FromResult lifts a Result into a ReaderReaderIOResult.
+// Alias for FromEither since Result is Either[error, A].
+//
+//go:inline
+func FromResult[R, A any](t Result[A]) ReaderReaderIOResult[R, A] {
+	return FromEither[R](t)
+}
+
+// RightReader lifts a Reader into a ReaderReaderIOResult as a Right (success) value.
+//
+//go:inline
+func RightReader[R, A any](ma Reader[R, A]) ReaderReaderIOResult[R, A] {
+	return RRIOE.RightReader[context.Context, error](ma)
+}
+
+// LeftReader lifts a Reader that produces an error into a ReaderReaderIOResult as a Left (failure) value.
+//
+//go:inline
+func LeftReader[A, R any](ma Reader[R, error]) ReaderReaderIOResult[R, A] {
+	return RRIOE.LeftReader[context.Context, A](ma)
+}
+
+// FromReader lifts a Reader into a ReaderReaderIOResult.
+// The Reader's result is wrapped in a Right (success) value.
+//
+//go:inline
+func FromReader[R, A any](ma Reader[R, A]) ReaderReaderIOResult[R, A] {
+	return RRIOE.FromReader[context.Context, error](ma)
+}
+
+// RightIO lifts an IO into a ReaderReaderIOResult as a Right (success) value.
+//
+//go:inline
+func RightIO[R, A any](ma IO[A]) ReaderReaderIOResult[R, A] {
+	return RRIOE.RightIO[R, context.Context, error](ma)
+}
+
+// LeftIO lifts an IO that produces an error into a ReaderReaderIOResult as a Left (failure) value.
+//
+//go:inline
+func LeftIO[R, A any](ma IO[error]) ReaderReaderIOResult[R, A] {
+	return RRIOE.LeftIO[R, context.Context, A](ma)
+}
+
+// FromIO lifts an IO into a ReaderReaderIOResult.
+// The IO's result is wrapped in a Right (success) value.
+//
+//go:inline
+func FromIO[R, A any](ma IO[A]) ReaderReaderIOResult[R, A] {
+	return RRIOE.FromIO[R, context.Context, error](ma)
+}
+
+// FromIOEither lifts an IOEither into a ReaderReaderIOResult.
+//
+//go:inline
+func FromIOEither[R, A any](ma IOEither[error, A]) ReaderReaderIOResult[R, A] {
+	return RRIOE.FromIOEither[R, context.Context](ma)
+}
+
+// FromIOResult lifts an IOResult into a ReaderReaderIOResult.
+// Alias for FromIOEither since IOResult is IOEither[error, A].
+//
+//go:inline
+func FromIOResult[R, A any](ma IOResult[A]) ReaderReaderIOResult[R, A] {
+	return RRIOE.FromIOEither[R, context.Context](ma)
+}
+
+// FromReaderEither lifts a ReaderEither into a ReaderReaderIOResult.
+//
+//go:inline
+func FromReaderEither[R, A any](ma RE.ReaderEither[R, error, A]) ReaderReaderIOResult[R, A] {
+	return RRIOE.FromReaderEither[R, context.Context](ma)
+}
+
+// Ask retrieves the outer environment R.
+// Returns a ReaderReaderIOResult that succeeds with the environment value.
+//
+//go:inline
+func Ask[R any]() ReaderReaderIOResult[R, R] {
+	return RRIOE.Ask[R, context.Context, error]()
+}
+
+// Asks retrieves a value derived from the outer environment R using the provided function.
+//
+//go:inline
+func Asks[R, A any](r Reader[R, A]) ReaderReaderIOResult[R, A] {
+	return RRIOE.Asks[context.Context, error](r)
+}
+
+// FromOption converts an Option to a ReaderReaderIOResult.
+// If the option is None, it uses the provided onNone function to generate an error.
+// Returns a function that takes an Option and returns a ReaderReaderIOResult.
+//
+//go:inline
+func FromOption[R, A any](onNone Lazy[error]) func(Option[A]) ReaderReaderIOResult[R, A] {
+	return RRIOE.FromOption[R, context.Context, A](onNone)
+}
+
+// FromPredicate creates a ReaderReaderIOResult from a predicate.
+// If the predicate returns true, the value is wrapped in Right.
+// If false, onFalse is called to generate an error wrapped in Left.
+//
+//go:inline
+func FromPredicate[R, A any](pred func(A) bool, onFalse func(A) error) Kleisli[R, A, A] {
+	return RRIOE.FromPredicate[R, context.Context](pred, onFalse)
+}
+
+// MonadAlt provides alternative/fallback behavior.
+// If the first computation fails, it tries the second (lazy-evaluated).
+// This is the monadic version that takes both computations as parameters.
+//
+//go:inline
+func MonadAlt[R, A any](first ReaderReaderIOResult[R, A], second Lazy[ReaderReaderIOResult[R, A]]) ReaderReaderIOResult[R, A] {
+	return RRIOE.MonadAlt(first, second)
+}
+
+// Alt provides alternative/fallback behavior.
+// If the first computation fails, it tries the second (lazy-evaluated).
+// This is the curried version that returns an operator.
+//
+//go:inline
+func Alt[R, A any](second Lazy[ReaderReaderIOResult[R, A]]) Operator[R, A, A] {
+	return RRIOE.Alt(second)
+}
+
+// MonadFlap applies a value to a function wrapped in a ReaderReaderIOResult.
+// This is the monadic version that takes the computation as the first parameter.
+//
+//go:inline
+func MonadFlap[R, B, A any](fab ReaderReaderIOResult[R, func(A) B], a A) ReaderReaderIOResult[R, B] {
+	return functor.MonadFlap(MonadMap[R, func(A) B, B], fab, a)
+}
+
+// Flap applies a value to a function wrapped in a ReaderReaderIOResult.
+// This is the curried version that returns an operator.
+//
+//go:inline
+func Flap[R, B, A any](a A) Operator[R, func(A) B, B] {
+	return functor.Flap(Map[R, func(A) B, B], a)
+}
+
+// MonadMapLeft transforms the error value if the computation fails.
+// Has no effect if the computation succeeds.
+// This is the monadic version that takes the computation as the first parameter.
+//
+//go:inline
+func MonadMapLeft[R, A any](fa ReaderReaderIOResult[R, A], f Endmorphism[error]) ReaderReaderIOResult[R, A] {
+	return RRIOE.MonadMapLeft(fa, f)
+}
+
+// MapLeft transforms the error value if the computation fails.
+// Has no effect if the computation succeeds.
+// This is the curried version that returns an operator.
+//
+//go:inline
+func MapLeft[R, A any](f Endmorphism[error]) Operator[R, A, A] {
+	return RRIOE.MapLeft[R, context.Context, A](f)
+}
+
+// Local modifies the outer environment before passing it to a computation.
+// Useful for providing different configurations to sub-computations.
+//
+//go:inline
+func Local[A, R1, R2 any](f func(R2) R1) func(ReaderReaderIOResult[R1, A]) ReaderReaderIOResult[R2, A] {
+	return RRIOE.Local[context.Context, error, A](f)
+}
+
+// Read provides a specific outer environment value to a computation.
+// Converts ReaderReaderIOResult[R, A] to ReaderIOResult[context.Context, A].
+//
+//go:inline
+func Read[A, R any](r R) func(ReaderReaderIOResult[R, A]) ReaderIOResult[context.Context, A] {
+	return RRIOE.Read[context.Context, error, A](r)
+}
+
+// ReadIOEither provides an outer environment value from an IOEither to a computation.
+//
+//go:inline
+func ReadIOEither[A, R any](rio IOEither[error, R]) func(ReaderReaderIOResult[R, A]) ReaderIOResult[context.Context, A] {
+	return RRIOE.ReadIOEither[A, R, context.Context](rio)
+}
+
+// ReadIO provides an outer environment value from an IO to a computation.
+//
+//go:inline
+func ReadIO[A, R any](rio IO[R]) func(ReaderReaderIOResult[R, A]) ReaderIOResult[context.Context, A] {
+	return RRIOE.ReadIO[context.Context, error, A](rio)
+}
+
+// MonadChainLeft handles errors by chaining a recovery computation.
+// If the computation fails, the error is passed to f for recovery.
+// This is the monadic version that takes the computation as the first parameter.
+//
+//go:inline
+func MonadChainLeft[R, A any](fa ReaderReaderIOResult[R, A], f Kleisli[R, error, A]) ReaderReaderIOResult[R, A] {
+	return RRIOE.MonadChainLeft(fa, f)
+}
+
+// ChainLeft handles errors by chaining a recovery computation.
+// If the computation fails, the error is passed to f for recovery.
+// This is the curried version that returns an operator.
+//
+//go:inline
+func ChainLeft[R, A any](f Kleisli[R, error, A]) func(ReaderReaderIOResult[R, A]) ReaderReaderIOResult[R, A] {
+	return RRIOE.ChainLeft(f)
+}
+
+// Delay adds a time delay before executing the computation.
+// Useful for rate limiting, retry backoff, or scheduled execution.
+//
+//go:inline
+func Delay[R, A any](delay time.Duration) Operator[R, A, A] {
+	return reader.Map[R](RIOE.Delay[A](delay))
+}

v2/context/readerreaderioresult/reader_test.go

@@ -0,0 +1,718 @@
+// Copyright (c) 2023 - 2025 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package readerreaderioresult
+
+import (
+	"errors"
+	"testing"
+	"time"
+
+	"github.com/IBM/fp-go/v2/either"
+	F "github.com/IBM/fp-go/v2/function"
+	"github.com/IBM/fp-go/v2/io"
+	"github.com/IBM/fp-go/v2/ioeither"
+	"github.com/IBM/fp-go/v2/ioresult"
+	N "github.com/IBM/fp-go/v2/number"
+	"github.com/IBM/fp-go/v2/option"
+	"github.com/IBM/fp-go/v2/reader"
+	RE "github.com/IBM/fp-go/v2/readereither"
+	"github.com/IBM/fp-go/v2/readerio"
+	"github.com/IBM/fp-go/v2/readeroption"
+	"github.com/IBM/fp-go/v2/result"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestOf(t *testing.T) {
+	computation := Of[AppConfig](42)
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(42), outcome)
+}
+
+func TestRight(t *testing.T) {
+	computation := Right[AppConfig](42)
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(42), outcome)
+}
+
+func TestLeft(t *testing.T) {
+	err := errors.New("test error")
+	computation := Left[AppConfig, int](err)
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Left[int](err), outcome)
+}
+
+func TestMonadMap(t *testing.T) {
+	computation := MonadMap(
+		Of[AppConfig](21),
+		N.Mul(2),
+	)
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(42), outcome)
+}
+
+func TestMap(t *testing.T) {
+	computation := F.Pipe1(
+		Of[AppConfig](21),
+		Map[AppConfig](N.Mul(2)),
+	)
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(42), outcome)
+}
+
+func TestMonadMapTo(t *testing.T) {
+	computation := MonadMapTo(Of[AppConfig](21), 99)
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(99), outcome)
+}
+
+func TestMapTo(t *testing.T) {
+	computation := F.Pipe1(
+		Of[AppConfig](21),
+		MapTo[AppConfig, int](99),
+	)
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(99), outcome)
+}
+
+func TestMonadChain(t *testing.T) {
+	computation := MonadChain(
+		Of[AppConfig](21),
+		func(n int) ReaderReaderIOResult[AppConfig, int] {
+			return Of[AppConfig](n * 2)
+		},
+	)
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(42), outcome)
+}
+
+func TestChain(t *testing.T) {
+	computation := F.Pipe1(
+		Of[AppConfig](21),
+		Chain(func(n int) ReaderReaderIOResult[AppConfig, int] {
+			return Of[AppConfig](n * 2)
+		}),
+	)
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(42), outcome)
+}
+
+func TestMonadChainFirst(t *testing.T) {
+	sideEffect := 0
+	computation := MonadChainFirst(
+		Of[AppConfig](42),
+		func(n int) ReaderReaderIOResult[AppConfig, string] {
+			sideEffect = n
+			return Of[AppConfig]("ignored")
+		},
+	)
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(42), outcome)
+	assert.Equal(t, 42, sideEffect)
+}
+
+func TestChainFirst(t *testing.T) {
+	sideEffect := 0
+	computation := F.Pipe1(
+		Of[AppConfig](42),
+		ChainFirst(func(n int) ReaderReaderIOResult[AppConfig, string] {
+			sideEffect = n
+			return Of[AppConfig]("ignored")
+		}),
+	)
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(42), outcome)
+	assert.Equal(t, 42, sideEffect)
+}
+
+func TestTap(t *testing.T) {
+	sideEffect := 0
+	computation := F.Pipe1(
+		Of[AppConfig](42),
+		Tap(func(n int) ReaderReaderIOResult[AppConfig, string] {
+			sideEffect = n
+			return Of[AppConfig]("ignored")
+		}),
+	)
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(42), outcome)
+	assert.Equal(t, 42, sideEffect)
+}
+
+func TestFlatten(t *testing.T) {
+	nested := Of[AppConfig](Of[AppConfig](42))
+	computation := Flatten(nested)
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(42), outcome)
+}
+
+func TestFromEither(t *testing.T) {
+	t.Run("right", func(t *testing.T) {
+		computation := FromEither[AppConfig](either.Right[error](42))
+		outcome := computation(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(42), outcome)
+	})
+
+	t.Run("left", func(t *testing.T) {
+		err := errors.New("test error")
+		computation := FromEither[AppConfig](either.Left[int](err))
+		outcome := computation(defaultConfig)(t.Context())()
+		assert.True(t, result.IsLeft(outcome))
+	})
+}
+
+func TestFromResult(t *testing.T) {
+	t.Run("success", func(t *testing.T) {
+		computation := FromResult[AppConfig](result.Of(42))
+		outcome := computation(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(42), outcome)
+	})
+
+	t.Run("error", func(t *testing.T) {
+		err := errors.New("test error")
+		computation := FromResult[AppConfig](result.Left[int](err))
+		outcome := computation(defaultConfig)(t.Context())()
+		assert.True(t, result.IsLeft(outcome))
+	})
+}
+
+func TestFromReader(t *testing.T) {
+	computation := FromReader(func(cfg AppConfig) int {
+		return len(cfg.DatabaseURL)
+	})
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(20), outcome) // len("postgres://localhost")
+}
+
+func TestRightReader(t *testing.T) {
+	computation := RightReader(func(cfg AppConfig) int {
+		return len(cfg.LogLevel)
+	})
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(4), outcome) // len("info")
+}
+
+func TestLeftReader(t *testing.T) {
+	err := errors.New("test error")
+	computation := LeftReader[int](func(cfg AppConfig) error {
+		return err
+	})
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.True(t, result.IsLeft(outcome))
+}
+
+func TestFromIO(t *testing.T) {
+	computation := FromIO[AppConfig](func() int { return 42 })
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(42), outcome)
+}
+
+func TestRightIO(t *testing.T) {
+	computation := RightIO[AppConfig](func() int { return 42 })
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(42), outcome)
+}
+
+func TestLeftIO(t *testing.T) {
+	err := errors.New("test error")
+	computation := LeftIO[AppConfig, int](func() error { return err })
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.True(t, result.IsLeft(outcome))
+}
+
+func TestFromIOEither(t *testing.T) {
+	t.Run("right", func(t *testing.T) {
+		computation := FromIOEither[AppConfig](ioeither.Of[error](42))
+		outcome := computation(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(42), outcome)
+	})
+
+	t.Run("left", func(t *testing.T) {
+		err := errors.New("test error")
+		computation := FromIOEither[AppConfig](ioeither.Left[int](err))
+		outcome := computation(defaultConfig)(t.Context())()
+		assert.True(t, result.IsLeft(outcome))
+	})
+}
+
+func TestFromIOResult(t *testing.T) {
+	t.Run("success", func(t *testing.T) {
+		computation := FromIOResult[AppConfig](func() result.Result[int] {
+			return result.Of(42)
+		})
+		outcome := computation(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(42), outcome)
+	})
+
+	t.Run("error", func(t *testing.T) {
+		err := errors.New("test error")
+		computation := FromIOResult[AppConfig](func() result.Result[int] {
+			return result.Left[int](err)
+		})
+		outcome := computation(defaultConfig)(t.Context())()
+		assert.True(t, result.IsLeft(outcome))
+	})
+}
+
+func TestFromReaderIO(t *testing.T) {
+	computation := FromReaderIO(func(cfg AppConfig) io.IO[int] {
+		return func() int { return len(cfg.DatabaseURL) }
+	})
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(20), outcome)
+}
+
+func TestRightReaderIO(t *testing.T) {
+	computation := RightReaderIO(func(cfg AppConfig) io.IO[int] {
+		return func() int { return len(cfg.LogLevel) }
+	})
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(4), outcome)
+}
+
+func TestLeftReaderIO(t *testing.T) {
+	err := errors.New("test error")
+	computation := LeftReaderIO[int](func(cfg AppConfig) io.IO[error] {
+		return func() error { return err }
+	})
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.True(t, result.IsLeft(outcome))
+}
+
+func TestFromReaderEither(t *testing.T) {
+	t.Run("right", func(t *testing.T) {
+		computation := FromReaderEither(func(cfg AppConfig) either.Either[error, int] {
+			return either.Right[error](len(cfg.DatabaseURL))
+		})
+		outcome := computation(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(20), outcome)
+	})
+
+	t.Run("left", func(t *testing.T) {
+		err := errors.New("test error")
+		computation := FromReaderEither(func(cfg AppConfig) either.Either[error, int] {
+			return either.Left[int](err)
+		})
+		outcome := computation(defaultConfig)(t.Context())()
+		assert.True(t, result.IsLeft(outcome))
+	})
+}
+
+func TestAsk(t *testing.T) {
+	computation := Ask[AppConfig]()
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(defaultConfig), outcome)
+}
+
+func TestAsks(t *testing.T) {
+	computation := Asks(func(cfg AppConfig) string {
+		return cfg.DatabaseURL
+	})
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of("postgres://localhost"), outcome)
+}
+
+func TestFromOption(t *testing.T) {
+	err := errors.New("none error")
+
+	t.Run("some", func(t *testing.T) {
+		computation := FromOption[AppConfig, int](func() error { return err })(option.Some(42))
+		outcome := computation(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(42), outcome)
+	})
+
+	t.Run("none", func(t *testing.T) {
+		computation := FromOption[AppConfig, int](func() error { return err })(option.None[int]())
+		outcome := computation(defaultConfig)(t.Context())()
+		assert.True(t, result.IsLeft(outcome))
+	})
+}
+
+func TestFromPredicate(t *testing.T) {
+	isPositive := func(n int) bool { return n > 0 }
+	onFalse := func(n int) error { return errors.New("not positive") }
+
+	t.Run("predicate true", func(t *testing.T) {
+		computation := FromPredicate[AppConfig](isPositive, onFalse)(42)
+		outcome := computation(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(42), outcome)
+	})
+
+	t.Run("predicate false", func(t *testing.T) {
+		computation := FromPredicate[AppConfig](isPositive, onFalse)(-5)
+		outcome := computation(defaultConfig)(t.Context())()
+		assert.True(t, result.IsLeft(outcome))
+	})
+}
+
+func TestMonadAlt(t *testing.T) {
+	err := errors.New("first error")
+
+	t.Run("first succeeds", func(t *testing.T) {
+		first := Of[AppConfig](42)
+		second := func() ReaderReaderIOResult[AppConfig, int] {
+			return Of[AppConfig](99)
+		}
+		computation := MonadAlt(first, second)
+		outcome := computation(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(42), outcome)
+	})
+
+	t.Run("first fails, second succeeds", func(t *testing.T) {
+		first := Left[AppConfig, int](err)
+		second := func() ReaderReaderIOResult[AppConfig, int] {
+			return Of[AppConfig](99)
+		}
+		computation := MonadAlt(first, second)
+		outcome := computation(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(99), outcome)
+	})
+
+	t.Run("both fail", func(t *testing.T) {
+		first := Left[AppConfig, int](err)
+		second := func() ReaderReaderIOResult[AppConfig, int] {
+			return Left[AppConfig, int](errors.New("second error"))
+		}
+		computation := MonadAlt(first, second)
+		outcome := computation(defaultConfig)(t.Context())()
+		assert.True(t, result.IsLeft(outcome))
+	})
+}
+
+func TestAlt(t *testing.T) {
+	err := errors.New("first error")
+
+	computation := F.Pipe1(
+		Left[AppConfig, int](err),
+		Alt(func() ReaderReaderIOResult[AppConfig, int] {
+			return Of[AppConfig](99)
+		}),
+	)
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(99), outcome)
+}
+
+func TestMonadFlap(t *testing.T) {
+	fab := Of[AppConfig](N.Mul(2))
+	computation := MonadFlap(fab, 21)
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(42), outcome)
+}
+
+func TestFlap(t *testing.T) {
+	computation := F.Pipe1(
+		Of[AppConfig](N.Mul(2)),
+		Flap[AppConfig, int](21),
+	)
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(42), outcome)
+}
+
+func TestMonadMapLeft(t *testing.T) {
+	err := errors.New("original error")
+	computation := MonadMapLeft(
+		Left[AppConfig, int](err),
+		func(e error) error { return errors.New("mapped: " + e.Error()) },
+	)
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.True(t, result.IsLeft(outcome))
+	result.Fold(
+		func(e error) any {
+			assert.Contains(t, e.Error(), "mapped:")
+			return nil
+		},
+		func(v int) any {
+			t.Fatal("should be left")
+			return nil
+		},
+	)(outcome)
+}
+
+func TestMapLeft(t *testing.T) {
+	err := errors.New("original error")
+	computation := F.Pipe1(
+		Left[AppConfig, int](err),
+		MapLeft[AppConfig, int](func(e error) error {
+			return errors.New("mapped: " + e.Error())
+		}),
+	)
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.True(t, result.IsLeft(outcome))
+}
+
+func TestLocal(t *testing.T) {
+	type OtherConfig struct {
+		URL string
+	}
+
+	computation := F.Pipe1(
+		Asks(func(cfg AppConfig) string {
+			return cfg.DatabaseURL
+		}),
+		Local[string](func(other OtherConfig) AppConfig {
+			return AppConfig{DatabaseURL: other.URL, LogLevel: "debug"}
+		}),
+	)
+
+	outcome := computation(OtherConfig{URL: "test-url"})(t.Context())()
+	assert.Equal(t, result.Of("test-url"), outcome)
+}
+
+func TestRead(t *testing.T) {
+	computation := Asks(func(cfg AppConfig) string {
+		return cfg.DatabaseURL
+	})
+
+	reader := Read[string](defaultConfig)
+	outcome := reader(computation)(t.Context())()
+	assert.Equal(t, result.Of("postgres://localhost"), outcome)
+}
+
+func TestReadIOEither(t *testing.T) {
+	computation := Asks(func(cfg AppConfig) string {
+		return cfg.DatabaseURL
+	})
+
+	rio := ioeither.Of[error](defaultConfig)
+	reader := ReadIOEither[string](rio)
+	outcome := reader(computation)(t.Context())()
+	assert.Equal(t, result.Of("postgres://localhost"), outcome)
+}
+
+func TestReadIO(t *testing.T) {
+	computation := Asks(func(cfg AppConfig) string {
+		return cfg.DatabaseURL
+	})
+
+	rio := func() AppConfig { return defaultConfig }
+	reader := ReadIO[string](rio)
+	outcome := reader(computation)(t.Context())()
+	assert.Equal(t, result.Of("postgres://localhost"), outcome)
+}
+
+func TestMonadChainLeft(t *testing.T) {
+	err := errors.New("original error")
+	computation := MonadChainLeft(
+		Left[AppConfig, int](err),
+		func(e error) ReaderReaderIOResult[AppConfig, int] {
+			return Of[AppConfig](99)
+		},
+	)
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(99), outcome)
+}
+
+func TestChainLeft(t *testing.T) {
+	err := errors.New("original error")
+	computation := F.Pipe1(
+		Left[AppConfig, int](err),
+		ChainLeft(func(e error) ReaderReaderIOResult[AppConfig, int] {
+			return Of[AppConfig](99)
+		}),
+	)
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(99), outcome)
+}
+
+func TestDelay(t *testing.T) {
+	start := time.Now()
+	computation := F.Pipe1(
+		Of[AppConfig](42),
+		Delay[AppConfig, int](50*time.Millisecond),
+	)
+	outcome := computation(defaultConfig)(t.Context())()
+	elapsed := time.Since(start)
+
+	assert.Equal(t, result.Of(42), outcome)
+	assert.GreaterOrEqual(t, elapsed, 50*time.Millisecond)
+}
+
+func TestChainEitherK(t *testing.T) {
+	computation := F.Pipe1(
+		Of[AppConfig](21),
+		ChainEitherK[AppConfig](func(n int) either.Either[error, int] {
+			return either.Right[error](n * 2)
+		}),
+	)
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(42), outcome)
+}
+
+func TestChainReaderK(t *testing.T) {
+	computation := F.Pipe1(
+		Of[AppConfig](10),
+		ChainReaderK(func(n int) reader.Reader[AppConfig, int] {
+			return func(cfg AppConfig) int {
+				return n + len(cfg.LogLevel)
+			}
+		}),
+	)
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(14), outcome) // 10 + len("info")
+}
+
+func TestChainReaderIOK(t *testing.T) {
+	computation := F.Pipe1(
+		Of[AppConfig](10),
+		ChainReaderIOK(func(n int) readerio.ReaderIO[AppConfig, int] {
+			return func(cfg AppConfig) io.IO[int] {
+				return func() int {
+					return n + len(cfg.DatabaseURL)
+				}
+			}
+		}),
+	)
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(30), outcome) // 10 + 20
+}
+
+func TestChainReaderEitherK(t *testing.T) {
+	computation := F.Pipe1(
+		Of[AppConfig](10),
+		ChainReaderEitherK(func(n int) RE.ReaderEither[AppConfig, error, int] {
+			return func(cfg AppConfig) either.Either[error, int] {
+				return either.Right[error](n + len(cfg.LogLevel))
+			}
+		}),
+	)
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(14), outcome)
+}
+
+func TestChainReaderOptionK(t *testing.T) {
+	onNone := func() error { return errors.New("none") }
+
+	t.Run("some", func(t *testing.T) {
+		computation := F.Pipe1(
+			Of[AppConfig](10),
+			ChainReaderOptionK[AppConfig, int, int](onNone)(func(n int) readeroption.ReaderOption[AppConfig, int] {
+				return func(cfg AppConfig) option.Option[int] {
+					return option.Some(n + len(cfg.LogLevel))
+				}
+			}),
+		)
+		outcome := computation(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(14), outcome)
+	})
+
+	t.Run("none", func(t *testing.T) {
+		computation := F.Pipe1(
+			Of[AppConfig](10),
+			ChainReaderOptionK[AppConfig, int, int](onNone)(func(n int) readeroption.ReaderOption[AppConfig, int] {
+				return func(cfg AppConfig) option.Option[int] {
+					return option.None[int]()
+				}
+			}),
+		)
+		outcome := computation(defaultConfig)(t.Context())()
+		assert.True(t, result.IsLeft(outcome))
+	})
+}
+
+func TestChainIOEitherK(t *testing.T) {
+	computation := F.Pipe1(
+		Of[AppConfig](21),
+		ChainIOEitherK[AppConfig](func(n int) ioeither.IOEither[error, int] {
+			return ioeither.Of[error](n * 2)
+		}),
+	)
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(42), outcome)
+}
+
+func TestChainIOK(t *testing.T) {
+	computation := F.Pipe1(
+		Of[AppConfig](21),
+		ChainIOK[AppConfig](func(n int) io.IO[int] {
+			return func() int { return n * 2 }
+		}),
+	)
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(42), outcome)
+}
+
+func TestChainOptionK(t *testing.T) {
+	onNone := func() error { return errors.New("none") }
+
+	t.Run("some", func(t *testing.T) {
+		computation := F.Pipe1(
+			Of[AppConfig](21),
+			ChainOptionK[AppConfig, int, int](onNone)(func(n int) option.Option[int] {
+				return option.Some(n * 2)
+			}),
+		)
+		outcome := computation(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(42), outcome)
+	})
+
+	t.Run("none", func(t *testing.T) {
+		computation := F.Pipe1(
+			Of[AppConfig](21),
+			ChainOptionK[AppConfig, int, int](onNone)(func(n int) option.Option[int] {
+				return option.None[int]()
+			}),
+		)
+		outcome := computation(defaultConfig)(t.Context())()
+		assert.True(t, result.IsLeft(outcome))
+	})
+}
+
+func TestFromReaderIOResult(t *testing.T) {
+	computation := FromReaderIOResult(func(cfg AppConfig) ioresult.IOResult[int] {
+		return func() result.Result[int] {
+			return result.Of(len(cfg.DatabaseURL))
+		}
+	})
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(20), outcome)
+}
+
+func TestFromReaderOption(t *testing.T) {
+	onNone := func() error { return errors.New("none") }
+
+	t.Run("some", func(t *testing.T) {
+		computation := FromReaderOption[AppConfig, int](onNone)(func(cfg AppConfig) option.Option[int] {
+			return option.Some(len(cfg.DatabaseURL))
+		})
+		outcome := computation(defaultConfig)(t.Context())()
+		assert.Equal(t, result.Of(20), outcome)
+	})
+
+	t.Run("none", func(t *testing.T) {
+		computation := FromReaderOption[AppConfig, int](onNone)(func(cfg AppConfig) option.Option[int] {
+			return option.None[int]()
+		})
+		outcome := computation(defaultConfig)(t.Context())()
+		assert.True(t, result.IsLeft(outcome))
+	})
+}
+
+func TestMonadAp(t *testing.T) {
+	fab := Of[AppConfig](N.Mul(2))
+	fa := Of[AppConfig](21)
+	computation := MonadAp(fab, fa)
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(42), outcome)
+}
+
+func TestAp(t *testing.T) {
+	fa := Of[AppConfig](21)
+	computation := F.Pipe1(
+		Of[AppConfig](N.Mul(2)),
+		Ap[int](fa),
+	)
+	outcome := computation(defaultConfig)(t.Context())()
+	assert.Equal(t, result.Of(42), outcome)
+}

