fix: improve lens handling

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

.gitignore

@@ -2,4 +2,5 @@ fp-go.exe
 fp-go
 main.exe
 build/
-.idea
+.idea
+*.exe

either/core.go

@@ -21,8 +21,8 @@ import (
 
 type (
 	either struct {
-		isLeft bool
 		value  any
+		isLeft bool
 	}
 
 	// Either defines a data structure that logically holds either an E or an A. The flag discriminates the cases
@@ -73,12 +73,12 @@ func IsRight[E, A any](val Either[E, A]) bool {
 
 // Left creates a new instance of an [Either] representing the left value.
 func Left[A, E any](value E) Either[E, A] {
-	return Either[E, A]{true, value}
+	return Either[E, A]{value, true}
 }
 
 // Right creates a new instance of an [Either] representing the right value.
 func Right[E, A any](value A) Either[E, A] {
-	return Either[E, A]{false, value}
+	return Either[E, A]{value, false}
 }
 
 // MonadFold extracts the values from an [Either] by invoking the [onLeft] callback or the [onRight] callback depending on the case
@@ -94,8 +94,7 @@ func Unwrap[E, A any](ma Either[E, A]) (A, E) {
 	if ma.isLeft {
 		var a A
 		return a, ma.value.(E)
-	} else {
-		var e E
-		return ma.value.(A), e
 	}
+	var e E
+	return ma.value.(A), e
 }

v2/README.md

@@ -2,25 +2,152 @@
 
 [![Go Reference](https://pkg.go.dev/badge/github.com/IBM/fp-go/v2.svg)](https://pkg.go.dev/github.com/IBM/fp-go/v2)
 [![Coverage Status](https://coveralls.io/repos/github/IBM/fp-go/badge.svg?branch=main&flag=v2)](https://coveralls.io/github/IBM/fp-go?branch=main)
+[![Go Report Card](https://goreportcard.com/badge/github.com/IBM/fp-go/v2)](https://goreportcard.com/report/github.com/IBM/fp-go/v2)
 
-Version 2 of fp-go leverages [generic type aliases](https://github.com/golang/go/issues/46477) introduced in Go 1.24, providing a more ergonomic and streamlined API.
+**fp-go** is a comprehensive functional programming library for Go, bringing type-safe functional patterns inspired by [fp-ts](https://gcanti.github.io/fp-ts/) to the Go ecosystem. Version 2 leverages [generic type aliases](https://github.com/golang/go/issues/46477) introduced in Go 1.24, providing a more ergonomic and streamlined API.
 
 ## 📚 Table of Contents
 
+- [Overview](#-overview)
+- [Features](#-features)
 - [Requirements](#-requirements)
-- [Breaking Changes](#-breaking-changes)
+- [Installation](#-installation)
+- [Quick Start](#-quick-start)
+- [Breaking Changes](#️-breaking-changes)
 - [Key Improvements](#-key-improvements)
 - [Migration Guide](#-migration-guide)
-- [Installation](#-installation)
 - [What's New](#-whats-new)
+- [Documentation](#-documentation)
+- [Contributing](#-contributing)
+- [License](#-license)
+
+## 🎯 Overview
+
+fp-go brings the power of functional programming to Go with:
+
+- **Type-safe abstractions** - Monads, Functors, Applicatives, and more
+- **Composable operations** - Build complex logic from simple, reusable functions
+- **Error handling** - Elegant error management with `Either`, `Result`, and `IOEither`
+- **Lazy evaluation** - Control when and how computations execute
+- **Optics** - Powerful lens, prism, and traversal operations for immutable data manipulation
+
+## ✨ Features
+
+- 🔒 **Type Safety** - Leverage Go's generics for compile-time guarantees
+- 🧩 **Composability** - Chain operations naturally with functional composition
+- 📦 **Rich Type System** - `Option`, `Either`, `Result`, `IO`, `Reader`, and more
+- 🎯 **Practical** - Designed for real-world Go applications
+- 🚀 **Performance** - Zero-cost abstractions where possible
+- 📖 **Well-documented** - Comprehensive API documentation and examples
+- 🧪 **Battle-tested** - Extensive test coverage
 
 ## 🔧 Requirements
 
 - **Go 1.24 or later** (for generic type alias support)
 
-## ⚠️ Breaking Changes
+## 📦 Installation
 
-### 1. Generic Type Aliases
+```bash
+go get github.com/IBM/fp-go/v2
+```
+
+## 🚀 Quick Start
+
+### Working with Option
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/IBM/fp-go/v2/option"
+)
+
+func main() {
+    // Create an Option
+    some := option.Some(42)
+    none := option.None[int]()
+    
+    // Map over values
+    doubled := option.Map(func(x int) int { return x * 2 })(some)
+    fmt.Println(option.GetOrElse(0)(doubled)) // Output: 84
+    
+    // Chain operations
+    result := option.Chain(func(x int) option.Option[string] {
+        if x > 0 {
+            return option.Some(fmt.Sprintf("Positive: %d", x))
+        }
+        return option.None[string]()
+    })(some)
+    
+    fmt.Println(option.GetOrElse("No value")(result)) // Output: Positive: 42
+}
+```
+
+### Error Handling with Result
+
+```go
+package main
+
+import (
+    "errors"
+    "fmt"
+    "github.com/IBM/fp-go/v2/result"
+)
+
+func divide(a, b int) result.Result[int] {
+    if b == 0 {
+        return result.Error[int](errors.New("division by zero"))
+    }
+    return result.Ok(a / b)
+}
+
+func main() {
+    res := divide(10, 2)
+    
+    // Pattern match on the result
+    result.Fold(
+        func(err error) { fmt.Println("Error:", err) },
+        func(val int) { fmt.Println("Result:", val) },
+    )(res)
+    // Output: Result: 5
+    
+    // Or use GetOrElse for a default value
+    value := result.GetOrElse(0)(divide(10, 0))
+    fmt.Println("Value:", value) // Output: Value: 0
+}
+```
+
+### Composing IO Operations
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/IBM/fp-go/v2/io"
+)
+
+func main() {
+    // Define pure IO operations
+    readInput := io.MakeIO(func() string {
+        return "Hello, fp-go!"
+    })
+    
+    // Transform the result
+    uppercase := io.Map(func(s string) string {
+        return fmt.Sprintf(">>> %s <<<", s)
+    })(readInput)
+    
+    // Execute the IO operation
+    result := uppercase()
+    fmt.Println(result) // Output: >>> Hello, fp-go! <<<
+}
+```
+
+### From V1 to V2
+
+#### 1. Generic Type Aliases
 
 V2 uses [generic type aliases](https://github.com/golang/go/issues/46477) which require Go 1.24+. This is the most significant change and enables cleaner type definitions.
 
@@ -34,7 +161,7 @@ type ReaderIOEither[R, E, A any] RD.Reader[R, IOE.IOEither[E, A]]
 type ReaderIOEither[R, E, A any] = RD.Reader[R, IOE.IOEither[E, A]]
 ```
 
-### 2. Generic Type Parameter Ordering
+#### 2. Generic Type Parameter Ordering
 
 Type parameters that **cannot** be inferred from function arguments now come first, improving type inference.
 
@@ -52,7 +179,7 @@ func Ap[B, R, E, A any](fa ReaderIOEither[R, E, A]) func(ReaderIOEither[R, E, fu
 
 This change allows the Go compiler to infer more types automatically, reducing the need for explicit type parameters.
 
-### 3. Pair Monad Semantics
+#### 3. Pair Monad Semantics
 
 Monadic operations for `Pair` now operate on the **second argument** to align with the [Haskell definition](https://hackage.haskell.org/package/TypeCompose-0.9.14/docs/Data-Pair.html).
 
@@ -70,6 +197,36 @@ pair := MakePair(1, "hello")
 result := Map(func(s string) string { return s + "!" })(pair) // Pair(1, "hello!")
 ```
 
+#### 4. Endomorphism Compose Semantics
+
+The `Compose` function for endomorphisms now follows **mathematical function composition** (right-to-left execution), aligning with standard functional programming conventions.
+
+**V1:**
+```go
+// Compose executed left-to-right
+double := func(x int) int { return x * 2 }
+increment := func(x int) int { return x + 1 }
+composed := Compose(double, increment)
+result := composed(5) // (5 * 2) + 1 = 11
+```
+
+**V2:**
+```go
+// Compose executes RIGHT-TO-LEFT (mathematical composition)
+double := func(x int) int { return x * 2 }
+increment := func(x int) int { return x + 1 }
+composed := Compose(double, increment)
+result := composed(5) // (5 + 1) * 2 = 12
+
+// Use MonadChain for LEFT-TO-RIGHT execution
+chained := MonadChain(double, increment)
+result2 := chained(5) // (5 * 2) + 1 = 11
+```
+
+**Key Difference:**
+- `Compose(f, g)` now means `f ∘ g`, which applies `g` first, then `f` (right-to-left)
+- `MonadChain(f, g)` applies `f` first, then `g` (left-to-right)
+
 ## ✨ Key Improvements
 
 ### 1. Simplified Type Declarations
@@ -91,16 +248,16 @@ func processData(input string) ET.Either[error, OPT.Option[int]] {
 **V2 Approach:**
 ```go
 import (
-    "github.com/IBM/fp-go/v2/either"
+    "github.com/IBM/fp-go/v2/result"
     "github.com/IBM/fp-go/v2/option"
 )
 
 // Define type aliases once
-type Either[A any] = either.Either[error, A]
+type Result[A any] = result.Result[A]
 type Option[A any] = option.Option[A]
 
 // Use them throughout your codebase
-func processData(input string) Either[Option[int]] {
+func processData(input string) Result[Option[int]] {
     // implementation
 }
 ```
@@ -230,20 +387,14 @@ Create project-wide type aliases for common patterns:
 package myapp
 
 import (
-    "github.com/IBM/fp-go/v2/either"
+    "github.com/IBM/fp-go/v2/result"
     "github.com/IBM/fp-go/v2/option"
-    "github.com/IBM/fp-go/v2/ioeither"
+    "github.com/IBM/fp-go/v2/ioresult"
 )
 
-type Either[A any] = either.Either[error, A]
+type Result[A any] = result.Result[A]
 type Option[A any] = option.Option[A]
-type IOEither[A any] = ioeither.IOEither[error, A]
+type IOResult[A any] = ioresult.IOResult[A]
-```
-
-## 📦 Installation
-
-```bash
-go get github.com/IBM/fp-go/v2
 ```
 
 ## 🆕 What's New
@@ -269,7 +420,7 @@ import (
 
 func process() IOET.IOEither[error, string] {
     return IOEG.Map[error, int, string](
-        func(x int) string { return fmt.Sprintf("%d", x) },
+        strconv.Itoa,
     )(fetchData())
 }
 ```
@@ -277,25 +428,37 @@ func process() IOET.IOEither[error, string] {
 **V2 Simplified Example:**
 ```go
 import (
-    "github.com/IBM/fp-go/v2/either"
+    "strconv"
-    "github.com/IBM/fp-go/v2/ioeither"
+    "github.com/IBM/fp-go/v2/ioresult"
 )
 
-type IOEither[A any] = ioeither.IOEither[error, A]
+type IOResult[A any] = ioresult.IOResult[A]
 
-func process() IOEither[string] {
+func process() IOResult[string] {
-    return ioeither.Map(
+    return ioresult.Map(
-        func(x int) string { return fmt.Sprintf("%d", x) },
+        strconv.Itoa,
     )(fetchData())
 }
 ```
 
-## 📚 Additional Resources
+## 📚 Documentation
 
-- [Main README](../README.md) - Core concepts and design philosophy
+- **[API Documentation](https://pkg.go.dev/github.com/IBM/fp-go/v2)** - Complete API reference
-- [API Documentation](https://pkg.go.dev/github.com/IBM/fp-go/v2)
+- **[Code Samples](./samples/)** - Practical examples and use cases
-- [Code Samples](../samples/)
+- **[Go 1.24 Release Notes](https://tip.golang.org/doc/go1.24)** - Information about generic type aliases
-- [Go 1.24 Release Notes](https://tip.golang.org/doc/go1.24)
+
+### Core Modules
+
+- **Option** - Represent optional values without nil
+- **Either** - Type-safe error handling with left/right values
+- **Result** - Simplified Either with error as left type
+- **IO** - Lazy evaluation and side effect management
+- **IOEither** - Combine IO with error handling
+- **Reader** - Dependency injection pattern
+- **ReaderIOEither** - Combine Reader, IO, and Either for complex workflows
+- **Array** - Functional array operations
+- **Record** - Functional record/map operations
+- **Optics** - Lens, Prism, Optional, and Traversal for immutable updates
 
 ## 🤔 Should I Migrate?
 
@@ -310,10 +473,25 @@ func process() IOEither[string] {
 - ⚠️ Migration effort outweighs benefits for your project
 - ⚠️ You need stability in production (V2 is newer)
 
+## 🤝 Contributing
+
+Contributions are welcome! Here's how you can help:
+
+1. **Report bugs** - Open an issue with a clear description and reproduction steps
+2. **Suggest features** - Share your ideas for improvements
+3. **Submit PRs** - Fix bugs or add features (please discuss major changes first)
+4. **Improve docs** - Help make the documentation clearer and more comprehensive
+
+Please read our contribution guidelines before submitting pull requests.
+
 ## 🐛 Issues and Feedback
 
 Found a bug or have a suggestion? Please [open an issue](https://github.com/IBM/fp-go/issues) on GitHub.
 
 ## 📄 License
 
-This project is licensed under the Apache License 2.0 - see the LICENSE file for details.
+This project is licensed under the Apache License 2.0. See the [LICENSE](https://github.com/IBM/fp-go/blob/main/LICENSE) file for details.
+
+---
+
+**Made with ❤️ by IBM**

v2/array/array.go

@@ -82,7 +82,7 @@ func MapWithIndex[A, B any](f func(int, A) B) func([]A) []B {
 //
 //go:inline
 func Map[A, B any](f func(a A) B) func([]A) []B {
-	return G.Map[[]A, []B, A, B](f)
+	return G.Map[[]A, []B](f)
 }
 
 // MapRef applies a function to a pointer to each element of an array, returning a new array with the results.
@@ -278,7 +278,7 @@ func Of[A any](a A) []A {
 //
 //go:inline
 func MonadChain[A, B any](fa []A, f func(a A) []B) []B {
-	return G.MonadChain[[]A, []B](fa, f)
+	return G.MonadChain(fa, f)
 }
 
 // Chain applies a function that returns an array to each element and flattens the results.
@@ -291,7 +291,7 @@ func MonadChain[A, B any](fa []A, f func(a A) []B) []B {
 //
 //go:inline
 func Chain[A, B any](f func(A) []B) func([]A) []B {
-	return G.Chain[[]A, []B](f)
+	return G.Chain[[]A](f)
 }
 
 // MonadAp applies an array of functions to an array of values, producing all combinations.
@@ -314,14 +314,14 @@ func Ap[B, A any](fa []A) func([]func(A) B) []B {
 //
 //go:inline
 func Match[A, B any](onEmpty func() B, onNonEmpty func([]A) B) func([]A) B {
-	return G.Match[[]A](onEmpty, onNonEmpty)
+	return G.Match(onEmpty, onNonEmpty)
 }
 
 // MatchLeft performs pattern matching on an array, calling onEmpty if empty or onNonEmpty with head and tail if not.
 //
 //go:inline
 func MatchLeft[A, B any](onEmpty func() B, onNonEmpty func(A, []A) B) func([]A) B {
-	return G.MatchLeft[[]A](onEmpty, onNonEmpty)
+	return G.MatchLeft(onEmpty, onNonEmpty)
 }
 
 // Tail returns all elements except the first, wrapped in an Option.
@@ -390,7 +390,7 @@ func Intersperse[A any](middle A) EM.Endomorphism[[]A] {
 // Intercalate inserts a separator between elements and concatenates them using a Monoid.
 func Intercalate[A any](m M.Monoid[A]) func(A) func([]A) A {
 	return func(middle A) func([]A) A {
-		return Match(m.Empty, F.Flow2(Intersperse(middle), ConcatAll[A](m)))
+		return Match(m.Empty, F.Flow2(Intersperse(middle), ConcatAll(m)))
 	}
 }
 
@@ -519,7 +519,7 @@ func Push[A any](a A) EM.Endomorphism[[]A] {
 //
 //go:inline
 func MonadFlap[B, A any](fab []func(A) B, a A) []B {
-	return G.MonadFlap[func(A) B, []func(A) B, []B, A, B](fab, a)
+	return G.MonadFlap[func(A) B, []func(A) B, []B](fab, a)
 }
 
 // Flap applies a value to an array of functions, producing an array of results.
@@ -527,7 +527,7 @@ func MonadFlap[B, A any](fab []func(A) B, a A) []B {
 //
 //go:inline
 func Flap[B, A any](a A) func([]func(A) B) []B {
-	return G.Flap[func(A) B, []func(A) B, []B, A, B](a)
+	return G.Flap[func(A) B, []func(A) B, []B](a)
 }
 
 // Prepend adds an element to the beginning of an array, returning a new array.

v2/array/array_test.go

@@ -97,7 +97,7 @@ func TestAp(t *testing.T) {
 				utils.Double,
 				utils.Triple,
 			},
-			Ap[int, int]([]int{1, 2, 3}),
+			Ap[int]([]int{1, 2, 3}),
 		),
 	)
 }

v2/array/bind.go

@@ -34,7 +34,7 @@ import (
 func Do[S any](
 	empty S,
 ) []S {
-	return G.Do[[]S, S](empty)
+	return G.Do[[]S](empty)
 }
 
 // Bind attaches the result of a computation to a context S1 to produce a context S2.
@@ -58,7 +58,7 @@ func Bind[S1, S2, T any](
 	setter func(T) func(S1) S2,
 	f func(S1) []T,
 ) func([]S1) []S2 {
-	return G.Bind[[]S1, []S2, []T, S1, S2, T](setter, f)
+	return G.Bind[[]S1, []S2](setter, f)
 }
 
 // Let attaches the result of a pure computation to a context S1 to produce a context S2.
@@ -80,7 +80,7 @@ func Let[S1, S2, T any](
 	setter func(T) func(S1) S2,
 	f func(S1) T,
 ) func([]S1) []S2 {
-	return G.Let[[]S1, []S2, S1, S2, T](setter, f)
+	return G.Let[[]S1, []S2](setter, f)
 }
 
 // LetTo attaches a constant value to a context S1 to produce a context S2.
@@ -102,7 +102,7 @@ func LetTo[S1, S2, T any](
 	setter func(T) func(S1) S2,
 	b T,
 ) func([]S1) []S2 {
-	return G.LetTo[[]S1, []S2, S1, S2, T](setter, b)
+	return G.LetTo[[]S1, []S2](setter, b)
 }
 
 // BindTo initializes a new state S1 from a value T.
@@ -121,7 +121,7 @@ func LetTo[S1, S2, T any](
 func BindTo[S1, T any](
 	setter func(T) S1,
 ) func([]T) []S1 {
-	return G.BindTo[[]S1, []T, S1, T](setter)
+	return G.BindTo[[]S1, []T](setter)
 }
 
 // ApS attaches a value to a context S1 to produce a context S2 by considering
@@ -144,5 +144,5 @@ func ApS[S1, S2, T any](
 	setter func(T) func(S1) S2,
 	fa []T,
 ) func([]S1) []S2 {
-	return G.ApS[[]S1, []S2, []T, S1, S2, T](setter, fa)
+	return G.ApS[[]S1, []S2](setter, fa)
 }

v2/array/examples_sort_test.go

@@ -87,6 +87,6 @@ func Example_sort() {
 	// [abc klm zyx]
 	// [zyx klm abc]
 	// [None[int] Some[int](42) Some[int](1337)]
-	// [{c {false 0}} {b {true 10}} {d {true 10}} {a {true 30}}]
+	// [{c {0 false}} {b {10 true}} {d {10 true}} {a {30 true}}]
 
 }

v2/array/generic/array.go

@@ -31,25 +31,25 @@ func Of[GA ~[]A, A any](value A) GA {
 
 func Reduce[GA ~[]A, A, B any](f func(B, A) B, initial B) func(GA) B {
 	return func(as GA) B {
-		return MonadReduce[GA](as, f, initial)
+		return MonadReduce(as, f, initial)
 	}
 }
 
 func ReduceWithIndex[GA ~[]A, A, B any](f func(int, B, A) B, initial B) func(GA) B {
 	return func(as GA) B {
-		return MonadReduceWithIndex[GA](as, f, initial)
+		return MonadReduceWithIndex(as, f, initial)
 	}
 }
 
 func ReduceRight[GA ~[]A, A, B any](f func(A, B) B, initial B) func(GA) B {
 	return func(as GA) B {
-		return MonadReduceRight[GA](as, f, initial)
+		return MonadReduceRight(as, f, initial)
 	}
 }
 
 func ReduceRightWithIndex[GA ~[]A, A, B any](f func(int, A, B) B, initial B) func(GA) B {
 	return func(as GA) B {
-		return MonadReduceRightWithIndex[GA](as, f, initial)
+		return MonadReduceRightWithIndex(as, f, initial)
 	}
 }
 

v2/array/generic/bind.go

@@ -21,14 +21,56 @@ import (
 	F "github.com/IBM/fp-go/v2/internal/functor"
 )
 
-// Bind creates an empty context of type [S] to be used with the [Bind] operation
+// 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.
+//
+// Example:
+//
+//	type State struct {
+//	    X int
+//	    Y int
+//	}
+//	result := generic.Do[[]State, State](State{})
 func Do[GS ~[]S, S any](
 	empty S,
 ) GS {
 	return Of[GS](empty)
 }
 
-// Bind attaches the result of a computation to a context [S1] to produce a context [S2]
+// 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.
+// For arrays, this produces the cartesian product where later steps can use values from earlier steps.
+//
+// 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 {
+//	    X int
+//	    Y int
+//	}
+//
+//	result := F.Pipe2(
+//	    generic.Do[[]State, State](State{}),
+//	    generic.Bind[[]State, []State, []int, State, State, int](
+//	        func(x int) func(State) State {
+//	            return func(s State) State { s.X = x; return s }
+//	        },
+//	        func(s State) []int {
+//	            return []int{1, 2, 3}
+//	        },
+//	    ),
+//	    generic.Bind[[]State, []State, []int, State, State, int](
+//	        func(y int) func(State) State {
+//	            return func(s State) State { s.Y = y; return s }
+//	        },
+//	        func(s State) []int {
+//	            // This can access s.X from the previous step
+//	            return []int{s.X * 10, s.X * 20}
+//	        },
+//	    ),
+//	) // Produces: {1,10}, {1,20}, {2,20}, {2,40}, {3,30}, {3,60}
 func Bind[GS1 ~[]S1, GS2 ~[]S2, GT ~[]T, S1, S2, T any](
 	setter func(T) func(S1) S2,
 	f func(S1) GT,
@@ -75,7 +117,39 @@ func BindTo[GS1 ~[]S1, GT ~[]T, S1, T any](
 	)
 }
 
-// ApS attaches a value to a context [S1] to produce a context [S2] by considering the context and the value concurrently
+// ApS attaches a value to a context [S1] to produce a context [S2] by considering
+// the context and the value concurrently (using Applicative rather than Monad).
+// This allows independent computations to be combined without one depending on the result of the other.
+//
+// Unlike Bind, which sequences operations, ApS can be used when operations are independent
+// and can conceptually run in parallel. For arrays, this produces the cartesian product.
+//
+// Example:
+//
+//	type State struct {
+//	    X int
+//	    Y string
+//	}
+//
+//	// These operations are independent and can be combined with ApS
+//	xValues := []int{1, 2}
+//	yValues := []string{"a", "b"}
+//
+//	result := F.Pipe2(
+//	    generic.Do[[]State, State](State{}),
+//	    generic.ApS[[]State, []State, []int, State, State, int](
+//	        func(x int) func(State) State {
+//	            return func(s State) State { s.X = x; return s }
+//	        },
+//	        xValues,
+//	    ),
+//	    generic.ApS[[]State, []State, []string, State, State, string](
+//	        func(y string) func(State) State {
+//	            return func(s State) State { s.Y = y; return s }
+//	        },
+//	        yValues,
+//	    ),
+//	) // [{1,"a"}, {1,"b"}, {2,"a"}, {2,"b"}]
 func ApS[GS1 ~[]S1, GS2 ~[]S2, GT ~[]T, S1, S2, T any](
 	setter func(T) func(S1) S2,
 	fa GT,

v2/array/generic/monad.go

@@ -22,19 +22,19 @@ import (
 type arrayMonad[A, B any, GA ~[]A, GB ~[]B, GAB ~[]func(A) B] struct{}
 
 func (o *arrayMonad[A, B, GA, GB, GAB]) Of(a A) GA {
-	return Of[GA, A](a)
+	return Of[GA](a)
 }
 
 func (o *arrayMonad[A, B, GA, GB, GAB]) Map(f func(A) B) func(GA) GB {
-	return Map[GA, GB, A, B](f)
+	return Map[GA, GB](f)
 }
 
 func (o *arrayMonad[A, B, GA, GB, GAB]) Chain(f func(A) GB) func(GA) GB {
-	return Chain[GA, GB, A, B](f)
+	return Chain[GA](f)
 }
 
 func (o *arrayMonad[A, B, GA, GB, GAB]) Ap(fa GA) func(GAB) GB {
-	return Ap[GB, GAB, GA, B, A](fa)
+	return Ap[GB, GAB](fa)
 }
 
 // Monad implements the monadic operations for an array

v2/array/nonempty/array.go

@@ -97,11 +97,11 @@ func Flatten[A any](mma NonEmptyArray[NonEmptyArray[A]]) NonEmptyArray[A] {
 }
 
 func MonadChain[A, B any](fa NonEmptyArray[A], f func(a A) NonEmptyArray[B]) NonEmptyArray[B] {
-	return G.MonadChain[NonEmptyArray[A], NonEmptyArray[B]](fa, f)
+	return G.MonadChain(fa, f)
 }
 
 func Chain[A, B any](f func(A) NonEmptyArray[B]) func(NonEmptyArray[A]) NonEmptyArray[B] {
-	return G.Chain[NonEmptyArray[A], NonEmptyArray[B]](f)
+	return G.Chain[NonEmptyArray[A]](f)
 }
 
 func MonadAp[B, A any](fab NonEmptyArray[func(A) B], fa NonEmptyArray[A]) NonEmptyArray[B] {

v2/array/sort.go

@@ -94,5 +94,5 @@ func SortByKey[K, T any](ord O.Ord[K], f func(T) K) func(ma []T) []T {
 //
 //go:inline
 func SortBy[T any](ord []O.Ord[T]) func(ma []T) []T {
-	return G.SortBy[[]T, []O.Ord[T]](ord)
+	return G.SortBy[[]T](ord)
 }

v2/array/uniq.go

@@ -18,7 +18,7 @@ import (
 //
 //go:inline
 func StrictUniq[A comparable](as []A) []A {
-	return G.StrictUniq[[]A](as)
+	return G.StrictUniq(as)
 }
 
 // Uniq converts an array of arbitrary items into an array of unique items

v2/array/zip.go

@@ -36,7 +36,7 @@ import (
 //
 //go:inline
 func ZipWith[FCT ~func(A, B) C, A, B, C any](fa []A, fb []B, f FCT) []C {
-	return G.ZipWith[[]A, []B, []C, FCT](fa, fb, f)
+	return G.ZipWith[[]A, []B, []C](fa, fb, f)
 }
 
 // Zip takes two arrays and returns an array of corresponding pairs (tuples).
@@ -79,5 +79,5 @@ func Zip[A, B any](fb []B) func([]A) []T.Tuple2[A, B] {
 //
 //go:inline
 func Unzip[A, B any](cs []T.Tuple2[A, B]) T.Tuple2[[]A, []B] {
-	return G.Unzip[[]A, []B, []T.Tuple2[A, B]](cs)
+	return G.Unzip[[]A, []B](cs)
 }

v2/assert/assert_test.go

@@ -19,8 +19,8 @@ import (
 	"fmt"
 	"testing"
 
-	E "github.com/IBM/fp-go/v2/either"
+	"github.com/IBM/fp-go/v2/eq"
-	EQ "github.com/IBM/fp-go/v2/eq"
+	"github.com/IBM/fp-go/v2/result"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -28,82 +28,82 @@ var (
 	errTest = fmt.Errorf("test failure")
 
 	// Eq is the equal predicate checking if objects are equal
-	Eq = EQ.FromEquals(assert.ObjectsAreEqual)
+	Eq = eq.FromEquals(assert.ObjectsAreEqual)
 )
 
-func wrap1[T any](wrapped func(t assert.TestingT, expected, actual any, msgAndArgs ...any) bool, t *testing.T, expected T) func(actual T) E.Either[error, T] {
+func wrap1[T any](wrapped func(t assert.TestingT, expected, actual any, msgAndArgs ...any) bool, t *testing.T, expected T) result.Kleisli[T, T] {
-	return func(actual T) E.Either[error, T] {
+	return func(actual T) Result[T] {
 		ok := wrapped(t, expected, actual)
 		if ok {
-			return E.Of[error](actual)
+			return result.Of(actual)
 		}
-		return E.Left[T](errTest)
+		return result.Left[T](errTest)
 	}
 }
 
 // NotEqual tests if the expected and the actual values are not equal
-func NotEqual[T any](t *testing.T, expected T) func(actual T) E.Either[error, T] {
+func NotEqual[T any](t *testing.T, expected T) result.Kleisli[T, T] {
 	return wrap1(assert.NotEqual, t, expected)
 }
 
 // Equal tests if the expected and the actual values are equal
-func Equal[T any](t *testing.T, expected T) func(actual T) E.Either[error, T] {
+func Equal[T any](t *testing.T, expected T) result.Kleisli[T, T] {
 	return wrap1(assert.Equal, t, expected)
 }
 
 // Length tests if an array has the expected length
-func Length[T any](t *testing.T, expected int) func(actual []T) E.Either[error, []T] {
+func Length[T any](t *testing.T, expected int) result.Kleisli[[]T, []T] {
-	return func(actual []T) E.Either[error, []T] {
+	return func(actual []T) Result[[]T] {
 		ok := assert.Len(t, actual, expected)
 		if ok {
-			return E.Of[error](actual)
+			return result.Of(actual)
 		}
-		return E.Left[[]T](errTest)
+		return result.Left[[]T](errTest)
 	}
 }
 
 // NoError validates that there is no error
-func NoError[T any](t *testing.T) func(actual E.Either[error, T]) E.Either[error, T] {
+func NoError[T any](t *testing.T) result.Operator[T, T] {
-	return func(actual E.Either[error, T]) E.Either[error, T] {
+	return func(actual Result[T]) Result[T] {
-		return E.MonadFold(actual, func(e error) E.Either[error, T] {
+		return result.MonadFold(actual, func(e error) Result[T] {
 			assert.NoError(t, e)
-			return E.Left[T](e)
+			return result.Left[T](e)
-		}, func(value T) E.Either[error, T] {
+		}, func(value T) Result[T] {
 			assert.NoError(t, nil)
-			return E.Right[error](value)
+			return result.Of(value)
 		})
 	}
 }
 
 // ArrayContains tests if a value is contained in an array
-func ArrayContains[T any](t *testing.T, expected T) func(actual []T) E.Either[error, []T] {
+func ArrayContains[T any](t *testing.T, expected T) result.Kleisli[[]T, []T] {
-	return func(actual []T) E.Either[error, []T] {
+	return func(actual []T) Result[[]T] {
 		ok := assert.Contains(t, actual, expected)
 		if ok {
-			return E.Of[error](actual)
+			return result.Of(actual)
 		}
-		return E.Left[[]T](errTest)
+		return result.Left[[]T](errTest)
 	}
 }
 
 // ContainsKey tests if a key is contained in a map
-func ContainsKey[T any, K comparable](t *testing.T, expected K) func(actual map[K]T) E.Either[error, map[K]T] {
+func ContainsKey[T any, K comparable](t *testing.T, expected K) result.Kleisli[map[K]T, map[K]T] {
-	return func(actual map[K]T) E.Either[error, map[K]T] {
+	return func(actual map[K]T) Result[map[K]T] {
 		ok := assert.Contains(t, actual, expected)
 		if ok {
-			return E.Of[error](actual)
+			return result.Of(actual)
 		}
-		return E.Left[map[K]T](errTest)
+		return result.Left[map[K]T](errTest)
 	}
 }
 
 // NotContainsKey tests if a key is not contained in a map
-func NotContainsKey[T any, K comparable](t *testing.T, expected K) func(actual map[K]T) E.Either[error, map[K]T] {
+func NotContainsKey[T any, K comparable](t *testing.T, expected K) result.Kleisli[map[K]T, map[K]T] {
-	return func(actual map[K]T) E.Either[error, map[K]T] {
+	return func(actual map[K]T) Result[map[K]T] {
 		ok := assert.NotContains(t, actual, expected)
 		if ok {
-			return E.Of[error](actual)
+			return result.Of(actual)
 		}
-		return E.Left[map[K]T](errTest)
+		return result.Left[map[K]T](errTest)
 	}
 }

v2/assert/types.go

@@ -0,0 +1,7 @@
+package assert
+
+import "github.com/IBM/fp-go/v2/result"
+
+type (
+	Result[T any] = result.Result[T]
+)

v2/bounded/bounded.go

@@ -53,7 +53,7 @@ func MakeBounded[T any](o ord.Ord[T], t, b T) Bounded[T] {
 
 // Clamp returns a function that clamps against the bounds defined in the bounded type
 func Clamp[T any](b Bounded[T]) func(T) T {
-	return ord.Clamp[T](b)(b.Bottom(), b.Top())
+	return ord.Clamp(b)(b.Bottom(), b.Top())
 }
 
 // Reverse reverses the ordering and swaps the bounds

v2/builder/builder.go

@@ -0,0 +1,7 @@
+package builder
+
+type (
+	Builder[T any] interface {
+		Build() Result[T]
+	}
+)

v2/builder/prism.go

@@ -0,0 +1,12 @@
+package builder
+
+import (
+	F "github.com/IBM/fp-go/v2/function"
+	"github.com/IBM/fp-go/v2/optics/prism"
+	"github.com/IBM/fp-go/v2/result"
+)
+
+// BuilderPrism createa a [Prism] that converts between a builder and its type
+func BuilderPrism[T any, B Builder[T]](creator func(T) B) Prism[B, T] {
+	return prism.MakePrism(F.Flow2(B.Build, result.ToOption[T]), creator)
+}

v2/builder/types.go

@@ -0,0 +1,15 @@
+package builder
+
+import (
+	"github.com/IBM/fp-go/v2/optics/prism"
+	"github.com/IBM/fp-go/v2/option"
+	"github.com/IBM/fp-go/v2/result"
+)
+
+type (
+	Result[T any] = result.Result[T]
+
+	Prism[S, A any] = prism.Prism[S, A]
+
+	Option[T any] = option.Option[T]
+)

v2/bytes/bytes.go

@@ -15,14 +15,163 @@
 
 package bytes
 
+// Empty returns an empty byte slice.
+//
+// This function returns the identity element for the byte slice Monoid,
+// which is an empty byte slice. It's useful as a starting point for
+// building byte slices or as a default value.
+//
+// Returns:
+//   - An empty byte slice ([]byte{})
+//
+// Properties:
+//   - Empty() is the identity element for Monoid.Concat
+//   - Monoid.Concat(Empty(), x) == x
+//   - Monoid.Concat(x, Empty()) == x
+//
+// Example - Basic usage:
+//
+//	empty := Empty()
+//	fmt.Println(len(empty)) // 0
+//
+// Example - As identity element:
+//
+//	data := []byte("hello")
+//	result1 := Monoid.Concat(Empty(), data) // []byte("hello")
+//	result2 := Monoid.Concat(data, Empty()) // []byte("hello")
+//
+// Example - Building byte slices:
+//
+//	// Start with empty and build up
+//	buffer := Empty()
+//	buffer = Monoid.Concat(buffer, []byte("Hello"))
+//	buffer = Monoid.Concat(buffer, []byte(" "))
+//	buffer = Monoid.Concat(buffer, []byte("World"))
+//	// buffer: []byte("Hello World")
+//
+// See also:
+//   - Monoid.Empty(): Alternative way to get empty byte slice
+//   - ConcatAll(): For concatenating multiple byte slices
 func Empty() []byte {
 	return Monoid.Empty()
 }
 
+// ToString converts a byte slice to a string.
+//
+// This function performs a direct conversion from []byte to string.
+// The conversion creates a new string with a copy of the byte data.
+//
+// Parameters:
+//   - a: The byte slice to convert
+//
+// Returns:
+//   - A string containing the same data as the byte slice
+//
+// Performance Note:
+//
+// This conversion allocates a new string. For performance-critical code
+// that needs to avoid allocations, consider using unsafe.String (Go 1.20+)
+// or working directly with byte slices.
+//
+// Example - Basic conversion:
+//
+//	bytes := []byte("hello")
+//	str := ToString(bytes)
+//	fmt.Println(str) // "hello"
+//
+// Example - Converting binary data:
+//
+//	// ASCII codes for "Hello"
+//	data := []byte{0x48, 0x65, 0x6c, 0x6c, 0x6f}
+//	str := ToString(data)
+//	fmt.Println(str) // "Hello"
+//
+// Example - Empty byte slice:
+//
+//	empty := Empty()
+//	str := ToString(empty)
+//	fmt.Println(str == "") // true
+//
+// Example - UTF-8 encoded text:
+//
+//	utf8Bytes := []byte("Hello, 世界")
+//	str := ToString(utf8Bytes)
+//	fmt.Println(str) // "Hello, 世界"
+//
+// Example - Round-trip conversion:
+//
+//	original := "test string"
+//	bytes := []byte(original)
+//	result := ToString(bytes)
+//	fmt.Println(original == result) // true
+//
+// See also:
+//   - []byte(string): For converting string to byte slice
+//   - Size(): For getting the length of a byte slice
 func ToString(a []byte) string {
 	return string(a)
 }
 
+// Size returns the number of bytes in a byte slice.
+//
+// This function returns the length of the byte slice, which is the number
+// of bytes it contains. This is equivalent to len(as) but provided as a
+// named function for use in functional composition.
+//
+// Parameters:
+//   - as: The byte slice to measure
+//
+// Returns:
+//   - The number of bytes in the slice
+//
+// Example - Basic usage:
+//
+//	data := []byte("hello")
+//	size := Size(data)
+//	fmt.Println(size) // 5
+//
+// Example - Empty slice:
+//
+//	empty := Empty()
+//	size := Size(empty)
+//	fmt.Println(size) // 0
+//
+// Example - Binary data:
+//
+//	binary := []byte{0x01, 0x02, 0x03, 0x04}
+//	size := Size(binary)
+//	fmt.Println(size) // 4
+//
+// Example - UTF-8 encoded text:
+//
+//	// Note: Size returns byte count, not character count
+//	utf8 := []byte("Hello, 世界")
+//	byteCount := Size(utf8)
+//	fmt.Println(byteCount) // 13 (not 9 characters)
+//
+// Example - Using in functional composition:
+//
+//	import "github.com/IBM/fp-go/v2/array"
+//
+//	slices := [][]byte{
+//	    []byte("a"),
+//	    []byte("bb"),
+//	    []byte("ccc"),
+//	}
+//
+//	// Map to get sizes
+//	sizes := array.Map(Size)(slices)
+//	// sizes: []int{1, 2, 3}
+//
+// Example - Checking if slice is empty:
+//
+//	data := []byte("test")
+//	isEmpty := Size(data) == 0
+//	fmt.Println(isEmpty) // false
+//
+// See also:
+//   - len(): Built-in function for getting slice length
+//   - ToString(): For converting byte slice to string
 func Size(as []byte) int {
 	return len(as)
 }

v2/bytes/bytes_test.go

@@ -187,6 +187,299 @@ func TestOrd(t *testing.T) {
 	})
 }
 
+// TestOrdProperties tests mathematical properties of Ord
+func TestOrdProperties(t *testing.T) {
+	t.Run("reflexivity: x == x", func(t *testing.T) {
+		testCases := [][]byte{
+			[]byte{},
+			[]byte("a"),
+			[]byte("test"),
+			[]byte{0x01, 0x02, 0x03},
+		}
+
+		for _, tc := range testCases {
+			assert.Equal(t, 0, Ord.Compare(tc, tc),
+				"Compare(%v, %v) should be 0", tc, tc)
+			assert.True(t, Ord.Equals(tc, tc),
+				"Equals(%v, %v) should be true", tc, tc)
+		}
+	})
+
+	t.Run("antisymmetry: if x <= y and y <= x then x == y", func(t *testing.T) {
+		testCases := []struct {
+			a, b []byte
+		}{
+			{[]byte("abc"), []byte("abc")},
+			{[]byte{}, []byte{}},
+			{[]byte{0x01}, []byte{0x01}},
+		}
+
+		for _, tc := range testCases {
+			cmp1 := Ord.Compare(tc.a, tc.b)
+			cmp2 := Ord.Compare(tc.b, tc.a)
+
+			if cmp1 <= 0 && cmp2 <= 0 {
+				assert.True(t, Ord.Equals(tc.a, tc.b),
+					"If %v <= %v and %v <= %v, they should be equal", tc.a, tc.b, tc.b, tc.a)
+			}
+		}
+	})
+
+	t.Run("transitivity: if x <= y and y <= z then x <= z", func(t *testing.T) {
+		x := []byte("a")
+		y := []byte("b")
+		z := []byte("c")
+
+		cmpXY := Ord.Compare(x, y)
+		cmpYZ := Ord.Compare(y, z)
+		cmpXZ := Ord.Compare(x, z)
+
+		if cmpXY <= 0 && cmpYZ <= 0 {
+			assert.True(t, cmpXZ <= 0,
+				"If %v <= %v and %v <= %v, then %v <= %v", x, y, y, z, x, z)
+		}
+	})
+
+	t.Run("totality: either x <= y or y <= x", func(t *testing.T) {
+		testCases := []struct {
+			a, b []byte
+		}{
+			{[]byte("abc"), []byte("abd")},
+			{[]byte("xyz"), []byte("abc")},
+			{[]byte{}, []byte("a")},
+			{[]byte{0x01}, []byte{0x02}},
+		}
+
+		for _, tc := range testCases {
+			cmp1 := Ord.Compare(tc.a, tc.b)
+			cmp2 := Ord.Compare(tc.b, tc.a)
+
+			assert.True(t, cmp1 <= 0 || cmp2 <= 0,
+				"Either %v <= %v or %v <= %v must be true", tc.a, tc.b, tc.b, tc.a)
+		}
+	})
+}
+
+// TestEdgeCases tests edge cases and boundary conditions
+func TestEdgeCases(t *testing.T) {
+	t.Run("very large byte slices", func(t *testing.T) {
+		large := make([]byte, 1000000)
+		for i := range large {
+			large[i] = byte(i % 256)
+		}
+
+		size := Size(large)
+		assert.Equal(t, 1000000, size)
+
+		str := ToString(large)
+		assert.Equal(t, 1000000, len(str))
+	})
+
+	t.Run("concatenating many slices", func(t *testing.T) {
+		slices := make([][]byte, 100)
+		for i := range slices {
+			slices[i] = []byte{byte(i)}
+		}
+
+		result := ConcatAll(slices...)
+		assert.Equal(t, 100, Size(result))
+	})
+
+	t.Run("null bytes in slice", func(t *testing.T) {
+		data := []byte{0x00, 0x01, 0x00, 0x02}
+		size := Size(data)
+		assert.Equal(t, 4, size)
+
+		str := ToString(data)
+		assert.Equal(t, 4, len(str))
+	})
+
+	t.Run("comparing slices with null bytes", func(t *testing.T) {
+		a := []byte{0x00, 0x01}
+		b := []byte{0x00, 0x02}
+		assert.Equal(t, -1, Ord.Compare(a, b))
+	})
+}
+
+// TestMonoidConcatPerformance tests concatenation performance characteristics
+func TestMonoidConcatPerformance(t *testing.T) {
+	t.Run("ConcatAll vs repeated Concat", func(t *testing.T) {
+		slices := [][]byte{
+			[]byte("a"),
+			[]byte("b"),
+			[]byte("c"),
+			[]byte("d"),
+			[]byte("e"),
+		}
+
+		// Using ConcatAll
+		result1 := ConcatAll(slices...)
+
+		// Using repeated Concat
+		result2 := Monoid.Empty()
+		for _, s := range slices {
+			result2 = Monoid.Concat(result2, s)
+		}
+
+		assert.Equal(t, result1, result2)
+		assert.Equal(t, []byte("abcde"), result1)
+	})
+}
+
+// TestRoundTrip tests round-trip conversions
+func TestRoundTrip(t *testing.T) {
+	t.Run("string to bytes to string", func(t *testing.T) {
+		original := "Hello, World! 世界"
+		bytes := []byte(original)
+		result := ToString(bytes)
+		assert.Equal(t, original, result)
+	})
+
+	t.Run("bytes to string to bytes", func(t *testing.T) {
+		original := []byte{0x48, 0x65, 0x6c, 0x6c, 0x6f}
+		str := ToString(original)
+		result := []byte(str)
+		assert.Equal(t, original, result)
+	})
+}
+
+// TestConcatAllVariadic tests ConcatAll with various argument counts
+func TestConcatAllVariadic(t *testing.T) {
+	t.Run("zero arguments", func(t *testing.T) {
+		result := ConcatAll()
+		assert.Equal(t, []byte{}, result)
+	})
+
+	t.Run("one argument", func(t *testing.T) {
+		result := ConcatAll([]byte("test"))
+		assert.Equal(t, []byte("test"), result)
+	})
+
+	t.Run("two arguments", func(t *testing.T) {
+		result := ConcatAll([]byte("hello"), []byte("world"))
+		assert.Equal(t, []byte("helloworld"), result)
+	})
+
+	t.Run("many arguments", func(t *testing.T) {
+		result := ConcatAll(
+			[]byte("a"),
+			[]byte("b"),
+			[]byte("c"),
+			[]byte("d"),
+			[]byte("e"),
+			[]byte("f"),
+			[]byte("g"),
+			[]byte("h"),
+			[]byte("i"),
+			[]byte("j"),
+		)
+		assert.Equal(t, []byte("abcdefghij"), result)
+	})
+}
+
+// Benchmark tests
+func BenchmarkToString(b *testing.B) {
+	data := []byte("Hello, World!")
+
+	b.Run("small", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			_ = ToString(data)
+		}
+	})
+
+	b.Run("large", func(b *testing.B) {
+		large := make([]byte, 10000)
+		for i := range large {
+			large[i] = byte(i % 256)
+		}
+		b.ResetTimer()
+		for i := 0; i < b.N; i++ {
+			_ = ToString(large)
+		}
+	})
+}
+
+func BenchmarkSize(b *testing.B) {
+	data := []byte("Hello, World!")
+
+	for i := 0; i < b.N; i++ {
+		_ = Size(data)
+	}
+}
+
+func BenchmarkMonoidConcat(b *testing.B) {
+	a := []byte("Hello")
+	c := []byte(" World")
+
+	b.Run("small slices", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			_ = Monoid.Concat(a, c)
+		}
+	})
+
+	b.Run("large slices", func(b *testing.B) {
+		large1 := make([]byte, 10000)
+		large2 := make([]byte, 10000)
+		b.ResetTimer()
+		for i := 0; i < b.N; i++ {
+			_ = Monoid.Concat(large1, large2)
+		}
+	})
+}
+
+func BenchmarkConcatAll(b *testing.B) {
+	slices := [][]byte{
+		[]byte("Hello"),
+		[]byte(" "),
+		[]byte("World"),
+		[]byte("!"),
+	}
+
+	b.Run("few slices", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			_ = ConcatAll(slices...)
+		}
+	})
+
+	b.Run("many slices", func(b *testing.B) {
+		many := make([][]byte, 100)
+		for i := range many {
+			many[i] = []byte{byte(i)}
+		}
+		b.ResetTimer()
+		for i := 0; i < b.N; i++ {
+			_ = ConcatAll(many...)
+		}
+	})
+}
+
+func BenchmarkOrdCompare(b *testing.B) {
+	a := []byte("abc")
+	c := []byte("abd")
+
+	b.Run("equal", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			_ = Ord.Compare(a, a)
+		}
+	})
+
+	b.Run("different", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			_ = Ord.Compare(a, c)
+		}
+	})
+
+	b.Run("large slices", func(b *testing.B) {
+		large1 := make([]byte, 10000)
+		large2 := make([]byte, 10000)
+		large2[9999] = 1
+		b.ResetTimer()
+		for i := 0; i < b.N; i++ {
+			_ = Ord.Compare(large1, large2)
+		}
+	})
+}
+
 // Example tests
 func ExampleEmpty() {
 	empty := Empty()
@@ -219,3 +512,17 @@ func ExampleConcatAll() {
 
 	// Output:
 }
+
+func ExampleMonoid_concat() {
+	result := Monoid.Concat([]byte("Hello"), []byte(" World"))
+	println(string(result)) // Hello World
+
+	// Output:
+}
+
+func ExampleOrd_compare() {
+	cmp := Ord.Compare([]byte("abc"), []byte("abd"))
+	println(cmp) // -1 (abc < abd)
+
+	// Output:
+}

v2/bytes/coverage.out

@@ -0,0 +1,4 @@
+mode: set
+github.com/IBM/fp-go/v2/bytes/bytes.go:55.21,57.2 1 1
+github.com/IBM/fp-go/v2/bytes/bytes.go:111.32,113.2 1 1
+github.com/IBM/fp-go/v2/bytes/bytes.go:175.26,177.2 1 1

v2/bytes/monoid.go

@@ -23,12 +23,219 @@ import (
 )
 
 var (
-	// monoid for byte arrays
+	// Monoid is the Monoid instance for byte slices.
+	//
+	// This Monoid combines byte slices through concatenation, with an empty
+	// byte slice as the identity element. It satisfies the monoid laws:
+	//
+	// Identity laws:
+	//   - Monoid.Concat(Monoid.Empty(), x) == x (left identity)
+	//   - Monoid.Concat(x, Monoid.Empty()) == x (right identity)
+	//
+	// Associativity law:
+	//   - Monoid.Concat(Monoid.Concat(a, b), c) == Monoid.Concat(a, Monoid.Concat(b, c))
+	//
+	// Operations:
+	//   - Empty(): Returns an empty byte slice []byte{}
+	//   - Concat(a, b []byte): Concatenates two byte slices
+	//
+	// Example - Basic concatenation:
+	//
+	//	result := Monoid.Concat([]byte("Hello"), []byte(" World"))
+	//	// result: []byte("Hello World")
+	//
+	// Example - Identity element:
+	//
+	//	empty := Monoid.Empty()
+	//	data := []byte("test")
+	//	result1 := Monoid.Concat(empty, data) // []byte("test")
+	//	result2 := Monoid.Concat(data, empty) // []byte("test")
+	//
+	// Example - Building byte buffers:
+	//
+	//	buffer := Monoid.Empty()
+	//	buffer = Monoid.Concat(buffer, []byte("Line 1\n"))
+	//	buffer = Monoid.Concat(buffer, []byte("Line 2\n"))
+	//	buffer = Monoid.Concat(buffer, []byte("Line 3\n"))
+	//
+	// Example - Associativity:
+	//
+	//	a := []byte("a")
+	//	b := []byte("b")
+	//	c := []byte("c")
+	//	left := Monoid.Concat(Monoid.Concat(a, b), c)   // []byte("abc")
+	//	right := Monoid.Concat(a, Monoid.Concat(b, c))  // []byte("abc")
+	//	// left == right
+	//
+	// See also:
+	//   - ConcatAll: For concatenating multiple byte slices at once
+	//   - Empty(): Convenience function for getting empty byte slice
 	Monoid = A.Monoid[byte]()
 
-	// ConcatAll concatenates all bytes
+	// ConcatAll efficiently concatenates multiple byte slices into a single slice.
+	//
+	// This function takes a variadic number of byte slices and combines them
+	// into a single byte slice. It pre-allocates the exact amount of memory
+	// needed, making it more efficient than repeated concatenation.
+	//
+	// Parameters:
+	//   - slices: Zero or more byte slices to concatenate
+	//
+	// Returns:
+	//   - A new byte slice containing all input slices concatenated in order
+	//
+	// Performance:
+	//
+	// ConcatAll is more efficient than using Monoid.Concat repeatedly because
+	// it calculates the total size upfront and allocates memory once, avoiding
+	// multiple allocations and copies.
+	//
+	// Example - Basic usage:
+	//
+	//	result := ConcatAll(
+	//	    []byte("Hello"),
+	//	    []byte(" "),
+	//	    []byte("World"),
+	//	)
+	//	// result: []byte("Hello World")
+	//
+	// Example - Empty input:
+	//
+	//	result := ConcatAll()
+	//	// result: []byte{}
+	//
+	// Example - Single slice:
+	//
+	//	result := ConcatAll([]byte("test"))
+	//	// result: []byte("test")
+	//
+	// Example - Building protocol messages:
+	//
+	//	import "encoding/binary"
+	//
+	//	header := []byte{0x01, 0x02}
+	//	length := make([]byte, 4)
+	//	binary.BigEndian.PutUint32(length, 100)
+	//	payload := []byte("data")
+	//	footer := []byte{0xFF}
+	//
+	//	message := ConcatAll(header, length, payload, footer)
+	//
+	// Example - With empty slices:
+	//
+	//	result := ConcatAll(
+	//	    []byte("a"),
+	//	    []byte{},
+	//	    []byte("b"),
+	//	    []byte{},
+	//	    []byte("c"),
+	//	)
+	//	// result: []byte("abc")
+	//
+	// Example - Building CSV line:
+	//
+	//	fields := [][]byte{
+	//	    []byte("John"),
+	//	    []byte("Doe"),
+	//	    []byte("30"),
+	//	}
+	//	separator := []byte(",")
+	//
+	//	// Interleave fields with separators
+	//	parts := [][]byte{
+	//	    fields[0], separator,
+	//	    fields[1], separator,
+	//	    fields[2],
+	//	}
+	//	line := ConcatAll(parts...)
+	//	// line: []byte("John,Doe,30")
+	//
+	// See also:
+	//   - Monoid.Concat: For concatenating exactly two byte slices
+	//   - bytes.Join: Standard library function for joining with separator
 	ConcatAll = A.ArrayConcatAll[byte]
 
-	// Ord implements the default ordering on bytes
+	// Ord is the Ord instance for byte slices providing lexicographic ordering.
+	//
+	// This Ord instance compares byte slices lexicographically (dictionary order),
+	// comparing bytes from left to right until a difference is found or one slice
+	// ends. It uses the standard library's bytes.Compare and bytes.Equal functions.
+	//
+	// Comparison rules:
+	//   - Compares byte-by-byte from left to right
+	//   - First differing byte determines the order
+	//   - Shorter slice is less than longer slice if all bytes match
+	//   - Empty slice is less than any non-empty slice
+	//
+	// Operations:
+	//   - Compare(a, b []byte) int: Returns -1 if a < b, 0 if a == b, 1 if a > b
+	//   - Equals(a, b []byte) bool: Returns true if slices are equal
+	//
+	// Example - Basic comparison:
+	//
+	//	cmp := Ord.Compare([]byte("abc"), []byte("abd"))
+	//	// cmp: -1 (abc < abd)
+	//
+	//	cmp = Ord.Compare([]byte("xyz"), []byte("abc"))
+	//	// cmp: 1 (xyz > abc)
+	//
+	//	cmp = Ord.Compare([]byte("test"), []byte("test"))
+	//	// cmp: 0 (equal)
+	//
+	// Example - Length differences:
+	//
+	//	cmp := Ord.Compare([]byte("ab"), []byte("abc"))
+	//	// cmp: -1 (shorter is less)
+	//
+	//	cmp = Ord.Compare([]byte("abc"), []byte("ab"))
+	//	// cmp: 1 (longer is greater)
+	//
+	// Example - Empty slices:
+	//
+	//	cmp := Ord.Compare([]byte{}, []byte("a"))
+	//	// cmp: -1 (empty is less)
+	//
+	//	cmp = Ord.Compare([]byte{}, []byte{})
+	//	// cmp: 0 (both empty)
+	//
+	// Example - Equality check:
+	//
+	//	equal := Ord.Equals([]byte("test"), []byte("test"))
+	//	// equal: true
+	//
+	//	equal = Ord.Equals([]byte("test"), []byte("Test"))
+	//	// equal: false (case-sensitive)
+	//
+	// Example - Sorting byte slices:
+	//
+	//	import "github.com/IBM/fp-go/v2/array"
+	//
+	//	data := [][]byte{
+	//	    []byte("zebra"),
+	//	    []byte("apple"),
+	//	    []byte("mango"),
+	//	}
+	//
+	//	sorted := array.Sort(Ord)(data)
+	//	// sorted: [[]byte("apple"), []byte("mango"), []byte("zebra")]
+	//
+	// Example - Binary data comparison:
+	//
+	//	cmp := Ord.Compare([]byte{0x01, 0x02}, []byte{0x01, 0x03})
+	//	// cmp: -1 (0x02 < 0x03)
+	//
+	// Example - Finding minimum:
+	//
+	//	import O "github.com/IBM/fp-go/v2/ord"
+	//
+	//	a := []byte("xyz")
+	//	b := []byte("abc")
+	//	min := O.Min(Ord)(a, b)
+	//	// min: []byte("abc")
+	//
+	// See also:
+	//   - bytes.Compare: Standard library comparison function
+	//   - bytes.Equal: Standard library equality function
+	//   - array.Sort: For sorting slices using an Ord instance
 	Ord = O.MakeOrd(bytes.Compare, bytes.Equal)
 )

v2/cli/commands.go

@@ -35,5 +35,6 @@ func Commands() []*C.Command {
 		IOCommand(),
 		IOOptionCommand(),
 		DICommand(),
+		LensCommand(),
 	}
 }