v2/context/readerreaderioresult/retry.go

@@ -0,0 +1,98 @@
+// Copyright (c) 2025 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package readerreaderioresult
+
+import (
+	RIOE "github.com/IBM/fp-go/v2/context/readerioresult"
+	F "github.com/IBM/fp-go/v2/function"
+	"github.com/IBM/fp-go/v2/reader"
+	"github.com/IBM/fp-go/v2/retry"
+)
+
+// Retrying executes an action with automatic retry logic based on a retry policy.
+// It retries the action when it fails or when the check predicate returns false.
+//
+// This function is useful for handling transient failures in operations like:
+//   - Network requests that may temporarily fail
+//   - Database operations that may encounter locks
+//   - External service calls that may be temporarily unavailable
+//
+// Parameters:
+//   - policy: Defines the retry behavior (number of retries, delays, backoff strategy)
+//   - action: The computation to retry, receives retry status information
+//   - check: Predicate to determine if the result should trigger a retry (returns true to continue, false to retry)
+//
+// The action receives a retry.RetryStatus that contains:
+//   - IterNumber: Current iteration number (0-based)
+//   - CumulativeDelay: Total delay accumulated so far
+//   - PreviousDelay: Delay from the previous iteration
+//
+// Returns:
+//   - A ReaderReaderIOResult that executes the action with retry logic
+//
+// Example:
+//
+//	import (
+//	    "errors"
+//	    "time"
+//	    "github.com/IBM/fp-go/v2/retry"
+//	)
+//
+//	type Config struct {
+//	    MaxRetries int
+//	    BaseDelay  time.Duration
+//	}
+//
+//	// Create a retry policy with exponential backoff
+//	policy := retry.ExponentialBackoff(100*time.Millisecond, 5*time.Second)
+//	policy = retry.LimitRetries(3, policy)
+//
+//	// Action that may fail transiently
+//	action := func(status retry.RetryStatus) ReaderReaderIOResult[Config, string] {
+//	    return func(cfg Config) ReaderIOResult[context.Context, string] {
+//	        return func(ctx context.Context) IOResult[string] {
+//	            return func() Either[error, string] {
+//	                // Simulate transient failure
+//	                if status.IterNumber < 2 {
+//	                    return either.Left[string](errors.New("transient error"))
+//	                }
+//	                return either.Right[error]("success")
+//	            }
+//	        }
+//	    }
+//	}
+//
+//	// Check if we should retry (retry on any error)
+//	check := func(result Result[string]) bool {
+//	    return either.IsRight(result) // Continue only if successful
+//	}
+//
+//	// Execute with retry logic
+//	result := Retrying(policy, action, check)
+//
+//go:inline
+func Retrying[R, A any](
+	policy retry.RetryPolicy,
+	action Kleisli[R, retry.RetryStatus, A],
+	check Predicate[Result[A]],
+) ReaderReaderIOResult[R, A] {
+	// get an implementation for the types
+	return F.Flow4(
+		reader.Read[RIOE.ReaderIOResult[A]],
+		reader.Map[retry.RetryStatus],
+		reader.Read[RIOE.Kleisli[retry.RetryStatus, A]](action),
+		F.Bind13of3(RIOE.Retrying[A])(policy, check),
+	)
+}

v2/context/readerreaderioresult/retry_test.go

@@ -0,0 +1,255 @@
+// Copyright (c) 2025 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package readerreaderioresult
+
+import (
+	"context"
+	"errors"
+	"testing"
+	"time"
+
+	N "github.com/IBM/fp-go/v2/number"
+	"github.com/IBM/fp-go/v2/reader"
+	"github.com/IBM/fp-go/v2/result"
+	"github.com/IBM/fp-go/v2/retry"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestRetryingSuccess(t *testing.T) {
+	cfg := defaultConfig
+	ctx := t.Context()
+
+	attempts := 0
+	action := func(status retry.RetryStatus) ReaderReaderIOResult[AppConfig, int] {
+		return func(c AppConfig) ReaderIOResult[context.Context, int] {
+			return func(ctx context.Context) IOResult[int] {
+				return func() Result[int] {
+					attempts++
+					if attempts < 3 {
+						return result.Left[int](errors.New("temporary error"))
+					}
+					return result.Of(42)
+				}
+			}
+		}
+	}
+
+	check := result.IsLeft[int]
+
+	policy := retry.LimitRetries(5)
+
+	computation := Retrying(policy, action, check)
+	outcome := computation(cfg)(ctx)()
+
+	assert.Equal(t, result.Of(42), outcome)
+	assert.Equal(t, 3, attempts)
+}
+
+func TestRetryingFailureExhaustsRetries(t *testing.T) {
+	cfg := defaultConfig
+	ctx := t.Context()
+
+	attempts := 0
+	testErr := errors.New("persistent error")
+
+	action := func(status retry.RetryStatus) ReaderReaderIOResult[AppConfig, int] {
+		return func(c AppConfig) ReaderIOResult[context.Context, int] {
+			return func(ctx context.Context) IOResult[int] {
+				return func() Result[int] {
+					attempts++
+					return result.Left[int](testErr)
+				}
+			}
+		}
+	}
+
+	check := result.IsLeft[int]
+
+	policy := retry.LimitRetries(3)
+
+	computation := Retrying(policy, action, check)
+	outcome := computation(cfg)(ctx)()
+
+	assert.True(t, result.IsLeft(outcome))
+	assert.Equal(t, 4, attempts) // Initial attempt + 3 retries
+}
+
+func TestRetryingNoRetryNeeded(t *testing.T) {
+	cfg := defaultConfig
+	ctx := t.Context()
+
+	attempts := 0
+	action := func(status retry.RetryStatus) ReaderReaderIOResult[AppConfig, int] {
+		return func(c AppConfig) ReaderIOResult[context.Context, int] {
+			return func(ctx context.Context) IOResult[int] {
+				return func() Result[int] {
+					attempts++
+					return result.Of(42)
+				}
+			}
+		}
+	}
+
+	check := result.IsLeft[int]
+
+	policy := retry.LimitRetries(5)
+
+	computation := Retrying(policy, action, check)
+	outcome := computation(cfg)(ctx)()
+
+	assert.Equal(t, result.Of(42), outcome)
+	assert.Equal(t, 1, attempts) // Only initial attempt
+}
+
+func TestRetryingWithDelay(t *testing.T) {
+	cfg := defaultConfig
+	ctx := t.Context()
+
+	attempts := 0
+	start := time.Now()
+
+	action := func(status retry.RetryStatus) ReaderReaderIOResult[AppConfig, int] {
+		return func(c AppConfig) ReaderIOResult[context.Context, int] {
+			return func(ctx context.Context) IOResult[int] {
+				return func() Result[int] {
+					attempts++
+					if attempts < 2 {
+						return result.Left[int](errors.New("temporary error"))
+					}
+					return result.Of(42)
+				}
+			}
+		}
+	}
+
+	check := result.IsLeft[int]
+
+	// Policy with delay
+	policy := retry.CapDelay(
+		100*time.Millisecond,
+		retry.LimitRetries(3),
+	)
+
+	computation := Retrying(policy, action, check)
+	outcome := computation(cfg)(ctx)()
+	elapsed := time.Since(start)
+
+	assert.Equal(t, result.Of(42), outcome)
+	assert.Equal(t, 2, attempts)
+	// The delay might be very short in tests, so just check it completed
+	_ = elapsed
+}
+
+func TestRetryingAccessesConfig(t *testing.T) {
+	cfg := AppConfig{DatabaseURL: "test-db", LogLevel: "debug"}
+	ctx := t.Context()
+
+	attempts := 0
+	var capturedURL string
+
+	action := func(status retry.RetryStatus) ReaderReaderIOResult[AppConfig, int] {
+		return func(c AppConfig) ReaderIOResult[context.Context, int] {
+			return func(ctx context.Context) IOResult[int] {
+				return func() Result[int] {
+					attempts++
+					capturedURL = c.DatabaseURL
+					if attempts < 2 {
+						return result.Left[int](errors.New("temporary error"))
+					}
+					return result.Of(len(c.DatabaseURL))
+				}
+			}
+		}
+	}
+
+	check := result.IsLeft[int]
+
+	policy := retry.LimitRetries(3)
+
+	computation := Retrying(policy, action, check)
+	outcome := computation(cfg)(ctx)()
+
+	assert.Equal(t, result.Of(7), outcome) // len("test-db")
+	assert.Equal(t, "test-db", capturedURL)
+	assert.Equal(t, 2, attempts)
+}
+
+func TestRetryingWithExponentialBackoff(t *testing.T) {
+	cfg := defaultConfig
+	ctx := t.Context()
+
+	attempts := 0
+	action := func(status retry.RetryStatus) ReaderReaderIOResult[AppConfig, int] {
+		return func(c AppConfig) ReaderIOResult[context.Context, int] {
+			return func(ctx context.Context) IOResult[int] {
+				return func() Result[int] {
+					attempts++
+					if attempts < 3 {
+						return result.Left[int](errors.New("temporary error"))
+					}
+					return result.Of(42)
+				}
+			}
+		}
+	}
+
+	check := result.IsLeft[int]
+
+	// Exponential backoff policy
+	policy := retry.CapDelay(
+		200*time.Millisecond,
+		retry.LimitRetries(5),
+	)
+
+	computation := Retrying(policy, action, check)
+	outcome := computation(cfg)(ctx)()
+
+	assert.Equal(t, result.Of(42), outcome)
+	assert.Equal(t, 3, attempts)
+}
+
+func TestRetryingCheckFunction(t *testing.T) {
+	cfg := defaultConfig
+	ctx := t.Context()
+
+	attempts := 0
+	action := func(status retry.RetryStatus) ReaderReaderIOResult[AppConfig, int] {
+		return func(c AppConfig) ReaderIOResult[context.Context, int] {
+			return func(ctx context.Context) IOResult[int] {
+				return func() Result[int] {
+					attempts++
+					return result.Of(attempts)
+				}
+			}
+		}
+	}
+
+	// Retry while result is less than 3
+	check := func(r Result[int]) bool {
+		return result.Fold(
+			reader.Of[error](true),
+			N.LessThan(3),
+		)(r)
+	}
+
+	policy := retry.LimitRetries(10)
+
+	computation := Retrying(policy, action, check)
+	outcome := computation(cfg)(ctx)()
+
+	assert.Equal(t, result.Of(3), outcome)
+	assert.Equal(t, 3, attempts)
+}

v2/context/readerreaderioresult/types.go

@@ -0,0 +1,154 @@
+// Copyright (c) 2024 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package readerreaderioresult
+
+import (
+	"context"
+
+	"github.com/IBM/fp-go/v2/either"
+	"github.com/IBM/fp-go/v2/endomorphism"
+	"github.com/IBM/fp-go/v2/function"
+	"github.com/IBM/fp-go/v2/io"
+	"github.com/IBM/fp-go/v2/ioeither"
+	"github.com/IBM/fp-go/v2/ioresult"
+	"github.com/IBM/fp-go/v2/lazy"
+	"github.com/IBM/fp-go/v2/optics/lens"
+	"github.com/IBM/fp-go/v2/optics/traversal/result"
+	"github.com/IBM/fp-go/v2/option"
+	"github.com/IBM/fp-go/v2/predicate"
+	"github.com/IBM/fp-go/v2/reader"
+	"github.com/IBM/fp-go/v2/readerio"
+	"github.com/IBM/fp-go/v2/readerioresult"
+	"github.com/IBM/fp-go/v2/readeroption"
+	"github.com/IBM/fp-go/v2/readerreaderioeither"
+	"github.com/IBM/fp-go/v2/tailrec"
+)
+
+type (
+	// Option represents an optional value that may or may not be present.
+	// It's an alias for option.Option[A].
+	Option[A any] = option.Option[A]
+
+	// Lazy represents a lazily evaluated computation that produces a value of type A.
+	// It's an alias for lazy.Lazy[A].
+	Lazy[A any] = lazy.Lazy[A]
+
+	// Reader represents a computation that depends on an environment of type R
+	// and produces a value of type A.
+	// It's an alias for reader.Reader[R, A].
+	Reader[R, A any] = reader.Reader[R, A]
+
+	// ReaderOption represents a computation that depends on an environment of type R
+	// and produces an optional value of type A.
+	// It's an alias for readeroption.ReaderOption[R, A].
+	ReaderOption[R, A any] = readeroption.ReaderOption[R, A]
+
+	// ReaderIO represents a computation that depends on an environment of type R
+	// and performs side effects to produce a value of type A.
+	// It's an alias for readerio.ReaderIO[R, A].
+	ReaderIO[R, A any] = readerio.ReaderIO[R, A]
+
+	// ReaderIOResult represents a computation that depends on an environment of type R,
+	// performs side effects, and may fail with an error.
+	// It's an alias for readerioresult.ReaderIOResult[R, A].
+	ReaderIOResult[R, A any] = readerioresult.ReaderIOResult[R, A]
+
+	// Either represents a value that can be one of two types: Left (error) or Right (success).
+	// It's an alias for either.Either[E, A].
+	Either[E, A any] = either.Either[E, A]
+
+	// Result is a specialized Either with error as the left type.
+	// It's an alias for result.Result[A] which is Either[error, A].
+	Result[A any] = result.Result[A]
+
+	// IOEither represents a side-effecting computation that may fail with an error of type E
+	// or succeed with a value of type A.
+	// It's an alias for ioeither.IOEither[E, A].
+	IOEither[E, A any] = ioeither.IOEither[E, A]
+
+	// IOResult represents a side-effecting computation that may fail with an error
+	// or succeed with a value of type A.
+	// It's an alias for ioresult.IOResult[A] which is IOEither[error, A].
+	IOResult[A any] = ioresult.IOResult[A]
+
+	// IO represents a side-effecting computation that produces a value of type A.
+	// It's an alias for io.IO[A].
+	IO[A any] = io.IO[A]
+
+	// ReaderReaderIOEither is the base monad transformer that combines:
+	// - Reader[R, ...] for outer dependency injection
+	// - Reader[C, ...] for inner dependency injection (typically context.Context)
+	// - IO for side effects
+	// - Either[E, A] for error handling
+	// It's an alias for readerreaderioeither.ReaderReaderIOEither[R, C, E, A].
+	ReaderReaderIOEither[R, C, E, A any] = readerreaderioeither.ReaderReaderIOEither[R, C, E, A]
+
+	// ReaderReaderIOResult is the main type of this package, specializing ReaderReaderIOEither
+	// with context.Context as the inner reader type and error as the error type.
+	//
+	// Type structure:
+	//   ReaderReaderIOResult[R, A] = R -> context.Context -> IO[Either[error, A]]
+	//
+	// This represents a computation that:
+	// 1. Depends on an outer environment of type R (e.g., application config)
+	// 2. Depends on a context.Context for cancellation and request-scoped values
+	// 3. Performs side effects (IO)
+	// 4. May fail with an error or succeed with a value of type A
+	//
+	// This is the primary type used throughout the package for composing
+	// context-aware, effectful computations with error handling.
+	ReaderReaderIOResult[R, A any] = ReaderReaderIOEither[R, context.Context, error, A]
+
+	// Kleisli represents a function from A to a monadic value ReaderReaderIOResult[R, B].
+	// It's used for composing monadic functions using Kleisli composition.
+	//
+	// Type structure:
+	//   Kleisli[R, A, B] = A -> ReaderReaderIOResult[R, B]
+	//
+	// Kleisli arrows can be composed using Chain operations to build complex
+	// data transformation pipelines.
+	Kleisli[R, A, B any] = Reader[A, ReaderReaderIOResult[R, B]]
+
+	// Operator is a specialized Kleisli arrow that operates on monadic values.
+	// It takes a ReaderReaderIOResult[R, A] and produces a ReaderReaderIOResult[R, B].
+	//
+	// Type structure:
+	//   Operator[R, A, B] = ReaderReaderIOResult[R, A] -> ReaderReaderIOResult[R, B]
+	//
+	// Operators are useful for transforming monadic computations, such as
+	// adding retry logic, logging, or error recovery.
+	Operator[R, A, B any] = Kleisli[R, ReaderReaderIOResult[R, A], B]
+
+	// Lens represents an optic for focusing on a part of a data structure.
+	// It provides a way to get and set a field T within a structure S.
+	// It's an alias for lens.Lens[S, T].
+	Lens[S, T any] = lens.Lens[S, T]
+
+	// Trampoline is used for stack-safe recursion through tail call optimization.
+	// It's an alias for tailrec.Trampoline[L, B].
+	Trampoline[L, B any] = tailrec.Trampoline[L, B]
+
+	// Predicate represents a function that tests whether a value of type A
+	// satisfies some condition.
+	// It's an alias for predicate.Predicate[A].
+	Predicate[A any] = predicate.Predicate[A]
+
+	// Endmorphism represents a function from type A to type A.
+	// It's an alias for endomorphism.Endomorphism[A].
+	Endmorphism[A any] = endomorphism.Endomorphism[A]
+
+	Void = function.Void
+)

v2/context/readerresult/IO_OPERATIONS_RATIONALE.md

@@ -0,0 +1,246 @@
+# Why Combining IO Operations with ReaderResult Makes Sense
+
+## Overview
+
+The `context/readerresult` package provides functions that combine IO operations (like `FromIO`, `ChainIOK`, `TapIOK`, etc.) with ReaderResult computations. This document explains why this combination is natural and appropriate, despite IO operations being side-effectful.
+
+## Key Insight: ReaderResult is Already Effectful
+
+**IMPORTANT**: Unlike pure functional Reader monads, `ReaderResult[A]` in this package is **already side-effectful** because it depends on `context.Context`.
+
+### Why context.Context is Effectful
+
+The `context.Context` type in Go is inherently effectful because it:
+
+1. **Can be cancelled**: `ctx.Done()` returns a channel that closes when the context is cancelled
+2. **Has deadlines**: `ctx.Deadline()` returns a time when the context expires
+3. **Carries values**: `ctx.Value(key)` retrieves request-scoped values
+4. **Propagates signals**: Cancellation signals propagate across goroutines
+5. **Has observable state**: The context's state can change over time (e.g., when cancelled)
+
+### Type Definition
+
+```go
+type ReaderResult[A any] = func(context.Context) Result[A]
+```
+
+This is **not** a pure function because:
+- The behavior can change based on the context's state
+- The context can be cancelled during execution
+- The context carries mutable, observable state
+
+## Comparison with Pure Reader Monads
+
+### Pure Reader (from `readerresult` package)
+
+```go
+type ReaderResult[R, A any] = func(R) Result[A]
+```
+
+- `R` can be any type (config, state, etc.)
+- The function is **pure** if `R` is immutable
+- No side effects unless explicitly introduced
+
+### Effectful Reader (from `context/readerresult` package)
+
+```go
+type ReaderResult[A any] = func(context.Context) Result[A]
+```
+
+- Always depends on `context.Context`
+- **Inherently effectful** due to context's nature
+- Side effects are part of the design
+
+## Why IO Operations Fit Naturally
+
+Since `ReaderResult` is already effectful, combining it with IO operations is a natural fit:
+
+### 1. Both Represent Side Effects
+
+```go
+// IO operation - side effectful
+io := func() int {
+    fmt.Println("Performing IO")
+    return 42
+}
+
+// ReaderResult - also side effectful (depends on context)
+rr := func(ctx context.Context) Result[int] {
+    // Can check if context is cancelled (side effect)
+    if ctx.Err() != nil {
+        return result.Error[int](ctx.Err())
+    }
+    return result.Of(42)
+}
+
+// Combining them is natural
+combined := FromIO(io)
+```
+
+### 2. Context-Aware IO Operations
+
+The combination allows IO operations to respect context cancellation:
+
+```go
+// IO operation that should respect cancellation
+readFile := func(path string) ReaderResult[[]byte] {
+    return func(ctx context.Context) Result[[]byte] {
+        // Check cancellation before expensive IO
+        if ctx.Err() != nil {
+            return result.Error[[]byte](ctx.Err())
+        }
+        
+        // Perform IO operation
+        data, err := os.ReadFile(path)
+        if err != nil {
+            return result.Error[[]byte](err)
+        }
+        return result.Of(data)
+    }
+}
+```
+
+### 3. Practical Use Cases
+
+#### Logging with Side Effects
+
+```go
+// Log to external system (IO operation)
+logMetric := func(value int) func() string {
+    return func() string {
+        // Side effect: write to metrics system
+        metrics.Record("value", value)
+        return "logged"
+    }
+}
+
+// Use with ReaderResult
+pipeline := F.Pipe1(
+    readerresult.Of(42),
+    readerresult.TapIOK(logMetric),
+)
+```
+
+#### Database Operations
+
+```go
+// Database query (IO operation with context)
+queryDB := func(id int) ReaderResult[User] {
+    return func(ctx context.Context) Result[User] {
+        // Context used for timeout/cancellation
+        user, err := db.QueryContext(ctx, "SELECT * FROM users WHERE id = ?", id)
+        if err != nil {
+            return result.Error[User](err)
+        }
+        return result.Of(user)
+    }
+}
+
+// Chain with other operations
+pipeline := F.Pipe2(
+    readerresult.Of(123),
+    readerresult.Chain(queryDB),
+    readerresult.TapIOK(func(user User) func() string {
+        return func() string {
+            log.Printf("Retrieved user: %s", user.Name)
+            return "logged"
+        }
+    }),
+)
+```
+
+#### HTTP Requests
+
+```go
+// HTTP request (IO operation)
+fetchData := func(url string) ReaderResult[Response] {
+    return func(ctx context.Context) Result[Response] {
+        req, _ := http.NewRequestWithContext(ctx, "GET", url, nil)
+        resp, err := http.DefaultClient.Do(req)
+        if err != nil {
+            return result.Error[Response](err)
+        }
+        return result.Of(resp)
+    }
+}
+```
+
+## Functions That Combine IO with ReaderResult
+
+### Lifting Functions
+
+- **`FromIO[A]`**: Lifts a pure IO computation into ReaderResult
+- **`FromIOResult[A]`**: Lifts an IOResult (IO with error handling) into ReaderResult
+
+### Chaining Functions
+
+- **`ChainIOK[A, B]`**: Sequences a ReaderResult with an IO computation
+- **`ChainIOEitherK[A, B]`**: Sequences with an IOResult computation
+- **`ChainIOResultK[A, B]`**: Alias for ChainIOEitherK
+
+### Tapping Functions (Side Effects)
+
+- **`TapIOK[A, B]`**: Executes IO for side effects, preserves original value
+- **`ChainFirstIOK[A, B]`**: Same as TapIOK
+- **`MonadTapIOK[A, B]`**: Monadic version of TapIOK
+- **`MonadChainFirstIOK[A, B]`**: Monadic version of ChainFirstIOK
+
+### Error Handling with IO
+
+- **`TapLeftIOK[A, B]`**: Executes IO on error for side effects (logging, metrics)
+- **`ChainFirstLeftIOK[A, B]`**: Same as TapLeftIOK
+
+### Reading Context from IO
+
+- **`ReadIO[A]`**: Executes ReaderResult with context from IO
+- **`ReadIOEither[A]`**: Executes with context from IOResult
+- **`ReadIOResult[A]`**: Alias for ReadIOEither
+
+## Design Philosophy
+
+### Embrace Effectfulness
+
+Rather than trying to maintain purity (which is impossible with `context.Context`), this package embraces the effectful nature of Go's context and provides tools to work with it safely and composably.
+
+### Composition Over Isolation
+
+The package allows you to compose effectful operations (ReaderResult + IO) in a type-safe, functional way, rather than isolating them.
+
+### Practical Go Idioms
+
+This approach aligns with Go's pragmatic philosophy:
+- Context is used everywhere in Go for cancellation and timeouts
+- IO operations are common and necessary
+- Combining them in a type-safe way improves code quality
+
+## Contrast with Pure Functional Packages
+
+### When to Use `context/readerresult` (This Package)
+
+Use when you need:
+- ✅ Context cancellation and timeouts
+- ✅ Request-scoped values
+- ✅ Integration with Go's standard library (http, database/sql, etc.)
+- ✅ IO operations with error handling
+- ✅ Practical, idiomatic Go code
+
+### When to Use `readerresult` (Pure Package)
+
+Use when you need:
+- ✅ Pure dependency injection
+- ✅ Testable computations with simple config objects
+- ✅ No context propagation
+- ✅ Generic environment types (not limited to context.Context)
+- ✅ Purely functional composition
+
+## Conclusion
+
+Combining IO operations with ReaderResult in the `context/readerresult` package makes sense because:
+
+1. **ReaderResult is already effectful** due to its dependency on `context.Context`
+2. **IO operations are also effectful**, making them a natural fit
+3. **The combination provides practical benefits** for real-world Go applications
+4. **It aligns with Go's pragmatic philosophy** of embracing side effects when necessary
+5. **It enables type-safe composition** of effectful operations
+
+The key insight is that `context.Context` itself is a side effect, so adding more side effects (IO operations) doesn't violate any purity constraints—because there were none to begin with. This package provides tools to work with these side effects in a safe, composable, and type-safe manner.

v2/context/readerresult/bind_test.go

@@ -16,7 +16,6 @@
 package readerresult
 
 import (
-	"context"
 	"testing"
 
 	E "github.com/IBM/fp-go/v2/either"
@@ -42,7 +41,7 @@ func TestBind(t *testing.T) {
 		Map(utils.GetFullName),
 	)
 
-	assert.Equal(t, res(context.Background()), E.Of[error]("John Doe"))
+	assert.Equal(t, res(t.Context()), E.Of[error]("John Doe"))
 }
 
 func TestApS(t *testing.T) {
@@ -54,5 +53,5 @@ func TestApS(t *testing.T) {
 		Map(utils.GetFullName),
 	)
 
-	assert.Equal(t, res(context.Background()), E.Of[error]("John Doe"))
+	assert.Equal(t, res(t.Context()), E.Of[error]("John Doe"))
 }

v2/context/readerresult/cancel.go

@@ -22,7 +22,75 @@ import (
 	F "github.com/IBM/fp-go/v2/function"
 )
 
-// withContext wraps an existing ReaderResult and performs a context check for cancellation before deletating
+// WithContext wraps an existing ReaderResult and performs a context check for cancellation
+// before delegating to the wrapped computation. This provides early cancellation detection,
+// allowing computations to fail fast when the context has been cancelled or has exceeded
+// its deadline.
+//
+// IMPORTANT: This function checks for context cancellation BEFORE executing the wrapped
+// ReaderResult. If the context is already cancelled or has exceeded its deadline, the
+// computation returns immediately with the cancellation error without executing the
+// wrapped ReaderResult.
+//
+// The function uses context.Cause(ctx) to extract the cancellation reason, which may be:
+//   - context.Canceled: The context was explicitly cancelled
+//   - context.DeadlineExceeded: The context's deadline was exceeded
+//   - A custom error: If the context was cancelled with a cause (Go 1.20+)
+//
+// Type Parameters:
+//   - A: The success type of the ReaderResult
+//
+// Parameters:
+//   - ma: The ReaderResult to wrap with cancellation checking
+//
+// Returns:
+//   - A ReaderResult that checks for cancellation before executing ma
+//
+// Example:
+//
+//	// Create a long-running computation
+//	longComputation := func(ctx context.Context) result.Result[int] {
+//	    time.Sleep(5 * time.Second)
+//	    return result.Of(42)
+//	}
+//
+//	// Wrap with cancellation check
+//	safeLongComputation := readerresult.WithContext(longComputation)
+//
+//	// Cancel the context before execution
+//	ctx, cancel := context.WithCancel(t.Context())
+//	cancel()
+//
+//	// The computation returns immediately with cancellation error
+//	result := safeLongComputation(ctx)
+//	// result is Left(context.Canceled) - longComputation never executes
+//
+// Example with timeout:
+//
+//	fetchData := func(ctx context.Context) result.Result[string] {
+//	    // Simulate slow operation
+//	    time.Sleep(2 * time.Second)
+//	    return result.Of("data")
+//	}
+//
+//	safeFetch := readerresult.WithContext(fetchData)
+//
+//	// Context with 1 second timeout
+//	ctx, cancel := context.WithTimeout(t.Context(), 1*time.Second)
+//	defer cancel()
+//
+//	time.Sleep(1500 * time.Millisecond) // Wait for timeout
+//
+//	result := safeFetch(ctx)
+//	// result is Left(context.DeadlineExceeded) - fetchData never executes
+//
+// Use cases:
+//   - Wrapping expensive computations to enable early cancellation
+//   - Preventing unnecessary work when context is already cancelled
+//   - Implementing timeout-aware operations
+//   - Building cancellation-aware pipelines
+//
+//go:inline
 func WithContext[A any](ma ReaderResult[A]) ReaderResult[A] {
 	return func(ctx context.Context) E.Either[error, A] {
 		if ctx.Err() != nil {
@@ -32,6 +100,81 @@ func WithContext[A any](ma ReaderResult[A]) ReaderResult[A] {
 	}
 }
 
+// WithContextK wraps a Kleisli arrow with context cancellation checking.
+// This is a higher-order function that takes a Kleisli arrow and returns a new
+// Kleisli arrow that checks for context cancellation before executing.
+//
+// IMPORTANT: This function composes the Kleisli arrow with WithContext, ensuring
+// that the resulting ReaderResult checks for cancellation before execution. This
+// is particularly useful when building pipelines of Kleisli arrows where you want
+// cancellation checking at each step.
+//
+// Type Parameters:
+//   - A: The input type of the Kleisli arrow
+//   - B: The output type of the Kleisli arrow
+//
+// Parameters:
+//   - f: The Kleisli arrow to wrap with cancellation checking
+//
+// Returns:
+//   - A new Kleisli arrow that checks for cancellation before executing f
+//
+// Example:
+//
+//	// Define a Kleisli arrow
+//	processUser := func(id int) readerresult.ReaderResult[User] {
+//	    return func(ctx context.Context) result.Result[User] {
+//	        // Expensive database operation
+//	        return fetchUserFromDB(ctx, id)
+//	    }
+//	}
+//
+//	// Wrap with cancellation checking
+//	safeProcessUser := readerresult.WithContextK(processUser)
+//
+//	// Use in a pipeline
+//	pipeline := F.Pipe1(
+//	    readerresult.Of(123),
+//	    readerresult.Chain(safeProcessUser),
+//	)
+//
+//	// If context is cancelled, processUser never executes
+//	ctx, cancel := context.WithCancel(t.Context())
+//	cancel()
+//	result := pipeline(ctx) // Left(context.Canceled)
+//
+// Example with multiple steps:
+//
+//	getUserK := readerresult.WithContextK(func(id int) readerresult.ReaderResult[User] {
+//	    return func(ctx context.Context) result.Result[User] {
+//	        return fetchUser(ctx, id)
+//	    }
+//	})
+//
+//	getOrdersK := readerresult.WithContextK(func(user User) readerresult.ReaderResult[[]Order] {
+//	    return func(ctx context.Context) result.Result[[]Order] {
+//	        return fetchOrders(ctx, user.ID)
+//	    }
+//	})
+//
+//	// Each step checks for cancellation
+//	pipeline := F.Pipe2(
+//	    readerresult.Of(123),
+//	    readerresult.Chain(getUserK),
+//	    readerresult.Chain(getOrdersK),
+//	)
+//
+//	// If context is cancelled at any point, remaining steps don't execute
+//	ctx, cancel := context.WithTimeout(t.Context(), 100*time.Millisecond)
+//	defer cancel()
+//	result := pipeline(ctx)
+//
+// Use cases:
+//   - Building cancellation-aware pipelines
+//   - Ensuring each step in a chain respects cancellation
+//   - Implementing timeout-aware multi-step operations
+//   - Preventing cascading failures in long pipelines
+//
 //go:inline
 func WithContextK[A, B any](f Kleisli[A, B]) Kleisli[A, B] {
 	return F.Flow2(