v2/cli/lens.go

@@ -0,0 +1,645 @@
+// 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 cli
+
+import (
+	"bytes"
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"log"
+	"os"
+	"path/filepath"
+	"reflect"
+	"strings"
+	"text/template"
+
+	C "github.com/urfave/cli/v2"
+)
+
+const (
+	keyLensDir     = "dir"
+	keyVerbose     = "verbose"
+	lensAnnotation = "fp-go:Lens"
+)
+
+var (
+	flagLensDir = &C.StringFlag{
+		Name:  keyLensDir,
+		Value: ".",
+		Usage: "Directory to scan for Go files",
+	}
+
+	flagVerbose = &C.BoolFlag{
+		Name:    keyVerbose,
+		Aliases: []string{"v"},
+		Value:   false,
+		Usage:   "Enable verbose output",
+	}
+)
+
+// structInfo holds information about a struct that needs lens generation
+type structInfo struct {
+	Name    string
+	Fields  []fieldInfo
+	Imports map[string]string // package path -> alias
+}
+
+// fieldInfo holds information about a struct field
+type fieldInfo struct {
+	Name         string
+	TypeName     string
+	BaseType     string // TypeName without leading * for pointer types
+	IsOptional   bool   // true if field is a pointer or has json omitempty tag
+	IsComparable bool   // true if the type is comparable (can use ==)
+}
+
+// templateData holds data for template rendering
+type templateData struct {
+	PackageName string
+	Structs     []structInfo
+}
+
+const lensStructTemplate = `
+// {{.Name}}Lenses provides lenses for accessing fields of {{.Name}}
+type {{.Name}}Lenses struct {
+{{- range .Fields}}
+	{{.Name}} {{if .IsOptional}}LO.LensO[{{$.Name}}, {{.TypeName}}]{{else}}L.Lens[{{$.Name}}, {{.TypeName}}]{{end}}
+{{- end}}
+}
+
+// {{.Name}}RefLenses provides lenses for accessing fields of {{.Name}} via a reference to {{.Name}}
+type {{.Name}}RefLenses struct {
+{{- range .Fields}}
+	{{.Name}} {{if .IsOptional}}LO.LensO[*{{$.Name}}, {{.TypeName}}]{{else}}L.Lens[*{{$.Name}}, {{.TypeName}}]{{end}}
+{{- end}}
+}
+`
+
+const lensConstructorTemplate = `
+// Make{{.Name}}Lenses creates a new {{.Name}}Lenses with lenses for all fields
+func Make{{.Name}}Lenses() {{.Name}}Lenses {
+{{- range .Fields}}
+{{- if .IsOptional}}
+	iso{{.Name}} := I.FromZero[{{.TypeName}}]()
+{{- end}}
+{{- end}}
+	return {{.Name}}Lenses{
+{{- range .Fields}}
+{{- if .IsOptional}}
+		{{.Name}}: L.MakeLens(
+			func(s {{$.Name}}) O.Option[{{.TypeName}}] { return iso{{.Name}}.Get(s.{{.Name}}) },
+			func(s {{$.Name}}, v O.Option[{{.TypeName}}]) {{$.Name}} { s.{{.Name}} = iso{{.Name}}.ReverseGet(v); return s },
+		),
+{{- else}}
+		{{.Name}}: L.MakeLens(
+			func(s {{$.Name}}) {{.TypeName}} { return s.{{.Name}} },
+			func(s {{$.Name}}, v {{.TypeName}}) {{$.Name}} { s.{{.Name}} = v; return s },
+		),
+{{- end}}
+{{- end}}
+	}
+}
+
+// Make{{.Name}}RefLenses creates a new {{.Name}}RefLenses with lenses for all fields
+func Make{{.Name}}RefLenses() {{.Name}}RefLenses {
+	return {{.Name}}RefLenses{
+{{- range .Fields}}
+{{- if .IsOptional}}
+{{- if .IsComparable}}
+		{{.Name}}: LO.FromIso[*{{$.Name}}](I.FromZero[{{.TypeName}}]())(L.MakeLensStrict(
+			func(s *{{$.Name}}) {{.TypeName}} { return s.{{.Name}} },
+			func(s *{{$.Name}}, v {{.TypeName}}) *{{$.Name}} { s.{{.Name}} = v; return s },
+		)),
+{{- else}}
+		{{.Name}}: LO.FromIso[*{{$.Name}}](I.FromZero[{{.TypeName}}]())(L.MakeLensRef(
+			func(s *{{$.Name}}) {{.TypeName}} { return s.{{.Name}} },
+			func(s *{{$.Name}}, v {{.TypeName}}) *{{$.Name}} { s.{{.Name}} = v; return s },
+		)),
+{{- end}}
+{{- else}}
+{{- if .IsComparable}}
+		{{.Name}}: L.MakeLensStrict(
+			func(s *{{$.Name}}) {{.TypeName}} { return s.{{.Name}} },
+			func(s *{{$.Name}}, v {{.TypeName}}) *{{$.Name}} { s.{{.Name}} = v; return s },
+		),
+{{- else}}
+		{{.Name}}: L.MakeLensRef(
+			func(s *{{$.Name}}) {{.TypeName}} { return s.{{.Name}} },
+			func(s *{{$.Name}}, v {{.TypeName}}) *{{$.Name}} { s.{{.Name}} = v; return s },
+		),
+{{- end}}
+{{- end}}
+{{- end}}
+	}
+}
+`
+
+var (
+	structTmpl      *template.Template
+	constructorTmpl *template.Template
+)
+
+func init() {
+	var err error
+	structTmpl, err = template.New("struct").Parse(lensStructTemplate)
+	if err != nil {
+		panic(err)
+	}
+	constructorTmpl, err = template.New("constructor").Parse(lensConstructorTemplate)
+	if err != nil {
+		panic(err)
+	}
+}
+
+// hasLensAnnotation checks if a comment group contains the lens annotation
+func hasLensAnnotation(doc *ast.CommentGroup) bool {
+	if doc == nil {
+		return false
+	}
+	for _, comment := range doc.List {
+		if strings.Contains(comment.Text, lensAnnotation) {
+			return true
+		}
+	}
+	return false
+}
+
+// getTypeName extracts the type name from a field type expression
+func getTypeName(expr ast.Expr) string {
+	switch t := expr.(type) {
+	case *ast.Ident:
+		return t.Name
+	case *ast.StarExpr:
+		return "*" + getTypeName(t.X)
+	case *ast.ArrayType:
+		return "[]" + getTypeName(t.Elt)
+	case *ast.MapType:
+		return "map[" + getTypeName(t.Key) + "]" + getTypeName(t.Value)
+	case *ast.SelectorExpr:
+		return getTypeName(t.X) + "." + t.Sel.Name
+	case *ast.InterfaceType:
+		return "interface{}"
+	case *ast.IndexExpr:
+		// Generic type with single type parameter (Go 1.18+)
+		// e.g., Option[string]
+		return getTypeName(t.X) + "[" + getTypeName(t.Index) + "]"
+	case *ast.IndexListExpr:
+		// Generic type with multiple type parameters (Go 1.18+)
+		// e.g., Map[string, int]
+		var params []string
+		for _, index := range t.Indices {
+			params = append(params, getTypeName(index))
+		}
+		return getTypeName(t.X) + "[" + strings.Join(params, ", ") + "]"
+	default:
+		return "any"
+	}
+}
+
+// extractImports extracts package imports from a type expression
+// Returns a map of package path -> package name
+func extractImports(expr ast.Expr, imports map[string]string) {
+	switch t := expr.(type) {
+	case *ast.StarExpr:
+		extractImports(t.X, imports)
+	case *ast.ArrayType:
+		extractImports(t.Elt, imports)
+	case *ast.MapType:
+		extractImports(t.Key, imports)
+		extractImports(t.Value, imports)
+	case *ast.SelectorExpr:
+		// This is a qualified identifier like "option.Option"
+		if ident, ok := t.X.(*ast.Ident); ok {
+			// ident.Name is the package name (e.g., "option")
+			// We need to track this for import resolution
+			imports[ident.Name] = ident.Name
+		}
+	case *ast.IndexExpr:
+		// Generic type with single type parameter
+		extractImports(t.X, imports)
+		extractImports(t.Index, imports)
+	case *ast.IndexListExpr:
+		// Generic type with multiple type parameters
+		extractImports(t.X, imports)
+		for _, index := range t.Indices {
+			extractImports(index, imports)
+		}
+	}
+}
+
+// hasOmitEmpty checks if a struct tag contains json omitempty
+func hasOmitEmpty(tag *ast.BasicLit) bool {
+	if tag == nil {
+		return false
+	}
+	// Parse the struct tag
+	tagValue := strings.Trim(tag.Value, "`")
+	structTag := reflect.StructTag(tagValue)
+	jsonTag := structTag.Get("json")
+
+	// Check if omitempty is present
+	parts := strings.Split(jsonTag, ",")
+	for _, part := range parts {
+		if strings.TrimSpace(part) == "omitempty" {
+			return true
+		}
+	}
+	return false
+}
+
+// isPointerType checks if a type expression is a pointer
+func isPointerType(expr ast.Expr) bool {
+	_, ok := expr.(*ast.StarExpr)
+	return ok
+}
+
+// isComparableType checks if a type expression represents a comparable type.
+// Comparable types in Go include:
+// - Basic types (bool, numeric types, string)
+// - Pointer types
+// - Channel types
+// - Interface types
+// - Structs where all fields are comparable
+// - Arrays where the element type is comparable
+//
+// Non-comparable types include:
+// - Slices
+// - Maps
+// - Functions
+func isComparableType(expr ast.Expr) bool {
+	switch t := expr.(type) {
+	case *ast.Ident:
+		// Basic types and named types
+		// We assume named types are comparable unless they're known non-comparable types
+		name := t.Name
+		// Known non-comparable built-in types
+		if name == "error" {
+			// error is an interface, which is comparable
+			return true
+		}
+		// Most basic types and named types are comparable
+		// We can't determine if a custom type is comparable without type checking,
+		// so we assume it is (conservative approach)
+		return true
+	case *ast.StarExpr:
+		// Pointer types are always comparable
+		return true
+	case *ast.ArrayType:
+		// Arrays are comparable if their element type is comparable
+		if t.Len == nil {
+			// This is a slice (no length), slices are not comparable
+			return false
+		}
+		// Fixed-size array, check element type
+		return isComparableType(t.Elt)
+	case *ast.MapType:
+		// Maps are not comparable
+		return false
+	case *ast.FuncType:
+		// Functions are not comparable
+		return false
+	case *ast.InterfaceType:
+		// Interface types are comparable
+		return true
+	case *ast.StructType:
+		// Structs are comparable if all fields are comparable
+		// We can't easily determine this without full type information,
+		// so we conservatively return false for struct literals
+		return false
+	case *ast.SelectorExpr:
+		// Qualified identifier (e.g., pkg.Type)
+		// We can't determine comparability without type information
+		// Check for known non-comparable types from standard library
+		if ident, ok := t.X.(*ast.Ident); ok {
+			pkgName := ident.Name
+			typeName := t.Sel.Name
+			// Check for known non-comparable types
+			if pkgName == "context" && typeName == "Context" {
+				// context.Context is an interface, which is comparable
+				return true
+			}
+			// For other qualified types, we assume they're comparable
+			// This is a conservative approach
+		}
+		return true
+	case *ast.IndexExpr, *ast.IndexListExpr:
+		// Generic types - we can't determine comparability without type information
+		// For common generic types, we can make educated guesses
+		var baseExpr ast.Expr
+		if idx, ok := t.(*ast.IndexExpr); ok {
+			baseExpr = idx.X
+		} else if idxList, ok := t.(*ast.IndexListExpr); ok {
+			baseExpr = idxList.X
+		}
+
+		if sel, ok := baseExpr.(*ast.SelectorExpr); ok {
+			if ident, ok := sel.X.(*ast.Ident); ok {
+				pkgName := ident.Name
+				typeName := sel.Sel.Name
+				// Check for known non-comparable generic types
+				if pkgName == "option" && typeName == "Option" {
+					// Option types are not comparable (they contain a slice internally)
+					return false
+				}
+				if pkgName == "either" && typeName == "Either" {
+					// Either types are not comparable
+					return false
+				}
+			}
+		}
+		// For other generic types, conservatively assume not comparable
+		return false
+	case *ast.ChanType:
+		// Channel types are comparable
+		return true
+	default:
+		// Unknown type, conservatively assume not comparable
+		return false
+	}
+}
+
+// parseFile parses a Go file and extracts structs with lens annotations
+func parseFile(filename string) ([]structInfo, string, error) {
+	fset := token.NewFileSet()
+	node, err := parser.ParseFile(fset, filename, nil, parser.ParseComments)
+	if err != nil {
+		return nil, "", err
+	}
+
+	var structs []structInfo
+	packageName := node.Name.Name
+
+	// Build import map: package name -> import path
+	fileImports := make(map[string]string)
+	for _, imp := range node.Imports {
+		path := strings.Trim(imp.Path.Value, `"`)
+		var name string
+		if imp.Name != nil {
+			name = imp.Name.Name
+		} else {
+			// Extract package name from path (last component)
+			parts := strings.Split(path, "/")
+			name = parts[len(parts)-1]
+		}
+		fileImports[name] = path
+	}
+
+	// First pass: collect all GenDecls with their doc comments
+	declMap := make(map[*ast.TypeSpec]*ast.CommentGroup)
+	ast.Inspect(node, func(n ast.Node) bool {
+		if gd, ok := n.(*ast.GenDecl); ok {
+			for _, spec := range gd.Specs {
+				if ts, ok := spec.(*ast.TypeSpec); ok {
+					declMap[ts] = gd.Doc
+				}
+			}
+		}
+		return true
+	})
+
+	// Second pass: process type specs
+	ast.Inspect(node, func(n ast.Node) bool {
+		// Look for type declarations
+		typeSpec, ok := n.(*ast.TypeSpec)
+		if !ok {
+			return true
+		}
+
+		// Check if it's a struct type
+		structType, ok := typeSpec.Type.(*ast.StructType)
+		if !ok {
+			return true
+		}
+
+		// Get the doc comment from our map
+		doc := declMap[typeSpec]
+		if !hasLensAnnotation(doc) {
+			return true
+		}
+
+		// Extract field information and collect imports
+		var fields []fieldInfo
+		structImports := make(map[string]string)
+
+		for _, field := range structType.Fields.List {
+			if len(field.Names) == 0 {
+				// Embedded field, skip for now
+				continue
+			}
+			for _, name := range field.Names {
+				// Only export lenses for exported fields
+				if name.IsExported() {
+					typeName := getTypeName(field.Type)
+					isOptional := false
+					baseType := typeName
+					isComparable := false
+
+					// Check if field is optional:
+					// 1. Pointer types are always optional
+					// 2. Non-pointer types with json omitempty tag are optional
+					if isPointerType(field.Type) {
+						isOptional = true
+						// Strip leading * for base type
+						baseType = strings.TrimPrefix(typeName, "*")
+					} else if hasOmitEmpty(field.Tag) {
+						// Non-pointer type with omitempty is also optional
+						isOptional = true
+					}
+
+					// Check if the type is comparable (for non-optional fields)
+					// For optional fields, we don't need to check since they use LensO
+					isComparable = isComparableType(field.Type)
+
+					// Extract imports from this field's type
+					fieldImports := make(map[string]string)
+					extractImports(field.Type, fieldImports)
+
+					// Resolve package names to full import paths
+					for pkgName := range fieldImports {
+						if importPath, ok := fileImports[pkgName]; ok {
+							structImports[importPath] = pkgName
+						}
+					}
+
+					fields = append(fields, fieldInfo{
+						Name:         name.Name,
+						TypeName:     typeName,
+						BaseType:     baseType,
+						IsOptional:   isOptional,
+						IsComparable: isComparable,
+					})
+				}
+			}
+		}
+
+		if len(fields) > 0 {
+			structs = append(structs, structInfo{
+				Name:    typeSpec.Name.Name,
+				Fields:  fields,
+				Imports: structImports,
+			})
+		}
+
+		return true
+	})
+
+	return structs, packageName, nil
+}
+
+// generateLensHelpers scans a directory for Go files and generates lens code
+func generateLensHelpers(dir, filename string, verbose bool) error {
+	// Get absolute path
+	absDir, err := filepath.Abs(dir)
+	if err != nil {
+		return err
+	}
+
+	if verbose {
+		log.Printf("Scanning directory: %s", absDir)
+	}
+
+	// Find all Go files in the directory
+	files, err := filepath.Glob(filepath.Join(absDir, "*.go"))
+	if err != nil {
+		return err
+	}
+
+	if verbose {
+		log.Printf("Found %d Go files", len(files))
+	}
+
+	// Parse all files and collect structs
+	var allStructs []structInfo
+	var packageName string
+
+	for _, file := range files {
+		// Skip generated files and test files
+		if strings.HasSuffix(file, "_test.go") || strings.Contains(file, "gen.go") {
+			if verbose {
+				log.Printf("Skipping file: %s", filepath.Base(file))
+			}
+			continue
+		}
+
+		if verbose {
+			log.Printf("Parsing file: %s", filepath.Base(file))
+		}
+
+		structs, pkg, err := parseFile(file)
+		if err != nil {
+			log.Printf("Warning: failed to parse %s: %v", file, err)
+			continue
+		}
+
+		if verbose && len(structs) > 0 {
+			log.Printf("Found %d annotated struct(s) in %s", len(structs), filepath.Base(file))
+			for _, s := range structs {
+				log.Printf("  - %s (%d fields)", s.Name, len(s.Fields))
+			}
+		}
+
+		if packageName == "" {
+			packageName = pkg
+		}
+
+		allStructs = append(allStructs, structs...)
+	}
+
+	if len(allStructs) == 0 {
+		log.Printf("No structs with %s annotation found in %s", lensAnnotation, absDir)
+		return nil
+	}
+
+	// Collect all unique imports from all structs
+	allImports := make(map[string]string) // import path -> alias
+	for _, s := range allStructs {
+		for importPath, alias := range s.Imports {
+			allImports[importPath] = alias
+		}
+	}
+
+	// Create output file
+	outPath := filepath.Join(absDir, filename)
+	f, err := os.Create(filepath.Clean(outPath))
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	log.Printf("Generating lens code in [%s] for package [%s] with [%d] structs ...", outPath, packageName, len(allStructs))
+
+	// Write header
+	writePackage(f, packageName)
+
+	// Write imports
+	f.WriteString("import (\n")
+	// Standard fp-go imports always needed
+	f.WriteString("\tL \"github.com/IBM/fp-go/v2/optics/lens\"\n")
+	f.WriteString("\tLO \"github.com/IBM/fp-go/v2/optics/lens/option\"\n")
+	f.WriteString("\tO \"github.com/IBM/fp-go/v2/option\"\n")
+	f.WriteString("\tI \"github.com/IBM/fp-go/v2/optics/iso/option\"\n")
+
+	// Add additional imports collected from field types
+	for importPath, alias := range allImports {
+		f.WriteString("\t" + alias + " \"" + importPath + "\"\n")
+	}
+
+	f.WriteString(")\n")
+
+	// Generate lens code for each struct using templates
+	for _, s := range allStructs {
+		var buf bytes.Buffer
+
+		// Generate struct type
+		if err := structTmpl.Execute(&buf, s); err != nil {
+			return err
+		}
+
+		// Generate constructor
+		if err := constructorTmpl.Execute(&buf, s); err != nil {
+			return err
+		}
+
+		// Write to file
+		if _, err := f.Write(buf.Bytes()); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// LensCommand creates the CLI command for lens generation
+func LensCommand() *C.Command {
+	return &C.Command{
+		Name:        "lens",
+		Usage:       "generate lens code for annotated structs",
+		Description: "Scans Go files for structs annotated with 'fp-go:Lens' and generates lens types. Pointer types and non-pointer types with json omitempty tag generate LensO (optional lens).",
+		Flags: []C.Flag{
+			flagLensDir,
+			flagFilename,
+			flagVerbose,
+		},
+		Action: func(ctx *C.Context) error {
+			return generateLensHelpers(
+				ctx.String(keyLensDir),
+				ctx.String(keyFilename),
+				ctx.Bool(keyVerbose),
+			)
+		},
+	}
+}

v2/cli/lens_test.go

@@ -0,0 +1,749 @@
+// 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 cli
+
+import (
+	"bytes"
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestHasLensAnnotation(t *testing.T) {
+	tests := []struct {
+		name     string
+		comment  string
+		expected bool
+	}{
+		{
+			name:     "has annotation",
+			comment:  "// fp-go:Lens",
+			expected: true,
+		},
+		{
+			name:     "has annotation with other text",
+			comment:  "// This is a struct with fp-go:Lens annotation",
+			expected: true,
+		},
+		{
+			name:     "no annotation",
+			comment:  "// This is just a regular comment",
+			expected: false,
+		},
+		{
+			name:     "nil comment",
+			comment:  "",
+			expected: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var doc *ast.CommentGroup
+			if tt.comment != "" {
+				doc = &ast.CommentGroup{
+					List: []*ast.Comment{
+						{Text: tt.comment},
+					},
+				}
+			}
+			result := hasLensAnnotation(doc)
+			assert.Equal(t, tt.expected, result)
+		})
+	}
+}
+
+func TestGetTypeName(t *testing.T) {
+	tests := []struct {
+		name     string
+		code     string
+		expected string
+	}{
+		{
+			name:     "simple type",
+			code:     "type T struct { F string }",
+			expected: "string",
+		},
+		{
+			name:     "pointer type",
+			code:     "type T struct { F *string }",
+			expected: "*string",
+		},
+		{
+			name:     "slice type",
+			code:     "type T struct { F []int }",
+			expected: "[]int",
+		},
+		{
+			name:     "map type",
+			code:     "type T struct { F map[string]int }",
+			expected: "map[string]int",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			fset := token.NewFileSet()
+			file, err := parser.ParseFile(fset, "", "package test\n"+tt.code, 0)
+			require.NoError(t, err)
+
+			var fieldType ast.Expr
+			ast.Inspect(file, func(n ast.Node) bool {
+				if field, ok := n.(*ast.Field); ok && len(field.Names) > 0 {
+					fieldType = field.Type
+					return false
+				}
+				return true
+			})
+
+			require.NotNil(t, fieldType)
+			result := getTypeName(fieldType)
+			assert.Equal(t, tt.expected, result)
+		})
+	}
+}
+
+func TestIsPointerType(t *testing.T) {
+	tests := []struct {
+		name     string
+		code     string
+		expected bool
+	}{
+		{
+			name:     "pointer type",
+			code:     "type T struct { F *string }",
+			expected: true,
+		},
+		{
+			name:     "non-pointer type",
+			code:     "type T struct { F string }",
+			expected: false,
+		},
+		{
+			name:     "slice type",
+			code:     "type T struct { F []string }",
+			expected: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			fset := token.NewFileSet()
+			file, err := parser.ParseFile(fset, "", "package test\n"+tt.code, 0)
+			require.NoError(t, err)
+
+			var fieldType ast.Expr
+			ast.Inspect(file, func(n ast.Node) bool {
+				if field, ok := n.(*ast.Field); ok && len(field.Names) > 0 {
+					fieldType = field.Type
+					return false
+				}
+				return true
+			})
+
+			require.NotNil(t, fieldType)
+			result := isPointerType(fieldType)
+			assert.Equal(t, tt.expected, result)
+		})
+	}
+}
+
+func TestIsComparableType(t *testing.T) {
+	tests := []struct {
+		name     string
+		code     string
+		expected bool
+	}{
+		{
+			name:     "basic type - string",
+			code:     "type T struct { F string }",
+			expected: true,
+		},
+		{
+			name:     "basic type - int",
+			code:     "type T struct { F int }",
+			expected: true,
+		},
+		{
+			name:     "basic type - bool",
+			code:     "type T struct { F bool }",
+			expected: true,
+		},
+		{
+			name:     "pointer type",
+			code:     "type T struct { F *string }",
+			expected: true,
+		},
+		{
+			name:     "slice type - not comparable",
+			code:     "type T struct { F []string }",
+			expected: false,
+		},
+		{
+			name:     "map type - not comparable",
+			code:     "type T struct { F map[string]int }",
+			expected: false,
+		},
+		{
+			name:     "array type - comparable if element is",
+			code:     "type T struct { F [5]int }",
+			expected: true,
+		},
+		{
+			name:     "interface type",
+			code:     "type T struct { F interface{} }",
+			expected: true,
+		},
+		{
+			name:     "channel type",
+			code:     "type T struct { F chan int }",
+			expected: true,
+		},
+		{
+			name:     "function type - not comparable",
+			code:     "type T struct { F func() }",
+			expected: false,
+		},
+		{
+			name:     "struct literal - conservatively not comparable",
+			code:     "type T struct { F struct{ X int } }",
+			expected: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			fset := token.NewFileSet()
+			file, err := parser.ParseFile(fset, "", "package test\n"+tt.code, 0)
+			require.NoError(t, err)
+
+			var fieldType ast.Expr
+			ast.Inspect(file, func(n ast.Node) bool {
+				if field, ok := n.(*ast.Field); ok && len(field.Names) > 0 {
+					fieldType = field.Type
+					return false
+				}
+				return true
+			})
+
+			require.NotNil(t, fieldType)
+			result := isComparableType(fieldType)
+			assert.Equal(t, tt.expected, result)
+		})
+	}
+}
+
+func TestHasOmitEmpty(t *testing.T) {
+	tests := []struct {
+		name     string
+		tag      string
+		expected bool
+	}{
+		{
+			name:     "has omitempty",
+			tag:      "`json:\"field,omitempty\"`",
+			expected: true,
+		},
+		{
+			name:     "has omitempty with other options",
+			tag:      "`json:\"field,omitempty,string\"`",
+			expected: true,
+		},
+		{
+			name:     "no omitempty",
+			tag:      "`json:\"field\"`",
+			expected: false,
+		},
+		{
+			name:     "no tag",
+			tag:      "",
+			expected: false,
+		},
+		{
+			name:     "different tag",
+			tag:      "`xml:\"field\"`",
+			expected: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var tag *ast.BasicLit
+			if tt.tag != "" {
+				tag = &ast.BasicLit{
+					Value: tt.tag,
+				}
+			}
+			result := hasOmitEmpty(tag)
+			assert.Equal(t, tt.expected, result)
+		})
+	}
+}
+
+func TestParseFile(t *testing.T) {
+	// Create a temporary test file
+	tmpDir := t.TempDir()
+	testFile := filepath.Join(tmpDir, "test.go")
+
+	testCode := `package testpkg
+
+// fp-go:Lens
+type Person struct {
+	Name  string
+	Age   int
+	Phone *string
+}
+
+// fp-go:Lens
+type Address struct {
+	Street string
+	City   string
+}
+
+// Not annotated
+type Other struct {
+	Field string
+}
+`
+
+	err := os.WriteFile(testFile, []byte(testCode), 0644)
+	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, 2)
+
+	// Check Person struct
+	person := structs[0]
+	assert.Equal(t, "Person", person.Name)
+	assert.Len(t, person.Fields, 3)
+
+	assert.Equal(t, "Name", person.Fields[0].Name)
+	assert.Equal(t, "string", person.Fields[0].TypeName)
+	assert.False(t, person.Fields[0].IsOptional)
+
+	assert.Equal(t, "Age", person.Fields[1].Name)
+	assert.Equal(t, "int", person.Fields[1].TypeName)
+	assert.False(t, person.Fields[1].IsOptional)
+
+	assert.Equal(t, "Phone", person.Fields[2].Name)
+	assert.Equal(t, "*string", person.Fields[2].TypeName)
+	assert.True(t, person.Fields[2].IsOptional)
+
+	// Check Address struct
+	address := structs[1]
+	assert.Equal(t, "Address", address.Name)
+	assert.Len(t, address.Fields, 2)
+
+	assert.Equal(t, "Street", address.Fields[0].Name)
+	assert.Equal(t, "City", address.Fields[1].Name)
+}
+
+func TestParseFileWithOmitEmpty(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 {
+	Name     string
+	Value    string  ` + "`json:\"value,omitempty\"`" + `
+	Count    int     ` + "`json:\",omitempty\"`" + `
+	Optional *string ` + "`json:\"optional,omitempty\"`" + `
+	Required int     ` + "`json:\"required\"`" + `
+}
+`
+
+	err := os.WriteFile(testFile, []byte(testCode), 0644)
+	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, 5)
+
+	// Name - no tag, not optional
+	assert.Equal(t, "Name", config.Fields[0].Name)
+	assert.Equal(t, "string", config.Fields[0].TypeName)
+	assert.False(t, config.Fields[0].IsOptional)
+
+	// Value - has omitempty, should be optional
+	assert.Equal(t, "Value", config.Fields[1].Name)
+	assert.Equal(t, "string", config.Fields[1].TypeName)
+	assert.True(t, config.Fields[1].IsOptional, "Value field with omitempty should be optional")
+
+	// Count - has omitempty (no field name in tag), should be optional
+	assert.Equal(t, "Count", config.Fields[2].Name)
+	assert.Equal(t, "int", config.Fields[2].TypeName)
+	assert.True(t, config.Fields[2].IsOptional, "Count field with omitempty should be optional")
+
+	// Optional - pointer with omitempty, should be optional
+	assert.Equal(t, "Optional", config.Fields[3].Name)
+	assert.Equal(t, "*string", config.Fields[3].TypeName)
+	assert.True(t, config.Fields[3].IsOptional)
+
+	// Required - has json tag but no omitempty, not optional
+	assert.Equal(t, "Required", config.Fields[4].Name)
+	assert.Equal(t, "int", config.Fields[4].TypeName)
+	assert.False(t, config.Fields[4].IsOptional, "Required field without omitempty should not be optional")
+}
+
+func TestParseFileWithComparableTypes(t *testing.T) {
+	// Create a temporary test file
+	tmpDir := t.TempDir()
+	testFile := filepath.Join(tmpDir, "test.go")
+
+	testCode := `package testpkg
+
+// fp-go:Lens
+type TypeTest struct {
+	Name      string
+	Age       int
+	Pointer   *string
+	Slice     []string
+	Map       map[string]int
+	Channel   chan int
+}
+`
+
+	err := os.WriteFile(testFile, []byte(testCode), 0644)
+	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 TypeTest struct
+	typeTest := structs[0]
+	assert.Equal(t, "TypeTest", typeTest.Name)
+	assert.Len(t, typeTest.Fields, 6)
+
+	// Name - string is comparable
+	assert.Equal(t, "Name", typeTest.Fields[0].Name)
+	assert.Equal(t, "string", typeTest.Fields[0].TypeName)
+	assert.False(t, typeTest.Fields[0].IsOptional)
+	assert.True(t, typeTest.Fields[0].IsComparable, "string should be comparable")
+
+	// Age - int is comparable
+	assert.Equal(t, "Age", typeTest.Fields[1].Name)
+	assert.Equal(t, "int", typeTest.Fields[1].TypeName)
+	assert.False(t, typeTest.Fields[1].IsOptional)
+	assert.True(t, typeTest.Fields[1].IsComparable, "int should be comparable")
+
+	// Pointer - pointer is optional, IsComparable not checked for optional fields
+	assert.Equal(t, "Pointer", typeTest.Fields[2].Name)
+	assert.Equal(t, "*string", typeTest.Fields[2].TypeName)
+	assert.True(t, typeTest.Fields[2].IsOptional)
+
+	// Slice - not comparable
+	assert.Equal(t, "Slice", typeTest.Fields[3].Name)
+	assert.Equal(t, "[]string", typeTest.Fields[3].TypeName)
+	assert.False(t, typeTest.Fields[3].IsOptional)
+	assert.False(t, typeTest.Fields[3].IsComparable, "slice should not be comparable")
+
+	// Map - not comparable
+	assert.Equal(t, "Map", typeTest.Fields[4].Name)
+	assert.Equal(t, "map[string]int", typeTest.Fields[4].TypeName)
+	assert.False(t, typeTest.Fields[4].IsOptional)
+	assert.False(t, typeTest.Fields[4].IsComparable, "map should not be comparable")
+
+	// Channel - comparable (note: getTypeName returns "any" for channel types, but isComparableType correctly identifies them)
+	assert.Equal(t, "Channel", typeTest.Fields[5].Name)
+	assert.Equal(t, "any", typeTest.Fields[5].TypeName) // getTypeName doesn't handle chan types specifically
+	assert.False(t, typeTest.Fields[5].IsOptional)
+	assert.True(t, typeTest.Fields[5].IsComparable, "channel should be comparable")
+}
+
+func TestLensRefTemplatesWithComparable(t *testing.T) {
+	s := structInfo{
+		Name: "TestStruct",
+		Fields: []fieldInfo{
+			{Name: "Name", TypeName: "string", IsOptional: false, IsComparable: true},
+			{Name: "Age", TypeName: "int", IsOptional: false, IsComparable: true},
+			{Name: "Data", TypeName: "[]byte", IsOptional: false, IsComparable: false},
+			{Name: "Pointer", TypeName: "*string", IsOptional: true, IsComparable: false},
+		},
+	}
+
+	// Test constructor template for RefLenses
+	var constructorBuf bytes.Buffer
+	err := constructorTmpl.Execute(&constructorBuf, s)
+	require.NoError(t, err)
+
+	constructorStr := constructorBuf.String()
+
+	// Check that MakeLensStrict is used for comparable types in RefLenses
+	assert.Contains(t, constructorStr, "func MakeTestStructRefLenses() TestStructRefLenses")
+
+	// Name field - comparable, should use MakeLensStrict
+	assert.Contains(t, constructorStr, "Name: L.MakeLensStrict(",
+		"comparable field Name should use MakeLensStrict in RefLenses")
+
+	// Age field - comparable, should use MakeLensStrict
+	assert.Contains(t, constructorStr, "Age: L.MakeLensStrict(",
+		"comparable field Age should use MakeLensStrict in RefLenses")
+
+	// Data field - not comparable, should use MakeLensRef
+	assert.Contains(t, constructorStr, "Data: L.MakeLensRef(",
+		"non-comparable field Data should use MakeLensRef in RefLenses")
+
+}
+
+func TestGenerateLensHelpersWithComparable(t *testing.T) {
+	// Create a temporary directory with test files
+	tmpDir := t.TempDir()
+
+	testCode := `package testpkg
+
+// fp-go:Lens
+type TestStruct struct {
+	Name  string
+	Count int
+	Data  []byte
+}
+`
+
+	testFile := filepath.Join(tmpDir, "test.go")
+	err := os.WriteFile(testFile, []byte(testCode), 0644)
+	require.NoError(t, err)
+
+	// Generate lens code
+	outputFile := "gen.go"
+	err = generateLensHelpers(tmpDir, outputFile, 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 in RefLenses
+	assert.Contains(t, contentStr, "MakeTestStructRefLenses")
+
+	// Name and Count are comparable, should use MakeLensStrict
+	assert.Contains(t, contentStr, "L.MakeLensStrict",
+		"comparable fields should use MakeLensStrict in RefLenses")
+
+	// Data is not comparable (slice), should use MakeLensRef
+	assert.Contains(t, contentStr, "L.MakeLensRef",
+		"non-comparable fields should use MakeLensRef in RefLenses")
+
+	// Verify the pattern appears for Name field (comparable)
+	namePattern := "Name: L.MakeLensStrict("
+	assert.Contains(t, contentStr, namePattern,
+		"Name field should use MakeLensStrict")
+
+	// Verify the pattern appears for Data field (not comparable)
+	dataPattern := "Data: L.MakeLensRef("
+	assert.Contains(t, contentStr, dataPattern,
+		"Data field should use MakeLensRef")
+}
+
+func TestGenerateLensHelpers(t *testing.T) {
+	// Create a temporary directory with test files
+	tmpDir := t.TempDir()
+
+	testCode := `package testpkg
+
+// fp-go:Lens
+type TestStruct struct {
+	Name  string
+	Value *int
+}
+`
+
+	testFile := filepath.Join(tmpDir, "test.go")
+	err := os.WriteFile(testFile, []byte(testCode), 0644)
+	require.NoError(t, err)
+
+	// Generate lens code
+	outputFile := "gen.go"
+	err = generateLensHelpers(tmpDir, outputFile, 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, "Code generated by go generate")
+	assert.Contains(t, contentStr, "TestStructLens")
+	assert.Contains(t, contentStr, "MakeTestStructLens")
+	assert.Contains(t, contentStr, "L.Lens[TestStruct, string]")
+	assert.Contains(t, contentStr, "LO.LensO[TestStruct, *int]")
+	assert.Contains(t, contentStr, "I.FromZero")
+}
+
+func TestGenerateLensHelpersNoAnnotations(t *testing.T) {
+	// Create a temporary directory with test files
+	tmpDir := t.TempDir()
+
+	testCode := `package testpkg
+
+// No annotation
+type TestStruct struct {
+	Name string
+}
+`
+
+	testFile := filepath.Join(tmpDir, "test.go")
+	err := os.WriteFile(testFile, []byte(testCode), 0644)
+	require.NoError(t, err)
+
+	// Generate lens code (should not create file)
+	outputFile := "gen.go"
+	err = generateLensHelpers(tmpDir, outputFile, false)
+	require.NoError(t, err)
+
+	// Verify the generated file does not exist
+	genPath := filepath.Join(tmpDir, outputFile)
+	_, err = os.Stat(genPath)
+	assert.True(t, os.IsNotExist(err))
+}
+
+func TestLensTemplates(t *testing.T) {
+	s := structInfo{
+		Name: "TestStruct",
+		Fields: []fieldInfo{
+			{Name: "Name", TypeName: "string", IsOptional: false},
+			{Name: "Value", TypeName: "*int", IsOptional: true},
+		},
+	}
+
+	// Test struct template
+	var structBuf bytes.Buffer
+	err := structTmpl.Execute(&structBuf, s)
+	require.NoError(t, err)
+
+	structStr := structBuf.String()
+	assert.Contains(t, structStr, "type TestStructLenses struct")
+	assert.Contains(t, structStr, "Name L.Lens[TestStruct, string]")
+	assert.Contains(t, structStr, "Value LO.LensO[TestStruct, *int]")
+
+	// Test constructor template
+	var constructorBuf bytes.Buffer
+	err = constructorTmpl.Execute(&constructorBuf, s)
+	require.NoError(t, err)
+
+	constructorStr := constructorBuf.String()
+	assert.Contains(t, constructorStr, "func MakeTestStructLenses() TestStructLenses")
+	assert.Contains(t, constructorStr, "return TestStructLenses{")
+	assert.Contains(t, constructorStr, "Name: L.MakeLens(")
+	assert.Contains(t, constructorStr, "Value: L.MakeLens(")
+	assert.Contains(t, constructorStr, "I.FromZero")
+}
+
+func TestLensTemplatesWithOmitEmpty(t *testing.T) {
+	s := structInfo{
+		Name: "ConfigStruct",
+		Fields: []fieldInfo{
+			{Name: "Name", TypeName: "string", IsOptional: false},
+			{Name: "Value", TypeName: "string", IsOptional: true},    // non-pointer with omitempty
+			{Name: "Count", TypeName: "int", IsOptional: true},       // non-pointer with omitempty
+			{Name: "Pointer", TypeName: "*string", IsOptional: true}, // pointer
+		},
+	}
+
+	// Test struct template
+	var structBuf bytes.Buffer
+	err := structTmpl.Execute(&structBuf, s)
+	require.NoError(t, err)
+
+	structStr := structBuf.String()
+	assert.Contains(t, structStr, "type ConfigStructLenses struct")
+	assert.Contains(t, structStr, "Name L.Lens[ConfigStruct, string]")
+	assert.Contains(t, structStr, "Value LO.LensO[ConfigStruct, string]", "non-pointer with omitempty should use LensO")
+	assert.Contains(t, structStr, "Count LO.LensO[ConfigStruct, int]", "non-pointer with omitempty should use LensO")
+	assert.Contains(t, structStr, "Pointer LO.LensO[ConfigStruct, *string]")
+
+	// Test constructor template
+	var constructorBuf bytes.Buffer
+	err = constructorTmpl.Execute(&constructorBuf, s)
+	require.NoError(t, err)
+
+	constructorStr := constructorBuf.String()
+	assert.Contains(t, constructorStr, "func MakeConfigStructLenses() ConfigStructLenses")
+	assert.Contains(t, constructorStr, "isoValue := I.FromZero[string]()")
+	assert.Contains(t, constructorStr, "isoCount := I.FromZero[int]()")
+	assert.Contains(t, constructorStr, "isoPointer := I.FromZero[*string]()")
+}
+
+func TestLensCommandFlags(t *testing.T) {
+	cmd := LensCommand()
+
+	assert.Equal(t, "lens", cmd.Name)
+	assert.Equal(t, "generate lens code for annotated structs", cmd.Usage)
+	assert.Contains(t, strings.ToLower(cmd.Description), "fp-go:lens")
+	assert.Contains(t, strings.ToLower(cmd.Description), "lenso")
+
+	// Check flags
+	assert.Len(t, cmd.Flags, 3)
+
+	var hasDir, hasFilename, hasVerbose bool
+	for _, flag := range cmd.Flags {
+		switch flag.Names()[0] {
+		case "dir":
+			hasDir = true
+		case "filename":
+			hasFilename = true
+		case "verbose":
+			hasVerbose = true
+		}
+	}
+
+	assert.True(t, hasDir, "should have dir flag")
+	assert.True(t, hasFilename, "should have filename flag")
+	assert.True(t, hasVerbose, "should have verbose flag")
+}