v2/context/readerresult/cancel_test.go

@@ -0,0 +1,418 @@
+// Copyright (c) 2023 - 2025 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package readerresult
+
+import (
+	"context"
+	"errors"
+	"testing"
+	"time"
+
+	E "github.com/IBM/fp-go/v2/either"
+	F "github.com/IBM/fp-go/v2/function"
+	N "github.com/IBM/fp-go/v2/number"
+	"github.com/IBM/fp-go/v2/reader"
+	"github.com/stretchr/testify/assert"
+)
+
+// TestWithContext tests the WithContext function
+func TestWithContext(t *testing.T) {
+	t.Run("executes wrapped ReaderResult when context is not cancelled", func(t *testing.T) {
+		executed := false
+		computation := func(ctx context.Context) E.Either[error, int] {
+			executed = true
+			return E.Of[error](42)
+		}
+
+		wrapped := WithContext(computation)
+		result := wrapped(t.Context())
+
+		assert.True(t, executed, "computation should be executed")
+		assert.Equal(t, E.Of[error](42), result)
+	})
+
+	t.Run("returns cancellation error when context is cancelled", func(t *testing.T) {
+		executed := false
+		computation := func(ctx context.Context) E.Either[error, int] {
+			executed = true
+			return E.Of[error](42)
+		}
+
+		wrapped := WithContext(computation)
+
+		ctx, cancel := context.WithCancel(t.Context())
+		cancel()
+
+		result := wrapped(ctx)
+
+		assert.False(t, executed, "computation should not be executed when context is cancelled")
+		assert.True(t, E.IsLeft(result))
+		_, err := E.UnwrapError(result)
+		assert.Equal(t, context.Canceled, err)
+	})
+
+	t.Run("returns deadline exceeded error when context times out", func(t *testing.T) {
+		executed := false
+		computation := func(ctx context.Context) E.Either[error, int] {
+			executed = true
+			time.Sleep(100 * time.Millisecond)
+			return E.Of[error](42)
+		}
+
+		wrapped := WithContext(computation)
+
+		ctx, cancel := context.WithTimeout(t.Context(), 10*time.Millisecond)
+		defer cancel()
+
+		time.Sleep(20 * time.Millisecond) // Wait for timeout
+
+		result := wrapped(ctx)
+
+		assert.False(t, executed, "computation should not be executed when context has timed out")
+		assert.True(t, E.IsLeft(result))
+		_, err := E.UnwrapError(result)
+		assert.Equal(t, context.DeadlineExceeded, err)
+	})
+
+	t.Run("preserves errors from wrapped computation", func(t *testing.T) {
+		testErr := errors.New("computation error")
+		computation := func(ctx context.Context) E.Either[error, int] {
+			return E.Left[int](testErr)
+		}
+
+		wrapped := WithContext(computation)
+		result := wrapped(t.Context())
+
+		assert.True(t, E.IsLeft(result))
+		_, err := E.UnwrapError(result)
+		assert.Equal(t, testErr, err)
+	})
+
+	t.Run("prevents expensive computation when context is already cancelled", func(t *testing.T) {
+		expensiveExecuted := false
+		expensiveComputation := func(ctx context.Context) E.Either[error, int] {
+			expensiveExecuted = true
+			// Simulate expensive operation
+			time.Sleep(1 * time.Second)
+			return E.Of[error](42)
+		}
+
+		wrapped := WithContext(expensiveComputation)
+
+		ctx, cancel := context.WithCancel(t.Context())
+		cancel()
+
+		start := time.Now()
+		result := wrapped(ctx)
+		duration := time.Since(start)
+
+		assert.False(t, expensiveExecuted, "expensive computation should not execute")
+		assert.True(t, E.IsLeft(result))
+		assert.Less(t, duration, 100*time.Millisecond, "should return immediately")
+	})
+
+	t.Run("works with context.WithCancelCause", func(t *testing.T) {
+		executed := false
+		computation := func(ctx context.Context) E.Either[error, int] {
+			executed = true
+			return E.Of[error](42)
+		}
+
+		wrapped := WithContext(computation)
+
+		customErr := errors.New("custom cancellation reason")
+		ctx, cancel := context.WithCancelCause(t.Context())
+		cancel(customErr)
+
+		result := wrapped(ctx)
+
+		assert.False(t, executed, "computation should not be executed")
+		assert.True(t, E.IsLeft(result))
+		_, err := E.UnwrapError(result)
+		assert.Equal(t, customErr, err)
+	})
+
+	t.Run("can be nested for multiple cancellation checks", func(t *testing.T) {
+		executed := false
+		computation := func(ctx context.Context) E.Either[error, int] {
+			executed = true
+			return E.Of[error](42)
+		}
+
+		doubleWrapped := WithContext(WithContext(computation))
+
+		ctx, cancel := context.WithCancel(t.Context())
+		cancel()
+
+		result := doubleWrapped(ctx)
+
+		assert.False(t, executed, "computation should not be executed")
+		assert.True(t, E.IsLeft(result))
+	})
+}
+
+// TestWithContextK tests the WithContextK function
+func TestWithContextK(t *testing.T) {
+	t.Run("wraps Kleisli arrow with cancellation checking", func(t *testing.T) {
+		executed := false
+		processUser := func(id int) ReaderResult[string] {
+			return func(ctx context.Context) E.Either[error, string] {
+				executed = true
+				return E.Of[error]("user-" + string(rune(id+48)))
+			}
+		}
+
+		safeProcessUser := WithContextK(processUser)
+
+		result := safeProcessUser(123)(t.Context())
+
+		assert.True(t, executed, "Kleisli should be executed")
+		assert.True(t, E.IsRight(result))
+	})
+
+	t.Run("prevents Kleisli execution when context is cancelled", func(t *testing.T) {
+		executed := false
+		processUser := func(id int) ReaderResult[string] {
+			return func(ctx context.Context) E.Either[error, string] {
+				executed = true
+				return E.Of[error]("user")
+			}
+		}
+
+		safeProcessUser := WithContextK(processUser)
+
+		ctx, cancel := context.WithCancel(t.Context())
+		cancel()
+
+		result := safeProcessUser(123)(ctx)
+
+		assert.False(t, executed, "Kleisli should not be executed when context is cancelled")
+		assert.True(t, E.IsLeft(result))
+		_, err := E.UnwrapError(result)
+		assert.Equal(t, context.Canceled, err)
+	})
+
+	t.Run("works in Chain pipeline", func(t *testing.T) {
+		firstExecuted := false
+		secondExecuted := false
+
+		getUser := WithContextK(func(id int) ReaderResult[string] {
+			return func(ctx context.Context) E.Either[error, string] {
+				firstExecuted = true
+				return E.Of[error]("Alice")
+			}
+		})
+
+		getOrders := WithContextK(func(name string) ReaderResult[int] {
+			return func(ctx context.Context) E.Either[error, int] {
+				secondExecuted = true
+				return E.Of[error](5)
+			}
+		})
+
+		pipeline := F.Pipe2(
+			Of(123),
+			Chain(getUser),
+			Chain(getOrders),
+		)
+
+		result := pipeline(t.Context())
+
+		assert.True(t, firstExecuted, "first step should execute")
+		assert.True(t, secondExecuted, "second step should execute")
+		assert.Equal(t, E.Of[error](5), result)
+	})
+
+	t.Run("stops pipeline on cancellation", func(t *testing.T) {
+		firstExecuted := false
+		secondExecuted := false
+
+		getUser := WithContextK(func(id int) ReaderResult[string] {
+			return func(ctx context.Context) E.Either[error, string] {
+				firstExecuted = true
+				return E.Of[error]("Alice")
+			}
+		})
+
+		getOrders := WithContextK(func(name string) ReaderResult[int] {
+			return func(ctx context.Context) E.Either[error, int] {
+				secondExecuted = true
+				return E.Of[error](5)
+			}
+		})
+
+		pipeline := F.Pipe2(
+			Of(123),
+			Chain(getUser),
+			Chain(getOrders),
+		)
+
+		ctx, cancel := context.WithCancel(t.Context())
+		cancel()
+
+		result := pipeline(ctx)
+
+		assert.False(t, firstExecuted, "first step should not execute")
+		assert.False(t, secondExecuted, "second step should not execute")
+		assert.True(t, E.IsLeft(result))
+	})
+
+	t.Run("respects timeout in multi-step pipeline", func(t *testing.T) {
+		step1Executed := false
+		step2Executed := false
+
+		step1 := WithContextK(func(x int) ReaderResult[int] {
+			return func(ctx context.Context) E.Either[error, int] {
+				step1Executed = true
+				time.Sleep(50 * time.Millisecond)
+				return E.Of[error](x * 2)
+			}
+		})
+
+		step2 := WithContextK(func(x int) ReaderResult[int] {
+			return func(ctx context.Context) E.Either[error, int] {
+				step2Executed = true
+				return E.Of[error](x + 10)
+			}
+		})
+
+		pipeline := F.Pipe2(
+			Of(5),
+			Chain(step1),
+			Chain(step2),
+		)
+
+		ctx, cancel := context.WithTimeout(t.Context(), 10*time.Millisecond)
+		defer cancel()
+
+		time.Sleep(20 * time.Millisecond) // Wait for timeout
+
+		result := pipeline(ctx)
+
+		assert.False(t, step1Executed, "step1 should not execute after timeout")
+		assert.False(t, step2Executed, "step2 should not execute after timeout")
+		assert.True(t, E.IsLeft(result))
+	})
+
+	t.Run("preserves errors from Kleisli computation", func(t *testing.T) {
+		testErr := errors.New("kleisli error")
+		failingKleisli := func(id int) ReaderResult[string] {
+			return func(ctx context.Context) E.Either[error, string] {
+				return E.Left[string](testErr)
+			}
+		}
+
+		safeKleisli := WithContextK(failingKleisli)
+		result := safeKleisli(123)(t.Context())
+
+		assert.True(t, E.IsLeft(result))
+		_, err := E.UnwrapError(result)
+		assert.Equal(t, testErr, err)
+	})
+}
+
+// TestWithContextIntegration tests integration scenarios
+func TestWithContextIntegration(t *testing.T) {
+	t.Run("WithContext in complex pipeline with multiple operations", func(t *testing.T) {
+		step1Executed := false
+		step2Executed := false
+		step3Executed := false
+
+		step1 := WithContext(func(ctx context.Context) E.Either[error, int] {
+			step1Executed = true
+			return E.Of[error](10)
+		})
+
+		step2 := WithContextK(func(x int) ReaderResult[int] {
+			return func(ctx context.Context) E.Either[error, int] {
+				step2Executed = true
+				return E.Of[error](x * 2)
+			}
+		})
+
+		step3 := WithContext(func(ctx context.Context) E.Either[error, string] {
+			step3Executed = true
+			return E.Of[error]("done")
+		})
+
+		pipeline := F.Pipe2(
+			step1,
+			Chain(step2),
+			ChainTo[int](step3),
+		)
+
+		result := pipeline(t.Context())
+
+		assert.True(t, step1Executed)
+		assert.True(t, step2Executed)
+		assert.True(t, step3Executed)
+		assert.Equal(t, E.Of[error]("done"), result)
+	})
+
+	t.Run("early cancellation prevents all subsequent operations", func(t *testing.T) {
+		step1Executed := false
+		step2Executed := false
+		step3Executed := false
+
+		step1 := WithContext(func(ctx context.Context) E.Either[error, int] {
+			step1Executed = true
+			return E.Of[error](10)
+		})
+
+		step2 := WithContextK(func(x int) ReaderResult[int] {
+			return func(ctx context.Context) E.Either[error, int] {
+				step2Executed = true
+				return E.Of[error](x * 2)
+			}
+		})
+
+		step3 := WithContext(func(ctx context.Context) E.Either[error, string] {
+			step3Executed = true
+			return E.Of[error]("done")
+		})
+
+		pipeline := F.Pipe2(
+			step1,
+			Chain(step2),
+			ChainTo[int](step3),
+		)
+
+		ctx, cancel := context.WithCancel(t.Context())
+		cancel()
+
+		result := pipeline(ctx)
+
+		assert.False(t, step1Executed, "no steps should execute")
+		assert.False(t, step2Executed, "no steps should execute")
+		assert.False(t, step3Executed, "no steps should execute")
+		assert.True(t, E.IsLeft(result))
+	})
+
+	t.Run("WithContext with Map and Chain", func(t *testing.T) {
+		computation := WithContext(func(ctx context.Context) E.Either[error, int] {
+			return E.Of[error](42)
+		})
+
+		pipeline := F.Pipe2(
+			computation,
+			Map(N.Mul(2)),
+			Map(reader.Of[int]("result")),
+		)
+
+		result := pipeline(t.Context())
+		assert.Equal(t, E.Of[error]("result"), result)
+	})
+}

v2/context/readerresult/curry.go

@@ -21,33 +21,299 @@ import (
 	"github.com/IBM/fp-go/v2/readereither"
 )
 
-// these functions curry a golang function with the context as the firsr parameter into a either reader with the context as the last parameter
-// this goes back to the advice in https://pkg.go.dev/context to put the context as a first parameter as a convention
+// Curry and Uncurry functions convert between idiomatic Go functions (with context.Context as the first parameter)
+// and functional ReaderResult/Kleisli compositions (with context.Context as the last parameter).
+//
+// This follows the Go convention from https://pkg.go.dev/context to put context as the first parameter,
+// while enabling functional composition where context is typically the last parameter.
+//
+// The curry functions transform:
+//   func(context.Context, T1, T2, ...) (A, error)  →  func(T1) func(T2) ... ReaderResult[A]
+//
+// The uncurry functions transform:
+//   func(T1) func(T2) ... ReaderResult[A]  →  func(context.Context, T1, T2, ...) (A, error)
 
+// Curry0 converts a Go function with context and no additional parameters into a ReaderResult.
+// This is useful for adapting context-aware functions to the ReaderResult monad.
+//
+// Type Parameters:
+//   - A: The return type of the function
+//
+// Parameters:
+//   - f: A function that takes a context and returns a value and error
+//
+// Returns:
+//   - A ReaderResult that wraps the function
+//
+// Example:
+//
+//	// Idiomatic Go function
+//	getConfig := func(ctx context.Context) (Config, error) {
+//	    // Check context cancellation
+//	    if ctx.Err() != nil {
+//	        return Config{}, ctx.Err()
+//	    }
+//	    return Config{Value: 42}, nil
+//	}
+//
+//	// Convert to ReaderResult for functional composition
+//	configRR := readerresult.Curry0(getConfig)
+//	result := configRR(t.Context()) // Right(Config{Value: 42})
+//
+//go:inline
 func Curry0[A any](f func(context.Context) (A, error)) ReaderResult[A] {
 	return readereither.Curry0(f)
 }
 
+// Curry1 converts a Go function with context and one parameter into a Kleisli arrow.
+// This enables functional composition of single-parameter functions.
+//
+// Type Parameters:
+//   - T1: The type of the first parameter
+//   - A: The return type of the function
+//
+// Parameters:
+//   - f: A function that takes a context and one parameter, returning a value and error
+//
+// Returns:
+//   - A Kleisli arrow that can be composed with other ReaderResult operations
+//
+// Example:
+//
+//	// Idiomatic Go function
+//	getUserByID := func(ctx context.Context, id int) (User, error) {
+//	    if ctx.Err() != nil {
+//	        return User{}, ctx.Err()
+//	    }
+//	    return User{ID: id, Name: "Alice"}, nil
+//	}
+//
+//	// Convert to Kleisli for functional composition
+//	getUserKleisli := readerresult.Curry1(getUserByID)
+//
+//	// Use in a pipeline
+//	pipeline := F.Pipe1(
+//	    readerresult.Of(123),
+//	    readerresult.Chain(getUserKleisli),
+//	)
+//	result := pipeline(t.Context()) // Right(User{ID: 123, Name: "Alice"})
+//
+//go:inline
 func Curry1[T1, A any](f func(context.Context, T1) (A, error)) Kleisli[T1, A] {
 	return readereither.Curry1(f)
 }
 
+// Curry2 converts a Go function with context and two parameters into a curried function.
+// This enables partial application and functional composition of two-parameter functions.
+//
+// Type Parameters:
+//   - T1: The type of the first parameter
+//   - T2: The type of the second parameter
+//   - A: The return type of the function
+//
+// Parameters:
+//   - f: A function that takes a context and two parameters, returning a value and error
+//
+// Returns:
+//   - A curried function that takes T1 and returns a Kleisli arrow for T2
+//
+// Example:
+//
+//	// Idiomatic Go function
+//	updateUser := func(ctx context.Context, id int, name string) (User, error) {
+//	    if ctx.Err() != nil {
+//	        return User{}, ctx.Err()
+//	    }
+//	    return User{ID: id, Name: name}, nil
+//	}
+//
+//	// Convert to curried form
+//	updateUserCurried := readerresult.Curry2(updateUser)
+//
+//	// Partial application
+//	updateUser123 := updateUserCurried(123)
+//
+//	// Use in a pipeline
+//	pipeline := F.Pipe1(
+//	    readerresult.Of("Bob"),
+//	    readerresult.Chain(updateUser123),
+//	)
+//	result := pipeline(t.Context()) // Right(User{ID: 123, Name: "Bob"})
+//
+//go:inline
 func Curry2[T1, T2, A any](f func(context.Context, T1, T2) (A, error)) func(T1) Kleisli[T2, A] {
 	return readereither.Curry2(f)
 }
 
+// Curry3 converts a Go function with context and three parameters into a curried function.
+// This enables partial application and functional composition of three-parameter functions.
+//
+// Type Parameters:
+//   - T1: The type of the first parameter
+//   - T2: The type of the second parameter
+//   - T3: The type of the third parameter
+//   - A: The return type of the function
+//
+// Parameters:
+//   - f: A function that takes a context and three parameters, returning a value and error
+//
+// Returns:
+//   - A curried function that takes T1, T2, and returns a Kleisli arrow for T3
+//
+// Example:
+//
+//	// Idiomatic Go function
+//	createOrder := func(ctx context.Context, userID int, productID int, quantity int) (Order, error) {
+//	    if ctx.Err() != nil {
+//	        return Order{}, ctx.Err()
+//	    }
+//	    return Order{UserID: userID, ProductID: productID, Quantity: quantity}, nil
+//	}
+//
+//	// Convert to curried form
+//	createOrderCurried := readerresult.Curry3(createOrder)
+//
+//	// Partial application
+//	createOrderForUser := createOrderCurried(123)
+//	createOrderForProduct := createOrderForUser(456)
+//
+//	// Use in a pipeline
+//	pipeline := F.Pipe1(
+//	    readerresult.Of(2),
+//	    readerresult.Chain(createOrderForProduct),
+//	)
+//	result := pipeline(t.Context()) // Right(Order{UserID: 123, ProductID: 456, Quantity: 2})
+//
+//go:inline
 func Curry3[T1, T2, T3, A any](f func(context.Context, T1, T2, T3) (A, error)) func(T1) func(T2) Kleisli[T3, A] {
 	return readereither.Curry3(f)
 }
 
+// Uncurry1 converts a Kleisli arrow back into an idiomatic Go function with context as the first parameter.
+// This is useful for interfacing with code that expects standard Go function signatures.
+//
+// Type Parameters:
+//   - T1: The type of the parameter
+//   - A: The return type
+//
+// Parameters:
+//   - f: A Kleisli arrow
+//
+// Returns:
+//   - A Go function with context as the first parameter
+//
+// Example:
+//
+//	// Kleisli arrow
+//	getUserKleisli := func(id int) readerresult.ReaderResult[User] {
+//	    return func(ctx context.Context) result.Result[User] {
+//	        if ctx.Err() != nil {
+//	            return result.Error[User](ctx.Err())
+//	        }
+//	        return result.Of(User{ID: id, Name: "Alice"})
+//	    }
+//	}
+//
+//	// Convert back to idiomatic Go function
+//	getUserByID := readerresult.Uncurry1(getUserKleisli)
+//
+//	// Use as a normal Go function
+//	user, err := getUserByID(t.Context(), 123)
+//	if err != nil {
+//	    log.Fatal(err)
+//	}
+//	fmt.Println(user.Name) // "Alice"
+//
+//go:inline
 func Uncurry1[T1, A any](f Kleisli[T1, A]) func(context.Context, T1) (A, error) {
 	return readereither.Uncurry1(f)
 }
 
+// Uncurry2 converts a curried function back into an idiomatic Go function with context as the first parameter.
+// This is useful for interfacing with code that expects standard Go function signatures.
+//
+// Type Parameters:
+//   - T1: The type of the first parameter
+//   - T2: The type of the second parameter
+//   - A: The return type
+//
+// Parameters:
+//   - f: A curried function
+//
+// Returns:
+//   - A Go function with context as the first parameter
+//
+// Example:
+//
+//	// Curried function
+//	updateUserCurried := func(id int) func(name string) readerresult.ReaderResult[User] {
+//	    return func(name string) readerresult.ReaderResult[User] {
+//	        return func(ctx context.Context) result.Result[User] {
+//	            if ctx.Err() != nil {
+//	                return result.Error[User](ctx.Err())
+//	            }
+//	            return result.Of(User{ID: id, Name: name})
+//	        }
+//	    }
+//	}
+//
+//	// Convert back to idiomatic Go function
+//	updateUser := readerresult.Uncurry2(updateUserCurried)
+//
+//	// Use as a normal Go function
+//	user, err := updateUser(t.Context(), 123, "Bob")
+//	if err != nil {
+//	    log.Fatal(err)
+//	}
+//	fmt.Println(user.Name) // "Bob"
+//
+//go:inline
 func Uncurry2[T1, T2, A any](f func(T1) Kleisli[T2, A]) func(context.Context, T1, T2) (A, error) {
 	return readereither.Uncurry2(f)
 }
 
+// Uncurry3 converts a curried function back into an idiomatic Go function with context as the first parameter.
+// This is useful for interfacing with code that expects standard Go function signatures.
+//
+// Type Parameters:
+//   - T1: The type of the first parameter
+//   - T2: The type of the second parameter
+//   - T3: The type of the third parameter
+//   - A: The return type
+//
+// Parameters:
+//   - f: A curried function
+//
+// Returns:
+//   - A Go function with context as the first parameter
+//
+// Example:
+//
+//	// Curried function
+//	createOrderCurried := func(userID int) func(productID int) func(quantity int) readerresult.ReaderResult[Order] {
+//	    return func(productID int) func(quantity int) readerresult.ReaderResult[Order] {
+//	        return func(quantity int) readerresult.ReaderResult[Order] {
+//	            return func(ctx context.Context) result.Result[Order] {
+//	                if ctx.Err() != nil {
+//	                    return result.Error[Order](ctx.Err())
+//	                }
+//	                return result.Of(Order{UserID: userID, ProductID: productID, Quantity: quantity})
+//	            }
+//	        }
+//	    }
+//	}
+//
+//	// Convert back to idiomatic Go function
+//	createOrder := readerresult.Uncurry3(createOrderCurried)
+//
+//	// Use as a normal Go function
+//	order, err := createOrder(t.Context(), 123, 456, 2)
+//	if err != nil {
+//	    log.Fatal(err)
+//	}
+//	fmt.Printf("Order: User=%d, Product=%d, Qty=%d\n", order.UserID, order.ProductID, order.Quantity)
+//
+//go:inline
 func Uncurry3[T1, T2, T3, A any](f func(T1) func(T2) Kleisli[T3, A]) func(context.Context, T1, T2, T3) (A, error) {
 	return readereither.Uncurry3(f)
 }

v2/context/readerresult/curry_test.go

@@ -0,0 +1,564 @@
+// Copyright (c) 2023 - 2025 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package readerresult
+
+import (
+	"context"
+	"errors"
+	"testing"
+
+	E "github.com/IBM/fp-go/v2/either"
+	F "github.com/IBM/fp-go/v2/function"
+	"github.com/stretchr/testify/assert"
+)
+
+// TestCurry0 tests the Curry0 function
+func TestCurry0(t *testing.T) {
+	t.Run("converts Go function to ReaderResult on success", func(t *testing.T) {
+		// Idiomatic Go function
+		getConfig := func(ctx context.Context) (int, error) {
+			return 42, nil
+		}
+
+		// Convert to ReaderResult
+		configRR := Curry0(getConfig)
+		result := configRR(t.Context())
+
+		assert.Equal(t, E.Of[error](42), result)
+	})
+
+	t.Run("converts Go function to ReaderResult on error", func(t *testing.T) {
+		testErr := errors.New("config error")
+		getConfig := func(ctx context.Context) (int, error) {
+			return 0, testErr
+		}
+
+		configRR := Curry0(getConfig)
+		result := configRR(t.Context())
+
+		assert.Equal(t, E.Left[int](testErr), result)
+	})
+
+	t.Run("respects context cancellation", func(t *testing.T) {
+		getConfig := func(ctx context.Context) (int, error) {
+			if ctx.Err() != nil {
+				return 0, ctx.Err()
+			}
+			return 42, nil
+		}
+
+		configRR := Curry0(getConfig)
+
+		// Test with cancelled context
+		ctx, cancel := context.WithCancel(t.Context())
+		cancel()
+		result := configRR(ctx)
+
+		assert.True(t, E.IsLeft(result))
+	})
+
+	t.Run("can be used in functional composition", func(t *testing.T) {
+		getConfig := func(ctx context.Context) (int, error) {
+			return 42, nil
+		}
+
+		pipeline := F.Pipe1(
+			Curry0(getConfig),
+			Map(func(x int) string {
+				return "value"
+			}),
+		)
+
+		result := pipeline(t.Context())
+		assert.True(t, E.IsRight(result))
+	})
+}
+
+// TestCurry1 tests the Curry1 function
+func TestCurry1(t *testing.T) {
+	t.Run("converts Go function to Kleisli on success", func(t *testing.T) {
+		getUserByID := func(ctx context.Context, id int) (string, error) {
+			return "Alice", nil
+		}
+
+		getUserKleisli := Curry1(getUserByID)
+
+		// Use in a pipeline
+		pipeline := F.Pipe1(
+			Of(123),
+			Chain(getUserKleisli),
+		)
+
+		result := pipeline(t.Context())
+		assert.Equal(t, E.Of[error]("Alice"), result)
+	})
+
+	t.Run("converts Go function to Kleisli on error", func(t *testing.T) {
+		testErr := errors.New("user not found")
+		getUserByID := func(ctx context.Context, id int) (string, error) {
+			return "", testErr
+		}
+
+		getUserKleisli := Curry1(getUserByID)
+		result := getUserKleisli(123)(t.Context())
+
+		assert.Equal(t, E.Left[string](testErr), result)
+	})
+
+	t.Run("respects context cancellation", func(t *testing.T) {
+		getUserByID := func(ctx context.Context, id int) (string, error) {
+			if ctx.Err() != nil {
+				return "", ctx.Err()
+			}
+			return "Alice", nil
+		}
+
+		getUserKleisli := Curry1(getUserByID)
+
+		ctx, cancel := context.WithCancel(t.Context())
+		cancel()
+		result := getUserKleisli(123)(ctx)
+
+		assert.True(t, E.IsLeft(result))
+	})
+
+	t.Run("can be composed with other operations", func(t *testing.T) {
+		getUserByID := func(ctx context.Context, id int) (string, error) {
+			return "Alice", nil
+		}
+
+		pipeline := F.Pipe2(
+			Of(123),
+			Chain(Curry1(getUserByID)),
+			Map(func(name string) int {
+				return len(name)
+			}),
+		)
+
+		result := pipeline(t.Context())
+		assert.Equal(t, E.Of[error](5), result) // len("Alice") = 5
+	})
+}
+
+// TestCurry2 tests the Curry2 function
+func TestCurry2(t *testing.T) {
+	t.Run("converts Go function to curried form on success", func(t *testing.T) {
+		updateUser := func(ctx context.Context, id int, name string) (string, error) {
+			return name, nil
+		}
+
+		updateUserCurried := Curry2(updateUser)
+
+		// Partial application
+		updateUser123 := updateUserCurried(123)
+
+		// Use in a pipeline
+		pipeline := F.Pipe1(
+			Of("Bob"),
+			Chain(updateUser123),
+		)
+
+		result := pipeline(t.Context())
+		assert.Equal(t, E.Of[error]("Bob"), result)
+	})
+
+	t.Run("converts Go function to curried form on error", func(t *testing.T) {
+		testErr := errors.New("update failed")
+		updateUser := func(ctx context.Context, id int, name string) (string, error) {
+			return "", testErr
+		}
+
+		updateUserCurried := Curry2(updateUser)
+		result := updateUserCurried(123)("Bob")(t.Context())
+
+		assert.Equal(t, E.Left[string](testErr), result)
+	})
+
+	t.Run("supports partial application", func(t *testing.T) {
+		concat := func(ctx context.Context, a string, b string) (string, error) {
+			return a + b, nil
+		}
+
+		concatCurried := Curry2(concat)
+
+		// Partial application
+		prependHello := concatCurried("Hello, ")
+
+		result1 := prependHello("World")(t.Context())
+		result2 := prependHello("Alice")(t.Context())
+
+		assert.Equal(t, E.Of[error]("Hello, World"), result1)
+		assert.Equal(t, E.Of[error]("Hello, Alice"), result2)
+	})
+
+	t.Run("respects context cancellation", func(t *testing.T) {
+		updateUser := func(ctx context.Context, id int, name string) (string, error) {
+			if ctx.Err() != nil {
+				return "", ctx.Err()
+			}
+			return name, nil
+		}
+
+		updateUserCurried := Curry2(updateUser)
+
+		ctx, cancel := context.WithCancel(t.Context())
+		cancel()
+		result := updateUserCurried(123)("Bob")(ctx)
+
+		assert.True(t, E.IsLeft(result))
+	})
+}
+
+// TestCurry3 tests the Curry3 function
+func TestCurry3(t *testing.T) {
+	t.Run("converts Go function to curried form on success", func(t *testing.T) {
+		createOrder := func(ctx context.Context, userID int, productID int, quantity int) (int, error) {
+			return userID + productID + quantity, nil
+		}
+
+		createOrderCurried := Curry3(createOrder)
+
+		// Partial application
+		createOrderForUser := createOrderCurried(100)
+		createOrderForProduct := createOrderForUser(200)
+
+		// Use in a pipeline
+		pipeline := F.Pipe1(
+			Of(3),
+			Chain(createOrderForProduct),
+		)
+
+		result := pipeline(t.Context())
+		assert.Equal(t, E.Of[error](303), result) // 100 + 200 + 3
+	})
+
+	t.Run("converts Go function to curried form on error", func(t *testing.T) {
+		testErr := errors.New("order creation failed")
+		createOrder := func(ctx context.Context, userID int, productID int, quantity int) (int, error) {
+			return 0, testErr
+		}
+
+		createOrderCurried := Curry3(createOrder)
+		result := createOrderCurried(100)(200)(3)(t.Context())
+
+		assert.Equal(t, E.Left[int](testErr), result)
+	})
+
+	t.Run("supports multiple levels of partial application", func(t *testing.T) {
+		sum3 := func(ctx context.Context, a int, b int, c int) (int, error) {
+			return a + b + c, nil
+		}
+
+		sum3Curried := Curry3(sum3)
+
+		// First level partial application
+		add10 := sum3Curried(10)
+
+		// Second level partial application
+		add10And20 := add10(20)
+
+		result1 := add10And20(5)(t.Context())
+		result2 := add10And20(15)(t.Context())
+
+		assert.Equal(t, E.Of[error](35), result1) // 10 + 20 + 5
+		assert.Equal(t, E.Of[error](45), result2) // 10 + 20 + 15
+	})
+
+	t.Run("respects context cancellation", func(t *testing.T) {
+		createOrder := func(ctx context.Context, userID int, productID int, quantity int) (int, error) {
+			if ctx.Err() != nil {
+				return 0, ctx.Err()
+			}
+			return userID + productID + quantity, nil
+		}
+
+		createOrderCurried := Curry3(createOrder)
+
+		ctx, cancel := context.WithCancel(t.Context())
+		cancel()
+		result := createOrderCurried(100)(200)(3)(ctx)
+
+		assert.True(t, E.IsLeft(result))
+	})
+}
+
+// TestUncurry1 tests the Uncurry1 function
+func TestUncurry1(t *testing.T) {
+	t.Run("converts Kleisli back to Go function on success", func(t *testing.T) {
+		getUserKleisli := func(id int) ReaderResult[string] {
+			return func(ctx context.Context) E.Either[error, string] {
+				return E.Of[error]("Alice")
+			}
+		}
+
+		getUserByID := Uncurry1(getUserKleisli)
+
+		user, err := getUserByID(t.Context(), 123)
+		assert.NoError(t, err)
+		assert.Equal(t, "Alice", user)
+	})
+
+	t.Run("converts Kleisli back to Go function on error", func(t *testing.T) {
+		testErr := errors.New("user not found")
+		getUserKleisli := func(id int) ReaderResult[string] {
+			return func(ctx context.Context) E.Either[error, string] {
+				return E.Left[string](testErr)
+			}
+		}
+
+		getUserByID := Uncurry1(getUserKleisli)
+
+		user, err := getUserByID(t.Context(), 123)
+		assert.Error(t, err)
+		assert.Equal(t, testErr, err)
+		assert.Equal(t, "", user)
+	})
+
+	t.Run("respects context in uncurried function", func(t *testing.T) {
+		getUserKleisli := func(id int) ReaderResult[string] {
+			return func(ctx context.Context) E.Either[error, string] {
+				if ctx.Err() != nil {
+					return E.Left[string](ctx.Err())
+				}
+				return E.Of[error]("Alice")
+			}
+		}
+
+		getUserByID := Uncurry1(getUserKleisli)
+
+		ctx, cancel := context.WithCancel(t.Context())
+		cancel()
+
+		user, err := getUserByID(ctx, 123)
+		assert.Error(t, err)
+		assert.Equal(t, "", user)
+	})
+
+	t.Run("round-trip with Curry1", func(t *testing.T) {
+		// Original Go function
+		original := func(ctx context.Context, id int) (string, error) {
+			return "Alice", nil
+		}
+
+		// Curry then uncurry
+		roundTrip := Uncurry1(Curry1(original))
+
+		user, err := roundTrip(t.Context(), 123)
+		assert.NoError(t, err)
+		assert.Equal(t, "Alice", user)
+	})
+}
+
+// TestUncurry2 tests the Uncurry2 function
+func TestUncurry2(t *testing.T) {
+	t.Run("converts curried function back to Go function on success", func(t *testing.T) {
+		updateUserCurried := func(id int) func(name string) ReaderResult[string] {
+			return func(name string) ReaderResult[string] {
+				return func(ctx context.Context) E.Either[error, string] {
+					return E.Of[error](name)
+				}
+			}
+		}
+
+		updateUser := Uncurry2(updateUserCurried)
+
+		result, err := updateUser(t.Context(), 123, "Bob")
+		assert.NoError(t, err)
+		assert.Equal(t, "Bob", result)
+	})
+
+	t.Run("converts curried function back to Go function on error", func(t *testing.T) {
+		testErr := errors.New("update failed")
+		updateUserCurried := func(id int) func(name string) ReaderResult[string] {
+			return func(name string) ReaderResult[string] {
+				return func(ctx context.Context) E.Either[error, string] {
+					return E.Left[string](testErr)
+				}
+			}
+		}
+
+		updateUser := Uncurry2(updateUserCurried)
+
+		result, err := updateUser(t.Context(), 123, "Bob")
+		assert.Error(t, err)
+		assert.Equal(t, testErr, err)
+		assert.Equal(t, "", result)
+	})
+
+	t.Run("respects context in uncurried function", func(t *testing.T) {
+		updateUserCurried := func(id int) func(name string) ReaderResult[string] {
+			return func(name string) ReaderResult[string] {
+				return func(ctx context.Context) E.Either[error, string] {
+					if ctx.Err() != nil {
+						return E.Left[string](ctx.Err())
+					}
+					return E.Of[error](name)
+				}
+			}
+		}
+
+		updateUser := Uncurry2(updateUserCurried)
+
+		ctx, cancel := context.WithCancel(t.Context())
+		cancel()
+
+		result, err := updateUser(ctx, 123, "Bob")
+		assert.Error(t, err)
+		assert.Equal(t, "", result)
+	})
+
+	t.Run("round-trip with Curry2", func(t *testing.T) {
+		// Original Go function
+		original := func(ctx context.Context, a string, b string) (string, error) {
+			return a + b, nil
+		}
+
+		// Curry then uncurry
+		roundTrip := Uncurry2(Curry2(original))
+
+		result, err := roundTrip(t.Context(), "Hello, ", "World")
+		assert.NoError(t, err)
+		assert.Equal(t, "Hello, World", result)
+	})
+}
+
+// TestUncurry3 tests the Uncurry3 function
+func TestUncurry3(t *testing.T) {
+	t.Run("converts curried function back to Go function on success", func(t *testing.T) {
+		createOrderCurried := func(userID int) func(productID int) func(quantity int) ReaderResult[int] {
+			return func(productID int) func(quantity int) ReaderResult[int] {
+				return func(quantity int) ReaderResult[int] {
+					return func(ctx context.Context) E.Either[error, int] {
+						return E.Of[error](userID + productID + quantity)
+					}
+				}
+			}
+		}
+
+		createOrder := Uncurry3(createOrderCurried)
+
+		result, err := createOrder(t.Context(), 100, 200, 3)
+		assert.NoError(t, err)
+		assert.Equal(t, 303, result) // 100 + 200 + 3
+	})
+
+	t.Run("converts curried function back to Go function on error", func(t *testing.T) {
+		testErr := errors.New("order creation failed")
+		createOrderCurried := func(userID int) func(productID int) func(quantity int) ReaderResult[int] {
+			return func(productID int) func(quantity int) ReaderResult[int] {
+				return func(quantity int) ReaderResult[int] {
+					return func(ctx context.Context) E.Either[error, int] {
+						return E.Left[int](testErr)
+					}
+				}
+			}
+		}
+
+		createOrder := Uncurry3(createOrderCurried)
+
+		result, err := createOrder(t.Context(), 100, 200, 3)
+		assert.Error(t, err)
+		assert.Equal(t, testErr, err)
+		assert.Equal(t, 0, result)
+	})
+
+	t.Run("respects context in uncurried function", func(t *testing.T) {
+		createOrderCurried := func(userID int) func(productID int) func(quantity int) ReaderResult[int] {
+			return func(productID int) func(quantity int) ReaderResult[int] {
+				return func(quantity int) ReaderResult[int] {
+					return func(ctx context.Context) E.Either[error, int] {
+						if ctx.Err() != nil {
+							return E.Left[int](ctx.Err())
+						}
+						return E.Of[error](userID + productID + quantity)
+					}
+				}
+			}
+		}
+
+		createOrder := Uncurry3(createOrderCurried)
+
+		ctx, cancel := context.WithCancel(t.Context())
+		cancel()
+
+		result, err := createOrder(ctx, 100, 200, 3)
+		assert.Error(t, err)
+		assert.Equal(t, 0, result)
+	})
+
+	t.Run("round-trip with Curry3", func(t *testing.T) {
+		// Original Go function
+		original := func(ctx context.Context, a int, b int, c int) (int, error) {
+			return a + b + c, nil
+		}
+
+		// Curry then uncurry
+		roundTrip := Uncurry3(Curry3(original))
+
+		result, err := roundTrip(t.Context(), 10, 20, 5)
+		assert.NoError(t, err)
+		assert.Equal(t, 35, result) // 10 + 20 + 5
+	})
+}
+
+// TestCurryUncurryIntegration tests integration between curry and uncurry functions
+func TestCurryUncurryIntegration(t *testing.T) {
+	t.Run("Curry1 and Uncurry1 are inverses", func(t *testing.T) {
+		original := func(ctx context.Context, x int) (int, error) {
+			return x * 2, nil
+		}
+
+		// Curry then uncurry should give back equivalent function
+		roundTrip := Uncurry1(Curry1(original))
+
+		result1, err1 := original(t.Context(), 21)
+		result2, err2 := roundTrip(t.Context(), 21)
+
+		assert.NoError(t, err1)
+		assert.NoError(t, err2)
+		assert.Equal(t, result1, result2)
+	})
+
+	t.Run("Curry2 and Uncurry2 are inverses", func(t *testing.T) {
+		original := func(ctx context.Context, x int, y int) (int, error) {
+			return x + y, nil
+		}
+
+		roundTrip := Uncurry2(Curry2(original))
+
+		result1, err1 := original(t.Context(), 10, 20)
+		result2, err2 := roundTrip(t.Context(), 10, 20)
+
+		assert.NoError(t, err1)
+		assert.NoError(t, err2)
+		assert.Equal(t, result1, result2)
+	})
+
+	t.Run("Curry3 and Uncurry3 are inverses", func(t *testing.T) {
+		original := func(ctx context.Context, x int, y int, z int) (int, error) {
+			return x * y * z, nil
+		}
+
+		roundTrip := Uncurry3(Curry3(original))
+
+		result1, err1 := original(t.Context(), 2, 3, 4)
+		result2, err2 := roundTrip(t.Context(), 2, 3, 4)
+
+		assert.NoError(t, err1)
+		assert.NoError(t, err2)
+		assert.Equal(t, result1, result2)
+	})
+}

v2/context/readerresult/filter.go

@@ -43,7 +43,7 @@ import (
 //	onNegative := func(n int) error { return fmt.Errorf("%d is not positive", n) }
 //
 //	filter := readerresult.FilterOrElse(isPositive, onNegative)
-//	result := filter(readerresult.Right(42))(context.Background())
+//	result := filter(readerresult.Right(42))(t.Context())
 //
 //go:inline
 func FilterOrElse[A any](pred Predicate[A], onFalse func(A) error) Operator[A, A] {

v2/context/readerresult/flip.go

@@ -63,7 +63,7 @@ import (
 //	// Sequenced: takes context first, then Database
 //	sequenced := SequenceReader(original)
 //
-//	ctx := context.Background()
+//	ctx := t.Context()
 //	db := Database{ConnectionString: "localhost:5432"}
 //
 //	// Apply context first to get a function that takes database
@@ -135,7 +135,7 @@ func SequenceReader[R, A any](ma ReaderResult[Reader[R, A]]) reader.Kleisli[cont
 //
 //	// Now we can provide Config first, then context
 //	cfg := Config{MaxRetries: 3}
-//	ctx := context.Background()
+//	ctx := t.Context()
 //
 //	result := flipped(cfg)(ctx)
 //	// result is Result[string] containing "Value: 42, MaxRetries: 3"

v2/context/readerresult/logging.go

@@ -96,7 +96,7 @@ func curriedLog(
 //	logDebug := SLogWithCallback[User](slog.LevelDebug, getLogger, "User data")
 //
 //	// Use in a pipeline
-//	ctx := context.Background()
+//	ctx := t.Context()
 //	user := result.Of(User{ID: 123, Name: "Alice"})
 //	logged := logDebug(user)(ctx) // Logs: level=DEBUG msg="User data" value={ID:123 Name:Alice}
 //	// logged still contains the User value
@@ -149,7 +149,7 @@ func SLogWithCallback[A any](
 //
 // Example - Logging a successful computation:
 //
-//	ctx := context.Background()
+//	ctx := t.Context()
 //
 //	// Simple value logging
 //	res := result.Of(42)
@@ -172,7 +172,7 @@ func SLogWithCallback[A any](
 //	    return result.Of(fmt.Sprintf("Processed: %s", user.Name))
 //	}
 //
-//	ctx := context.Background()
+//	ctx := t.Context()
 //
 //	// Log at each step
 //	userResult := fetchUser(123)
@@ -195,7 +195,7 @@ func SLogWithCallback[A any](
 //
 //	// Set up a custom logger in the context
 //	logger := slog.New(slog.NewJSONHandler(os.Stdout, nil))
-//	ctx := logging.WithLogger(logger)(context.Background())
+//	ctx := logging.WithLogger(logger)(t.Context())
 //
 //	res := result.Of("important data")
 //	logged := SLog[string]("Critical operation")(res)(ctx)

v2/context/readerresult/logging_test.go

@@ -37,7 +37,7 @@ func TestSLogLogsSuccessValue(t *testing.T) {
 	oldLogger := logging.SetLogger(logger)
 	defer logging.SetLogger(oldLogger)
 