v2/constant/const_test.go

@@ -27,7 +27,7 @@ import (
 
 func TestMap(t *testing.T) {
 	fa := Make[string, int]("foo")
-	assert.Equal(t, fa, F.Pipe1(fa, Map[string, int](utils.Double)))
+	assert.Equal(t, fa, F.Pipe1(fa, Map[string](utils.Double)))
 }
 
 func TestOf(t *testing.T) {

v2/context/ioresult/ioeither.go

@@ -13,20 +13,19 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package ioeither
+package ioresult
 
 import (
 	"context"
 
-	"github.com/IBM/fp-go/v2/either"
+	"github.com/IBM/fp-go/v2/result"
-	IOE "github.com/IBM/fp-go/v2/ioeither"
 )
 
 // withContext wraps an existing IOEither and performs a context check for cancellation before delegating
-func WithContext[A any](ctx context.Context, ma IOE.IOEither[error, A]) IOE.IOEither[error, A] {
+func WithContext[A any](ctx context.Context, ma IOResult[A]) IOResult[A] {
-	return func() either.Either[error, A] {
+	return func() Result[A] {
 		if err := context.Cause(ctx); err != nil {
-			return either.Left[A](err)
+			return result.Left[A](err)
 		}
 		return ma()
 	}

v2/context/ioresult/types.go

@@ -0,0 +1,11 @@
+package ioresult
+
+import (
+	"github.com/IBM/fp-go/v2/ioresult"
+	"github.com/IBM/fp-go/v2/result"
+)
+
+type (
+	IOResult[T any] = ioresult.IOResult[T]
+	Result[T any]   = result.Result[T]
+)

v2/context/readereither/bind.go

@@ -1,68 +0,0 @@
-// 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 readereither
-
-import (
-	"context"
-
-	G "github.com/IBM/fp-go/v2/readereither/generic"
-)
-
-// Bind creates an empty context of type [S] to be used with the [Bind] operation
-func Do[S any](
-	empty S,
-) ReaderEither[S] {
-	return G.Do[ReaderEither[S], context.Context, error, S](empty)
-}
-
-// Bind attaches the result of a computation to a context [S1] to produce a context [S2]
-func Bind[S1, S2, T any](
-	setter func(T) func(S1) S2,
-	f func(S1) ReaderEither[T],
-) func(ReaderEither[S1]) ReaderEither[S2] {
-	return G.Bind[ReaderEither[S1], ReaderEither[S2], ReaderEither[T], context.Context, error, S1, S2, T](setter, f)
-}
-
-// Let attaches the result of a computation to a context [S1] to produce a context [S2]
-func Let[S1, S2, T any](
-	setter func(T) func(S1) S2,
-	f func(S1) T,
-) func(ReaderEither[S1]) ReaderEither[S2] {
-	return G.Let[ReaderEither[S1], ReaderEither[S2], context.Context, error, S1, S2, T](setter, f)
-}
-
-// LetTo attaches the a value to a context [S1] to produce a context [S2]
-func LetTo[S1, S2, T any](
-	setter func(T) func(S1) S2,
-	b T,
-) func(ReaderEither[S1]) ReaderEither[S2] {
-	return G.LetTo[ReaderEither[S1], ReaderEither[S2], context.Context, error, S1, S2, T](setter, b)
-}
-
-// BindTo initializes a new state [S1] from a value [T]
-func BindTo[S1, T any](
-	setter func(T) S1,
-) func(ReaderEither[T]) ReaderEither[S1] {
-	return G.BindTo[ReaderEither[S1], ReaderEither[T], context.Context, error, S1, T](setter)
-}
-
-// ApS attaches a value to a context [S1] to produce a context [S2] by considering the context and the value concurrently
-func ApS[S1, S2, T any](
-	setter func(T) func(S1) S2,
-	fa ReaderEither[T],
-) func(ReaderEither[S1]) ReaderEither[S2] {
-	return G.ApS[ReaderEither[S1], ReaderEither[S2], ReaderEither[T], context.Context, error, S1, S2, T](setter, fa)
-}

v2/context/readerioeither/bind.go

@@ -1,89 +0,0 @@
-// 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 readerioeither
-
-import (
-	"github.com/IBM/fp-go/v2/internal/apply"
-	"github.com/IBM/fp-go/v2/internal/chain"
-	"github.com/IBM/fp-go/v2/internal/functor"
-)
-
-// Bind creates an empty context of type [S] to be used with the [Bind] operation
-func Do[S any](
-	empty S,
-) ReaderIOEither[S] {
-	return Of(empty)
-}
-
-// Bind attaches the result of a computation to a context [S1] to produce a context [S2]
-func Bind[S1, S2, T any](
-	setter func(T) func(S1) S2,
-	f func(S1) ReaderIOEither[T],
-) func(ReaderIOEither[S1]) ReaderIOEither[S2] {
-	return chain.Bind(
-		Chain[S1, S2],
-		Map[T, S2],
-		setter,
-		f,
-	)
-}
-
-// Let attaches the result of a computation to a context [S1] to produce a context [S2]
-func Let[S1, S2, T any](
-	setter func(T) func(S1) S2,
-	f func(S1) T,
-) func(ReaderIOEither[S1]) ReaderIOEither[S2] {
-	return functor.Let(
-		Map[S1, S2],
-		setter,
-		f,
-	)
-}
-
-// LetTo attaches the a value to a context [S1] to produce a context [S2]
-func LetTo[S1, S2, T any](
-	setter func(T) func(S1) S2,
-	b T,
-) func(ReaderIOEither[S1]) ReaderIOEither[S2] {
-	return functor.LetTo(
-		Map[S1, S2],
-		setter,
-		b,
-	)
-}
-
-// BindTo initializes a new state [S1] from a value [T]
-func BindTo[S1, T any](
-	setter func(T) S1,
-) Operator[T, S1] {
-	return chain.BindTo(
-		Map[T, S1],
-		setter,
-	)
-}
-
-// ApS attaches a value to a context [S1] to produce a context [S2] by considering the context and the value concurrently
-func ApS[S1, S2, T any](
-	setter func(T) func(S1) S2,
-	fa ReaderIOEither[T],
-) func(ReaderIOEither[S1]) ReaderIOEither[S2] {
-	return apply.ApS(
-		Ap[S2, T],
-		Map[S1, func(T) S2],
-		setter,
-		fa,
-	)
-}

v2/context/readerioeither/coverage.out

@@ -1,251 +0,0 @@
-mode: set
-github.com/IBM/fp-go/v2/context/readerioeither/bind.go:27.21,29.2 1 1
-github.com/IBM/fp-go/v2/context/readerioeither/bind.go:35.47,42.2 1 1
-github.com/IBM/fp-go/v2/context/readerioeither/bind.go:48.47,54.2 1 0
-github.com/IBM/fp-go/v2/context/readerioeither/bind.go:60.47,66.2 1 0
-github.com/IBM/fp-go/v2/context/readerioeither/bind.go:71.46,76.2 1 0
-github.com/IBM/fp-go/v2/context/readerioeither/bind.go:82.47,89.2 1 1
-github.com/IBM/fp-go/v2/context/readerioeither/bracket.go:33.21,44.2 1 0
-github.com/IBM/fp-go/v2/context/readerioeither/cancel.go:35.65,36.47 1 1
-github.com/IBM/fp-go/v2/context/readerioeither/cancel.go:36.47,37.44 1 1
-github.com/IBM/fp-go/v2/context/readerioeither/cancel.go:37.44,39.4 1 1
-github.com/IBM/fp-go/v2/context/readerioeither/cancel.go:40.3,40.40 1 1
-github.com/IBM/fp-go/v2/context/readerioeither/eq.go:42.84,44.2 1 0
-github.com/IBM/fp-go/v2/context/readerioeither/gen.go:18.91,20.2 1 0
-github.com/IBM/fp-go/v2/context/readerioeither/gen.go:24.93,26.2 1 0
-github.com/IBM/fp-go/v2/context/readerioeither/gen.go:30.101,32.2 1 0
-github.com/IBM/fp-go/v2/context/readerioeither/gen.go:36.103,38.2 1 0
-github.com/IBM/fp-go/v2/context/readerioeither/gen.go:43.36,48.2 1 0
-github.com/IBM/fp-go/v2/context/readerioeither/gen.go:53.36,58.2 1 0
-github.com/IBM/fp-go/v2/context/readerioeither/gen.go:63.36,68.2 1 0
-github.com/IBM/fp-go/v2/context/readerioeither/gen.go:71.98,76.2 1 0
-github.com/IBM/fp-go/v2/context/readerioeither/gen.go:79.101,84.2 1 0
-github.com/IBM/fp-go/v2/context/readerioeither/gen.go:87.101,92.2 1 0
-github.com/IBM/fp-go/v2/context/readerioeither/gen.go:95.129,96.68 1 0
-github.com/IBM/fp-go/v2/context/readerioeither/gen.go:96.68,102.4 1 0
-github.com/IBM/fp-go/v2/context/readerioeither/gen.go:106.132,107.68 1 0
-github.com/IBM/fp-go/v2/context/readerioeither/gen.go:107.68,113.4 1 0
-github.com/IBM/fp-go/v2/context/readerioeither/gen.go:117.132,118.68 1 0
-github.com/IBM/fp-go/v2/context/readerioeither/gen.go:118.68,124.4 1 0
-github.com/IBM/fp-go/v2/context/readerioeither/gen.go:129.113,131.2 1 0
-github.com/IBM/fp-go/v2/context/readerioeither/gen.go:135.115,137.2 1 0
-github.com/IBM/fp-go/v2/context/readerioeither/gen.go:143.40,150.2 1 0
-github.com/IBM/fp-go/v2/context/readerioeither/gen.go:156.40,163.2 1 0
-github.com/IBM/fp-go/v2/context/readerioeither/gen.go:169.40,176.2 1 0
-github.com/IBM/fp-go/v2/context/readerioeither/gen.go:179.126,185.2 1 0
-github.com/IBM/fp-go/v2/context/readerioeither/gen.go:188.129,194.2 1 0
-github.com/IBM/fp-go/v2/context/readerioeither/gen.go:197.129,203.2 1 0
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v2/context/readerioeither/http/builder/coverage.out

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v2/context/readerioeither/http/coverage.out

@@ -1,11 +0,0 @@
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-github.com/IBM/fp-go/v2/context/readerioeither/http/request.go:222.74,227.2 1 1
-github.com/IBM/fp-go/v2/context/readerioeither/http/request.go:234.76,236.2 1 1
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-github.com/IBM/fp-go/v2/context/readerioeither/http/request.go:281.76,286.2 1 1

v2/context/readerioeither/reader.go

@@ -1,636 +0,0 @@
-// 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 readerioeither
-
-import (
-	"context"
-	"time"
-
-	"github.com/IBM/fp-go/v2/either"
-	"github.com/IBM/fp-go/v2/errors"
-	"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/readerioeither"
-)
-
-const (
-	// useParallel is the feature flag to control if we use the parallel or the sequential implementation of ap
-	useParallel = true
-)
-
-// FromEither converts an [Either] into a [ReaderIOEither].
-// The resulting computation ignores the context and immediately returns the Either value.
-//
-// Parameters:
-//   - e: The Either value to lift into ReaderIOEither
-//
-// Returns a ReaderIOEither that produces the given Either value.
-func FromEither[A any](e Either[A]) ReaderIOEither[A] {
-	return readerioeither.FromEither[context.Context](e)
-}
-
-// Left creates a [ReaderIOEither] that represents a failed computation with the given error.
-//
-// Parameters:
-//   - l: The error value
-//
-// Returns a ReaderIOEither that always fails with the given error.
-func Left[A any](l error) ReaderIOEither[A] {
-	return readerioeither.Left[context.Context, A](l)
-}
-
-// Right creates a [ReaderIOEither] that represents a successful computation with the given value.
-//
-// Parameters:
-//   - r: The success value
-//
-// Returns a ReaderIOEither that always succeeds with the given value.
-func Right[A any](r A) ReaderIOEither[A] {
-	return readerioeither.Right[context.Context, error](r)
-}
-
-// MonadMap transforms the success value of a [ReaderIOEither] using the provided function.
-// If the computation fails, the error is propagated unchanged.
-//
-// Parameters:
-//   - fa: The ReaderIOEither to transform
-//   - f: The transformation function
-//
-// Returns a new ReaderIOEither with the transformed value.
-func MonadMap[A, B any](fa ReaderIOEither[A], f func(A) B) ReaderIOEither[B] {
-	return readerioeither.MonadMap(fa, f)
-}
-
-// Map transforms the success value of a [ReaderIOEither] using the provided function.
-// This is the curried version of [MonadMap], useful for composition.
-//
-// Parameters:
-//   - f: The transformation function
-//
-// Returns a function that transforms a ReaderIOEither.
-func Map[A, B any](f func(A) B) Operator[A, B] {
-	return readerioeither.Map[context.Context, error](f)
-}
-
-// MonadMapTo replaces the success value of a [ReaderIOEither] with a constant value.
-// If the computation fails, the error is propagated unchanged.
-//
-// Parameters:
-//   - fa: The ReaderIOEither to transform
-//   - b: The constant value to use
-//
-// Returns a new ReaderIOEither with the constant value.
-func MonadMapTo[A, B any](fa ReaderIOEither[A], b B) ReaderIOEither[B] {
-	return readerioeither.MonadMapTo(fa, b)
-}
-
-// MapTo replaces the success value of a [ReaderIOEither] with a constant value.
-// This is the curried version of [MonadMapTo].
-//
-// Parameters:
-//   - b: The constant value to use
-//
-// Returns a function that transforms a ReaderIOEither.
-func MapTo[A, B any](b B) Operator[A, B] {
-	return readerioeither.MapTo[context.Context, error, A](b)
-}
-
-// MonadChain sequences two [ReaderIOEither] computations, where the second depends on the result of the first.
-// If the first computation fails, the second is not executed.
-//
-// Parameters:
-//   - ma: The first ReaderIOEither
-//   - f: Function that produces the second ReaderIOEither based on the first's result
-//
-// Returns a new ReaderIOEither representing the sequenced computation.
-func MonadChain[A, B any](ma ReaderIOEither[A], f func(A) ReaderIOEither[B]) ReaderIOEither[B] {
-	return readerioeither.MonadChain(ma, f)
-}
-
-// Chain sequences two [ReaderIOEither] computations, where the second depends on the result of the first.
-// This is the curried version of [MonadChain], useful for composition.
-//
-// Parameters:
-//   - f: Function that produces the second ReaderIOEither based on the first's result
-//
-// Returns a function that sequences ReaderIOEither computations.
-func Chain[A, B any](f func(A) ReaderIOEither[B]) Operator[A, B] {
-	return readerioeither.Chain(f)
-}
-
-// MonadChainFirst sequences two [ReaderIOEither] computations but returns the result of the first.
-// The second computation is executed for its side effects only.
-//
-// Parameters:
-//   - ma: The first ReaderIOEither
-//   - f: Function that produces the second ReaderIOEither
-//
-// Returns a ReaderIOEither with the result of the first computation.
-func MonadChainFirst[A, B any](ma ReaderIOEither[A], f func(A) ReaderIOEither[B]) ReaderIOEither[A] {
-	return readerioeither.MonadChainFirst(ma, f)
-}
-
-// ChainFirst sequences two [ReaderIOEither] computations but returns the result of the first.
-// This is the curried version of [MonadChainFirst].
-//
-// Parameters:
-//   - f: Function that produces the second ReaderIOEither
-//
-// Returns a function that sequences ReaderIOEither computations.
-func ChainFirst[A, B any](f func(A) ReaderIOEither[B]) Operator[A, A] {
-	return readerioeither.ChainFirst(f)
-}
-
-// Of creates a [ReaderIOEither] that always succeeds with the given value.
-// This is the same as [Right] and represents the monadic return operation.
-//
-// Parameters:
-//   - a: The value to wrap
-//
-// Returns a ReaderIOEither that always succeeds with the given value.
-func Of[A any](a A) ReaderIOEither[A] {
-	return readerioeither.Of[context.Context, error](a)
-}
-
-func withCancelCauseFunc[A any](cancel context.CancelCauseFunc, ma IOEither[A]) IOEither[A] {
-	return function.Pipe3(
-		ma,
-		ioeither.Swap[error, A],
-		ioeither.ChainFirstIOK[A](func(err error) func() any {
-			return io.FromImpure(func() { cancel(err) })
-		}),
-		ioeither.Swap[A, error],
-	)
-}
-
-// MonadApPar implements parallel applicative application for [ReaderIOEither].
-// It executes both computations in parallel and creates a sub-context that will be canceled
-// if either operation fails. This provides automatic cancellation propagation.
-//
-// Parameters:
-//   - fab: ReaderIOEither containing a function
-//   - fa: ReaderIOEither containing a value
-//
-// Returns a ReaderIOEither with the function applied to the value.
-func MonadApPar[B, A any](fab ReaderIOEither[func(A) B], fa ReaderIOEither[A]) ReaderIOEither[B] {
-	// context sensitive input
-	cfab := WithContext(fab)
-	cfa := WithContext(fa)
-
-	return func(ctx context.Context) IOEither[B] {
-		// quick check for cancellation
-		if err := context.Cause(ctx); err != nil {
-			return ioeither.Left[B](err)
-		}
-
-		return func() Either[B] {
-			// quick check for cancellation
-			if err := context.Cause(ctx); err != nil {
-				return either.Left[B](err)
-			}
-
-			// create sub-contexts for fa and fab, so they can cancel one other
-			ctxSub, cancelSub := context.WithCancelCause(ctx)
-			defer cancelSub(nil) // cancel has to be called in all paths
-
-			fabIOE := withCancelCauseFunc(cancelSub, cfab(ctxSub))
-			faIOE := withCancelCauseFunc(cancelSub, cfa(ctxSub))
-
-			return ioeither.MonadApPar(fabIOE, faIOE)()
-		}
-	}
-}
-
-// MonadAp implements applicative application for [ReaderIOEither].
-// By default, it uses parallel execution ([MonadApPar]) but can be configured to use
-// sequential execution ([MonadApSeq]) via the useParallel constant.
-//
-// Parameters:
-//   - fab: ReaderIOEither containing a function
-//   - fa: ReaderIOEither containing a value
-//
-// Returns a ReaderIOEither with the function applied to the value.
-func MonadAp[B, A any](fab ReaderIOEither[func(A) B], fa ReaderIOEither[A]) ReaderIOEither[B] {
-	// dispatch to the configured version
-	if useParallel {
-		return MonadApPar(fab, fa)
-	}
-	return MonadApSeq(fab, fa)
-}
-
-// MonadApSeq implements sequential applicative application for [ReaderIOEither].
-// It executes the function computation first, then the value computation.
-//
-// Parameters:
-//   - fab: ReaderIOEither containing a function
-//   - fa: ReaderIOEither containing a value
-//
-// Returns a ReaderIOEither with the function applied to the value.
-func MonadApSeq[B, A any](fab ReaderIOEither[func(A) B], fa ReaderIOEither[A]) ReaderIOEither[B] {
-	return readerioeither.MonadApSeq(fab, fa)
-}
-
-// Ap applies a function wrapped in a [ReaderIOEither] to a value wrapped in a ReaderIOEither.
-// This is the curried version of [MonadAp], using the default execution mode.
-//
-// Parameters:
-//   - fa: ReaderIOEither containing a value
-//
-// Returns a function that applies a ReaderIOEither function to the value.
-func Ap[B, A any](fa ReaderIOEither[A]) Operator[func(A) B, B] {
-	return function.Bind2nd(MonadAp[B, A], fa)
-}
-
-// ApSeq applies a function wrapped in a [ReaderIOEither] to a value sequentially.
-// This is the curried version of [MonadApSeq].
-//
-// Parameters:
-//   - fa: ReaderIOEither containing a value
-//
-// Returns a function that applies a ReaderIOEither function to the value sequentially.
-func ApSeq[B, A any](fa ReaderIOEither[A]) Operator[func(A) B, B] {
-	return function.Bind2nd(MonadApSeq[B, A], fa)
-}
-
-// ApPar applies a function wrapped in a [ReaderIOEither] to a value in parallel.
-// This is the curried version of [MonadApPar].
-//
-// Parameters:
-//   - fa: ReaderIOEither containing a value
-//
-// Returns a function that applies a ReaderIOEither function to the value in parallel.
-func ApPar[B, A any](fa ReaderIOEither[A]) Operator[func(A) B, B] {
-	return function.Bind2nd(MonadApPar[B, A], fa)
-}
-
-// FromPredicate creates a [ReaderIOEither] from a predicate function.
-// If the predicate returns true, the value is wrapped in Right; otherwise, Left with the error from onFalse.
-//
-// Parameters:
-//   - pred: Predicate function to test the value
-//   - onFalse: Function to generate an error when predicate fails
-//
-// Returns a function that converts a value to ReaderIOEither based on the predicate.
-func FromPredicate[A any](pred func(A) bool, onFalse func(A) error) func(A) ReaderIOEither[A] {
-	return readerioeither.FromPredicate[context.Context](pred, onFalse)
-}
-
-// OrElse provides an alternative [ReaderIOEither] computation if the first one fails.
-// The alternative is only executed if the first computation results in a Left (error).
-//
-// Parameters:
-//   - onLeft: Function that produces an alternative ReaderIOEither from the error
-//
-// Returns a function that provides fallback behavior for failed computations.
-func OrElse[A any](onLeft func(error) ReaderIOEither[A]) Operator[A, A] {
-	return readerioeither.OrElse[context.Context](onLeft)
-}
-
-// Ask returns a [ReaderIOEither] that provides access to the context.
-// This is useful for accessing the [context.Context] within a computation.
-//
-// Returns a ReaderIOEither that produces the context.
-func Ask() ReaderIOEither[context.Context] {
-	return readerioeither.Ask[context.Context, error]()
-}
-
-// MonadChainEitherK chains a function that returns an [Either] into a [ReaderIOEither] computation.
-// This is useful for integrating pure Either-returning functions into ReaderIOEither workflows.
-//
-// Parameters:
-//   - ma: The ReaderIOEither to chain from
-//   - f: Function that produces an Either
-//
-// Returns a new ReaderIOEither with the chained computation.
-func MonadChainEitherK[A, B any](ma ReaderIOEither[A], f func(A) Either[B]) ReaderIOEither[B] {
-	return readerioeither.MonadChainEitherK[context.Context](ma, f)
-}
-
-// ChainEitherK chains a function that returns an [Either] into a [ReaderIOEither] computation.
-// This is the curried version of [MonadChainEitherK].
-//
-// Parameters:
-//   - f: Function that produces an Either
-//
-// Returns a function that chains the Either-returning function.
-func ChainEitherK[A, B any](f func(A) Either[B]) func(ma ReaderIOEither[A]) ReaderIOEither[B] {
-	return readerioeither.ChainEitherK[context.Context](f)
-}
-
-// MonadChainFirstEitherK chains a function that returns an [Either] but keeps the original value.
-// The Either-returning function is executed for its validation/side effects only.
-//
-// Parameters:
-//   - ma: The ReaderIOEither to chain from
-//   - f: Function that produces an Either
-//
-// Returns a ReaderIOEither with the original value if both computations succeed.
-func MonadChainFirstEitherK[A, B any](ma ReaderIOEither[A], f func(A) Either[B]) ReaderIOEither[A] {
-	return readerioeither.MonadChainFirstEitherK[context.Context](ma, f)
-}
-
-// ChainFirstEitherK chains a function that returns an [Either] but keeps the original value.
-// This is the curried version of [MonadChainFirstEitherK].
-//
-// Parameters:
-//   - f: Function that produces an Either
-//
-// Returns a function that chains the Either-returning function.
-func ChainFirstEitherK[A, B any](f func(A) Either[B]) func(ma ReaderIOEither[A]) ReaderIOEither[A] {
-	return readerioeither.ChainFirstEitherK[context.Context](f)
-}
-
-// ChainOptionK chains a function that returns an [Option] into a [ReaderIOEither] computation.
-// If the Option is None, the provided error function is called.
-//
-// Parameters:
-//   - onNone: Function to generate an error when Option is None
-//
-// Returns a function that chains Option-returning functions into ReaderIOEither.
-func ChainOptionK[A, B any](onNone func() error) func(func(A) Option[B]) Operator[A, B] {
-	return readerioeither.ChainOptionK[context.Context, A, B](onNone)
-}
-
-// FromIOEither converts an [IOEither] into a [ReaderIOEither].
-// The resulting computation ignores the context.
-//
-// Parameters:
-//   - t: The IOEither to convert
-//
-// Returns a ReaderIOEither that executes the IOEither.
-func FromIOEither[A any](t ioeither.IOEither[error, A]) ReaderIOEither[A] {
-	return readerioeither.FromIOEither[context.Context](t)
-}
-
-// FromIO converts an [IO] into a [ReaderIOEither].
-// The IO computation always succeeds, so it's wrapped in Right.
-//
-// Parameters:
-//   - t: The IO to convert
-//
-// Returns a ReaderIOEither that executes the IO and wraps the result in Right.
-func FromIO[A any](t IO[A]) ReaderIOEither[A] {
-	return readerioeither.FromIO[context.Context, error](t)
-}
-
-// FromLazy converts a [Lazy] computation into a [ReaderIOEither].
-// The Lazy computation always succeeds, so it's wrapped in Right.
-// This is an alias for [FromIO] since Lazy and IO have the same structure.
-//
-// Parameters:
-//   - t: The Lazy computation to convert
-//
-// Returns a ReaderIOEither that executes the Lazy computation and wraps the result in Right.
-func FromLazy[A any](t Lazy[A]) ReaderIOEither[A] {
-	return readerioeither.FromIO[context.Context, error](t)
-}
-
-// Never returns a [ReaderIOEither] that blocks indefinitely until the context is canceled.
-// This is useful for creating computations that wait for external cancellation signals.
-//
-// Returns a ReaderIOEither that waits for context cancellation and returns the cancellation error.
-func Never[A any]() ReaderIOEither[A] {
-	return func(ctx context.Context) IOEither[A] {
-		return func() Either[A] {
-			<-ctx.Done()
-			return either.Left[A](context.Cause(ctx))
-		}
-	}
-}
-
-// MonadChainIOK chains a function that returns an [IO] into a [ReaderIOEither] computation.
-// The IO computation always succeeds, so it's wrapped in Right.
-//
-// Parameters:
-//   - ma: The ReaderIOEither to chain from
-//   - f: Function that produces an IO
-//
-// Returns a new ReaderIOEither with the chained IO computation.
-func MonadChainIOK[A, B any](ma ReaderIOEither[A], f func(A) IO[B]) ReaderIOEither[B] {
-	return readerioeither.MonadChainIOK(ma, f)
-}
-
-// ChainIOK chains a function that returns an [IO] into a [ReaderIOEither] computation.
-// This is the curried version of [MonadChainIOK].
-//
-// Parameters:
-//   - f: Function that produces an IO
-//
-// Returns a function that chains the IO-returning function.
-func ChainIOK[A, B any](f func(A) IO[B]) func(ma ReaderIOEither[A]) ReaderIOEither[B] {
-	return readerioeither.ChainIOK[context.Context, error](f)
-}
-
-// MonadChainFirstIOK chains a function that returns an [IO] but keeps the original value.
-// The IO computation is executed for its side effects only.
-//
-// Parameters:
-//   - ma: The ReaderIOEither to chain from
-//   - f: Function that produces an IO
-//
-// Returns a ReaderIOEither with the original value after executing the IO.
-func MonadChainFirstIOK[A, B any](ma ReaderIOEither[A], f func(A) IO[B]) ReaderIOEither[A] {
-	return readerioeither.MonadChainFirstIOK(ma, f)
-}
-
-// ChainFirstIOK chains a function that returns an [IO] but keeps the original value.
-// This is the curried version of [MonadChainFirstIOK].
-//
-// Parameters:
-//   - f: Function that produces an IO
-//
-// Returns a function that chains the IO-returning function.
-func ChainFirstIOK[A, B any](f func(A) IO[B]) func(ma ReaderIOEither[A]) ReaderIOEither[A] {
-	return readerioeither.ChainFirstIOK[context.Context, error](f)
-}
-
-// ChainIOEitherK chains a function that returns an [IOEither] into a [ReaderIOEither] computation.
-// This is useful for integrating IOEither-returning functions into ReaderIOEither workflows.
-//
-// Parameters:
-//   - f: Function that produces an IOEither
-//
-// Returns a function that chains the IOEither-returning function.
-func ChainIOEitherK[A, B any](f func(A) ioeither.IOEither[error, B]) func(ma ReaderIOEither[A]) ReaderIOEither[B] {
-	return readerioeither.ChainIOEitherK[context.Context](f)
-}
-
-// Delay creates an operation that delays execution by the specified duration.
-// The computation waits for either the delay to expire or the context to be canceled.
-//
-// Parameters:
-//   - delay: The duration to wait before executing the computation
-//
-// Returns a function that delays a ReaderIOEither computation.
-func Delay[A any](delay time.Duration) func(ma ReaderIOEither[A]) ReaderIOEither[A] {
-	return func(ma ReaderIOEither[A]) ReaderIOEither[A] {
-		return func(ctx context.Context) IOEither[A] {
-			return func() Either[A] {
-				// manage the timeout
-				timeoutCtx, cancelTimeout := context.WithTimeout(ctx, delay)
-				defer cancelTimeout()
-				// whatever comes first
-				select {
-				case <-timeoutCtx.Done():
-					return ma(ctx)()
-				case <-ctx.Done():
-					return either.Left[A](context.Cause(ctx))
-				}
-			}
-		}
-	}
-}
-
-// Timer returns the current time after waiting for the specified delay.
-// This is useful for creating time-based computations.
-//
-// Parameters:
-//   - delay: The duration to wait before returning the time
-//
-// Returns a ReaderIOEither that produces the current time after the delay.
-func Timer(delay time.Duration) ReaderIOEither[time.Time] {
-	return function.Pipe2(
-		io.Now,
-		FromIO[time.Time],
-		Delay[time.Time](delay),
-	)
-}
-
-// Defer creates a [ReaderIOEither] by lazily generating a new computation each time it's executed.
-// This is useful for creating computations that should be re-evaluated on each execution.
-//
-// Parameters:
-//   - gen: Lazy generator function that produces a ReaderIOEither
-//
-// Returns a ReaderIOEither that generates a fresh computation on each execution.
-func Defer[A any](gen Lazy[ReaderIOEither[A]]) ReaderIOEither[A] {
-	return readerioeither.Defer(gen)
-}
-
-// TryCatch wraps a function that returns a tuple (value, error) into a [ReaderIOEither].
-// This is the standard way to convert Go error-returning functions into ReaderIOEither.
-//
-// Parameters:
-//   - f: Function that takes a context and returns a function producing (value, error)
-//
-// Returns a ReaderIOEither that wraps the error-returning function.
-func TryCatch[A any](f func(context.Context) func() (A, error)) ReaderIOEither[A] {
-	return readerioeither.TryCatch(f, errors.IdentityError)
-}
-
-// MonadAlt provides an alternative [ReaderIOEither] if the first one fails.
-// The alternative is lazily evaluated only if needed.
-//
-// Parameters:
-//   - first: The primary ReaderIOEither to try
-//   - second: Lazy alternative ReaderIOEither to use if first fails
-//
-// Returns a ReaderIOEither that tries the first, then the second if first fails.
-func MonadAlt[A any](first ReaderIOEither[A], second Lazy[ReaderIOEither[A]]) ReaderIOEither[A] {
-	return readerioeither.MonadAlt(first, second)
-}
-
-// Alt provides an alternative [ReaderIOEither] if the first one fails.
-// This is the curried version of [MonadAlt].
-//
-// Parameters:
-//   - second: Lazy alternative ReaderIOEither to use if first fails
-//
-// Returns a function that provides fallback behavior.
-func Alt[A any](second Lazy[ReaderIOEither[A]]) Operator[A, A] {
-	return readerioeither.Alt(second)
-}
-
-// Memoize computes the value of the provided [ReaderIOEither] monad lazily but exactly once.
-// The context used to compute the value is the context of the first call, so do not use this
-// method if the value has a functional dependency on the content of the context.
-//
-// Parameters:
-//   - rdr: The ReaderIOEither to memoize
-//
-// Returns a ReaderIOEither that caches its result after the first execution.
-func Memoize[A any](rdr ReaderIOEither[A]) ReaderIOEither[A] {
-	return readerioeither.Memoize(rdr)
-}
-
-// Flatten converts a nested [ReaderIOEither] into a flat [ReaderIOEither].
-// This is equivalent to [MonadChain] with the identity function.
-//
-// Parameters:
-//   - rdr: The nested ReaderIOEither to flatten
-//
-// Returns a flattened ReaderIOEither.
-func Flatten[A any](rdr ReaderIOEither[ReaderIOEither[A]]) ReaderIOEither[A] {
-	return readerioeither.Flatten(rdr)
-}
-
-// MonadFlap applies a value to a function wrapped in a [ReaderIOEither].
-// This is the reverse of [MonadAp], useful in certain composition scenarios.
-//
-// Parameters:
-//   - fab: ReaderIOEither containing a function
-//   - a: The value to apply to the function
-//
-// Returns a ReaderIOEither with the function applied to the value.
-func MonadFlap[B, A any](fab ReaderIOEither[func(A) B], a A) ReaderIOEither[B] {
-	return readerioeither.MonadFlap(fab, a)
-}
-
-// Flap applies a value to a function wrapped in a [ReaderIOEither].
-// This is the curried version of [MonadFlap].
-//
-// Parameters:
-//   - a: The value to apply to the function
-//
-// Returns a function that applies the value to a ReaderIOEither function.
-func Flap[B, A any](a A) Operator[func(A) B, B] {
-	return readerioeither.Flap[context.Context, error, B](a)
-}
-
-// Fold handles both success and error cases of a [ReaderIOEither] by providing handlers for each.
-// Both handlers return ReaderIOEither, allowing for further composition.
-//
-// Parameters:
-//   - onLeft: Handler for error case
-//   - onRight: Handler for success case
-//
-// Returns a function that folds a ReaderIOEither into a new ReaderIOEither.
-func Fold[A, B any](onLeft func(error) ReaderIOEither[B], onRight func(A) ReaderIOEither[B]) Operator[A, B] {
-	return readerioeither.Fold(onLeft, onRight)
-}
-
-// GetOrElse extracts the value from a [ReaderIOEither], providing a default via a function if it fails.
-// The result is a [ReaderIO] that always succeeds.
-//
-// Parameters:
-//   - onLeft: Function to provide a default value from the error
-//
-// Returns a function that converts a ReaderIOEither to a ReaderIO.
-func GetOrElse[A any](onLeft func(error) ReaderIO[A]) func(ReaderIOEither[A]) ReaderIO[A] {
-	return readerioeither.GetOrElse(onLeft)
-}
-
-// OrLeft transforms the error of a [ReaderIOEither] using the provided function.
-// The success value is left unchanged.
-//
-// Parameters:
-//   - onLeft: Function to transform the error
-//
-// Returns a function that transforms the error of a ReaderIOEither.
-func OrLeft[A any](onLeft func(error) ReaderIO[error]) Operator[A, A] {
-	return readerioeither.OrLeft[A](onLeft)
-}

v2/context/readerioeither/reader_extended_test.go

@@ -1,532 +0,0 @@
-// 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 readerioeither
-
-import (
-	"context"
-	"errors"
-	"fmt"
-	"testing"
-	"time"
-
-	E "github.com/IBM/fp-go/v2/either"
-	O "github.com/IBM/fp-go/v2/option"
-	"github.com/stretchr/testify/assert"
-)
-
-func TestFromEither(t *testing.T) {
-	ctx := context.Background()
-
-	// Test with Right
-	rightVal := E.Right[error](42)
-	result := FromEither(rightVal)(ctx)()
-	assert.Equal(t, E.Right[error](42), result)
-
-	// Test with Left
-	err := errors.New("test error")
-	leftVal := E.Left[int](err)
-	result = FromEither(leftVal)(ctx)()
-	assert.Equal(t, E.Left[int](err), result)
-}
-
-func TestLeftRight(t *testing.T) {
-	ctx := context.Background()
-
-	// Test Left
-	err := errors.New("test error")
-	result := Left[int](err)(ctx)()
-	assert.True(t, E.IsLeft(result))
-
-	// Test Right
-	result = Right(42)(ctx)()
-	assert.True(t, E.IsRight(result))
-	val, _ := E.Unwrap(result)
-	assert.Equal(t, 42, val)
-}
-
-func TestOf(t *testing.T) {
-	ctx := context.Background()
-	result := Of(42)(ctx)()
-	assert.Equal(t, E.Right[error](42), result)
-}
-
-func TestMonadMap(t *testing.T) {
-	ctx := context.Background()
-
-	// Test with Right
-	result := MonadMap(Right(42), func(x int) int { return x * 2 })(ctx)()
-	assert.Equal(t, E.Right[error](84), result)
-
-	// Test with Left
-	err := errors.New("test error")
-	result = MonadMap(Left[int](err), func(x int) int { return x * 2 })(ctx)()
-	assert.Equal(t, E.Left[int](err), result)
-}
-
-func TestMonadMapTo(t *testing.T) {
-	ctx := context.Background()
-
-	// Test with Right
-	result := MonadMapTo(Right(42), "hello")(ctx)()
-	assert.Equal(t, E.Right[error]("hello"), result)
-
-	// Test with Left
-	err := errors.New("test error")
-	result = MonadMapTo(Left[int](err), "hello")(ctx)()
-	assert.Equal(t, E.Left[string](err), result)
-}
-
-func TestMonadChain(t *testing.T) {
-	ctx := context.Background()
-
-	// Test with Right
-	result := MonadChain(Right(42), func(x int) ReaderIOEither[int] {
-		return Right(x * 2)
-	})(ctx)()
-	assert.Equal(t, E.Right[error](84), result)
-
-	// Test with Left
-	err := errors.New("test error")
-	result = MonadChain(Left[int](err), func(x int) ReaderIOEither[int] {
-		return Right(x * 2)
-	})(ctx)()
-	assert.Equal(t, E.Left[int](err), result)
-
-	// Test where function returns Left
-	result = MonadChain(Right(42), func(x int) ReaderIOEither[int] {
-		return Left[int](errors.New("chain error"))
-	})(ctx)()
-	assert.True(t, E.IsLeft(result))
-}
-
-func TestMonadChainFirst(t *testing.T) {
-	ctx := context.Background()
-
-	// Test with Right
-	result := MonadChainFirst(Right(42), func(x int) ReaderIOEither[string] {
-		return Right("ignored")
-	})(ctx)()
-	assert.Equal(t, E.Right[error](42), result)
-
-	// Test with Left in first
-	err := errors.New("test error")
-	result = MonadChainFirst(Left[int](err), func(x int) ReaderIOEither[string] {
-		return Right("ignored")
-	})(ctx)()
-	assert.Equal(t, E.Left[int](err), result)
-
-	// Test with Left in second
-	result = MonadChainFirst(Right(42), func(x int) ReaderIOEither[string] {
-		return Left[string](errors.New("chain error"))
-	})(ctx)()
-	assert.True(t, E.IsLeft(result))
-}
-
-func TestMonadApSeq(t *testing.T) {
-	ctx := context.Background()
-
-	// Test with both Right
-	fct := Right(func(x int) int { return x * 2 })
-	val := Right(42)
-	result := MonadApSeq(fct, val)(ctx)()
-	assert.Equal(t, E.Right[error](84), result)
-
-	// Test with Left function
-	err := errors.New("function error")
-	fct = Left[func(int) int](err)
-	result = MonadApSeq(fct, val)(ctx)()
-	assert.Equal(t, E.Left[int](err), result)
-
-	// Test with Left value
-	fct = Right(func(x int) int { return x * 2 })
-	err = errors.New("value error")
-	val = Left[int](err)
-	result = MonadApSeq(fct, val)(ctx)()
-	assert.Equal(t, E.Left[int](err), result)
-}
-
-func TestMonadApPar(t *testing.T) {
-	ctx := context.Background()
-
-	// Test with both Right
-	fct := Right(func(x int) int { return x * 2 })
-	val := Right(42)
-	result := MonadApPar(fct, val)(ctx)()
-	assert.Equal(t, E.Right[error](84), result)
-}
-
-func TestFromPredicate(t *testing.T) {
-	ctx := context.Background()
-
-	pred := func(x int) bool { return x > 0 }
-	onFalse := func(x int) error { return fmt.Errorf("value %d is not positive", x) }
-
-	// Test with predicate true
-	result := FromPredicate(pred, onFalse)(42)(ctx)()
-	assert.Equal(t, E.Right[error](42), result)
-
-	// Test with predicate false
-	result = FromPredicate(pred, onFalse)(-1)(ctx)()
-	assert.True(t, E.IsLeft(result))
-}
-
-func TestAsk(t *testing.T) {
-	ctx := context.WithValue(context.Background(), "key", "value")
-	result := Ask()(ctx)()
-	assert.True(t, E.IsRight(result))
-	retrievedCtx, _ := E.Unwrap(result)
-	assert.Equal(t, "value", retrievedCtx.Value("key"))
-}
-
-func TestMonadChainEitherK(t *testing.T) {
-	ctx := context.Background()
-
-	// Test with Right
-	result := MonadChainEitherK(Right(42), func(x int) E.Either[error, int] {
-		return E.Right[error](x * 2)
-	})(ctx)()
-	assert.Equal(t, E.Right[error](84), result)
-
-	// Test with Left in Either
-	result = MonadChainEitherK(Right(42), func(x int) E.Either[error, int] {
-		return E.Left[int](errors.New("either error"))
-	})(ctx)()
-	assert.True(t, E.IsLeft(result))
-}
-
-func TestMonadChainFirstEitherK(t *testing.T) {
-	ctx := context.Background()
-
-	// Test with Right
-	result := MonadChainFirstEitherK(Right(42), func(x int) E.Either[error, string] {
-		return E.Right[error]("ignored")
-	})(ctx)()
-	assert.Equal(t, E.Right[error](42), result)
-
-	// Test with Left in Either
-	result = MonadChainFirstEitherK(Right(42), func(x int) E.Either[error, string] {
-		return E.Left[string](errors.New("either error"))
-	})(ctx)()
-	assert.True(t, E.IsLeft(result))
-}
-
-func TestChainOptionKFunc(t *testing.T) {
-	ctx := context.Background()
-
-	onNone := func() error { return errors.New("none error") }
-
-	// Test with Some
-	chainFunc := ChainOptionK[int, int](onNone)
-	result := chainFunc(func(x int) O.Option[int] {
-		return O.Some(x * 2)
-	})(Right(42))(ctx)()
-	assert.Equal(t, E.Right[error](84), result)
-
-	// Test with None
-	result = chainFunc(func(x int) O.Option[int] {
-		return O.None[int]()
-	})(Right(42))(ctx)()
-	assert.True(t, E.IsLeft(result))
-}
-
-func TestFromIOEither(t *testing.T) {
-	ctx := context.Background()
-
-	// Test with Right
-	ioe := func() E.Either[error, int] {
-		return E.Right[error](42)
-	}
-	result := FromIOEither(ioe)(ctx)()
-	assert.Equal(t, E.Right[error](42), result)
-
-	// Test with Left
-	err := errors.New("test error")
-	ioe = func() E.Either[error, int] {
-		return E.Left[int](err)
-	}
-	result = FromIOEither(ioe)(ctx)()
-	assert.Equal(t, E.Left[int](err), result)
-}
-
-func TestFromIO(t *testing.T) {
-	ctx := context.Background()
-
-	io := func() int { return 42 }
-	result := FromIO(io)(ctx)()
-	assert.Equal(t, E.Right[error](42), result)
-}
-
-func TestFromLazy(t *testing.T) {
-	ctx := context.Background()
-
-	lazy := func() int { return 42 }
-	result := FromLazy(lazy)(ctx)()
-	assert.Equal(t, E.Right[error](42), result)
-}
-
-func TestNeverWithCancel(t *testing.T) {
-	ctx, cancel := context.WithCancel(context.Background())
-
-	// Start Never in a goroutine
-	done := make(chan E.Either[error, int])
-	go func() {
-		done <- Never[int]()(ctx)()
-	}()
-
-	// Cancel the context
-	cancel()
-
-	// Should receive cancellation error
-	result := <-done
-	assert.True(t, E.IsLeft(result))
-}
-
-func TestMonadChainIOK(t *testing.T) {
-	ctx := context.Background()
-
-	// Test with Right
-	result := MonadChainIOK(Right(42), func(x int) func() int {
-		return func() int { return x * 2 }
-	})(ctx)()
-	assert.Equal(t, E.Right[error](84), result)
-}
-
-func TestMonadChainFirstIOK(t *testing.T) {
-	ctx := context.Background()
-
-	// Test with Right
-	result := MonadChainFirstIOK(Right(42), func(x int) func() string {
-		return func() string { return "ignored" }
-	})(ctx)()
-	assert.Equal(t, E.Right[error](42), result)
-}
-
-func TestDelayFunc(t *testing.T) {
-	ctx := context.Background()
-	delay := 100 * time.Millisecond
-
-	start := time.Now()
-	delayFunc := Delay[int](delay)
-	result := delayFunc(Right(42))(ctx)()
-	elapsed := time.Since(start)
-
-	assert.True(t, E.IsRight(result))
-	assert.GreaterOrEqual(t, elapsed, delay)
-}
-
-func TestDefer(t *testing.T) {
-	ctx := context.Background()
-	count := 0
-
-	gen := func() ReaderIOEither[int] {
-		count++
-		return Right(count)
-	}
-
-	deferred := Defer(gen)
-
-	// First call
-	result1 := deferred(ctx)()
-	assert.Equal(t, E.Right[error](1), result1)
-
-	// Second call should generate new value
-	result2 := deferred(ctx)()
-	assert.Equal(t, E.Right[error](2), result2)
-}
-
-func TestTryCatch(t *testing.T) {
-	ctx := context.Background()
-
-	// Test success
-	result := TryCatch(func(ctx context.Context) func() (int, error) {
-		return func() (int, error) {
-			return 42, nil
-		}
-	})(ctx)()
-	assert.Equal(t, E.Right[error](42), result)
-
-	// Test error
-	err := errors.New("test error")
-	result = TryCatch(func(ctx context.Context) func() (int, error) {
-		return func() (int, error) {
-			return 0, err
-		}
-	})(ctx)()
-	assert.Equal(t, E.Left[int](err), result)
-}
-
-func TestMonadAlt(t *testing.T) {
-	ctx := context.Background()
-
-	// Test with Right (alternative not called)
-	result := MonadAlt(Right(42), func() ReaderIOEither[int] {
-		return Right(99)
-	})(ctx)()
-	assert.Equal(t, E.Right[error](42), result)
-
-	// Test with Left (alternative called)
-	err := errors.New("test error")
-	result = MonadAlt(Left[int](err), func() ReaderIOEither[int] {
-		return Right(99)
-	})(ctx)()
-	assert.Equal(t, E.Right[error](99), result)
-}
-
-func TestMemoize(t *testing.T) {
-	ctx := context.Background()
-	count := 0
-
-	rdr := Memoize(FromLazy(func() int {
-		count++
-		return count
-	}))
-
-	// First call
-	result1 := rdr(ctx)()
-	assert.Equal(t, E.Right[error](1), result1)
-
-	// Second call should return memoized value
-	result2 := rdr(ctx)()
-	assert.Equal(t, E.Right[error](1), result2)
-}
-
-func TestFlatten(t *testing.T) {
-	ctx := context.Background()
-
-	nested := Right(Right(42))
-	result := Flatten(nested)(ctx)()
-	assert.Equal(t, E.Right[error](42), result)
-}
-
-func TestMonadFlap(t *testing.T) {
-	ctx := context.Background()
-	fab := Right(func(x int) int { return x * 2 })
-	result := MonadFlap(fab, 42)(ctx)()
-	assert.Equal(t, E.Right[error](84), result)
-}
-
-func TestWithContext(t *testing.T) {
-	// Test with non-canceled context
-	ctx := context.Background()
-	result := WithContext(Right(42))(ctx)()
-	assert.Equal(t, E.Right[error](42), result)
-
-	// Test with canceled context
-	ctx, cancel := context.WithCancel(context.Background())
-	cancel()
-	result = WithContext(Right(42))(ctx)()
-	assert.True(t, E.IsLeft(result))
-}
-
-func TestMonadAp(t *testing.T) {
-	ctx := context.Background()
-
-	// Test with both Right
-	fct := Right(func(x int) int { return x * 2 })
-	val := Right(42)
-	result := MonadAp(fct, val)(ctx)()
-	assert.Equal(t, E.Right[error](84), result)
-}
-
-// Test traverse functions
-func TestSequenceArray(t *testing.T) {
-	ctx := context.Background()
-
-	// Test with all Right
-	arr := []ReaderIOEither[int]{Right(1), Right(2), Right(3)}
-	result := SequenceArray(arr)(ctx)()
-	assert.True(t, E.IsRight(result))
-	vals, _ := E.Unwrap(result)
-	assert.Equal(t, []int{1, 2, 3}, vals)
-
-	// Test with one Left
-	err := errors.New("test error")
-	arr = []ReaderIOEither[int]{Right(1), Left[int](err), Right(3)}
-	result = SequenceArray(arr)(ctx)()
-	assert.True(t, E.IsLeft(result))
-}
-
-func TestTraverseArray(t *testing.T) {
-	ctx := context.Background()
-
-	// Test transformation
-	arr := []int{1, 2, 3}
-	result := TraverseArray(func(x int) ReaderIOEither[int] {
-		return Right(x * 2)
-	})(arr)(ctx)()
-	assert.True(t, E.IsRight(result))
-	vals, _ := E.Unwrap(result)
-	assert.Equal(t, []int{2, 4, 6}, vals)
-}
-
-func TestSequenceRecord(t *testing.T) {
-	ctx := context.Background()
-
-	// Test with all Right
-	rec := map[string]ReaderIOEither[int]{
-		"a": Right(1),
-		"b": Right(2),
-	}
-	result := SequenceRecord(rec)(ctx)()
-	assert.True(t, E.IsRight(result))
-	vals, _ := E.Unwrap(result)
-	assert.Equal(t, 1, vals["a"])
-	assert.Equal(t, 2, vals["b"])
-}
-
-func TestTraverseRecord(t *testing.T) {
-	ctx := context.Background()
-
-	// Test transformation
-	rec := map[string]int{"a": 1, "b": 2}
-	result := TraverseRecord[string](func(x int) ReaderIOEither[int] {
-		return Right(x * 2)
-	})(rec)(ctx)()
-	assert.True(t, E.IsRight(result))
-	vals, _ := E.Unwrap(result)
-	assert.Equal(t, 2, vals["a"])
-	assert.Equal(t, 4, vals["b"])
-}
-
-// Test monoid functions
-func TestAltSemigroup(t *testing.T) {
-	ctx := context.Background()
-
-	sg := AltSemigroup[int]()
-
-	// Test with Right (first succeeds)
-	result := sg.Concat(Right(42), Right(99))(ctx)()
-	assert.Equal(t, E.Right[error](42), result)
-
-	// Test with Left then Right (fallback)
-	err := errors.New("test error")
-	result = sg.Concat(Left[int](err), Right(99))(ctx)()
-	assert.Equal(t, E.Right[error](99), result)
-}
-
-// Test Do notation
-func TestDo(t *testing.T) {
-	ctx := context.Background()
-
-	type State struct {
-		Value int
-	}
-
-	result := Do(State{Value: 42})(ctx)()
-	assert.True(t, E.IsRight(result))
-	state, _ := E.Unwrap(result)
-	assert.Equal(t, 42, state.Value)
-}