-	ctx := context.Background()
+	ctx := t.Context()
 
 	// Create a Result and log it
 	res1 := result.Of(42)
@@ -59,7 +59,7 @@ func TestSLogLogsErrorValue(t *testing.T) {
 	oldLogger := logging.SetLogger(logger)
 	defer logging.SetLogger(oldLogger)
 
-	ctx := context.Background()
+	ctx := t.Context()
 	testErr := errors.New("test error")
 
 	// Create an error Result and log it
@@ -83,7 +83,7 @@ func TestSLogInPipeline(t *testing.T) {
 	oldLogger := logging.SetLogger(logger)
 	defer logging.SetLogger(oldLogger)
 
-	ctx := context.Background()
+	ctx := t.Context()
 
 	// SLog takes a Result[A] and returns ReaderResult[A]
 	// So we need to start with a Result, apply SLog, then execute with context
@@ -104,7 +104,7 @@ func TestSLogWithContextLogger(t *testing.T) {
 		Level: slog.LevelInfo,
 	}))
 
-	ctx := logging.WithLogger(contextLogger)(context.Background())
+	ctx := logging.WithLogger(contextLogger)(t.Context())
 
 	res1 := result.Of("test value")
 	logged := SLog[string]("Context logger test")(res1)(ctx)
@@ -126,7 +126,7 @@ func TestSLogDisabled(t *testing.T) {
 	oldLogger := logging.SetLogger(logger)
 	defer logging.SetLogger(oldLogger)
 
-	ctx := context.Background()
+	ctx := t.Context()
 
 	res1 := result.Of(42)
 	logged := SLog[int]("This should not be logged")(res1)(ctx)
@@ -152,7 +152,7 @@ func TestSLogWithStruct(t *testing.T) {
 		Name string
 	}
 
-	ctx := context.Background()
+	ctx := t.Context()
 	user := User{ID: 123, Name: "Alice"}
 
 	res1 := result.Of(user)
@@ -177,7 +177,7 @@ func TestSLogWithCallbackCustomLevel(t *testing.T) {
 		return logger
 	}
 
-	ctx := context.Background()
+	ctx := t.Context()
 
 	// Create a Result and log it with custom callback
 	res1 := result.Of(42)
@@ -202,7 +202,7 @@ func TestSLogWithCallbackLogsError(t *testing.T) {
 		return logger
 	}
 
-	ctx := context.Background()
+	ctx := t.Context()
 	testErr := errors.New("warning error")
 
 	// Create an error Result and log it with custom callback
@@ -227,7 +227,7 @@ func TestSLogChainedOperations(t *testing.T) {
 	oldLogger := logging.SetLogger(logger)
 	defer logging.SetLogger(oldLogger)
 
-	ctx := context.Background()
+	ctx := t.Context()
 
 	// First log step 1
 	res1 := result.Of(5)
@@ -255,7 +255,7 @@ func TestSLogPreservesError(t *testing.T) {
 	oldLogger := logging.SetLogger(logger)
 	defer logging.SetLogger(oldLogger)
 
-	ctx := context.Background()
+	ctx := t.Context()
 	testErr := errors.New("original error")
 
 	res1 := result.Left[int](testErr)
@@ -280,7 +280,7 @@ func TestSLogMultipleValues(t *testing.T) {
 	oldLogger := logging.SetLogger(logger)
 	defer logging.SetLogger(oldLogger)
 
-	ctx := context.Background()
+	ctx := t.Context()
 
 	// Test with different types
 	intRes := SLog[int]("Integer")(result.Of(42))(ctx)

v2/context/readerresult/profunctor_test.go

@@ -41,7 +41,7 @@ func TestPromapBasic(t *testing.T) {
 		toString := strconv.Itoa
 
 		adapted := Promap(addKey, toString)(getValue)
-		result := adapted(context.Background())
+		result := adapted(t.Context())
 
 		assert.Equal(t, R.Of("42"), result)
 	})
@@ -63,7 +63,7 @@ func TestContramapBasic(t *testing.T) {
 		}
 
 		adapted := Contramap[int](addKey)(getValue)
-		result := adapted(context.Background())
+		result := adapted(t.Context())
 
 		assert.Equal(t, R.Of(100), result)
 	})
@@ -85,7 +85,7 @@ func TestLocalBasic(t *testing.T) {
 		}
 
 		adapted := Local[string](addUser)(getValue)
-		result := adapted(context.Background())
+		result := adapted(t.Context())
 
 		assert.Equal(t, R.Of("Alice"), result)
 	})

v2/context/readerresult/reader_test.go

@@ -22,6 +22,7 @@ import (
 
 	E "github.com/IBM/fp-go/v2/either"
 	F "github.com/IBM/fp-go/v2/function"
+	"github.com/IBM/fp-go/v2/option"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -38,7 +39,7 @@ func TestMapTo(t *testing.T) {
 		resultReader := toDone(originalReader)
 
 		// Execute the resulting reader
-		result := resultReader(context.Background())
+		result := resultReader(t.Context())
 
 		// Verify the constant value is returned
 		assert.Equal(t, E.Of[error]("done"), result)
@@ -58,7 +59,7 @@ func TestMapTo(t *testing.T) {
 			MapTo[int]("complete"),
 		)
 
-		result := pipeline(context.Background())
+		result := pipeline(t.Context())
 
 		assert.Equal(t, E.Of[error]("complete"), result)
 		assert.True(t, executed, "original reader should be executed in pipeline")
@@ -72,7 +73,7 @@ func TestMapTo(t *testing.T) {
 		}
 
 		resultReader := MapTo[int](true)(readerWithSideEffect)
-		result := resultReader(context.Background())
+		result := resultReader(t.Context())
 
 		assert.Equal(t, E.Of[error](true), result)
 		assert.True(t, sideEffectOccurred, "side effect should occur")
@@ -87,7 +88,7 @@ func TestMapTo(t *testing.T) {
 		}
 
 		resultReader := MapTo[int]("done")(failingReader)
-		result := resultReader(context.Background())
+		result := resultReader(t.Context())
 
 		assert.Equal(t, E.Left[string](testErr), result)
 		assert.True(t, executed, "failing reader should still be executed")
@@ -106,7 +107,7 @@ func TestMonadMapTo(t *testing.T) {
 		resultReader := MonadMapTo(originalReader, "done")
 
 		// Execute the resulting reader
-		result := resultReader(context.Background())
+		result := resultReader(t.Context())
 
 		// Verify the constant value is returned
 		assert.Equal(t, E.Of[error]("done"), result)
@@ -122,7 +123,7 @@ func TestMonadMapTo(t *testing.T) {
 		}
 
 		resultReader := MonadMapTo(complexReader, 42)
-		result := resultReader(context.Background())
+		result := resultReader(t.Context())
 
 		assert.Equal(t, E.Of[error](42), result)
 		assert.True(t, computationExecuted, "complex computation should be executed")
@@ -137,7 +138,7 @@ func TestMonadMapTo(t *testing.T) {
 		}
 
 		resultReader := MonadMapTo(failingReader, 99)
-		result := resultReader(context.Background())
+		result := resultReader(t.Context())
 
 		assert.Equal(t, E.Left[int](testErr), result)
 		assert.True(t, executed, "failing reader should still be executed")
@@ -164,7 +165,7 @@ func TestChainTo(t *testing.T) {
 		resultReader := thenSecond(firstReader)
 
 		// Execute the resulting reader
-		result := resultReader(context.Background())
+		result := resultReader(t.Context())
 
 		// Verify the second reader's result is returned
 		assert.Equal(t, E.Of[error]("result"), result)
@@ -192,7 +193,7 @@ func TestChainTo(t *testing.T) {
 			ChainTo[int](step2),
 		)
 
-		result := pipeline(context.Background())
+		result := pipeline(t.Context())
 
 		assert.Equal(t, E.Of[error]("complete"), result)
 		assert.True(t, firstExecuted, "first reader should be executed in pipeline")
@@ -211,7 +212,7 @@ func TestChainTo(t *testing.T) {
 		}
 
 		resultReader := ChainTo[int](secondReader)(readerWithSideEffect)
-		result := resultReader(context.Background())
+		result := resultReader(t.Context())
 
 		assert.Equal(t, E.Of[error](true), result)
 		assert.True(t, sideEffectOccurred, "side effect should occur in first reader")
@@ -233,7 +234,7 @@ func TestChainTo(t *testing.T) {
 		}
 
 		resultReader := ChainTo[int](secondReader)(failingReader)
-		result := resultReader(context.Background())
+		result := resultReader(t.Context())
 
 		assert.Equal(t, E.Left[string](testErr), result)
 		assert.True(t, firstExecuted, "first reader should be executed")
@@ -260,7 +261,7 @@ func TestMonadChainTo(t *testing.T) {
 		resultReader := MonadChainTo(firstReader, secondReader)
 
 		// Execute the resulting reader
-		result := resultReader(context.Background())
+		result := resultReader(t.Context())
 
 		// Verify the second reader's result is returned
 		assert.Equal(t, E.Of[error]("result"), result)
@@ -284,7 +285,7 @@ func TestMonadChainTo(t *testing.T) {
 		}
 
 		resultReader := MonadChainTo(complexFirstReader, secondReader)
-		result := resultReader(context.Background())
+		result := resultReader(t.Context())
 
 		assert.Equal(t, E.Of[error]("done"), result)
 		assert.True(t, firstExecuted, "complex first computation should be executed")
@@ -307,7 +308,7 @@ func TestMonadChainTo(t *testing.T) {
 		}
 
 		resultReader := MonadChainTo(failingReader, secondReader)
-		result := resultReader(context.Background())
+		result := resultReader(t.Context())
 
 		assert.Equal(t, E.Left[float64](testErr), result)
 		assert.True(t, firstExecuted, "first reader should be executed")
@@ -316,7 +317,7 @@ func TestMonadChainTo(t *testing.T) {
 }
 
 func TestOrElse(t *testing.T) {
-	ctx := context.Background()
+	ctx := t.Context()
 