v2/context/readerioeither/traverse.go

@@ -1,306 +0,0 @@
-// 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 readerioeither
-
-import (
-	"github.com/IBM/fp-go/v2/function"
-	"github.com/IBM/fp-go/v2/internal/array"
-	"github.com/IBM/fp-go/v2/internal/record"
-)
-
-// TraverseArray transforms an array [[]A] into [[]ReaderIOEither[B]] and then resolves that into a [ReaderIOEither[[]B]].
-// This uses the default applicative behavior (parallel or sequential based on useParallel flag).
-//
-// Parameters:
-//   - f: Function that transforms each element into a ReaderIOEither
-//
-// Returns a function that transforms an array into a ReaderIOEither of an array.
-func TraverseArray[A, B any](f func(A) ReaderIOEither[B]) func([]A) ReaderIOEither[[]B] {
-	return array.Traverse[[]A](
-		Of[[]B],
-		Map[[]B, func(B) []B],
-		Ap[[]B, B],
-
-		f,
-	)
-}
-
-// TraverseArrayWithIndex transforms an array [[]A] into [[]ReaderIOEither[B]] and then resolves that into a [ReaderIOEither[[]B]].
-// The transformation function receives both the index and the element.
-//
-// Parameters:
-//   - f: Function that transforms each element with its index into a ReaderIOEither
-//
-// Returns a function that transforms an array into a ReaderIOEither of an array.
-func TraverseArrayWithIndex[A, B any](f func(int, A) ReaderIOEither[B]) func([]A) ReaderIOEither[[]B] {
-	return array.TraverseWithIndex[[]A](
-		Of[[]B],
-		Map[[]B, func(B) []B],
-		Ap[[]B, B],
-
-		f,
-	)
-}
-
-// SequenceArray converts a homogeneous sequence of ReaderIOEither into a ReaderIOEither of sequence.
-// This is equivalent to TraverseArray with the identity function.
-//
-// Parameters:
-//   - ma: Array of ReaderIOEither values
-//
-// Returns a ReaderIOEither containing an array of values.
-func SequenceArray[A any](ma []ReaderIOEither[A]) ReaderIOEither[[]A] {
-	return TraverseArray(function.Identity[ReaderIOEither[A]])(ma)
-}
-
-// TraverseRecord transforms a record [map[K]A] into [map[K]ReaderIOEither[B]] and then resolves that into a [ReaderIOEither[map[K]B]].
-//
-// Parameters:
-//   - f: Function that transforms each value into a ReaderIOEither
-//
-// Returns a function that transforms a map into a ReaderIOEither of a map.
-func TraverseRecord[K comparable, A, B any](f func(A) ReaderIOEither[B]) func(map[K]A) ReaderIOEither[map[K]B] {
-	return record.Traverse[map[K]A](
-		Of[map[K]B],
-		Map[map[K]B, func(B) map[K]B],
-		Ap[map[K]B, B],
-
-		f,
-	)
-}
-
-// TraverseRecordWithIndex transforms a record [map[K]A] into [map[K]ReaderIOEither[B]] and then resolves that into a [ReaderIOEither[map[K]B]].
-// The transformation function receives both the key and the value.
-//
-// Parameters:
-//   - f: Function that transforms each key-value pair into a ReaderIOEither
-//
-// Returns a function that transforms a map into a ReaderIOEither of a map.
-func TraverseRecordWithIndex[K comparable, A, B any](f func(K, A) ReaderIOEither[B]) func(map[K]A) ReaderIOEither[map[K]B] {
-	return record.TraverseWithIndex[map[K]A](
-		Of[map[K]B],
-		Map[map[K]B, func(B) map[K]B],
-		Ap[map[K]B, B],
-
-		f,
-	)
-}
-
-// SequenceRecord converts a homogeneous map of ReaderIOEither into a ReaderIOEither of map.
-//
-// Parameters:
-//   - ma: Map of ReaderIOEither values
-//
-// Returns a ReaderIOEither containing a map of values.
-func SequenceRecord[K comparable, A any](ma map[K]ReaderIOEither[A]) ReaderIOEither[map[K]A] {
-	return TraverseRecord[K](function.Identity[ReaderIOEither[A]])(ma)
-}
-
-// MonadTraverseArraySeq transforms an array [[]A] into [[]ReaderIOEither[B]] and then resolves that into a [ReaderIOEither[[]B]].
-// This explicitly uses sequential execution.
-//
-// Parameters:
-//   - as: The array to traverse
-//   - f: Function that transforms each element into a ReaderIOEither
-//
-// Returns a ReaderIOEither containing an array of transformed values.
-func MonadTraverseArraySeq[A, B any](as []A, f func(A) ReaderIOEither[B]) ReaderIOEither[[]B] {
-	return array.MonadTraverse[[]A](
-		Of[[]B],
-		Map[[]B, func(B) []B],
-		ApSeq[[]B, B],
-		as,
-		f,
-	)
-}
-
-// TraverseArraySeq transforms an array [[]A] into [[]ReaderIOEither[B]] and then resolves that into a [ReaderIOEither[[]B]].
-// This is the curried version of [MonadTraverseArraySeq] with sequential execution.
-//
-// Parameters:
-//   - f: Function that transforms each element into a ReaderIOEither
-//
-// Returns a function that transforms an array into a ReaderIOEither of an array.
-func TraverseArraySeq[A, B any](f func(A) ReaderIOEither[B]) func([]A) ReaderIOEither[[]B] {
-	return array.Traverse[[]A](
-		Of[[]B],
-		Map[[]B, func(B) []B],
-		ApSeq[[]B, B],
-
-		f,
-	)
-}
-
-// TraverseArrayWithIndexSeq uses transforms an array [[]A] into [[]ReaderIOEither[B]] and then resolves that into a [ReaderIOEither[[]B]]
-func TraverseArrayWithIndexSeq[A, B any](f func(int, A) ReaderIOEither[B]) func([]A) ReaderIOEither[[]B] {
-	return array.TraverseWithIndex[[]A](
-		Of[[]B],
-		Map[[]B, func(B) []B],
-		ApSeq[[]B, B],
-
-		f,
-	)
-}
-
-// SequenceArraySeq converts a homogeneous sequence of ReaderIOEither into a ReaderIOEither of sequence.
-// This explicitly uses sequential execution.
-//
-// Parameters:
-//   - ma: Array of ReaderIOEither values
-//
-// Returns a ReaderIOEither containing an array of values.
-func SequenceArraySeq[A any](ma []ReaderIOEither[A]) ReaderIOEither[[]A] {
-	return MonadTraverseArraySeq(ma, function.Identity[ReaderIOEither[A]])
-}
-
-// MonadTraverseRecordSeq uses transforms a record [map[K]A] into [map[K]ReaderIOEither[B]] and then resolves that into a [ReaderIOEither[map[K]B]]
-func MonadTraverseRecordSeq[K comparable, A, B any](as map[K]A, f func(A) ReaderIOEither[B]) ReaderIOEither[map[K]B] {
-	return record.MonadTraverse[map[K]A](
-		Of[map[K]B],
-		Map[map[K]B, func(B) map[K]B],
-		ApSeq[map[K]B, B],
-		as,
-		f,
-	)
-}
-
-// TraverseRecordSeq uses transforms a record [map[K]A] into [map[K]ReaderIOEither[B]] and then resolves that into a [ReaderIOEither[map[K]B]]
-func TraverseRecordSeq[K comparable, A, B any](f func(A) ReaderIOEither[B]) func(map[K]A) ReaderIOEither[map[K]B] {
-	return record.Traverse[map[K]A](
-		Of[map[K]B],
-		Map[map[K]B, func(B) map[K]B],
-		ApSeq[map[K]B, B],
-
-		f,
-	)
-}
-
-// TraverseRecordWithIndexSeq uses transforms a record [map[K]A] into [map[K]ReaderIOEither[B]] and then resolves that into a [ReaderIOEither[map[K]B]]
-func TraverseRecordWithIndexSeq[K comparable, A, B any](f func(K, A) ReaderIOEither[B]) func(map[K]A) ReaderIOEither[map[K]B] {
-	return record.TraverseWithIndex[map[K]A](
-		Of[map[K]B],
-		Map[map[K]B, func(B) map[K]B],
-		ApSeq[map[K]B, B],
-
-		f,
-	)
-}
-
-// SequenceRecordSeq converts a homogeneous sequence of either into an either of sequence
-func SequenceRecordSeq[K comparable, A any](ma map[K]ReaderIOEither[A]) ReaderIOEither[map[K]A] {
-	return MonadTraverseRecordSeq(ma, function.Identity[ReaderIOEither[A]])
-}
-
-// MonadTraverseArrayPar transforms an array [[]A] into [[]ReaderIOEither[B]] and then resolves that into a [ReaderIOEither[[]B]].
-// This explicitly uses parallel execution.
-//
-// Parameters:
-//   - as: The array to traverse
-//   - f: Function that transforms each element into a ReaderIOEither
-//
-// Returns a ReaderIOEither containing an array of transformed values.
-func MonadTraverseArrayPar[A, B any](as []A, f func(A) ReaderIOEither[B]) ReaderIOEither[[]B] {
-	return array.MonadTraverse[[]A](
-		Of[[]B],
-		Map[[]B, func(B) []B],
-		ApPar[[]B, B],
-		as,
-		f,
-	)
-}
-
-// TraverseArrayPar transforms an array [[]A] into [[]ReaderIOEither[B]] and then resolves that into a [ReaderIOEither[[]B]].
-// This is the curried version of [MonadTraverseArrayPar] with parallel execution.
-//
-// Parameters:
-//   - f: Function that transforms each element into a ReaderIOEither
-//
-// Returns a function that transforms an array into a ReaderIOEither of an array.
-func TraverseArrayPar[A, B any](f func(A) ReaderIOEither[B]) func([]A) ReaderIOEither[[]B] {
-	return array.Traverse[[]A](
-		Of[[]B],
-		Map[[]B, func(B) []B],
-		ApPar[[]B, B],
-
-		f,
-	)
-}
-
-// TraverseArrayWithIndexPar uses transforms an array [[]A] into [[]ReaderIOEither[B]] and then resolves that into a [ReaderIOEither[[]B]]
-func TraverseArrayWithIndexPar[A, B any](f func(int, A) ReaderIOEither[B]) func([]A) ReaderIOEither[[]B] {
-	return array.TraverseWithIndex[[]A](
-		Of[[]B],
-		Map[[]B, func(B) []B],
-		ApPar[[]B, B],
-
-		f,
-	)
-}
-
-// SequenceArrayPar converts a homogeneous sequence of ReaderIOEither into a ReaderIOEither of sequence.
-// This explicitly uses parallel execution.
-//
-// Parameters:
-//   - ma: Array of ReaderIOEither values
-//
-// Returns a ReaderIOEither containing an array of values.
-func SequenceArrayPar[A any](ma []ReaderIOEither[A]) ReaderIOEither[[]A] {
-	return MonadTraverseArrayPar(ma, function.Identity[ReaderIOEither[A]])
-}
-
-// TraverseRecordPar uses transforms a record [map[K]A] into [map[K]ReaderIOEither[B]] and then resolves that into a [ReaderIOEither[map[K]B]]
-func TraverseRecordPar[K comparable, A, B any](f func(A) ReaderIOEither[B]) func(map[K]A) ReaderIOEither[map[K]B] {
-	return record.Traverse[map[K]A](
-		Of[map[K]B],
-		Map[map[K]B, func(B) map[K]B],
-		ApPar[map[K]B, B],
-
-		f,
-	)
-}
-
-// TraverseRecordWithIndexPar uses transforms a record [map[K]A] into [map[K]ReaderIOEither[B]] and then resolves that into a [ReaderIOEither[map[K]B]]
-func TraverseRecordWithIndexPar[K comparable, A, B any](f func(K, A) ReaderIOEither[B]) func(map[K]A) ReaderIOEither[map[K]B] {
-	return record.TraverseWithIndex[map[K]A](
-		Of[map[K]B],
-		Map[map[K]B, func(B) map[K]B],
-		ApPar[map[K]B, B],
-
-		f,
-	)
-}
-
-// MonadTraverseRecordPar uses transforms a record [map[K]A] into [map[K]ReaderIOEither[B]] and then resolves that into a [ReaderIOEither[map[K]B]]
-func MonadTraverseRecordPar[K comparable, A, B any](as map[K]A, f func(A) ReaderIOEither[B]) ReaderIOEither[map[K]B] {
-	return record.MonadTraverse[map[K]A](
-		Of[map[K]B],
-		Map[map[K]B, func(B) map[K]B],
-		ApPar[map[K]B, B],
-		as,
-		f,
-	)
-}
-
-// SequenceRecordPar converts a homogeneous map of ReaderIOEither into a ReaderIOEither of map.
-// This explicitly uses parallel execution.
-//
-// Parameters:
-//   - ma: Map of ReaderIOEither values
-//
-// Returns a ReaderIOEither containing a map of values.
-func SequenceRecordPar[K comparable, A any](ma map[K]ReaderIOEither[A]) ReaderIOEither[map[K]A] {
-	return MonadTraverseRecordPar(ma, function.Identity[ReaderIOEither[A]])
-}

v2/context/readerioresult/BENCHMARKS.md

@@ -0,0 +1,374 @@
+# ReaderIOResult Benchmarks
+
+This document describes the benchmark suite for the `context/readerioeither` package and how to interpret the results to identify performance bottlenecks.
+
+## Running Benchmarks
+
+To run all benchmarks:
+```bash
+cd context/readerioeither
+go test -bench=. -benchmem
+```
+
+To run specific benchmarks:
+```bash
+go test -bench=BenchmarkMap -benchmem
+go test -bench=BenchmarkChain -benchmem
+go test -bench=BenchmarkApPar -benchmem
+```
+
+To run with more iterations for stable results:
+```bash
+go test -bench=. -benchmem -benchtime=100000x
+```
+
+## Benchmark Categories
+
+### 1. Core Constructors
+- `BenchmarkLeft` - Creating Left (error) values (~64ns, 2 allocs)
+- `BenchmarkRight` - Creating Right (success) values (~64ns, 2 allocs)
+- `BenchmarkOf` - Creating Right values via Of (~47ns, 2 allocs)
+
+**Key Insights:**
+- All constructors allocate 2 times (64B total)
+- `Of` is slightly faster than `Right` due to inlining
+- Construction is very fast, suitable for hot paths
+
+### 2. Conversion Operations
+- `BenchmarkFromEither_Right/Left` - Converting Either to ReaderIOResult (~70ns, 2 allocs)
+- `BenchmarkFromIO` - Converting IO to ReaderIOResult (~78ns, 3 allocs)
+- `BenchmarkFromIOEither_Right/Left` - Converting IOEither (~23ns, 1 alloc)
+
+**Key Insights:**
+- FromIOEither is the fastest conversion (~23ns)
+- FromIO has an extra allocation due to wrapping
+- All conversions are lightweight
+
+### 3. Execution Operations
+- `BenchmarkExecute_Right` - Executing Right computation (~37ns, 1 alloc)
+- `BenchmarkExecute_Left` - Executing Left computation (~48ns, 1 alloc)
+- `BenchmarkExecute_WithContext` - Executing with context (~42ns, 1 alloc)
+
+**Key Insights:**
+- Execution is very fast with minimal allocations
+- Left path is slightly slower due to error handling
+- Context overhead is minimal (~5ns)
+
+### 4. Functor Operations (Map)
+- `BenchmarkMonadMap_Right/Left` - Direct map (~135ns, 5 allocs)
+- `BenchmarkMap_Right/Left` - Curried map (~24ns, 1 alloc)
+- `BenchmarkMapTo_Right` - Replacing with constant (~69ns, 1 alloc)
+
+**Key Insights:**
+- **Bottleneck:** MonadMap has 5 allocations (128B)
+- Curried Map is ~5x faster with fewer allocations
+- **Recommendation:** Use curried `Map` instead of `MonadMap`
+
+### 5. Monad Operations (Chain)
+- `BenchmarkMonadChain_Right/Left` - Direct chain (~190ns, 6 allocs)
+- `BenchmarkChain_Right/Left` - Curried chain (~28ns, 1 alloc)
+- `BenchmarkChainFirst_Right/Left` - Chain preserving original (~27ns, 1 alloc)
+- `BenchmarkFlatten_Right/Left` - Removing nesting (~147ns, 7 allocs)
+
+**Key Insights:**
+- **Bottleneck:** MonadChain has 6 allocations (160B)
+- Curried Chain is ~7x faster
+- ChainFirst is as fast as Chain
+- **Bottleneck:** Flatten has 7 allocations
+- **Recommendation:** Use curried `Chain` instead of `MonadChain`
+
+### 6. Applicative Operations (Ap)
+- `BenchmarkMonadApSeq_RightRight` - Sequential apply (~281ns, 8 allocs)
+- `BenchmarkMonadApPar_RightRight` - Parallel apply (~49ns, 3 allocs)
+- `BenchmarkExecuteApSeq_RightRight` - Executing sequential (~1403ns, 8 allocs)
+- `BenchmarkExecuteApPar_RightRight` - Executing parallel (~5606ns, 61 allocs)
+
+**Key Insights:**
+- **Major Bottleneck:** Parallel execution has 61 allocations (1896B)
+- Construction of ApPar is fast (~49ns), but execution is expensive
+- Sequential execution is faster for simple operations (~1.4μs vs ~5.6μs)
+- **Recommendation:** Use ApSeq for simple operations, ApPar only for truly independent, expensive computations
+- Parallel overhead includes context management and goroutine coordination
+
+### 7. Alternative Operations
+- `BenchmarkAlt_RightRight/LeftRight` - Providing alternatives (~210-344ns, 6 allocs)
+- `BenchmarkOrElse_Right/Left` - Recovery from Left (~40-52ns, 2 allocs)
+
+**Key Insights:**
+- Alt has significant overhead (6 allocations)
+- OrElse is much more efficient for error recovery
+- **Recommendation:** Prefer OrElse over Alt when possible
+
+### 8. Chain Operations with Different Types
+- `BenchmarkChainEitherK_Right/Left` - Chaining Either (~25ns, 1 alloc)
+- `BenchmarkChainIOK_Right/Left` - Chaining IO (~55ns, 1 alloc)
+- `BenchmarkChainIOEitherK_Right/Left` - Chaining IOEither (~53ns, 1 alloc)
+
+**Key Insights:**
+- All chain-K operations are efficient
+- ChainEitherK is fastest (pure transformation)
+- ChainIOK and ChainIOEitherK have similar performance
+
+### 9. Context Operations
+- `BenchmarkAsk` - Accessing context (~52ns, 3 allocs)
+- `BenchmarkDefer` - Lazy generation (~34ns, 1 alloc)
+- `BenchmarkMemoize` - Caching results (~82ns, 4 allocs)
+
+**Key Insights:**
+- Ask has 3 allocations for context wrapping
+- Defer is lightweight
+- Memoize has overhead but pays off for expensive computations
+
+### 10. Delay Operations
+- `BenchmarkDelay_Construction` - Creating delayed computation (~19ns, 1 alloc)
+- `BenchmarkTimer_Construction` - Creating timer (~92ns, 3 allocs)
+
+**Key Insights:**
+- Delay construction is very cheap
+- Timer has additional overhead for time operations
+
+### 11. TryCatch Operations
+- `BenchmarkTryCatch_Success/Error` - Creating TryCatch (~33ns, 1 alloc)
+- `BenchmarkExecuteTryCatch_Success/Error` - Executing TryCatch (~3ns, 0 allocs)
+
+**Key Insights:**
+- TryCatch construction is cheap
+- Execution is extremely fast with zero allocations
+- Excellent for wrapping Go error-returning functions
+
+### 12. Pipeline Operations
+- `BenchmarkPipeline_Map_Right/Left` - Single Map in pipeline (~200-306ns, 9 allocs)
+- `BenchmarkPipeline_Chain_Right/Left` - Single Chain in pipeline (~155-217ns, 7 allocs)
+- `BenchmarkPipeline_Complex_Right/Left` - Multiple operations (~777-1039ns, 25 allocs)
+- `BenchmarkExecutePipeline_Complex_Right` - Executing complex pipeline (~533ns, 10 allocs)
+
+**Key Insights:**
+- **Major Bottleneck:** Pipeline operations allocate heavily
+- Single Map: ~200ns with 9 allocations (224B)
+- Complex pipeline: ~900ns with 25 allocations (640B)
+- **Recommendation:** Avoid F.Pipe in hot paths, use direct function calls
+
+### 13. Do-Notation Operations
+- `BenchmarkDo` - Creating empty context (~45ns, 2 allocs)
+- `BenchmarkBind_Right` - Binding values (~25ns, 1 alloc)
+- `BenchmarkLet_Right` - Pure computations (~23ns, 1 alloc)
+- `BenchmarkApS_Right` - Applicative binding (~99ns, 4 allocs)
+
+**Key Insights:**
+- Do-notation operations are efficient
+- Bind and Let are very fast
+- ApS has more overhead (4 allocations)
+- Much better than either package's Bind (~130ns vs ~25ns)
+
+### 14. Traverse Operations
+- `BenchmarkTraverseArray_Empty` - Empty array (~689ns, 13 allocs)
+- `BenchmarkTraverseArray_Small` - 3 elements (~1971ns, 37 allocs)
+- `BenchmarkTraverseArray_Medium` - 10 elements (~4386ns, 93 allocs)
+- `BenchmarkTraverseArraySeq_Small` - Sequential (~1885ns, 52 allocs)
+- `BenchmarkTraverseArrayPar_Small` - Parallel (~1362ns, 37 allocs)
+- `BenchmarkExecuteTraverseArraySeq_Small` - Executing sequential (~1080ns, 34 allocs)
+- `BenchmarkExecuteTraverseArrayPar_Small` - Executing parallel (~18560ns, 202 allocs)
+
+**Key Insights:**
+- **Bottleneck:** Traverse operations allocate per element
+- Empty array still has 13 allocations (overhead)
+- Parallel construction is faster but execution is much slower
+- **Major Bottleneck:** Parallel execution: ~18.5μs with 202 allocations
+- Sequential execution is ~17x faster for small arrays
+- **Recommendation:** Use sequential traverse for small collections, parallel only for large, expensive operations
+
+### 15. Record Operations
+- `BenchmarkTraverseRecord_Small` - 3 entries (~1444ns, 55 allocs)
+- `BenchmarkSequenceRecord_Small` - 3 entries (~1073ns, 54 allocs)
+
+**Key Insights:**
+- Record operations have high allocation overhead
+- Similar performance to array traversal
+- Allocations scale with map size
+
+### 16. Resource Management
+- `BenchmarkWithResource_Success` - Creating resource wrapper (~193ns, 8 allocs)
+- `BenchmarkExecuteWithResource_Success` - Executing with resource (varies)
+- `BenchmarkExecuteWithResource_ErrorInBody` - Error handling (varies)
+
+**Key Insights:**
+- Resource management has 8 allocations for safety
+- Ensures proper cleanup even on errors
+- Overhead is acceptable for resource safety guarantees
+
+### 17. Context Cancellation
+- `BenchmarkExecute_CanceledContext` - Executing with canceled context
+- `BenchmarkExecuteApPar_CanceledContext` - Parallel with canceled context
+
+**Key Insights:**
+- Cancellation is handled efficiently
+- Minimal overhead for checking cancellation
+- ApPar respects cancellation properly
+
+## Performance Bottlenecks Summary
+
+### Critical Bottlenecks (>100ns or >5 allocations)
+
+1. **Pipeline operations with F.Pipe** (~200-1000ns, 9-25 allocations)
+   - **Impact:** High - commonly used pattern
+   - **Mitigation:** Use direct function calls in hot paths
+   - **Example:**
+     ```go
+     // Slow (200ns, 9 allocs)
+     result := F.Pipe1(rioe, Map[int](transform))
+     
+     // Fast (24ns, 1 alloc)
+     result := Map[int](transform)(rioe)
+     ```
+
+2. **MonadMap and MonadChain** (~135-207ns, 5-6 allocations)
+   - **Impact:** High - fundamental operations
+   - **Mitigation:** Use curried versions (Map, Chain)
+   - **Speedup:** 5-7x faster
+
+3. **Parallel applicative execution** (~5.6μs, 61 allocations)
+   - **Impact:** High when used
+   - **Mitigation:** Use ApSeq for simple operations
+   - **Note:** Only use ApPar for truly independent, expensive computations
+
+4. **Parallel traverse execution** (~18.5μs, 202 allocations)
+   - **Impact:** High for collections
+   - **Mitigation:** Use sequential traverse for small collections
+   - **Threshold:** Consider parallel only for >100 elements with expensive operations
+
+5. **Alt operations** (~210-344ns, 6 allocations)
+   - **Impact:** Medium
+   - **Mitigation:** Use OrElse for error recovery (40-52ns, 2 allocs)
+
+### Minor Bottlenecks (50-100ns or 3-4 allocations)
+
+6. **Flatten operations** (~147ns, 7 allocations)
+   - **Impact:** Low - less commonly used
+   - **Mitigation:** Avoid unnecessary nesting
+
+7. **Memoize** (~82ns, 4 allocations)
+   - **Impact:** Low - overhead pays off for expensive computations
+   - **Mitigation:** Only use for computations >1μs
+
+8. **ApS in do-notation** (~99ns, 4 allocations)
+   - **Impact:** Low
+   - **Mitigation:** Use Let or Bind when possible
+
+## Optimization Recommendations
+
+### For Hot Paths
+
+1. **Use curried functions over Monad* versions:**
+   ```go
+   // Instead of:
+   result := MonadMap(rioe, transform)  // 135ns, 5 allocs
+   
+   // Use:
+   result := Map[int](transform)(rioe)  // 24ns, 1 alloc
+   ```
+
+2. **Avoid F.Pipe in performance-critical code:**
+   ```go
+   // Instead of:
+   result := F.Pipe3(rioe, Map(f1), Chain(f2), Map(f3))  // 1000ns, 25 allocs
+   
+   // Use:
+   result := Map(f3)(Chain(f2)(Map(f1)(rioe)))  // Much faster
+   ```
+
+3. **Use sequential operations for small collections:**
+   ```go
+   // For arrays with <10 elements:
+   result := TraverseArraySeq(f)(arr)  // 1.9μs, 52 allocs
+   
+   // Instead of:
+   result := TraverseArrayPar(f)(arr)  // 18.5μs, 202 allocs (when executed)
+   ```
+
+4. **Prefer OrElse over Alt for error recovery:**
+   ```go
+   // Instead of:
+   result := Alt(alternative)(rioe)  // 210-344ns, 6 allocs
+   
+   // Use:
+   result := OrElse(recover)(rioe)  // 40-52ns, 2 allocs
+   ```
+
+### For Context Operations
+
+- Context operations are generally efficient
+- Ask has 3 allocations but is necessary for context access
+- Cancellation checking is fast and should be used liberally
+
+### For Resource Management
+
+- WithResource overhead (8 allocations) is acceptable for safety
+- Always use for resources that need cleanup
+- The RAII pattern prevents resource leaks
+
+### Memory Considerations
+
+- Most operations have 1-2 allocations
+- Monad* versions have 5-8 allocations
+- Pipeline operations allocate heavily
+- Parallel operations have significant allocation overhead
+- Traverse operations allocate per element
+
+## Comparative Analysis
+
+### Fastest Operations (<50ns, <2 allocations)
+- Constructors (Left, Right, Of)
+- Execution (Execute_Right/Left)
+- Curried operations (Map, Chain, ChainFirst)
+- TryCatch execution
+- Chain-K operations
+- Let and Bind in do-notation
+
+### Medium Speed (50-200ns, 2-8 allocations)
+- Conversion operations
+- MonadMap, MonadChain
+- Flatten
+- Memoize
+- Resource management construction
+- Traverse construction
+
+### Slower Operations (>200ns or >8 allocations)
+- Pipeline operations
+- Alt operations
+- Traverse operations (especially parallel)
+- Applicative operations (especially parallel execution)
+
+## Parallel vs Sequential Trade-offs
+
+### When to Use Sequential (ApSeq, TraverseArraySeq)
+- Small collections (<10 elements)
+- Fast operations (<1μs per element)
+- When allocations matter
+- Default choice for most use cases
+
+### When to Use Parallel (ApPar, TraverseArrayPar)
+- Large collections (>100 elements)
+- Expensive operations (>10μs per element)
+- Independent computations
+- When latency matters more than throughput
+- I/O-bound operations
+
+### Parallel Overhead
+- Construction: ~50ns, 3 allocs
+- Execution: +4-17μs, +40-160 allocs
+- Context management and goroutine coordination
+- Only worthwhile for truly expensive operations
+
+## Conclusion
+
+The `context/readerioeither` package is well-optimized with most operations completing in nanoseconds with minimal allocations. Key recommendations:
+
+1. Use curried functions (Map, Chain) instead of Monad* versions (5-7x faster)
+2. Avoid F.Pipe in hot paths (5-10x slower)
+3. Use sequential operations by default; parallel only for expensive, independent computations
+4. Prefer OrElse over Alt for error recovery (5x faster)
+5. TryCatch is excellent for wrapping Go functions (near-zero execution cost)
+6. Context operations are efficient; use liberally
+7. Resource management overhead is acceptable for safety guarantees
+
+For typical use cases, the performance is excellent. Only in extremely hot paths (millions of operations per second) should you consider the micro-optimizations suggested above.

v2/context/readerioresult/bind.go

@@ -0,0 +1,724 @@
+// 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 readerioresult
+
+import (
+	"context"
+
+	F "github.com/IBM/fp-go/v2/function"
+	"github.com/IBM/fp-go/v2/internal/apply"
+	"github.com/IBM/fp-go/v2/io"
+	"github.com/IBM/fp-go/v2/ioeither"
+	"github.com/IBM/fp-go/v2/ioresult"
+	L "github.com/IBM/fp-go/v2/optics/lens"
+	"github.com/IBM/fp-go/v2/reader"
+	"github.com/IBM/fp-go/v2/readerio"
+	RIOR "github.com/IBM/fp-go/v2/readerioresult"
+	"github.com/IBM/fp-go/v2/result"
+)
+
+// 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.
+//
+// Example:
+//
+//	type State struct {
+//	    User   User
+//	    Config Config
+//	}
+//	result := readerioeither.Do(State{})
+//
+//go:inline
+func Do[S any](
+	empty S,
+) ReaderIOResult[S] {
+	return RIOR.Of[context.Context](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 the context.Context from the environment.
+//
+// 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
+//	    Config Config
+//	}
+//
+//	result := F.Pipe2(
+//	    readerioeither.Do(State{}),
+//	    readerioeither.Bind(
+//	        func(user User) func(State) State {
+//	            return func(s State) State { s.User = user; return s }
+//	        },
+//	        func(s State) readerioeither.ReaderIOResult[User] {
+//	            return func(ctx context.Context) ioeither.IOEither[error, User] {
+//	                return ioeither.TryCatch(func() (User, error) {
+//	                    return fetchUser(ctx)
+//	                })
+//	            }
+//	        },
+//	    ),
+//	    readerioeither.Bind(
+//	        func(cfg Config) func(State) State {
+//	            return func(s State) State { s.Config = cfg; return s }
+//	        },
+//	        func(s State) readerioeither.ReaderIOResult[Config] {
+//	            // This can access s.User from the previous step
+//	            return func(ctx context.Context) ioeither.IOEither[error, Config] {
+//	                return ioeither.TryCatch(func() (Config, error) {
+//	                    return fetchConfigForUser(ctx, s.User.ID)
+//	                })
+//	            }
+//	        },
+//	    ),
+//	)
+//
+//go:inline
+func Bind[S1, S2, T any](
+	setter func(T) func(S1) S2,
+	f Kleisli[S1, T],
+) Operator[S1, S2] {
+	return RIOR.Bind(setter, f)
+}
+
+// Let attaches the result of a computation to a context [S1] to produce a context [S2]
+//
+//go:inline
+func Let[S1, S2, T any](
+	setter func(T) func(S1) S2,
+	f func(S1) T,
+) Operator[S1, S2] {
+	return RIOR.Let[context.Context](setter, f)
+}
+
+// LetTo attaches the a value to a context [S1] to produce a context [S2]
+//
+//go:inline
+func LetTo[S1, S2, T any](
+	setter func(T) func(S1) S2,
+	b T,
+) Operator[S1, S2] {
+	return RIOR.LetTo[context.Context](setter, b)
+}
+
+// BindTo initializes a new state [S1] from a value [T]
+//
+//go:inline
+func BindTo[S1, T any](
+	setter func(T) S1,
+) Operator[T, S1] {
+	return RIOR.BindTo[context.Context](setter)
+}
+
+// ApS attaches a value to a context [S1] to produce a context [S2] by considering
+// the context and the value concurrently (using Applicative rather than Monad).
+// This allows independent computations to be combined without one depending on the result of the other.
+//
+// Unlike Bind, which sequences operations, ApS can be used when operations are independent
+// and can conceptually run in parallel.
+//
+// Example:
+//
+//	type State struct {
+//	    User   User
+//	    Config Config
+//	}
+//
+//	// These operations are independent and can be combined with ApS
+//	getUser := func(ctx context.Context) ioeither.IOEither[error, User] {
+//	    return ioeither.TryCatch(func() (User, error) {
+//	        return fetchUser(ctx)
+//	    })
+//	}
+//	getConfig := func(ctx context.Context) ioeither.IOEither[error, Config] {
+//	    return ioeither.TryCatch(func() (Config, error) {
+//	        return fetchConfig(ctx)
+//	    })
+//	}
+//
+//	result := F.Pipe2(
+//	    readerioeither.Do(State{}),
+//	    readerioeither.ApS(
+//	        func(user User) func(State) State {
+//	            return func(s State) State { s.User = user; return s }
+//	        },
+//	        getUser,
+//	    ),
+//	    readerioeither.ApS(
+//	        func(cfg Config) func(State) State {
+//	            return func(s State) State { s.Config = cfg; return s }
+//	        },
+//	        getConfig,
+//	    ),
+//	)
+//
+//go:inline
+func ApS[S1, S2, T any](
+	setter func(T) func(S1) S2,
+	fa ReaderIOResult[T],
+) Operator[S1, S2] {
+	return apply.ApS(
+		Ap,
+		Map,
+		setter,
+		fa,
+	)
+}
+
+// ApSL attaches a value to a context using a lens-based setter.
+// This is a convenience function that combines ApS with a lens, allowing you to use
+// optics to update nested structures in a more composable way.
+//
+// The lens parameter provides both the getter and setter for a field within the structure S.
+// This eliminates the need to manually write setter functions.
+//
+// Example:
+//
+//	type State struct {
+//	    User   User
+//	    Config Config
+//	}
+//
+//	userLens := lens.MakeLens(
+//	    func(s State) User { return s.User },
+//	    func(s State, u User) State { s.User = u; return s },
+//	)
+//
+//	getUser := func(ctx context.Context) ioeither.IOEither[error, User] {
+//	    return ioeither.TryCatch(func() (User, error) {
+//	        return fetchUser(ctx)
+//	    })
+//	}
+//	result := F.Pipe2(
+//	    readerioeither.Of(State{}),
+//	    readerioeither.ApSL(userLens, getUser),
+//	)
+//
+//go:inline
+func ApSL[S, T any](
+	lens L.Lens[S, T],
+	fa ReaderIOResult[T],
+) Operator[S, S] {
+	return ApS(lens.Set, fa)
+}
+
+// BindL is a variant of Bind that uses a lens to focus on a specific part of the context.
+// This provides a more ergonomic API when working with nested structures, eliminating
+// the need to manually write setter functions.
+//
+// The lens parameter provides both a getter and setter for a field of type T within
+// the context S. The function f receives the current value of the focused field and
+// returns a ReaderIOResult computation that produces an updated value.
+//
+// Example:
+//
+//	type State struct {
+//	    User   User
+//	    Config Config
+//	}
+//
+//	userLens := lens.MakeLens(
+//	    func(s State) User { return s.User },
+//	    func(s State, u User) State { s.User = u; return s },
+//	)
+//
+//	result := F.Pipe2(
+//	    readerioeither.Do(State{}),
+//	    readerioeither.BindL(userLens, func(user User) readerioeither.ReaderIOResult[User] {
+//	        return func(ctx context.Context) ioeither.IOEither[error, User] {
+//	            return ioeither.TryCatch(func() (User, error) {
+//	                return fetchUser(ctx)
+//	            })
+//	        }
+//	    }),
+//	)
+//
+//go:inline
+func BindL[S, T any](
+	lens L.Lens[S, T],
+	f Kleisli[T, T],
+) Operator[S, S] {
+	return RIOR.BindL(lens, f)
+}
+
+// LetL is a variant of Let that uses a lens to focus on a specific part of the context.
+// This provides a more ergonomic API when working with nested structures, eliminating
+// the need to manually write setter functions.
+//
+// The lens parameter provides both a getter and setter for a field of type T within
+// the context S. The function f receives the current value of the focused field and
+// returns a new value (without wrapping in a ReaderIOResult).
+//
+// Example:
+//
+//	type State struct {
+//	    User   User
+//	    Config Config
+//	}
+//
+//	userLens := lens.MakeLens(
+//	    func(s State) User { return s.User },
+//	    func(s State, u User) State { s.User = u; return s },
+//	)
+//
+//	result := F.Pipe2(
+//	    readerioeither.Do(State{User: User{Name: "Alice"}}),
+//	    readerioeither.LetL(userLens, func(user User) User {
+//	        user.Name = "Bob"
+//	        return user
+//	    }),
+//	)
+//
+//go:inline
+func LetL[S, T any](
+	lens L.Lens[S, T],
+	f func(T) T,
+) Operator[S, S] {
+	return RIOR.LetL[context.Context](lens, f)
+}
+
+// LetToL is a variant of LetTo that uses a lens to focus on a specific part of the context.
+// This provides a more ergonomic API when working with nested structures, eliminating
+// the need to manually write setter functions.
+//
+// The lens parameter provides both a getter and setter for a field of type T within
+// the context S. The value b is set directly to the focused field.
+//
+// Example:
+//
+//	type State struct {
+//	    User   User
+//	    Config Config
+//	}
+//
+//	userLens := lens.MakeLens(
+//	    func(s State) User { return s.User },
+//	    func(s State, u User) State { s.User = u; return s },
+//	)
+//
+//	newUser := User{Name: "Bob", ID: 123}
+//	result := F.Pipe2(
+//	    readerioeither.Do(State{}),
+//	    readerioeither.LetToL(userLens, newUser),
+//	)
+//
+//go:inline
+func LetToL[S, T any](
+	lens L.Lens[S, T],
+	b T,
+) Operator[S, S] {
+	return RIOR.LetToL[context.Context](lens, b)
+}
+
+// BindIOEitherK is a variant of Bind that works with IOEither computations.
+// It lifts an IOEither Kleisli arrow into the ReaderIOResult context (with context.Context as environment).
+//
+// Parameters:
+//   - setter: Updates state from S1 to S2 using result T
+//   - f: An IOEither Kleisli arrow (S1 -> IOEither[error, T])
+//
+//go:inline
+func BindIOEitherK[S1, S2, T any](
+	setter func(T) func(S1) S2,
+	f ioresult.Kleisli[S1, T],
+) Operator[S1, S2] {
+	return Bind(setter, F.Flow2(f, FromIOEither[T]))
+}
+
+// BindIOResultK is a variant of Bind that works with IOResult computations.
+// This is an alias for BindIOEitherK for consistency with the Result naming convention.
+//
+// Parameters:
+//   - setter: Updates state from S1 to S2 using result T
+//   - f: An IOResult Kleisli arrow (S1 -> IOResult[T])
+//
+//go:inline
+func BindIOResultK[S1, S2, T any](
+	setter func(T) func(S1) S2,
+	f ioresult.Kleisli[S1, T],
+) Operator[S1, S2] {
+	return Bind(setter, F.Flow2(f, FromIOResult[T]))
+}
+
+// BindIOK is a variant of Bind that works with IO computations.
+// It lifts an IO Kleisli arrow into the ReaderIOResult context.
+//
+// Parameters:
+//   - setter: Updates state from S1 to S2 using result T
+//   - f: An IO Kleisli arrow (S1 -> IO[T])
+//
+//go:inline
+func BindIOK[S1, S2, T any](
+	setter func(T) func(S1) S2,
+	f io.Kleisli[S1, T],
+) Operator[S1, S2] {
+	return Bind(setter, F.Flow2(f, FromIO[T]))
+}
+
+// BindReaderK is a variant of Bind that works with Reader computations.
+// It lifts a Reader Kleisli arrow (with context.Context) into the ReaderIOResult context.
+//
+// Parameters:
+//   - setter: Updates state from S1 to S2 using result T
+//   - f: A Reader Kleisli arrow (S1 -> Reader[context.Context, T])
+//
+//go:inline
+func BindReaderK[S1, S2, T any](
+	setter func(T) func(S1) S2,
+	f reader.Kleisli[context.Context, S1, T],
+) Operator[S1, S2] {
+	return Bind(setter, F.Flow2(f, FromReader[T]))
+}
+
+// BindReaderIOK is a variant of Bind that works with ReaderIO computations.
+// It lifts a ReaderIO Kleisli arrow (with context.Context) into the ReaderIOResult context.
+//
+// Parameters:
+//   - setter: Updates state from S1 to S2 using result T
+//   - f: A ReaderIO Kleisli arrow (S1 -> ReaderIO[context.Context, T])
+//
+//go:inline
+func BindReaderIOK[S1, S2, T any](
+	setter func(T) func(S1) S2,
+	f readerio.Kleisli[context.Context, S1, T],
+) Operator[S1, S2] {
+	return Bind(setter, F.Flow2(f, FromReaderIO[T]))
+}
+
+// BindEitherK is a variant of Bind that works with Either (Result) computations.
+// It lifts an Either Kleisli arrow into the ReaderIOResult context.
+//
+// Parameters:
+//   - setter: Updates state from S1 to S2 using result T
+//   - f: An Either Kleisli arrow (S1 -> Either[error, T])
+//
+//go:inline
+func BindEitherK[S1, S2, T any](
+	setter func(T) func(S1) S2,
+	f result.Kleisli[S1, T],
+) Operator[S1, S2] {
+	return Bind(setter, F.Flow2(f, FromEither[T]))
+}
+
+// BindResultK is a variant of Bind that works with Result computations.
+// This is an alias for BindEitherK for consistency with the Result naming convention.
+//
+// Parameters:
+//   - setter: Updates state from S1 to S2 using result T
+//   - f: A Result Kleisli arrow (S1 -> Result[T])
+//
+//go:inline
+func BindResultK[S1, S2, T any](
+	setter func(T) func(S1) S2,
+	f result.Kleisli[S1, T],
+) Operator[S1, S2] {
+	return Bind(setter, F.Flow2(f, FromResult[T]))
+}
+
+// BindIOEitherKL is a lens-based variant of BindIOEitherK.
+// It combines a lens with an IOEither Kleisli arrow, focusing on a specific field
+// within the state structure.
+//
+// Parameters:
+//   - lens: A lens focusing on field T within state S
+//   - f: An IOEither Kleisli arrow (T -> IOEither[error, T])
+//
+//go:inline
+func BindIOEitherKL[S, T any](
+	lens L.Lens[S, T],
+	f ioresult.Kleisli[T, T],
+) Operator[S, S] {
+	return BindL(lens, F.Flow2(f, FromIOEither[T]))
+}
+
+// BindIOResultKL is a lens-based variant of BindIOResultK.
+// This is an alias for BindIOEitherKL for consistency with the Result naming convention.
+//
+// Parameters:
+//   - lens: A lens focusing on field T within state S
+//   - f: An IOResult Kleisli arrow (T -> IOResult[T])
+//
+//go:inline
+func BindIOResultKL[S, T any](
+	lens L.Lens[S, T],
+	f ioresult.Kleisli[T, T],
+) Operator[S, S] {
+	return BindL(lens, F.Flow2(f, FromIOEither[T]))
+}
+
+// BindIOKL is a lens-based variant of BindIOK.
+// It combines a lens with an IO Kleisli arrow, focusing on a specific field
+// within the state structure.
+//
+// Parameters:
+//   - lens: A lens focusing on field T within state S
+//   - f: An IO Kleisli arrow (T -> IO[T])
+//
+//go:inline
+func BindIOKL[S, T any](
+	lens L.Lens[S, T],
+	f io.Kleisli[T, T],
+) Operator[S, S] {
+	return BindL(lens, F.Flow2(f, FromIO[T]))
+}
+
+// BindReaderKL is a lens-based variant of BindReaderK.
+// It combines a lens with a Reader Kleisli arrow (with context.Context), focusing on a specific field
+// within the state structure.
+//
+// Parameters:
+//   - lens: A lens focusing on field T within state S
+//   - f: A Reader Kleisli arrow (T -> Reader[context.Context, T])
+//
+//go:inline
+func BindReaderKL[S, T any](
+	lens L.Lens[S, T],
+	f reader.Kleisli[context.Context, T, T],
+) Operator[S, S] {
+	return BindL(lens, F.Flow2(f, FromReader[T]))
+}
+
+// BindReaderIOKL is a lens-based variant of BindReaderIOK.
+// It combines a lens with a ReaderIO Kleisli arrow (with context.Context), focusing on a specific field
+// within the state structure.
+//
+// Parameters:
+//   - lens: A lens focusing on field T within state S
+//   - f: A ReaderIO Kleisli arrow (T -> ReaderIO[context.Context, T])
+//
+//go:inline
+func BindReaderIOKL[S, T any](
+	lens L.Lens[S, T],
+	f readerio.Kleisli[context.Context, T, T],
+) Operator[S, S] {
+	return BindL(lens, F.Flow2(f, FromReaderIO[T]))
+}
+
+// ApIOEitherS is an applicative variant that works with IOEither values.
+// Unlike BindIOEitherK, this uses applicative composition (ApS) instead of monadic
+// composition (Bind), allowing independent computations to be combined.
+//
+// Parameters:
+//   - setter: Updates state from S1 to S2 using result T
+//   - fa: An IOEither value
+//
+//go:inline
+func ApIOEitherS[S1, S2, T any](
+	setter func(T) func(S1) S2,
+	fa IOResult[T],
+) Operator[S1, S2] {
+	return F.Bind2nd(F.Flow2[ReaderIOResult[S1], ioresult.Operator[S1, S2]], ioeither.ApS(setter, fa))
+}
+
+// ApIOResultS is an applicative variant that works with IOResult values.
+// This is an alias for ApIOEitherS for consistency with the Result naming convention.
+//
+// Parameters:
+//   - setter: Updates state from S1 to S2 using result T
+//   - fa: An IOResult value
+//
+//go:inline
+func ApIOResultS[S1, S2, T any](
+	setter func(T) func(S1) S2,
+	fa IOResult[T],
+) Operator[S1, S2] {
+	return F.Bind2nd(F.Flow2[ReaderIOResult[S1], ioresult.Operator[S1, S2]], ioeither.ApS(setter, fa))
+}
+
+// ApIOS is an applicative variant that works with IO values.
+// It lifts an IO value into the ReaderIOResult context using applicative composition.
+//
+// Parameters:
+//   - setter: Updates state from S1 to S2 using result T
+//   - fa: An IO value
+//
+//go:inline
+func ApIOS[S1, S2, T any](
+	setter func(T) func(S1) S2,
+	fa IO[T],
+) Operator[S1, S2] {
+	return ApS(setter, FromIO(fa))
+}
+
+// ApReaderS is an applicative variant that works with Reader values.
+// It lifts a Reader value (with context.Context) into the ReaderIOResult context using applicative composition.
+//
+// Parameters:
+//   - setter: Updates state from S1 to S2 using result T
+//   - fa: A Reader value
+//
+//go:inline
+func ApReaderS[S1, S2, T any](
+	setter func(T) func(S1) S2,
+	fa Reader[context.Context, T],
+) Operator[S1, S2] {
+	return ApS(setter, FromReader(fa))
+}
+
+// ApReaderIOS is an applicative variant that works with ReaderIO values.
+// It lifts a ReaderIO value (with context.Context) into the ReaderIOResult context using applicative composition.
+//
+// Parameters:
+//   - setter: Updates state from S1 to S2 using result T
+//   - fa: A ReaderIO value
+//
+//go:inline
+func ApReaderIOS[S1, S2, T any](
+	setter func(T) func(S1) S2,
+	fa ReaderIO[T],
+) Operator[S1, S2] {
+	return ApS(setter, FromReaderIO(fa))
+}
+
+// ApEitherS is an applicative variant that works with Either (Result) values.
+// It lifts an Either value into the ReaderIOResult context using applicative composition.
+//
+// Parameters:
+//   - setter: Updates state from S1 to S2 using result T
+//   - fa: An Either value
+//
+//go:inline
+func ApEitherS[S1, S2, T any](
+	setter func(T) func(S1) S2,
+	fa Result[T],
+) Operator[S1, S2] {
+	return ApS(setter, FromEither(fa))
+}
+
+// ApResultS is an applicative variant that works with Result values.
+// This is an alias for ApEitherS for consistency with the Result naming convention.
+//
+// Parameters:
+//   - setter: Updates state from S1 to S2 using result T
+//   - fa: A Result value
+//
+//go:inline
+func ApResultS[S1, S2, T any](
+	setter func(T) func(S1) S2,
+	fa Result[T],
+) Operator[S1, S2] {
+	return ApS(setter, FromResult(fa))
+}
+
+// ApIOEitherSL is a lens-based variant of ApIOEitherS.
+// It combines a lens with an IOEither value using applicative composition.
+//
+// Parameters:
+//   - lens: A lens focusing on field T within state S
+//   - fa: An IOEither value
+//
+//go:inline
+func ApIOEitherSL[S, T any](
+	lens L.Lens[S, T],
+	fa IOResult[T],
+) Operator[S, S] {
+	return F.Bind2nd(F.Flow2[ReaderIOResult[S], ioresult.Operator[S, S]], ioresult.ApSL(lens, fa))
+}
+
+// ApIOResultSL is a lens-based variant of ApIOResultS.
+// This is an alias for ApIOEitherSL for consistency with the Result naming convention.
+//
+// Parameters:
+//   - lens: A lens focusing on field T within state S
+//   - fa: An IOResult value
+//
+//go:inline
+func ApIOResultSL[S, T any](
+	lens L.Lens[S, T],
+	fa IOResult[T],
+) Operator[S, S] {
+	return F.Bind2nd(F.Flow2[ReaderIOResult[S], ioresult.Operator[S, S]], ioresult.ApSL(lens, fa))
+}
+
+// ApIOSL is a lens-based variant of ApIOS.
+// It combines a lens with an IO value using applicative composition.
+//
+// Parameters:
+//   - lens: A lens focusing on field T within state S
+//   - fa: An IO value
+//
+//go:inline
+func ApIOSL[S, T any](
+	lens L.Lens[S, T],
+	fa IO[T],
+) Operator[S, S] {
+	return ApSL(lens, FromIO(fa))
+}
+
+// ApReaderSL is a lens-based variant of ApReaderS.
+// It combines a lens with a Reader value (with context.Context) using applicative composition.
+//
+// Parameters:
+//   - lens: A lens focusing on field T within state S
+//   - fa: A Reader value
+//
+//go:inline
+func ApReaderSL[S, T any](
+	lens L.Lens[S, T],
+	fa Reader[context.Context, T],
+) Operator[S, S] {
+	return ApSL(lens, FromReader(fa))
+}
+
+// ApReaderIOSL is a lens-based variant of ApReaderIOS.
+// It combines a lens with a ReaderIO value (with context.Context) using applicative composition.
+//
+// Parameters:
+//   - lens: A lens focusing on field T within state S
+//   - fa: A ReaderIO value
+//
+//go:inline
+func ApReaderIOSL[S, T any](
+	lens L.Lens[S, T],
+	fa ReaderIO[T],
+) Operator[S, S] {
+	return ApSL(lens, FromReaderIO(fa))
+}
+
+// ApEitherSL is a lens-based variant of ApEitherS.
+// It combines a lens with an Either value using applicative composition.
+//
+// Parameters:
+//   - lens: A lens focusing on field T within state S
+//   - fa: An Either value
+//
+//go:inline
+func ApEitherSL[S, T any](
+	lens L.Lens[S, T],
+	fa Result[T],
+) Operator[S, S] {
+	return ApSL(lens, FromEither(fa))
+}
+
+// ApResultSL is a lens-based variant of ApResultS.
+// This is an alias for ApEitherSL for consistency with the Result naming convention.
+//
+// Parameters:
+//   - lens: A lens focusing on field T within state S
+//   - fa: A Result value
+//
+//go:inline
+func ApResultSL[S, T any](
+	lens L.Lens[S, T],
+	fa Result[T],
+) Operator[S, S] {
+	return ApSL(lens, FromResult(fa))
+}

v2/context/readerioresult/bind_test.go

@@ -0,0 +1,275 @@
+// 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 readerioresult
+
+import (
+	"context"
+	"testing"
+
+	E "github.com/IBM/fp-go/v2/either"
+	F "github.com/IBM/fp-go/v2/function"
+	"github.com/IBM/fp-go/v2/internal/utils"
+	O "github.com/IBM/fp-go/v2/option"
+	"github.com/stretchr/testify/assert"
+)
+
+func getLastName(s utils.Initial) ReaderIOResult[string] {
+	return Of("Doe")
+}
+
+func getGivenName(s utils.WithLastName) ReaderIOResult[string] {
+	return Of("John")
+}
+
+func TestBind(t *testing.T) {
+
+	res := F.Pipe3(
+		Do(utils.Empty),
+		Bind(utils.SetLastName, getLastName),
+		Bind(utils.SetGivenName, getGivenName),
+		Map(utils.GetFullName),
+	)
+
+	assert.Equal(t, res(t.Context())(), E.Of[error]("John Doe"))
+}
+
+func TestApS(t *testing.T) {
+
+	res := F.Pipe3(
+		Do(utils.Empty),
+		ApS(utils.SetLastName, Of("Doe")),
+		ApS(utils.SetGivenName, Of("John")),
+		Map(utils.GetFullName),
+	)
+
+	assert.Equal(t, res(t.Context())(), E.Of[error]("John Doe"))
+}
+
+func TestApS_WithError(t *testing.T) {
+	// Test that ApS propagates errors correctly
+	testErr := assert.AnError
+
+	res := F.Pipe3(
+		Do(utils.Empty),
+		ApS(utils.SetLastName, Left[string](testErr)),
+		ApS(utils.SetGivenName, Of("John")),
+		Map(utils.GetFullName),
+	)
+
+	result := res(t.Context())()
+	assert.True(t, E.IsLeft(result))
+	assert.Equal(t, testErr, E.ToError(result))
+}
+
+func TestApS_WithSecondError(t *testing.T) {
+	// Test that ApS propagates errors from the second operation
+	testErr := assert.AnError
+
+	res := F.Pipe3(
+		Do(utils.Empty),
+		ApS(utils.SetLastName, Of("Doe")),
+		ApS(utils.SetGivenName, Left[string](testErr)),
+		Map(utils.GetFullName),
+	)
+
+	result := res(t.Context())()
+	assert.True(t, E.IsLeft(result))
+	assert.Equal(t, testErr, E.ToError(result))
+}
+
+func TestApS_MultipleFields(t *testing.T) {
+	// Test ApS with more than two fields
+	type Person struct {
+		FirstName  string
+		MiddleName string
+		LastName   string
+		Age        int
+	}
+
+	setFirstName := func(s string) func(Person) Person {
+		return func(p Person) Person {
+			p.FirstName = s
+			return p
+		}
+	}
+
+	setMiddleName := func(s string) func(Person) Person {
+		return func(p Person) Person {
+			p.MiddleName = s
+			return p
+		}
+	}
+
+	setLastName := func(s string) func(Person) Person {
+		return func(p Person) Person {
+			p.LastName = s
+			return p
+		}
+	}
+
+	setAge := func(a int) func(Person) Person {
+		return func(p Person) Person {
+			p.Age = a
+			return p
+		}
+	}
+
+	res := F.Pipe5(
+		Do(Person{}),
+		ApS(setFirstName, Of("John")),
+		ApS(setMiddleName, Of("Q")),
+		ApS(setLastName, Of("Doe")),
+		ApS(setAge, Of(42)),
+		Map(func(p Person) Person { return p }),
+	)
+
+	result := res(t.Context())()
+	assert.True(t, E.IsRight(result))
+	person := E.ToOption(result)
+	assert.True(t, O.IsSome(person))
+	p, _ := O.Unwrap(person)
+	assert.Equal(t, "John", p.FirstName)
+	assert.Equal(t, "Q", p.MiddleName)
+	assert.Equal(t, "Doe", p.LastName)
+	assert.Equal(t, 42, p.Age)
+}
+
+func TestApS_WithDifferentTypes(t *testing.T) {
+	// Test ApS with different value types
+	type State struct {
+		Name  string
+		Count int
+		Flag  bool
+	}
+
+	setName := func(s string) func(State) State {
+		return func(st State) State {
+			st.Name = s
+			return st
+		}
+	}
+
+	setCount := func(c int) func(State) State {
+		return func(st State) State {
+			st.Count = c
+			return st
+		}
+	}
+
+	setFlag := func(f bool) func(State) State {
+		return func(st State) State {
+			st.Flag = f
+			return st
+		}
+	}
+
+	res := F.Pipe4(
+		Do(State{}),
+		ApS(setName, Of("test")),
+		ApS(setCount, Of(100)),
+		ApS(setFlag, Of(true)),
+		Map(func(s State) State { return s }),
+	)
+
+	result := res(t.Context())()
+	assert.True(t, E.IsRight(result))
+	stateOpt := E.ToOption(result)
+	assert.True(t, O.IsSome(stateOpt))
+	state, _ := O.Unwrap(stateOpt)
+	assert.Equal(t, "test", state.Name)
+	assert.Equal(t, 100, state.Count)
+	assert.True(t, state.Flag)
+}
+
+func TestApS_EmptyState(t *testing.T) {
+	// Test ApS starting with an empty state
+	type Empty struct{}
+
+	res := Do(Empty{})
+
+	result := res(t.Context())()
+	assert.True(t, E.IsRight(result))
+	emptyOpt := E.ToOption(result)
+	assert.True(t, O.IsSome(emptyOpt))
+	empty, _ := O.Unwrap(emptyOpt)
+	assert.Equal(t, Empty{}, empty)
+}
+
+func TestApS_ChainedWithBind(t *testing.T) {
+	// Test mixing ApS with Bind operations
+	type State struct {
+		Independent string
+		Dependent   string
+	}
+
+	setIndependent := func(s string) func(State) State {
+		return func(st State) State {
+			st.Independent = s
+			return st
+		}
+	}
+
+	setDependent := func(s string) func(State) State {
+		return func(st State) State {
+			st.Dependent = s
+			return st
+		}
+	}
+
+	getDependentValue := func(s State) ReaderIOResult[string] {
+		// This depends on the Independent field
+		return Of(s.Independent + "-dependent")
+	}
+
+	res := F.Pipe3(
+		Do(State{}),
+		ApS(setIndependent, Of("value")),
+		Bind(setDependent, getDependentValue),
+		Map(func(s State) State { return s }),
+	)
+
+	result := res(t.Context())()
+	assert.True(t, E.IsRight(result))
+	stateOpt := E.ToOption(result)
+	assert.True(t, O.IsSome(stateOpt))
+	state, _ := O.Unwrap(stateOpt)
+	assert.Equal(t, "value", state.Independent)
+	assert.Equal(t, "value-dependent", state.Dependent)
+}
+
+func TestApS_WithContextCancellation(t *testing.T) {
+	// Test that ApS respects context cancellation
+	type State struct {
+		Value string
+	}
+
+	setValue := func(s string) func(State) State {
+		return func(st State) State {
+			st.Value = s
+			return st
+		}
+	}
+
+	// Create a computation that would succeed
+	computation := ApS(setValue, Of("test"))(Do(State{}))
+
+	// Create a cancelled context
+	ctx, cancel := context.WithCancel(t.Context())
+	cancel()
+
+	result := computation(ctx)()
+	assert.True(t, E.IsLeft(result))
+}

v2/context/readerioresult/bracket.go

@@ -13,13 +13,10 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package readerioeither
+package readerioresult
 
 import (
-	"context"
+	RIOR "github.com/IBM/fp-go/v2/readerioresult"
-
-	"github.com/IBM/fp-go/v2/internal/bracket"
-	"github.com/IBM/fp-go/v2/readerio"
 )
 
 // Bracket makes sure that a resource is cleaned up in the event of an error. The release action is called regardless of
@@ -27,18 +24,9 @@ import (
 func Bracket[
 	A, B, ANY any](
 
-	acquire ReaderIOEither[A],
+	acquire ReaderIOResult[A],
-	use func(A) ReaderIOEither[B],
+	use Kleisli[A, B],
-	release func(A, Either[B]) ReaderIOEither[ANY],
+	release func(A, Either[B]) ReaderIOResult[ANY],
-) ReaderIOEither[B] {
+) ReaderIOResult[B] {
-	return bracket.Bracket[ReaderIOEither[A], ReaderIOEither[B], ReaderIOEither[ANY], Either[B], A, B](
+	return RIOR.Bracket(acquire, use, release)
-		readerio.Of[context.Context, Either[B]],
-		MonadChain[A, B],
-		readerio.MonadChain[context.Context, Either[B], Either[B]],
-		MonadChain[ANY, B],
-
-		acquire,
-		use,
-		release,
-	)
 }

v2/context/readerioresult/cancel.go

@@ -13,26 +13,26 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package readerioeither
+package readerioresult
 
 import (
 	"context"
 
-	CIOE "github.com/IBM/fp-go/v2/context/ioeither"
+	CIOE "github.com/IBM/fp-go/v2/context/ioresult"
 	"github.com/IBM/fp-go/v2/ioeither"
 )
 
-// WithContext wraps an existing [ReaderIOEither] and performs a context check for cancellation before delegating.
+// WithContext wraps an existing [ReaderIOResult] and performs a context check for cancellation before delegating.
 // This ensures that if the context is already canceled, the computation short-circuits immediately
 // without executing the wrapped computation.
 //
 // This is useful for adding cancellation awareness to computations that might not check the context themselves.
 //
 // Parameters:
-//   - ma: The ReaderIOEither to wrap with context checking
+//   - ma: The ReaderIOResult to wrap with context checking
 //
-// Returns a ReaderIOEither that checks for cancellation before executing.
+// Returns a ReaderIOResult that checks for cancellation before executing.
-func WithContext[A any](ma ReaderIOEither[A]) ReaderIOEither[A] {
+func WithContext[A any](ma ReaderIOResult[A]) ReaderIOResult[A] {
 	return func(ctx context.Context) IOEither[A] {
 		if err := context.Cause(ctx); err != nil {
 			return ioeither.Left[A](err)

v2/context/readerioresult/coverage.out

@@ -0,0 +1,251 @@
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+github.com/IBM/fp-go/v2/context/readerioresult/cancel.go:35.65,36.47 1 1
+github.com/IBM/fp-go/v2/context/readerioresult/cancel.go:36.47,37.44 1 1
+github.com/IBM/fp-go/v2/context/readerioresult/cancel.go:37.44,39.4 1 1
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v2/context/readerioresult/doc.go

@@ -13,13 +13,13 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// Package readerioeither provides a specialized version of [readerioeither.ReaderIOEither] that uses
+// package readerioresult provides a specialized version of [readerioeither.ReaderIOResult] that uses
 // [context.Context] as the context type and [error] as the left (error) type. This package is designed
 // for typical Go applications where context-aware, effectful computations with error handling are needed.
 //
 // # Core Concept
 //
-// ReaderIOEither[A] represents a computation that:
+// ReaderIOResult[A] represents a computation that:
 //   - Depends on a [context.Context] (Reader aspect)
 //   - Performs side effects (IO aspect)
 //   - Can fail with an [error] (Either aspect)
@@ -27,7 +27,7 @@
 //
 // The type is defined as:
 //
-//	ReaderIOEither[A] = func(context.Context) func() Either[error, A]
+//	ReaderIOResult[A] = func(context.Context) func() Either[error, A]
 //
 // This combines three powerful functional programming concepts:
 //   - Reader: Dependency injection via context
@@ -50,7 +50,7 @@
 //   - [Left]: Create failed computations
 //   - [FromEither], [FromIO], [FromIOEither]: Convert from other types
 //   - [TryCatch]: Wrap error-returning functions
-//   - [Eitherize0-10]: Convert standard Go functions to ReaderIOEither
+//   - [Eitherize0-10]: Convert standard Go functions to ReaderIOResult
 //
 // Transformation:
 //   - [Map]: Transform success values
@@ -90,15 +90,15 @@
 //	import (
 //	    "context"
 //	    "fmt"
-//	    RIOE "github.com/IBM/fp-go/v2/context/readerioeither"
+//	    RIOE "github.com/IBM/fp-go/v2/context/readerioresult"
 //	    F "github.com/IBM/fp-go/v2/function"
 //	)
 //
 //	// Define a computation that reads from context and may fail
-//	func fetchUser(id string) RIOE.ReaderIOEither[User] {
+//	func fetchUser(id string) RIOE.ReaderIOResult[User] {
 //	    return F.Pipe2(
 //	        RIOE.Ask(),
-//	        RIOE.Chain(func(ctx context.Context) RIOE.ReaderIOEither[User] {
+//	        RIOE.Chain(func(ctx context.Context) RIOE.ReaderIOResult[User] {
 //	            return RIOE.TryCatch(func(ctx context.Context) func() (User, error) {
 //	                return func() (User, error) {
 //	                    return userService.Get(ctx, id)
@@ -138,8 +138,8 @@
 //	        openFile("data.txt"),
 //	        closeFile,
 //	    ),
-//	    func(use func(func(*os.File) RIOE.ReaderIOEither[string]) RIOE.ReaderIOEither[string]) RIOE.ReaderIOEither[string] {
+//	    func(use func(func(*os.File) RIOE.ReaderIOResult[string]) RIOE.ReaderIOResult[string]) RIOE.ReaderIOResult[string] {
-//	        return use(func(file *os.File) RIOE.ReaderIOEither[string] {
+//	        return use(func(file *os.File) RIOE.ReaderIOResult[string] {
 //	            return readContent(file)
 //	        })
 //	    },
@@ -166,4 +166,4 @@
 //	result := computation(ctx)() // Returns Left with cancellation error
 //
 //go:generate go run ../.. contextreaderioeither --count 10 --filename gen.go
-package readerioeither
+package readerioresult

v2/context/readerioresult/eq.go

@@ -13,7 +13,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package readerioeither
+package readerioresult
 
 import (
 	"context"
@@ -22,14 +22,14 @@ import (
 	RIOE "github.com/IBM/fp-go/v2/readerioeither"
 )
 
-// Eq implements the equals predicate for values contained in the [ReaderIOEither] monad.
+// Eq implements the equals predicate for values contained in the [ReaderIOResult] monad.
-// It creates an equality checker that can compare two ReaderIOEither values by executing them
+// It creates an equality checker that can compare two ReaderIOResult values by executing them
 // with a given context and comparing their results using the provided Either equality checker.
 //
 // Parameters:
 //   - eq: Equality checker for Either[A] values
 //
-// Returns a function that takes a context and returns an equality checker for ReaderIOEither[A].
+// Returns a function that takes a context and returns an equality checker for ReaderIOResult[A].
 //
 // Example:
 //
@@ -39,6 +39,8 @@ import (
 //	eqRIE := Eq(eqInt)
 //	ctx := context.Background()
 //	equal := eqRIE(ctx).Equals(Right[int](42), Right[int](42)) // true
-func Eq[A any](eq eq.Eq[Either[A]]) func(context.Context) eq.Eq[ReaderIOEither[A]] {
+//
+//go:inline
+func Eq[A any](eq eq.Eq[Either[A]]) func(context.Context) eq.Eq[ReaderIOResult[A]] {
 	return RIOE.Eq[context.Context](eq)
 }

v2/context/readerioresult/exec/exec.go

@@ -18,7 +18,7 @@ package exec
 import (
 	"context"
 
-	RIOE "github.com/IBM/fp-go/v2/context/readerioeither"
+	RIOE "github.com/IBM/fp-go/v2/context/readerioresult"
 	"github.com/IBM/fp-go/v2/exec"
 	F "github.com/IBM/fp-go/v2/function"
 	GE "github.com/IBM/fp-go/v2/internal/exec"
@@ -30,7 +30,7 @@ var (
 	Command = F.Curry3(command)
 )
 