 	// Test OrElse with Right - should pass through unchanged
 	t.Run("Right value unchanged", func(t *testing.T) {
@@ -380,3 +381,613 @@ func TestOrElse(t *testing.T) {
 		assert.Equal(t, E.Of[error](123), res)
 	})
 }
+
+// TestFromIO tests the FromIO function
+func TestFromIO(t *testing.T) {
+	t.Run("lifts IO computation into ReaderResult", func(t *testing.T) {
+		ioOp := func() int { return 42 }
+		rr := FromIO(ioOp)
+		result := rr(t.Context())
+		assert.Equal(t, E.Of[error](42), result)
+	})
+
+	t.Run("executes IO side effects", func(t *testing.T) {
+		executed := false
+		ioOp := func() int {
+			executed = true
+			return 100
+		}
+		rr := FromIO(ioOp)
+		result := rr(t.Context())
+		assert.True(t, executed, "IO operation should be executed")
+		assert.Equal(t, E.Of[error](100), result)
+	})
+}
+
+// TestFromIOResult tests the FromIOResult function
+func TestFromIOResult(t *testing.T) {
+	t.Run("lifts IOResult into ReaderResult on success", func(t *testing.T) {
+		ioResult := func() E.Either[error, int] {
+			return E.Of[error](42)
+		}
+		rr := FromIOResult(ioResult)
+		result := rr(t.Context())
+		assert.Equal(t, E.Of[error](42), result)
+	})
+
+	t.Run("lifts IOResult into ReaderResult on error", func(t *testing.T) {
+		testErr := errors.New("io error")
+		ioResult := func() E.Either[error, int] {
+			return E.Left[int](testErr)
+		}
+		rr := FromIOResult(ioResult)
+		result := rr(t.Context())
+		assert.Equal(t, E.Left[int](testErr), result)
+	})
+}
+
+// TestFromReader tests the FromReader function
+func TestFromReader(t *testing.T) {
+	t.Run("lifts Reader into ReaderResult", func(t *testing.T) {
+		reader := func(ctx context.Context) int {
+			return 42
+		}
+		rr := FromReader(reader)
+		result := rr(t.Context())
+		assert.Equal(t, E.Of[error](42), result)
+	})
+
+	t.Run("Reader can access context", func(t *testing.T) {
+		type ctxKey string
+		ctx := context.WithValue(t.Context(), ctxKey("key"), "value")
+		reader := func(ctx context.Context) string {
+			return ctx.Value(ctxKey("key")).(string)
+		}
+		rr := FromReader(reader)
+		result := rr(ctx)
+		assert.Equal(t, E.Of[error]("value"), result)
+	})
+}
+
+// TestFromEither tests the FromEither function
+func TestFromEither(t *testing.T) {
+	t.Run("lifts Right Either into ReaderResult", func(t *testing.T) {
+		either := E.Of[error](42)
+		rr := FromEither(either)
+		result := rr(t.Context())
+		assert.Equal(t, E.Of[error](42), result)
+	})
+
+	t.Run("lifts Left Either into ReaderResult", func(t *testing.T) {
+		testErr := errors.New("test error")
+		either := E.Left[int](testErr)
+		rr := FromEither(either)
+		result := rr(t.Context())
+		assert.Equal(t, E.Left[int](testErr), result)
+	})
+}
+
+// TestLeftRight tests the Left and Right functions
+func TestLeftRight(t *testing.T) {
+	t.Run("Left creates error ReaderResult", func(t *testing.T) {
+		testErr := errors.New("test error")
+		rr := Left[int](testErr)
+		result := rr(t.Context())
+		assert.Equal(t, E.Left[int](testErr), result)
+	})
+
+	t.Run("Right creates success ReaderResult", func(t *testing.T) {
+		rr := Right(42)
+		result := rr(t.Context())
+		assert.Equal(t, E.Of[error](42), result)
+	})
+}
+
+// TestMonadMapAndMap tests MonadMap and Map functions
+func TestMonadMapAndMap(t *testing.T) {
+	t.Run("MonadMap transforms success value", func(t *testing.T) {
+		rr := Of(42)
+		mapped := MonadMap(rr, func(x int) string {
+			return F.Pipe1(x, func(n int) string { return "value: " + F.Pipe1(n, func(i int) string { return string(rune(i + 48)) }) })
+		})
+		result := mapped(t.Context())
+		assert.True(t, E.IsRight(result))
+	})
+
+	t.Run("Map creates operator that transforms value", func(t *testing.T) {
+		toString := Map(func(x int) string {
+			return "value"
+		})
+		rr := Of(42)
+		result := toString(rr)(t.Context())
+		assert.True(t, E.IsRight(result))
+	})
+
+	t.Run("Map preserves errors", func(t *testing.T) {
+		testErr := errors.New("test error")
+		toString := Map(func(x int) string {
+			return "value"
+		})
+		rr := Left[int](testErr)
+		result := toString(rr)(t.Context())
+		assert.Equal(t, E.Left[string](testErr), result)
+	})
+}
+
+// TestMonadChainAndChain tests MonadChain and Chain functions
+func TestMonadChainAndChain(t *testing.T) {
+	t.Run("MonadChain sequences computations", func(t *testing.T) {
+		rr := Of(42)
+		chained := MonadChain(rr, func(x int) ReaderResult[string] {
+			return Of("result")
+		})
+		result := chained(t.Context())
+		assert.Equal(t, E.Of[error]("result"), result)
+	})
+
+	t.Run("Chain creates operator that sequences computations", func(t *testing.T) {
+		chainOp := Chain(func(x int) ReaderResult[string] {
+			return Of("result")
+		})
+		rr := Of(42)
+		result := chainOp(rr)(t.Context())
+		assert.Equal(t, E.Of[error]("result"), result)
+	})
+
+	t.Run("Chain short-circuits on error", func(t *testing.T) {
+		executed := false
+		testErr := errors.New("test error")
+		chainOp := Chain(func(x int) ReaderResult[string] {
+			executed = true
+			return Of("result")
+		})
+		rr := Left[int](testErr)
+		result := chainOp(rr)(t.Context())
+		assert.False(t, executed, "Chain should not execute on error")
+		assert.Equal(t, E.Left[string](testErr), result)
+	})
+}
+
+// TestAsk tests the Ask function
+func TestAsk(t *testing.T) {
+	t.Run("Ask returns the context", func(t *testing.T) {
+		ctx := t.Context()
+		rr := Ask()
+		result := rr(ctx)
+		assert.True(t, E.IsRight(result))
+	})
+
+	t.Run("Ask can be used in chain to access context", func(t *testing.T) {
+		type ctxKey string
+		ctx := context.WithValue(t.Context(), ctxKey("key"), "value")
+		pipeline := F.Pipe1(
+			Ask(),
+			Chain(func(c context.Context) ReaderResult[string] {
+				val := c.Value(ctxKey("key"))
+				if val != nil {
+					return Of(val.(string))
+				}
+				return Left[string](errors.New("key not found"))
+			}),
+		)
+		result := pipeline(ctx)
+		assert.Equal(t, E.Of[error]("value"), result)
+	})
+}
+
+// TestMonadChainEitherK tests MonadChainEitherK and ChainEitherK
+func TestMonadChainEitherK(t *testing.T) {
+	t.Run("MonadChainEitherK sequences with Either function", func(t *testing.T) {
+		rr := Of(42)
+		chained := MonadChainEitherK(rr, func(x int) E.Either[error, string] {
+			if x > 0 {
+				return E.Of[error]("positive")
+			}
+			return E.Left[string](errors.New("not positive"))
+		})
+		result := chained(t.Context())
+		assert.Equal(t, E.Of[error]("positive"), result)
+	})
+
+	t.Run("ChainEitherK creates operator", func(t *testing.T) {
+		validate := ChainEitherK(func(x int) E.Either[error, int] {
+			if x > 0 {
+				return E.Of[error](x)
+			}
+			return E.Left[int](errors.New("must be positive"))
+		})
+		result := validate(Of(42))(t.Context())
+		assert.Equal(t, E.Of[error](42), result)
+	})
+}
+
+// TestMonadFlap tests MonadFlap and Flap
+func TestMonadFlap(t *testing.T) {
+	t.Run("MonadFlap applies value to function", func(t *testing.T) {
+		fabRR := Of(func(x int) string {
+			return "value"
+		})
+		result := MonadFlap(fabRR, 42)(t.Context())
+		assert.True(t, E.IsRight(result))
+	})
+
+	t.Run("Flap creates operator", func(t *testing.T) {
+		applyTo42 := Flap[string](42)
+		fabRR := Of(func(x int) string {
+			return "value"
+		})
+		result := applyTo42(fabRR)(t.Context())
+		assert.True(t, E.IsRight(result))
+	})
+}
+
+// TestRead functions
+func TestReadFunctions(t *testing.T) {
+	t.Run("Read executes ReaderResult with context", func(t *testing.T) {
+		rr := Of(42)
+		ctx := t.Context()
+		runWithCtx := Read[int](ctx)
+		result := runWithCtx(rr)
+		assert.Equal(t, E.Of[error](42), result)
+	})
+
+	t.Run("ReadEither executes with Result context on success", func(t *testing.T) {
+		rr := Of(42)
+		ctxResult := E.Of[error](t.Context())
+		runWithCtxResult := ReadEither[int](ctxResult)
+		result := runWithCtxResult(rr)
+		assert.Equal(t, E.Of[error](42), result)
+	})
+
+	t.Run("ReadEither returns error when context Result is error", func(t *testing.T) {
+		rr := Of(42)
+		testErr := errors.New("context error")
+		ctxResult := E.Left[context.Context](testErr)
+		runWithCtxResult := ReadEither[int](ctxResult)
+		result := runWithCtxResult(rr)
+		assert.Equal(t, E.Left[int](testErr), result)
+	})
+
+	t.Run("ReadResult is alias for ReadEither", func(t *testing.T) {
+		rr := Of(42)
+		ctxResult := E.Of[error](t.Context())
+		runWithCtxResult := ReadResult[int](ctxResult)
+		result := runWithCtxResult(rr)
+		assert.Equal(t, E.Of[error](42), result)
+	})
+}
+
+// TestMonadChainFirst tests MonadChainFirst and ChainFirst
+func TestMonadChainFirst(t *testing.T) {
+	t.Run("MonadChainFirst executes second computation but returns first value", func(t *testing.T) {
+		secondExecuted := false
+		rr := Of(42)
+		withSideEffect := MonadChainFirst(rr, func(x int) ReaderResult[string] {
+			return func(ctx context.Context) E.Either[error, string] {
+				secondExecuted = true
+				return E.Of[error]("logged")
+			}
+		})
+		result := withSideEffect(t.Context())
+		assert.Equal(t, E.Of[error](42), result)
+		assert.True(t, secondExecuted, "second computation should execute")
+	})
+
+	t.Run("ChainFirst creates operator", func(t *testing.T) {
+		secondExecuted := false
+		logValue := ChainFirst(func(x int) ReaderResult[string] {
+			return func(ctx context.Context) E.Either[error, string] {
+				secondExecuted = true
+				return E.Of[error]("logged")
+			}
+		})
+		result := logValue(Of(42))(t.Context())
+		assert.Equal(t, E.Of[error](42), result)
+		assert.True(t, secondExecuted)
+	})
+}
+
+// TestChainIOK tests ChainIOK and MonadChainIOK
+func TestChainIOK(t *testing.T) {
+	t.Run("MonadChainIOK sequences with IO computation", func(t *testing.T) {
+		ioExecuted := false
+		rr := Of(42)
+		withIO := MonadChainIOK(rr, func(x int) func() string {
+			return func() string {
+				ioExecuted = true
+				return "done"
+			}
+		})
+		result := withIO(t.Context())
+		assert.Equal(t, E.Of[error]("done"), result)
+		assert.True(t, ioExecuted)
+	})
+
+	t.Run("ChainIOK creates operator", func(t *testing.T) {
+		ioExecuted := false
+		logIO := ChainIOK(func(x int) func() string {
+			return func() string {
+				ioExecuted = true
+				return "logged"
+			}
+		})
+		result := logIO(Of(42))(t.Context())
+		assert.Equal(t, E.Of[error]("logged"), result)
+		assert.True(t, ioExecuted)
+	})
+}
+
+// TestChainFirstIOK tests ChainFirstIOK, MonadChainFirstIOK, and TapIOK
+func TestChainFirstIOK(t *testing.T) {
+	t.Run("MonadChainFirstIOK executes IO but returns original value", func(t *testing.T) {
+		ioExecuted := false
+		rr := Of(42)
+		withLog := MonadChainFirstIOK(rr, func(x int) func() string {
+			return func() string {
+				ioExecuted = true
+				return "logged"
+			}
+		})
+		result := withLog(t.Context())
+		assert.Equal(t, E.Of[error](42), result)
+		assert.True(t, ioExecuted)
+	})
+
+	t.Run("ChainFirstIOK creates operator", func(t *testing.T) {
+		ioExecuted := false
+		logIO := ChainFirstIOK(func(x int) func() string {
+			return func() string {
+				ioExecuted = true
+				return "logged"
+			}
+		})
+		result := logIO(Of(42))(t.Context())
+		assert.Equal(t, E.Of[error](42), result)
+		assert.True(t, ioExecuted)
+	})
+
+	t.Run("TapIOK is alias for ChainFirstIOK", func(t *testing.T) {
+		ioExecuted := false
+		tapLog := TapIOK(func(x int) func() string {
+			return func() string {
+				ioExecuted = true
+				return "logged"
+			}
+		})
+		result := tapLog(Of(42))(t.Context())
+		assert.Equal(t, E.Of[error](42), result)
+		assert.True(t, ioExecuted)
+	})
+
+	t.Run("MonadTapIOK is alias for MonadChainFirstIOK", func(t *testing.T) {
+		ioExecuted := false
+		rr := Of(42)
+		withLog := MonadTapIOK(rr, func(x int) func() string {
+			return func() string {
+				ioExecuted = true
+				return "logged"
+			}
+		})
+		result := withLog(t.Context())
+		assert.Equal(t, E.Of[error](42), result)
+		assert.True(t, ioExecuted)
+	})
+}
+
+// TestChainIOEitherK tests ChainIOEitherK and ChainIOResultK
+func TestChainIOEitherK(t *testing.T) {
+	t.Run("ChainIOEitherK sequences with IOResult on success", func(t *testing.T) {
+		ioResultOp := ChainIOEitherK(func(x int) func() E.Either[error, string] {
+			return func() E.Either[error, string] {
+				if x > 0 {
+					return E.Of[error]("positive")
+				}
+				return E.Left[string](errors.New("not positive"))
+			}
+		})
+		result := ioResultOp(Of(42))(t.Context())
+		assert.Equal(t, E.Of[error]("positive"), result)
+	})
+
+	t.Run("ChainIOEitherK propagates IOResult error", func(t *testing.T) {
+		testErr := errors.New("io error")
+		ioResultOp := ChainIOEitherK(func(x int) func() E.Either[error, string] {
+			return func() E.Either[error, string] {
+				return E.Left[string](testErr)
+			}
+		})
+		result := ioResultOp(Of(42))(t.Context())
+		assert.Equal(t, E.Left[string](testErr), result)
+	})
+
+	t.Run("ChainIOResultK is alias for ChainIOEitherK", func(t *testing.T) {
+		ioResultOp := ChainIOResultK(func(x int) func() E.Either[error, string] {
+			return func() E.Either[error, string] {
+				return E.Of[error]("value")
+			}
+		})
+		result := ioResultOp(Of(42))(t.Context())
+		assert.Equal(t, E.Of[error]("value"), result)
+	})
+}
+
+// TestReadIO tests ReadIO, ReadIOEither, and ReadIOResult
+func TestReadIO(t *testing.T) {
+	t.Run("ReadIO executes with IO context", func(t *testing.T) {
+		getCtx := func() context.Context { return t.Context() }
+		rr := Of(42)
+		runWithIO := ReadIO[int](getCtx)
+		ioResult := runWithIO(rr)
+		result := ioResult()
+		assert.Equal(t, E.Of[error](42), result)
+	})
+
+	t.Run("ReadIOEither executes with IOResult context on success", func(t *testing.T) {
+		getCtx := func() E.Either[error, context.Context] {
+			return E.Of[error](t.Context())
+		}
+		rr := Of(42)
+		runWithIOResult := ReadIOEither[int](getCtx)
+		ioResult := runWithIOResult(rr)
+		result := ioResult()
+		assert.Equal(t, E.Of[error](42), result)
+	})
+
+	t.Run("ReadIOEither returns error when IOResult context is error", func(t *testing.T) {
+		testErr := errors.New("context error")
+		getCtx := func() E.Either[error, context.Context] {
+			return E.Left[context.Context](testErr)
+		}
+		rr := Of(42)
+		runWithIOResult := ReadIOEither[int](getCtx)
+		ioResult := runWithIOResult(rr)
+		result := ioResult()
+		assert.Equal(t, E.Left[int](testErr), result)
+	})
+
+	t.Run("ReadIOResult is alias for ReadIOEither", func(t *testing.T) {
+		getCtx := func() E.Either[error, context.Context] {
+			return E.Of[error](t.Context())
+		}
+		rr := Of(42)
+		runWithIOResult := ReadIOResult[int](getCtx)
+		ioResult := runWithIOResult(rr)
+		result := ioResult()
+		assert.Equal(t, E.Of[error](42), result)
+	})
+}
+
+// TestChainFirstLeft tests ChainFirstLeft, ChainFirstLeftIOK, and TapLeftIOK
+func TestChainFirstLeft(t *testing.T) {
+	t.Run("ChainFirstLeft executes on error but preserves it", func(t *testing.T) {
+		errorHandled := false
+		testErr := errors.New("test error")
+		logError := ChainFirstLeft[int](func(err error) ReaderResult[string] {
+			return func(ctx context.Context) E.Either[error, string] {
+				errorHandled = true
+				return E.Of[error]("logged")
+			}
+		})
+		rr := Left[int](testErr)
+		result := logError(rr)(t.Context())
+		assert.Equal(t, E.Left[int](testErr), result)
+		assert.True(t, errorHandled, "error handler should execute")
+	})
+
+	t.Run("ChainFirstLeft does not execute on success", func(t *testing.T) {
+		errorHandled := false
+		logError := ChainFirstLeft[int](func(err error) ReaderResult[string] {
+			return func(ctx context.Context) E.Either[error, string] {
+				errorHandled = true
+				return E.Of[error]("logged")
+			}
+		})
+		rr := Of(42)
+		result := logError(rr)(t.Context())
+		assert.Equal(t, E.Of[error](42), result)
+		assert.False(t, errorHandled, "error handler should not execute on success")
+	})
+
+	t.Run("ChainFirstLeftIOK executes IO on error", func(t *testing.T) {
+		ioExecuted := false
+		testErr := errors.New("test error")
+		logErrorIO := ChainFirstLeftIOK[int](func(err error) func() string {
+			return func() string {
+				ioExecuted = true
+				return "logged"
+			}
+		})
+		rr := Left[int](testErr)
+		result := logErrorIO(rr)(t.Context())
+		assert.Equal(t, E.Left[int](testErr), result)
+		assert.True(t, ioExecuted)
+	})
+
+	t.Run("TapLeftIOK is alias for ChainFirstLeftIOK", func(t *testing.T) {
+		ioExecuted := false
+		testErr := errors.New("test error")
+		tapErrorIO := TapLeftIOK[int](func(err error) func() string {
+			return func() string {
+				ioExecuted = true
+				return "logged"
+			}
+		})
+		rr := Left[int](testErr)
+		result := tapErrorIO(rr)(t.Context())
+		assert.Equal(t, E.Left[int](testErr), result)
+		assert.True(t, ioExecuted)
+	})
+}
+
+// TestFromPredicate tests the FromPredicate function
+func TestFromPredicate(t *testing.T) {
+	t.Run("FromPredicate returns Right when predicate is true", func(t *testing.T) {
+		isPositive := FromPredicate(
+			func(x int) bool { return x > 0 },
+			func(x int) error { return errors.New("not positive") },
+		)
+		result := isPositive(42)(t.Context())
+		assert.Equal(t, E.Of[error](42), result)
+	})
+
+	t.Run("FromPredicate returns Left when predicate is false", func(t *testing.T) {
+		isPositive := FromPredicate(
+			func(x int) bool { return x > 0 },
+			func(x int) error { return errors.New("not positive") },
+		)
+		result := isPositive(-1)(t.Context())
+		assert.True(t, E.IsLeft(result))
+	})
+}
+
+// TestMonadAp tests MonadAp and Ap
+func TestMonadAp(t *testing.T) {
+	t.Run("MonadAp applies function to value", func(t *testing.T) {
+		fabRR := Of(func(x int) string {
+			return "value"
+		})
+		faRR := Of(42)
+		result := MonadAp(fabRR, faRR)(t.Context())
+		assert.True(t, E.IsRight(result))
+	})
+
+	t.Run("Ap creates function that applies", func(t *testing.T) {
+		faRR := Of(42)
+		applyTo42 := Ap[int, string](faRR)
+		fabRR := Of(func(x int) string {
+			return "value"
+		})
+		result := applyTo42(fabRR)(t.Context())
+		assert.True(t, E.IsRight(result))
+	})
+}
+
+// TestChainOptionK tests the ChainOptionK function
+func TestChainOptionK(t *testing.T) {
+	t.Run("ChainOptionK returns Right when Option is Some", func(t *testing.T) {
+		chainOpt := ChainOptionK[int, string](func() error {
+			return errors.New("value not found")
+		})
+		optKleisli := func(x int) option.Option[string] {
+			if x > 0 {
+				return option.Some("value")
+			}
+			return option.None[string]()
+		}
+		operator := chainOpt(optKleisli)
+		result := operator(Of(42))(t.Context())
+		assert.True(t, E.IsRight(result))
+	})
+
+	t.Run("ChainOptionK returns Left when Option is None", func(t *testing.T) {
+		chainOpt := ChainOptionK[int, string](func() error {
+			return errors.New("value not found")
+		})
+		optKleisli := func(x int) option.Option[string] {
+			return option.None[string]()
+		}
+		operator := chainOpt(optKleisli)
+		result := operator(Of(42))(t.Context())
+		assert.True(t, E.IsLeft(result))
+	})
+}

v2/context/readerresult/rec.go

@@ -72,7 +72,7 @@ import (
 //
 // Example - Context cancellation:
 //
-//	ctx, cancel := context.WithCancel(context.Background())
+//	ctx, cancel := context.WithCancel(t.Context())
 //	cancel() // Cancel immediately
 //
 //	computation := TailRec(someStep)

v2/context/readerresult/rec_test.go

@@ -45,7 +45,7 @@ func TestTailRecFactorial(t *testing.T) {
 	}
 
 	factorial := TailRec(factorialStep)
-	result := factorial(State{5, 1})(context.Background())
+	result := factorial(State{5, 1})(t.Context())
 
 	assert.Equal(t, R.Of(120), result)
 }
@@ -68,7 +68,7 @@ func TestTailRecFibonacci(t *testing.T) {
 	}
 
 	fib := TailRec(fibStep)
-	result := fib(State{10, 0, 1})(context.Background())
+	result := fib(State{10, 0, 1})(t.Context())
 
 	assert.Equal(t, R.Of(89), result) // 10th Fibonacci number
 }
@@ -85,7 +85,7 @@ func TestTailRecCountdown(t *testing.T) {
 	}
 
 	countdown := TailRec(countdownStep)
-	result := countdown(10)(context.Background())
+	result := countdown(10)(t.Context())
 
 	assert.Equal(t, R.Of(0), result)
 }
@@ -99,7 +99,7 @@ func TestTailRecImmediateTermination(t *testing.T) {
 	}
 
 	immediate := TailRec(immediateStep)
-	result := immediate(42)(context.Background())
+	result := immediate(42)(t.Context())
 
 	assert.Equal(t, R.Of(84), result)
 }
@@ -116,7 +116,7 @@ func TestTailRecStackSafety(t *testing.T) {
 	}
 
 	countdown := TailRec(countdownStep)
-	result := countdown(10000)(context.Background())
+	result := countdown(10000)(t.Context())
 
 	assert.Equal(t, R.Of(0), result)
 }
@@ -138,7 +138,7 @@ func TestTailRecSumList(t *testing.T) {
 	}
 
 	sumList := TailRec(sumStep)
-	result := sumList(State{[]int{1, 2, 3, 4, 5}, 0})(context.Background())
+	result := sumList(State{[]int{1, 2, 3, 4, 5}, 0})(t.Context())
 
 	assert.Equal(t, R.Of(15), result)
 }
@@ -158,7 +158,7 @@ func TestTailRecCollatzConjecture(t *testing.T) {
 	}
 
 	collatz := TailRec(collatzStep)
-	result := collatz(10)(context.Background())
+	result := collatz(10)(t.Context())
 
 	assert.Equal(t, R.Of(1), result)
 }
@@ -180,7 +180,7 @@ func TestTailRecGCD(t *testing.T) {
 	}
 
 	gcd := TailRec(gcdStep)
-	result := gcd(State{48, 18})(context.Background())
+	result := gcd(State{48, 18})(t.Context())
 
 	assert.Equal(t, R.Of(6), result)
 }
@@ -202,7 +202,7 @@ func TestTailRecErrorPropagation(t *testing.T) {
 	}
 
 	computation := TailRec(errorStep)
-	result := computation(10)(context.Background())
+	result := computation(10)(t.Context())
 
 	assert.True(t, R.IsLeft(result))
 	_, err := R.Unwrap(result)
@@ -211,7 +211,7 @@ func TestTailRecErrorPropagation(t *testing.T) {
 
 // TestTailRecContextCancellationImmediate tests short circuit when context is already canceled
 func TestTailRecContextCancellationImmediate(t *testing.T) {
-	ctx, cancel := context.WithCancel(context.Background())
+	ctx, cancel := context.WithCancel(t.Context())
 	cancel() // Cancel immediately before execution
 
 	stepExecuted := false
@@ -237,7 +237,7 @@ func TestTailRecContextCancellationImmediate(t *testing.T) {
 
 // TestTailRecContextCancellationDuringExecution tests short circuit when context is canceled during execution
 func TestTailRecContextCancellationDuringExecution(t *testing.T) {
-	ctx, cancel := context.WithCancel(context.Background())
+	ctx, cancel := context.WithCancel(t.Context())
 
 	executionCount := 0
 	countdownStep := func(n int) ReaderResult[TR.Trampoline[int, int]] {
@@ -266,7 +266,7 @@ func TestTailRecContextCancellationDuringExecution(t *testing.T) {
 
 // TestTailRecContextWithTimeout tests behavior with timeout context
 func TestTailRecContextWithTimeout(t *testing.T) {
-	ctx, cancel := context.WithTimeout(context.Background(), 50*time.Millisecond)
+	ctx, cancel := context.WithTimeout(t.Context(), 50*time.Millisecond)
 	defer cancel()
 
 	executionCount := 0
@@ -295,7 +295,7 @@ func TestTailRecContextWithTimeout(t *testing.T) {
 // TestTailRecContextWithCause tests that context.Cause is properly returned
 func TestTailRecContextWithCause(t *testing.T) {
 	customErr := errors.New("custom cancellation reason")
-	ctx, cancel := context.WithCancelCause(context.Background())
+	ctx, cancel := context.WithCancelCause(t.Context())
 	cancel(customErr)
 
 	countdownStep := func(n int) ReaderResult[TR.Trampoline[int, int]] {
@@ -317,7 +317,7 @@ func TestTailRecContextWithCause(t *testing.T) {
 
 // TestTailRecContextCancellationMultipleIterations tests that cancellation is checked on each iteration
 func TestTailRecContextCancellationMultipleIterations(t *testing.T) {
-	ctx, cancel := context.WithCancel(context.Background())
+	ctx, cancel := context.WithCancel(t.Context())
 
 	executionCount := 0
 	maxExecutions := 5
@@ -348,7 +348,7 @@ func TestTailRecContextCancellationMultipleIterations(t *testing.T) {
 
 // TestTailRecContextNotCanceled tests normal execution when context is not canceled
 func TestTailRecContextNotCanceled(t *testing.T) {
-	ctx := context.Background()
+	ctx := t.Context()
 
 	executionCount := 0
 	countdownStep := func(n int) ReaderResult[TR.Trampoline[int, int]] {
@@ -386,7 +386,7 @@ func TestTailRecPowerOfTwo(t *testing.T) {
 	}
 
 	power := TailRec(powerStep)
-	result := power(State{0, 1, 10})(context.Background())
+	result := power(State{0, 1, 10})(t.Context())
 
 	assert.Equal(t, R.Of(1024), result) // 2^10
 }
@@ -412,7 +412,7 @@ func TestTailRecFindInRange(t *testing.T) {
 	}
 
 	find := TailRec(findStep)
-	result := find(State{0, 100, 42})(context.Background())
+	result := find(State{0, 100, 42})(t.Context())
 
 	assert.Equal(t, R.Of(42), result)
 }
@@ -438,7 +438,7 @@ func TestTailRecFindNotInRange(t *testing.T) {
 	}
 
 	find := TailRec(findStep)
-	result := find(State{0, 100, 200})(context.Background())
+	result := find(State{0, 100, 200})(t.Context())
 
 	assert.Equal(t, R.Of(-1), result)
 }
@@ -448,7 +448,7 @@ func TestTailRecWithContextValue(t *testing.T) {
 	type contextKey string
 	const multiplierKey contextKey = "multiplier"
 
-	ctx := context.WithValue(context.Background(), multiplierKey, 3)
+	ctx := context.WithValue(t.Context(), multiplierKey, 3)
 
 	countdownStep := func(n int) ReaderResult[TR.Trampoline[int, int]] {
 		return func(ctx context.Context) Result[TR.Trampoline[int, int]] {
@@ -492,7 +492,7 @@ func TestTailRecComplexState(t *testing.T) {
 	}
 
 	computation := TailRec(complexStep)
-	result := computation(ComplexState{5, 0, 1, false})(context.Background())
+	result := computation(ComplexState{5, 0, 1, false})(t.Context())
 
 	assert.Equal(t, R.Of("sum=15, product=120"), result)
 }

v2/context/readerresult/retry.go

@@ -90,7 +90,7 @@ import (
 //	retryingFetch := Retrying(policy, fetchData, shouldRetry)
 //
 //	// Execute with a cancellable context
-//	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+//	ctx, cancel := context.WithTimeout(t.Context(), 5*time.Second)
 //	defer cancel()
 //	finalResult := retryingFetch(ctx)
 //

v2/context/readerresult/sequence.go

@@ -20,20 +20,201 @@ import (
 	"github.com/IBM/fp-go/v2/tuple"
 )
 
-// SequenceT converts n inputs of higher kinded types into a higher kinded types of n strongly typed values, represented as a tuple
+// SequenceT functions convert multiple ReaderResult values into a single ReaderResult containing a tuple.
+// These functions execute all input ReaderResults with the same context and combine their results.
+//
+// IMPORTANT: All ReaderResults are executed, even if one fails. The implementation uses applicative
+// semantics, which means all computations run to collect their results. If any ReaderResult fails
+// (returns Left), the entire sequence fails and returns the first error encountered, but all
+// ReaderResults will have been executed for their side effects.
+//
+// These functions are useful for:
+//   - Combining multiple independent computations that all need the same context
+//   - Collecting results from operations where all side effects should occur
+//   - Building complex data structures from multiple ReaderResult sources
+//   - Validating multiple fields where you want all validations to run
+//
+// The sequence executes in order (left to right), so side effects occur in that order.
 
+// SequenceT1 converts a single ReaderResult into a ReaderResult containing a 1-tuple.
+// This is primarily useful for consistency in generic code or when you need to wrap
+// a single value in a tuple structure.
+//
+// Type Parameters:
+//   - A: The type of the value in the ReaderResult
+//
+// Parameters:
+//   - a: The ReaderResult to wrap in a tuple
+//
+// Returns:
+//   - A ReaderResult containing a Tuple1 with the value from the input
+//
+// Example:
+//
+//	rr := readerresult.Of(42)
+//	tupled := readerresult.SequenceT1(rr)
+//	result := tupled(t.Context())
+//	// result is Right(Tuple1{F1: 42})
+//
+//go:inline
 func SequenceT1[A any](a ReaderResult[A]) ReaderResult[tuple.Tuple1[A]] {
 	return readereither.SequenceT1(a)
 }
 
+// SequenceT2 combines two ReaderResults into a single ReaderResult containing a 2-tuple.
+// Both ReaderResults are executed with the same context. If either fails, the entire
+// sequence fails.
+//
+// Type Parameters:
+//   - A: The type of the first value
+//   - B: The type of the second value
+//
+// Parameters:
+//   - a: The first ReaderResult
+//   - b: The second ReaderResult
+//
+// Returns:
+//   - A ReaderResult containing a Tuple2 with both values
+//
+// Example:
+//
+//	getName := readerresult.Of("Alice")
+//	getAge := readerresult.Of(30)
+//	combined := readerresult.SequenceT2(getName, getAge)
+//	result := combined(t.Context())
+//	// result is Right(Tuple2{F1: "Alice", F2: 30})
+//
+// Example with error:
+//
+//	getName := readerresult.Of("Alice")
+//	getAge := readerresult.Left[int](errors.New("age not found"))
+//	combined := readerresult.SequenceT2(getName, getAge)
+//	result := combined(t.Context())
+//	// result is Left(error("age not found"))
+//
+//go:inline
 func SequenceT2[A, B any](a ReaderResult[A], b ReaderResult[B]) ReaderResult[tuple.Tuple2[A, B]] {
 	return readereither.SequenceT2(a, b)
 }
 
+// SequenceT3 combines three ReaderResults into a single ReaderResult containing a 3-tuple.
+// All ReaderResults are executed sequentially with the same context. If any fails,
+// the entire sequence fails immediately.
+//
+// Type Parameters:
+//   - A: The type of the first value
+//   - B: The type of the second value
+//   - C: The type of the third value
+//
+// Parameters:
+//   - a: The first ReaderResult
+//   - b: The second ReaderResult
+//   - c: The third ReaderResult
+//
+// Returns:
+//   - A ReaderResult containing a Tuple3 with all three values
+//
+// Example:
+//
+//	getUserID := readerresult.Of(123)
+//	getUserName := readerresult.Of("Alice")
+//	getUserEmail := readerresult.Of("alice@example.com")
+//	combined := readerresult.SequenceT3(getUserID, getUserName, getUserEmail)
+//	result := combined(t.Context())
+//	// result is Right(Tuple3{F1: 123, F2: "Alice", F3: "alice@example.com"})
+//
+// Example with context-aware operations:
+//
+//	fetchUser := func(ctx context.Context) result.Result[string] {
+//	    if ctx.Err() != nil {
+//	        return result.Error[string](ctx.Err())
+//	    }
+//	    return result.Of("Alice")
+//	}
+//	fetchAge := func(ctx context.Context) result.Result[int] {
+//	    return result.Of(30)
+//	}
+//	fetchCity := func(ctx context.Context) result.Result[string] {
+//	    return result.Of("NYC")
+//	}
+//	combined := readerresult.SequenceT3(fetchUser, fetchAge, fetchCity)
+//	result := combined(t.Context())
+//	// result is Right(Tuple3{F1: "Alice", F2: 30, F3: "NYC"})
+//
+//go:inline
 func SequenceT3[A, B, C any](a ReaderResult[A], b ReaderResult[B], c ReaderResult[C]) ReaderResult[tuple.Tuple3[A, B, C]] {
 	return readereither.SequenceT3(a, b, c)
 }
 
+// SequenceT4 combines four ReaderResults into a single ReaderResult containing a 4-tuple.
+// All ReaderResults are executed sequentially with the same context. If any fails,
+// the entire sequence fails immediately without executing the remaining ones.
+//
+// Type Parameters:
+//   - A: The type of the first value
+//   - B: The type of the second value
+//   - C: The type of the third value
+//   - D: The type of the fourth value
+//
+// Parameters:
+//   - a: The first ReaderResult
+//   - b: The second ReaderResult
+//   - c: The third ReaderResult
+//   - d: The fourth ReaderResult
+//
+// Returns:
+//   - A ReaderResult containing a Tuple4 with all four values
+//
+// Example:
+//
+//	getID := readerresult.Of(123)
+//	getName := readerresult.Of("Alice")
+//	getEmail := readerresult.Of("alice@example.com")
+//	getAge := readerresult.Of(30)
+//	combined := readerresult.SequenceT4(getID, getName, getEmail, getAge)
+//	result := combined(t.Context())
+//	// result is Right(Tuple4{F1: 123, F2: "Alice", F3: "alice@example.com", F4: 30})
+//
+// Example with early failure:
+//
+//	getID := readerresult.Of(123)
+//	getName := readerresult.Left[string](errors.New("name not found"))
+//	getEmail := readerresult.Of("alice@example.com")  // Not executed
+//	getAge := readerresult.Of(30)                      // Not executed
+//	combined := readerresult.SequenceT4(getID, getName, getEmail, getAge)
+//	result := combined(t.Context())
+//	// result is Left(error("name not found"))
+//	// getEmail and getAge are never executed due to early failure
+//
+// Example building a complex structure:
+//
+//	type UserProfile struct {
+//	    ID    int
+//	    Name  string
+//	    Email string
+//	    Age   int
+//	}
+//
+//	fetchUserData := readerresult.SequenceT4(
+//	    fetchUserID(userID),
+//	    fetchUserName(userID),
+//	    fetchUserEmail(userID),
+//	    fetchUserAge(userID),
+//	)
+//
+//	buildProfile := readerresult.Map(func(t tuple.Tuple4[int, string, string, int]) UserProfile {
+//	    return UserProfile{
+//	        ID:    t.F1,
+//	        Name:  t.F2,
+//	        Email: t.F3,
+//	        Age:   t.F4,
+//	    }
+//	})
+//
+//	userProfile := F.Pipe1(fetchUserData, buildProfile)
+//	result := userProfile(t.Context())
+//
+//go:inline
 func SequenceT4[A, B, C, D any](a ReaderResult[A], b ReaderResult[B], c ReaderResult[C], d ReaderResult[D]) ReaderResult[tuple.Tuple4[A, B, C, D]] {
 	return readereither.SequenceT4(a, b, c, d)
 }

v2/context/readerresult/sequence_test.go

@@ -0,0 +1,460 @@
+// Copyright (c) 2023 - 2025 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package readerresult
+
+import (
+	"context"
+	"errors"
+	"testing"
+
+	E "github.com/IBM/fp-go/v2/either"
+	"github.com/IBM/fp-go/v2/tuple"
+	"github.com/stretchr/testify/assert"
+)
+
+// TestSequenceT1 tests the SequenceT1 function
+func TestSequenceT1(t *testing.T) {
+	t.Run("wraps single success value in tuple", func(t *testing.T) {
+		rr := Of(42)
+		tupled := SequenceT1(rr)
+		result := tupled(t.Context())
+
+		assert.True(t, E.IsRight(result))
+		val, _ := E.Unwrap(result)
+		assert.Equal(t, 42, val.F1)
+	})
+
+	t.Run("preserves error", func(t *testing.T) {
+		testErr := errors.New("test error")
+		rr := Left[int](testErr)
+		tupled := SequenceT1(rr)
+		result := tupled(t.Context())
+
+		assert.True(t, E.IsLeft(result))
+		_, err := E.UnwrapError(result)
+		assert.Equal(t, testErr, err)
+	})
+
+	t.Run("respects context cancellation", func(t *testing.T) {
+		rr := func(ctx context.Context) E.Either[error, int] {
+			if ctx.Err() != nil {
+				return E.Left[int](ctx.Err())
+			}
+			return E.Of[error](42)
+		}
+
+		tupled := SequenceT1(rr)
+
+		ctx, cancel := context.WithCancel(t.Context())
+		cancel()
+
+		result := tupled(ctx)
+		assert.True(t, E.IsLeft(result))
+	})
+}
+
+// TestSequenceT2 tests the SequenceT2 function
+func TestSequenceT2(t *testing.T) {
+	t.Run("combines two success values into tuple", func(t *testing.T) {
+		getName := Of("Alice")
+		getAge := Of(30)
+
+		combined := SequenceT2(getName, getAge)
+		result := combined(t.Context())
+
+		assert.True(t, E.IsRight(result))
+		val, _ := E.Unwrap(result)
+		assert.Equal(t, "Alice", val.F1)
+		assert.Equal(t, 30, val.F2)
+	})
+
+	t.Run("fails if first ReaderResult fails", func(t *testing.T) {
+		testErr := errors.New("name not found")
+		getName := Left[string](testErr)
+		getAge := Of(30)
+
+		combined := SequenceT2(getName, getAge)
+		result := combined(t.Context())
+
+		assert.True(t, E.IsLeft(result))
+		_, err := E.UnwrapError(result)
+		assert.Equal(t, testErr, err)
+	})
+
+	t.Run("fails if second ReaderResult fails", func(t *testing.T) {
+		testErr := errors.New("age not found")
+		getName := Of("Alice")
+		getAge := Left[int](testErr)
+
+		combined := SequenceT2(getName, getAge)
+		result := combined(t.Context())
+
+		assert.True(t, E.IsLeft(result))
+		_, err := E.UnwrapError(result)
+		assert.Equal(t, testErr, err)
+	})
+
+	t.Run("executes both ReaderResults with same context", func(t *testing.T) {
+		type ctxKey string
+		ctx := context.WithValue(t.Context(), ctxKey("key"), "shared")
+
+		getName := func(ctx context.Context) E.Either[error, string] {
+			val := ctx.Value(ctxKey("key"))
+			if val != nil {
+				return E.Of[error](val.(string))
+			}
+			return E.Left[string](errors.New("key not found"))
+		}
+
+		getAge := func(ctx context.Context) E.Either[error, int] {
+			val := ctx.Value(ctxKey("key"))
+			if val != nil {
+				return E.Of[error](len(val.(string)))
+			}
+			return E.Left[int](errors.New("key not found"))
+		}
+
+		combined := SequenceT2(getName, getAge)
+		result := combined(ctx)
+
+		assert.True(t, E.IsRight(result))
+		val, _ := E.Unwrap(result)
+		assert.Equal(t, "shared", val.F1)
+		assert.Equal(t, 6, val.F2) // len("shared")
+	})
+
+	t.Run("executes all ReaderResults even if one fails", func(t *testing.T) {
+		firstExecuted := false
+		secondExecuted := false
+
+		first := func(ctx context.Context) E.Either[error, int] {
+			firstExecuted = true
+			return E.Left[int](errors.New("first failed"))
+		}
+
+		second := func(ctx context.Context) E.Either[error, string] {
+			secondExecuted = true
+			return E.Of[error]("second")
+		}
+
+		combined := SequenceT2(first, second)
+		result := combined(t.Context())
+
+		assert.True(t, firstExecuted, "first should be executed")
+		assert.True(t, secondExecuted, "second should be executed (applicative semantics)")
+		assert.True(t, E.IsLeft(result))
+	})
+}
+
+// TestSequenceT3 tests the SequenceT3 function
+func TestSequenceT3(t *testing.T) {
+	t.Run("combines three success values into tuple", func(t *testing.T) {
+		getUserID := Of(123)
+		getUserName := Of("Alice")
+		getUserEmail := Of("alice@example.com")
+
+		combined := SequenceT3(getUserID, getUserName, getUserEmail)
+		result := combined(t.Context())
+
+		assert.True(t, E.IsRight(result))
+		val, _ := E.Unwrap(result)
+		assert.Equal(t, 123, val.F1)
+		assert.Equal(t, "Alice", val.F2)
+		assert.Equal(t, "alice@example.com", val.F3)
+	})
+
+	t.Run("fails if any ReaderResult fails", func(t *testing.T) {
+		testErr := errors.New("email not found")
+		getUserID := Of(123)
+		getUserName := Of("Alice")
+		getUserEmail := Left[string](testErr)
+
+		combined := SequenceT3(getUserID, getUserName, getUserEmail)
+		result := combined(t.Context())
+
+		assert.True(t, E.IsLeft(result))
+		_, err := E.UnwrapError(result)
+		assert.Equal(t, testErr, err)
+	})
+
+	t.Run("executes all ReaderResults even if one fails", func(t *testing.T) {
+		firstExecuted := false
+		secondExecuted := false
+		thirdExecuted := false
+
+		first := func(ctx context.Context) E.Either[error, int] {
+			firstExecuted = true
+			return E.Of[error](1)
+		}
+
+		second := func(ctx context.Context) E.Either[error, int] {
+			secondExecuted = true
+			return E.Left[int](errors.New("second failed"))
+		}
+
+		third := func(ctx context.Context) E.Either[error, int] {
+			thirdExecuted = true
+			return E.Of[error](3)
+		}
+
+		combined := SequenceT3(first, second, third)
+		result := combined(t.Context())
+
+		assert.True(t, firstExecuted, "first should be executed")
+		assert.True(t, secondExecuted, "second should be executed")
+		assert.True(t, thirdExecuted, "third should be executed (applicative semantics)")
+		assert.True(t, E.IsLeft(result))
+	})
+
+	t.Run("respects context cancellation", func(t *testing.T) {
+		getUserID := func(ctx context.Context) E.Either[error, int] {
+			if ctx.Err() != nil {
+				return E.Left[int](ctx.Err())
+			}
+			return E.Of[error](123)
+		}
+
+		getUserName := Of("Alice")
+		getUserEmail := Of("alice@example.com")
+
+		combined := SequenceT3(getUserID, getUserName, getUserEmail)
+
+		ctx, cancel := context.WithCancel(t.Context())
+		cancel()
+
+		result := combined(ctx)
+		assert.True(t, E.IsLeft(result))
+	})
+}
+
+// TestSequenceT4 tests the SequenceT4 function
+func TestSequenceT4(t *testing.T) {
+	t.Run("combines four success values into tuple", func(t *testing.T) {
+		getID := Of(123)
+		getName := Of("Alice")
+		getEmail := Of("alice@example.com")
+		getAge := Of(30)
+
+		combined := SequenceT4(getID, getName, getEmail, getAge)
+		result := combined(t.Context())
+
+		assert.True(t, E.IsRight(result))
+		val, _ := E.Unwrap(result)
+		assert.Equal(t, 123, val.F1)
+		assert.Equal(t, "Alice", val.F2)
+		assert.Equal(t, "alice@example.com", val.F3)
+		assert.Equal(t, 30, val.F4)
+	})
+
+	t.Run("fails if any ReaderResult fails", func(t *testing.T) {
+		testErr := errors.New("name not found")
+		getID := Of(123)
+		getName := Left[string](testErr)
+		getEmail := Of("alice@example.com")
+		getAge := Of(30)
+
+		combined := SequenceT4(getID, getName, getEmail, getAge)
+		result := combined(t.Context())
+
+		assert.True(t, E.IsLeft(result))
+		_, err := E.UnwrapError(result)
+		assert.Equal(t, testErr, err)
+	})
+
+	t.Run("executes all ReaderResults even if one fails", func(t *testing.T) {
+		firstExecuted := false
+		secondExecuted := false
+		thirdExecuted := false
+		fourthExecuted := false
+
+		first := func(ctx context.Context) E.Either[error, int] {
+			firstExecuted = true
+			return E.Of[error](1)
+		}
+
+		second := func(ctx context.Context) E.Either[error, int] {
+			secondExecuted = true
+			return E.Left[int](errors.New("second failed"))
+		}
+
+		third := func(ctx context.Context) E.Either[error, int] {
+			thirdExecuted = true
+			return E.Of[error](3)
+		}
+
+		fourth := func(ctx context.Context) E.Either[error, int] {
+			fourthExecuted = true
+			return E.Of[error](4)
+		}
+
+		combined := SequenceT4(first, second, third, fourth)
+		result := combined(t.Context())
+
+		assert.True(t, firstExecuted, "first should be executed")
+		assert.True(t, secondExecuted, "second should be executed")
+		assert.True(t, thirdExecuted, "third should be executed (applicative semantics)")
+		assert.True(t, fourthExecuted, "fourth should be executed (applicative semantics)")
+		assert.True(t, E.IsLeft(result))
+	})
+
+	t.Run("can be used to build complex structures", func(t *testing.T) {
+		type UserProfile struct {
+			ID    int
+			Name  string
+			Email string
+			Age   int
+		}
+
+		fetchUserData := SequenceT4(
+			Of(123),
+			Of("Alice"),
+			Of("alice@example.com"),
+			Of(30),
+		)
+
+		buildProfile := Map(func(t tuple.Tuple4[int, string, string, int]) UserProfile {
+			return UserProfile{
+				ID:    t.F1,
+				Name:  t.F2,
+				Email: t.F3,
+				Age:   t.F4,
+			}
+		})
+
+		userProfile := func(ctx context.Context) E.Either[error, UserProfile] {
+			tupleResult := fetchUserData(ctx)
+			if E.IsLeft(tupleResult) {
+				_, err := E.UnwrapError(tupleResult)
+				return E.Left[UserProfile](err)
+			}
+			tupleVal, _ := E.Unwrap(tupleResult)
+			return buildProfile(Of(tupleVal))(ctx)
+		}
+
+		result := userProfile(t.Context())
+
+		assert.True(t, E.IsRight(result))
+		profile, _ := E.Unwrap(result)
+		assert.Equal(t, 123, profile.ID)
+		assert.Equal(t, "Alice", profile.Name)
+		assert.Equal(t, "alice@example.com", profile.Email)
+		assert.Equal(t, 30, profile.Age)
+	})
+
+	t.Run("executes all with same context", func(t *testing.T) {
+		type ctxKey string
+		ctx := context.WithValue(t.Context(), ctxKey("multiplier"), 2)
+
+		getBase := func(ctx context.Context) E.Either[error, int] {
+			return E.Of[error](10)
+		}
+
+		multiply := func(ctx context.Context) E.Either[error, int] {
+			mult := ctx.Value(ctxKey("multiplier")).(int)
+			return E.Of[error](mult)
+		}
+
+		getResult := func(ctx context.Context) E.Either[error, int] {
+			mult := ctx.Value(ctxKey("multiplier")).(int)
+			return E.Of[error](10 * mult)
+		}
+
+		getDescription := func(ctx context.Context) E.Either[error, string] {
+			return E.Of[error]("calculated")
+		}
+
+		combined := SequenceT4(getBase, multiply, getResult, getDescription)
+		result := combined(ctx)
+
+		assert.True(t, E.IsRight(result))
+		val, _ := E.Unwrap(result)
+		assert.Equal(t, 10, val.F1)
+		assert.Equal(t, 2, val.F2)
+		assert.Equal(t, 20, val.F3)
+		assert.Equal(t, "calculated", val.F4)
+	})
+}
+
+// TestSequenceIntegration tests integration scenarios
+func TestSequenceIntegration(t *testing.T) {
+	t.Run("SequenceT2 with Map to transform tuple", func(t *testing.T) {
+		getName := Of("Alice")
+		getAge := Of(30)
+
+		combined := SequenceT2(getName, getAge)
+		formatted := Map(func(t tuple.Tuple2[string, int]) string {
+			return t.F1 + " is " + string(rune(t.F2+48)) + " years old"
+		})
+
+		pipeline := func(ctx context.Context) E.Either[error, string] {
+			tupleResult := combined(ctx)
+			if E.IsLeft(tupleResult) {
+				_, err := E.UnwrapError(tupleResult)
+				return E.Left[string](err)
+			}
+			tupleVal, _ := E.Unwrap(tupleResult)
+			return formatted(Of(tupleVal))(ctx)
+		}
+
+		result := pipeline(t.Context())
+		assert.True(t, E.IsRight(result))
+	})
+
+	t.Run("SequenceT3 with Chain for dependent operations", func(t *testing.T) {
+		getX := Of(10)
+		getY := Of(20)
+		getZ := Of(30)
+
+		combined := SequenceT3(getX, getY, getZ)
+
+		sumTuple := func(t tuple.Tuple3[int, int, int]) ReaderResult[int] {
+			return Of(t.F1 + t.F2 + t.F3)
+		}
+
+		pipeline := func(ctx context.Context) E.Either[error, int] {
+			tupleResult := combined(ctx)
+			if E.IsLeft(tupleResult) {
+				_, err := E.UnwrapError(tupleResult)
+				return E.Left[int](err)
+			}
+			tupleVal, _ := E.Unwrap(tupleResult)
+			return sumTuple(tupleVal)(ctx)
+		}
+
+		result := pipeline(t.Context())
+		assert.True(t, E.IsRight(result))
+		val, _ := E.Unwrap(result)
+		assert.Equal(t, 60, val) // 10 + 20 + 30
+	})
+
+	t.Run("nested sequences", func(t *testing.T) {
+		// Create two pairs
+		pair1 := SequenceT2(Of(1), Of(2))
+		pair2 := SequenceT2(Of(3), Of(4))
+
+		// Combine the pairs
+		combined := SequenceT2(pair1, pair2)
+
+		result := combined(t.Context())
+		assert.True(t, E.IsRight(result))
+
+		val, _ := E.Unwrap(result)
+		assert.Equal(t, 1, val.F1.F1)
+		assert.Equal(t, 2, val.F1.F2)
+		assert.Equal(t, 3, val.F2.F1)
+		assert.Equal(t, 4, val.F2.F2)
+	})
+}