-func command(name string, args []string, in []byte) RIOE.ReaderIOEither[exec.CommandOutput] {
+func command(name string, args []string, in []byte) RIOE.ReaderIOResult[exec.CommandOutput] {
 	return func(ctx context.Context) IOE.IOEither[error, exec.CommandOutput] {
 		return IOE.TryCatchError(func() (exec.CommandOutput, error) {
 			return GE.Exec(ctx, name, args, in)

v2/context/readerioresult/file/file.go

@@ -20,7 +20,7 @@ import (
 	"io"
 	"os"
 
-	RIOE "github.com/IBM/fp-go/v2/context/readerioeither"
+	RIOE "github.com/IBM/fp-go/v2/context/readerioresult"
 	ET "github.com/IBM/fp-go/v2/either"
 	F "github.com/IBM/fp-go/v2/function"
 	"github.com/IBM/fp-go/v2/internal/file"
@@ -44,7 +44,7 @@ var (
 )
 
 // Close closes an object
-func Close[C io.Closer](c C) RIOE.ReaderIOEither[any] {
+func Close[C io.Closer](c C) RIOE.ReaderIOResult[any] {
 	return F.Pipe2(
 		c,
 		IOEF.Close[C],
@@ -53,8 +53,8 @@ func Close[C io.Closer](c C) RIOE.ReaderIOEither[any] {
 }
 
 // ReadFile reads a file in the scope of a context
-func ReadFile(path string) RIOE.ReaderIOEither[[]byte] {
+func ReadFile(path string) RIOE.ReaderIOResult[[]byte] {
-	return RIOE.WithResource[[]byte](Open(path), Close[*os.File])(func(r *os.File) RIOE.ReaderIOEither[[]byte] {
+	return RIOE.WithResource[[]byte](Open(path), Close[*os.File])(func(r *os.File) RIOE.ReaderIOResult[[]byte] {
 		return func(ctx context.Context) IOE.IOEither[error, []byte] {
 			return func() ET.Either[error, []byte] {
 				return file.ReadAll(ctx, r)

v2/context/readerioresult/file/file_test.go

@@ -19,7 +19,7 @@ import (
 	"context"
 	"fmt"
 
-	R "github.com/IBM/fp-go/v2/context/readerioeither"
+	R "github.com/IBM/fp-go/v2/context/readerioresult"
 	F "github.com/IBM/fp-go/v2/function"
 	"github.com/IBM/fp-go/v2/io"
 	J "github.com/IBM/fp-go/v2/json"

v2/context/readerioresult/file/tempfile.go

@@ -18,7 +18,7 @@ package file
 import (
 	"os"
 
-	RIOE "github.com/IBM/fp-go/v2/context/readerioeither"
+	RIOE "github.com/IBM/fp-go/v2/context/readerioresult"
 	F "github.com/IBM/fp-go/v2/function"
 	IO "github.com/IBM/fp-go/v2/io"
 	IOF "github.com/IBM/fp-go/v2/io/file"
@@ -38,7 +38,7 @@ var (
 )
 
 // CreateTemp created a temp file with proper parametrization
-func CreateTemp(dir, pattern string) RIOE.ReaderIOEither[*os.File] {
+func CreateTemp(dir, pattern string) RIOE.ReaderIOResult[*os.File] {
 	return F.Pipe2(
 		IOEF.CreateTemp(dir, pattern),
 		RIOE.FromIOEither[*os.File],
@@ -47,6 +47,6 @@ func CreateTemp(dir, pattern string) RIOE.ReaderIOEither[*os.File] {
 }
 
 // WithTempFile creates a temporary file, then invokes a callback to create a resource based on the file, then close and remove the temp file
-func WithTempFile[A any](f func(*os.File) RIOE.ReaderIOEither[A]) RIOE.ReaderIOEither[A] {
+func WithTempFile[A any](f func(*os.File) RIOE.ReaderIOResult[A]) RIOE.ReaderIOResult[A] {
 	return RIOE.WithResource[A](onCreateTempFile, onReleaseTempFile)(f)
 }

v2/context/readerioresult/file/tempfile_test.go

@@ -20,7 +20,7 @@ import (
 	"os"
 	"testing"
 
-	RIOE "github.com/IBM/fp-go/v2/context/readerioeither"
+	RIOE "github.com/IBM/fp-go/v2/context/readerioresult"
 	E "github.com/IBM/fp-go/v2/either"
 	F "github.com/IBM/fp-go/v2/function"
 	"github.com/stretchr/testify/assert"
@@ -35,7 +35,7 @@ func TestWithTempFile(t *testing.T) {
 
 func TestWithTempFileOnClosedFile(t *testing.T) {
 
-	res := WithTempFile(func(f *os.File) RIOE.ReaderIOEither[[]byte] {
+	res := WithTempFile(func(f *os.File) RIOE.ReaderIOResult[[]byte] {
 		return F.Pipe2(
 			f,
 			onWriteAll[*os.File]([]byte("Carsten")),

v2/context/readerioresult/file/write.go

@@ -19,12 +19,12 @@ import (
 	"context"
 	"io"
 
-	RIOE "github.com/IBM/fp-go/v2/context/readerioeither"
+	RIOE "github.com/IBM/fp-go/v2/context/readerioresult"
 	F "github.com/IBM/fp-go/v2/function"
 )
 
-func onWriteAll[W io.Writer](data []byte) func(w W) RIOE.ReaderIOEither[[]byte] {
+func onWriteAll[W io.Writer](data []byte) func(w W) RIOE.ReaderIOResult[[]byte] {
-	return func(w W) RIOE.ReaderIOEither[[]byte] {
+	return func(w W) RIOE.ReaderIOResult[[]byte] {
 		return F.Pipe1(
 			RIOE.TryCatch(func(_ context.Context) func() ([]byte, error) {
 				return func() ([]byte, error) {
@@ -38,9 +38,9 @@ func onWriteAll[W io.Writer](data []byte) func(w W) RIOE.ReaderIOEither[[]byte]
 }
 
 // WriteAll uses a generator function to create a stream, writes data to it and closes it
-func WriteAll[W io.WriteCloser](data []byte) func(acquire RIOE.ReaderIOEither[W]) RIOE.ReaderIOEither[[]byte] {
+func WriteAll[W io.WriteCloser](data []byte) func(acquire RIOE.ReaderIOResult[W]) RIOE.ReaderIOResult[[]byte] {
 	onWrite := onWriteAll[W](data)
-	return func(onCreate RIOE.ReaderIOEither[W]) RIOE.ReaderIOEither[[]byte] {
+	return func(onCreate RIOE.ReaderIOResult[W]) RIOE.ReaderIOResult[[]byte] {
 		return RIOE.WithResource[[]byte](
 			onCreate,
 			Close[W])(
@@ -50,7 +50,7 @@ func WriteAll[W io.WriteCloser](data []byte) func(acquire RIOE.ReaderIOEither[W]
 }
 
 // Write uses a generator function to create a stream, writes data to it and closes it
-func Write[R any, W io.WriteCloser](acquire RIOE.ReaderIOEither[W]) func(use func(W) RIOE.ReaderIOEither[R]) RIOE.ReaderIOEither[R] {
+func Write[R any, W io.WriteCloser](acquire RIOE.ReaderIOResult[W]) func(use func(W) RIOE.ReaderIOResult[R]) RIOE.ReaderIOResult[R] {
 	return RIOE.WithResource[R](
 		acquire,
 		Close[W])

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

@@ -14,12 +14,12 @@
 // limitations under the License.
 
 // Package builder provides utilities for building HTTP requests in a functional way
-// using the ReaderIOEither monad. It integrates with the http/builder package to
+// using the ReaderIOResult monad. It integrates with the http/builder package to
 // create composable, type-safe HTTP request builders with proper error handling
 // and context support.
 //
 // The main function, Requester, converts a Builder from the http/builder package
-// into a ReaderIOEither that produces HTTP requests. This allows for:
+// into a ReaderIOResult that produces HTTP requests. This allows for:
 //   - Immutable request building with method chaining
 //   - Automatic header management including Content-Length
 //   - Support for requests with and without bodies
@@ -31,7 +31,7 @@
 //	import (
 //	    "context"
 //	    B "github.com/IBM/fp-go/v2/http/builder"
-//	    RB "github.com/IBM/fp-go/v2/context/readerioeither/http/builder"
+//	    RB "github.com/IBM/fp-go/v2/context/readerioresult/http/builder"
 //	)
 //
 //	builder := F.Pipe3(
@@ -51,8 +51,8 @@ import (
 	"net/http"
 	"strconv"
 
-	RIOE "github.com/IBM/fp-go/v2/context/readerioeither"
+	RIOE "github.com/IBM/fp-go/v2/context/readerioresult"
-	RIOEH "github.com/IBM/fp-go/v2/context/readerioeither/http"
+	RIOEH "github.com/IBM/fp-go/v2/context/readerioresult/http"
 	E "github.com/IBM/fp-go/v2/either"
 	F "github.com/IBM/fp-go/v2/function"
 	R "github.com/IBM/fp-go/v2/http/builder"
@@ -61,7 +61,7 @@ import (
 	O "github.com/IBM/fp-go/v2/option"
 )
 
-// Requester converts an http/builder.Builder into a ReaderIOEither that produces HTTP requests.
+// Requester converts an http/builder.Builder into a ReaderIOResult that produces HTTP requests.
 // It handles both requests with and without bodies, automatically managing headers including
 // Content-Length for requests with bodies.
 //
@@ -86,14 +86,14 @@ import (
 //   - builder: A pointer to an http/builder.Builder containing request configuration
 //
 // Returns:
-//   - A Requester (ReaderIOEither[*http.Request]) that, when executed with a context,
+//   - A Requester (ReaderIOResult[*http.Request]) that, when executed with a context,
 //     produces either an error or a configured *http.Request
 //
 // Example with body:
 //
 //	import (
 //	    B "github.com/IBM/fp-go/v2/http/builder"
-//	    RB "github.com/IBM/fp-go/v2/context/readerioeither/http/builder"
+//	    RB "github.com/IBM/fp-go/v2/context/readerioresult/http/builder"
 //	)
 //
 //	builder := F.Pipe3(
@@ -116,7 +116,7 @@ import (
 //	result := requester(context.Background())()
 func Requester(builder *R.Builder) RIOEH.Requester {
 
-	withBody := F.Curry3(func(data []byte, url string, method string) RIOE.ReaderIOEither[*http.Request] {
+	withBody := F.Curry3(func(data []byte, url string, method string) RIOE.ReaderIOResult[*http.Request] {
 		return RIOE.TryCatch(func(ctx context.Context) func() (*http.Request, error) {
 			return func() (*http.Request, error) {
 				req, err := http.NewRequestWithContext(ctx, method, url, bytes.NewReader(data))
@@ -129,7 +129,7 @@ func Requester(builder *R.Builder) RIOEH.Requester {
 		})
 	})
 
-	withoutBody := F.Curry2(func(url string, method string) RIOE.ReaderIOEither[*http.Request] {
+	withoutBody := F.Curry2(func(url string, method string) RIOE.ReaderIOResult[*http.Request] {
 		return RIOE.TryCatch(func(ctx context.Context) func() (*http.Request, error) {
 			return func() (*http.Request, error) {
 				req, err := http.NewRequestWithContext(ctx, method, url, nil)
@@ -144,8 +144,8 @@ func Requester(builder *R.Builder) RIOEH.Requester {
 	return F.Pipe5(
 		builder.GetBody(),
 		O.Fold(LZ.Of(E.Of[error](withoutBody)), E.Map[error](withBody)),
-		E.Ap[func(string) RIOE.ReaderIOEither[*http.Request]](builder.GetTargetURL()),
+		E.Ap[func(string) RIOE.ReaderIOResult[*http.Request]](builder.GetTargetURL()),
-		E.Flap[error, RIOE.ReaderIOEither[*http.Request]](builder.GetMethod()),
+		E.Flap[error, RIOE.ReaderIOResult[*http.Request]](builder.GetMethod()),
 		E.GetOrElse(RIOE.Left[*http.Request]),
 		RIOE.Map(func(req *http.Request) *http.Request {
 			req.Header = H.Monoid.Concat(req.Header, builder.GetHeaders())

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

@@ -21,7 +21,7 @@ import (
 	"net/url"
 	"testing"
 
-	RIOE "github.com/IBM/fp-go/v2/context/readerioeither"
+	RIOE "github.com/IBM/fp-go/v2/context/readerioresult"
 	E "github.com/IBM/fp-go/v2/either"
 	F "github.com/IBM/fp-go/v2/function"
 	R "github.com/IBM/fp-go/v2/http/builder"

v2/context/readerioresult/http/builder/coverage.out

@@ -0,0 +1,15 @@
+mode: set
+github.com/IBM/fp-go/v2/context/readerioresult/http/builder/builder.go:117.52,119.103 1 1
+github.com/IBM/fp-go/v2/context/readerioresult/http/builder/builder.go:119.103,120.80 1 1
+github.com/IBM/fp-go/v2/context/readerioresult/http/builder/builder.go:120.80,121.41 1 1
+github.com/IBM/fp-go/v2/context/readerioresult/http/builder/builder.go:121.41,123.19 2 1
+github.com/IBM/fp-go/v2/context/readerioresult/http/builder/builder.go:123.19,126.6 2 1
+github.com/IBM/fp-go/v2/context/readerioresult/http/builder/builder.go:127.5,127.20 1 1
+github.com/IBM/fp-go/v2/context/readerioresult/http/builder/builder.go:132.2,132.93 1 1
+github.com/IBM/fp-go/v2/context/readerioresult/http/builder/builder.go:132.93,133.80 1 1
+github.com/IBM/fp-go/v2/context/readerioresult/http/builder/builder.go:133.80,134.41 1 1
+github.com/IBM/fp-go/v2/context/readerioresult/http/builder/builder.go:134.41,136.19 2 1
+github.com/IBM/fp-go/v2/context/readerioresult/http/builder/builder.go:136.19,138.6 1 1
+github.com/IBM/fp-go/v2/context/readerioresult/http/builder/builder.go:139.5,139.20 1 1
+github.com/IBM/fp-go/v2/context/readerioresult/http/builder/builder.go:144.2,150.50 1 1
+github.com/IBM/fp-go/v2/context/readerioresult/http/builder/builder.go:150.50,153.4 2 1

v2/context/readerioresult/http/coverage.out

@@ -0,0 +1,11 @@
+mode: set
+github.com/IBM/fp-go/v2/context/readerioresult/http/request.go:111.76,116.2 1 1
+github.com/IBM/fp-go/v2/context/readerioresult/http/request.go:134.49,136.2 1 1
+github.com/IBM/fp-go/v2/context/readerioresult/http/request.go:161.90,162.65 1 1
+github.com/IBM/fp-go/v2/context/readerioresult/http/request.go:162.65,166.76 1 1
+github.com/IBM/fp-go/v2/context/readerioresult/http/request.go:166.76,176.5 1 1
+github.com/IBM/fp-go/v2/context/readerioresult/http/request.go:198.73,203.2 1 1
+github.com/IBM/fp-go/v2/context/readerioresult/http/request.go:222.74,227.2 1 1
+github.com/IBM/fp-go/v2/context/readerioresult/http/request.go:234.76,236.2 1 1
+github.com/IBM/fp-go/v2/context/readerioresult/http/request.go:245.74,254.2 1 1
+github.com/IBM/fp-go/v2/context/readerioresult/http/request.go:281.76,286.2 1 1

v2/context/readerioresult/http/request.go

@@ -13,7 +13,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// Package http provides functional HTTP client utilities built on top of ReaderIOEither monad.
+// Package http provides functional HTTP client utilities built on top of ReaderIOResult monad.
 // It offers a composable way to make HTTP requests with context support, error handling,
 // and response parsing capabilities. The package follows functional programming principles
 // to ensure type-safe, testable, and maintainable HTTP operations.
@@ -36,7 +36,7 @@ import (
 	"net/http"
 
 	B "github.com/IBM/fp-go/v2/bytes"
-	RIOE "github.com/IBM/fp-go/v2/context/readerioeither"
+	RIOE "github.com/IBM/fp-go/v2/context/readerioresult"
 	F "github.com/IBM/fp-go/v2/function"
 	H "github.com/IBM/fp-go/v2/http"
 	IOE "github.com/IBM/fp-go/v2/ioeither"
@@ -50,13 +50,13 @@ type (
 	// It represents a computation that, given a context, produces either an error
 	// or an HTTP request. This allows for composable request building with proper
 	// error handling and context propagation.
-	Requester = RIOE.ReaderIOEither[*http.Request]
+	Requester = RIOE.ReaderIOResult[*http.Request]
 
 	// Client is an interface for executing HTTP requests in a functional way.
 	// It wraps the standard http.Client and provides a Do method that works
-	// with the ReaderIOEither monad for composable, type-safe HTTP operations.
+	// with the ReaderIOResult monad for composable, type-safe HTTP operations.
 	Client interface {
-		// Do executes an HTTP request and returns the response wrapped in a ReaderIOEither.
+		// Do executes an HTTP request and returns the response wrapped in a ReaderIOResult.
 		// It takes a Requester (which builds the request) and returns a computation that,
 		// when executed with a context, performs the HTTP request and returns either
 		// an error or the HTTP response.
@@ -65,8 +65,8 @@ type (
 		//   - req: A Requester that builds the HTTP request
 		//
 		// Returns:
-		//   - A ReaderIOEither that produces either an error or an *http.Response
+		//   - A ReaderIOResult that produces either an error or an *http.Response
-		Do(Requester) RIOE.ReaderIOEither[*http.Response]
+		Do(Requester) RIOE.ReaderIOResult[*http.Response]
 	}
 
 	// client is the internal implementation of the Client interface.
@@ -108,7 +108,7 @@ var (
 	MakeGetRequest = makeRequest("GET", nil)
 )
 
-func (client client) Do(req Requester) RIOE.ReaderIOEither[*http.Response] {
+func (client client) Do(req Requester) RIOE.ReaderIOResult[*http.Response] {
 	return F.Pipe1(
 		req,
 		RIOE.ChainIOEitherK(client.doIOE),
@@ -117,7 +117,7 @@ func (client client) Do(req Requester) RIOE.ReaderIOEither[*http.Response] {
 
 // MakeClient creates a functional HTTP client wrapper around a standard http.Client.
 // The returned Client provides methods for executing HTTP requests in a functional,
-// composable way using the ReaderIOEither monad.
+// composable way using the ReaderIOResult monad.
 //
 // Parameters:
 //   - httpClient: A standard *http.Client to wrap (e.g., http.DefaultClient)
@@ -149,7 +149,7 @@ func MakeClient(httpClient *http.Client) Client {
 //   - client: The HTTP client to use for executing the request
 //
 // Returns:
-//   - A function that takes a Requester and returns a ReaderIOEither[FullResponse]
+//   - A function that takes a Requester and returns a ReaderIOResult[FullResponse]
 //     where FullResponse is a tuple of (*http.Response, []byte)
 //
 // Example:
@@ -158,8 +158,8 @@ func MakeClient(httpClient *http.Client) Client {
 //	request := MakeGetRequest("https://api.example.com/data")
 //	fullResp := ReadFullResponse(client)(request)
 //	result := fullResp(context.Background())()
-func ReadFullResponse(client Client) func(Requester) RIOE.ReaderIOEither[H.FullResponse] {
+func ReadFullResponse(client Client) func(Requester) RIOE.ReaderIOResult[H.FullResponse] {
-	return func(req Requester) RIOE.ReaderIOEither[H.FullResponse] {
+	return func(req Requester) RIOE.ReaderIOResult[H.FullResponse] {
 		return F.Flow3(
 			client.Do(req),
 			IOE.ChainEitherK(H.ValidateResponse),
@@ -186,7 +186,7 @@ func ReadFullResponse(client Client) func(Requester) RIOE.ReaderIOEither[H.FullR
 //   - client: The HTTP client to use for executing the request
 //
 // Returns:
-//   - A function that takes a Requester and returns a ReaderIOEither[[]byte]
+//   - A function that takes a Requester and returns a ReaderIOResult[[]byte]
 //     containing the response body as bytes
 //
 // Example:
@@ -195,7 +195,7 @@ func ReadFullResponse(client Client) func(Requester) RIOE.ReaderIOEither[H.FullR
 //	request := MakeGetRequest("https://api.example.com/data")
 //	readBytes := ReadAll(client)
 //	result := readBytes(request)(context.Background())()
-func ReadAll(client Client) func(Requester) RIOE.ReaderIOEither[[]byte] {
+func ReadAll(client Client) func(Requester) RIOE.ReaderIOResult[[]byte] {
 	return F.Flow2(
 		ReadFullResponse(client),
 		RIOE.Map(H.Body),
@@ -210,7 +210,7 @@ func ReadAll(client Client) func(Requester) RIOE.ReaderIOEither[[]byte] {
 //   - client: The HTTP client to use for executing the request
 //
 // Returns:
-//   - A function that takes a Requester and returns a ReaderIOEither[string]
+//   - A function that takes a Requester and returns a ReaderIOResult[string]
 //     containing the response body as a string
 //
 // Example:
@@ -219,7 +219,7 @@ func ReadAll(client Client) func(Requester) RIOE.ReaderIOEither[[]byte] {
 //	request := MakeGetRequest("https://api.example.com/text")
 //	readText := ReadText(client)
 //	result := readText(request)(context.Background())()
-func ReadText(client Client) func(Requester) RIOE.ReaderIOEither[string] {
+func ReadText(client Client) func(Requester) RIOE.ReaderIOResult[string] {
 	return F.Flow2(
 		ReadAll(client),
 		RIOE.Map(B.ToString),
@@ -231,7 +231,7 @@ func ReadText(client Client) func(Requester) RIOE.ReaderIOEither[string] {
 // Deprecated: Use [ReadJSON] instead. This function is kept for backward compatibility
 // but will be removed in a future version. The capitalized version follows Go naming
 // conventions for acronyms.
-func ReadJson[A any](client Client) func(Requester) RIOE.ReaderIOEither[A] {
+func ReadJson[A any](client Client) func(Requester) RIOE.ReaderIOResult[A] {
 	return ReadJSON[A](client)
 }
 
@@ -242,7 +242,7 @@ func ReadJson[A any](client Client) func(Requester) RIOE.ReaderIOEither[A] {
 //  3. Reads the response body as bytes
 //
 // This function is used internally by ReadJSON to ensure proper JSON response handling.
-func readJSON(client Client) func(Requester) RIOE.ReaderIOEither[[]byte] {
+func readJSON(client Client) func(Requester) RIOE.ReaderIOResult[[]byte] {
 	return F.Flow3(
 		ReadFullResponse(client),
 		RIOE.ChainFirstEitherK(F.Flow2(
@@ -264,7 +264,7 @@ func readJSON(client Client) func(Requester) RIOE.ReaderIOEither[[]byte] {
 //   - client: The HTTP client to use for executing the request
 //
 // Returns:
-//   - A function that takes a Requester and returns a ReaderIOEither[A]
+//   - A function that takes a Requester and returns a ReaderIOResult[A]
 //     containing the parsed JSON data
 //
 // Example:
@@ -278,7 +278,7 @@ func readJSON(client Client) func(Requester) RIOE.ReaderIOEither[[]byte] {
 //	request := MakeGetRequest("https://api.example.com/user/1")
 //	readUser := ReadJSON[User](client)
 //	result := readUser(request)(context.Background())()
-func ReadJSON[A any](client Client) func(Requester) RIOE.ReaderIOEither[A] {
+func ReadJSON[A any](client Client) func(Requester) RIOE.ReaderIOResult[A] {
 	return F.Flow2(
 		readJSON(client),
 		RIOE.ChainEitherK(J.Unmarshal[A]),

v2/context/readerioresult/http/request_test.go

@@ -22,7 +22,7 @@ import (
 
 	H "net/http"
 
-	R "github.com/IBM/fp-go/v2/context/readerioeither"
+	R "github.com/IBM/fp-go/v2/context/readerioresult"
 	E "github.com/IBM/fp-go/v2/either"
 	"github.com/IBM/fp-go/v2/errors"
 	F "github.com/IBM/fp-go/v2/function"
@@ -66,7 +66,7 @@ func (b simpleRequestBuilder) WithHeader(key, value string) simpleRequestBuilder
 	return b
 }
 
-func (b simpleRequestBuilder) Build() R.ReaderIOEither[*H.Request] {
+func (b simpleRequestBuilder) Build() R.ReaderIOResult[*H.Request] {
 	return func(ctx context.Context) IOE.IOEither[error, *H.Request] {
 		return IOE.TryCatchError(func() (*H.Request, error) {
 			req, err := H.NewRequestWithContext(ctx, b.method, b.url, nil)

v2/context/readerioresult/monoid.go

@@ -13,96 +13,75 @@
 //   See the License for the specific language governing permissions and
 //   limitations under the License.
 
-package readerioeither
+package readerioresult
 
 import (
+	"context"
+
 	"github.com/IBM/fp-go/v2/monoid"
+	RIOR "github.com/IBM/fp-go/v2/readerioresult"
 )
 
 type (
-	Monoid[A any] = monoid.Monoid[ReaderIOEither[A]]
+	Monoid[A any] = monoid.Monoid[ReaderIOResult[A]]
 )
 
-// ApplicativeMonoid returns a [Monoid] that concatenates [ReaderIOEither] instances via their applicative.
+// ApplicativeMonoid returns a [Monoid] that concatenates [ReaderIOResult] instances via their applicative.
 // This uses the default applicative behavior (parallel or sequential based on useParallel flag).
 //
-// The monoid combines two ReaderIOEither values by applying the underlying monoid's combine operation
+// The monoid combines two ReaderIOResult values by applying the underlying monoid's combine operation
 // to their success values using applicative application.
 //
 // Parameters:
 //   - m: The underlying monoid for type A
 //
-// Returns a Monoid for ReaderIOEither[A].
+// Returns a Monoid for ReaderIOResult[A].
 func ApplicativeMonoid[A any](m monoid.Monoid[A]) Monoid[A] {
-	return monoid.ApplicativeMonoid(
+	return RIOR.ApplicativeMonoid[context.Context](m)
-		Of[A],
-		MonadMap[A, func(A) A],
-		MonadAp[A, A],
-		m,
-	)
 }
 
-// ApplicativeMonoidSeq returns a [Monoid] that concatenates [ReaderIOEither] instances via their applicative.
+// ApplicativeMonoidSeq returns a [Monoid] that concatenates [ReaderIOResult] instances via their applicative.
 // This explicitly uses sequential execution for combining values.
 //
 // Parameters:
 //   - m: The underlying monoid for type A
 //
-// Returns a Monoid for ReaderIOEither[A] with sequential execution.
+// Returns a Monoid for ReaderIOResult[A] with sequential execution.
 func ApplicativeMonoidSeq[A any](m monoid.Monoid[A]) Monoid[A] {
-	return monoid.ApplicativeMonoid(
+	return RIOR.ApplicativeMonoidSeq[context.Context](m)
-		Of[A],
-		MonadMap[A, func(A) A],
-		MonadApSeq[A, A],
-		m,
-	)
 }
 
-// ApplicativeMonoidPar returns a [Monoid] that concatenates [ReaderIOEither] instances via their applicative.
+// ApplicativeMonoidPar returns a [Monoid] that concatenates [ReaderIOResult] instances via their applicative.
 // This explicitly uses parallel execution for combining values.
 //
 // Parameters:
 //   - m: The underlying monoid for type A
 //
-// Returns a Monoid for ReaderIOEither[A] with parallel execution.
+// Returns a Monoid for ReaderIOResult[A] with parallel execution.
 func ApplicativeMonoidPar[A any](m monoid.Monoid[A]) Monoid[A] {
-	return monoid.ApplicativeMonoid(
+	return RIOR.ApplicativeMonoidPar[context.Context](m)
-		Of[A],
-		MonadMap[A, func(A) A],
-		MonadApPar[A, A],
-		m,
-	)
 }
 
-// AlternativeMonoid is the alternative [Monoid] for [ReaderIOEither].
+// AlternativeMonoid is the alternative [Monoid] for [ReaderIOResult].
-// This combines ReaderIOEither values using the alternative semantics,
+// This combines ReaderIOResult values using the alternative semantics,
 // where the second value is only evaluated if the first fails.
 //
 // Parameters:
 //   - m: The underlying monoid for type A
 //
-// Returns a Monoid for ReaderIOEither[A] with alternative semantics.
+// Returns a Monoid for ReaderIOResult[A] with alternative semantics.
 func AlternativeMonoid[A any](m monoid.Monoid[A]) Monoid[A] {
-	return monoid.AlternativeMonoid(
+	return RIOR.AlternativeMonoid[context.Context](m)
-		Of[A],
-		MonadMap[A, func(A) A],
-		MonadAp[A, A],
-		MonadAlt[A],
-		m,
-	)
 }
 
-// AltMonoid is the alternative [Monoid] for a [ReaderIOEither].
+// AltMonoid is the alternative [Monoid] for a [ReaderIOResult].
 // This creates a monoid where the empty value is provided lazily,
 // and combination uses the Alt operation (try first, fallback to second on failure).
 //
 // Parameters:
 //   - zero: Lazy computation that provides the empty/identity value
 //
-// Returns a Monoid for ReaderIOEither[A] with Alt-based combination.
+// Returns a Monoid for ReaderIOResult[A] with Alt-based combination.
-func AltMonoid[A any](zero Lazy[ReaderIOEither[A]]) Monoid[A] {
+func AltMonoid[A any](zero Lazy[ReaderIOResult[A]]) Monoid[A] {
-	return monoid.AltMonoid(
+	return RIOR.AltMonoid(zero)
-		zero,
-		MonadAlt[A],
-	)
 }

v2/context/readerioresult/reader.go

@@ -0,0 +1,843 @@
+// 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 readerioresult
+
+import (
+	"context"
+	"time"
+
+	"github.com/IBM/fp-go/v2/context/readerresult"
+	"github.com/IBM/fp-go/v2/either"
+	"github.com/IBM/fp-go/v2/errors"
+	"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/reader"
+	"github.com/IBM/fp-go/v2/readerio"
+	RIOR "github.com/IBM/fp-go/v2/readerioresult"
+	"github.com/IBM/fp-go/v2/readeroption"
+)
+
+const (
+	// useParallel is the feature flag to control if we use the parallel or the sequential implementation of ap
+	useParallel = true
+)
+
+// FromEither converts an [Either] into a [ReaderIOResult].
+// The resulting computation ignores the context and immediately returns the Either value.
+//
+// Parameters:
+//   - e: The Either value to lift into ReaderIOResult
+//
+// Returns a ReaderIOResult that produces the given Either value.
+//
+//go:inline
+func FromEither[A any](e Either[A]) ReaderIOResult[A] {
+	return RIOR.FromEither[context.Context](e)
+}
+
+// FromEither converts an [Either] into a [ReaderIOResult].
+// The resulting computation ignores the context and immediately returns the Either value.
+//
+// Parameters:
+//   - e: The Either value to lift into ReaderIOResult
+//
+// Returns a ReaderIOResult that produces the given Either value.
+//
+//go:inline
+func FromResult[A any](e Result[A]) ReaderIOResult[A] {
+	return RIOR.FromEither[context.Context](e)
+}
+
+// Left creates a [ReaderIOResult] that represents a failed computation with the given error.
+//
+// Parameters:
+//   - l: The error value
+//
+// Returns a ReaderIOResult that always fails with the given error.
+func Left[A any](l error) ReaderIOResult[A] {
+	return RIOR.Left[context.Context, A](l)
+}
+
+// Right creates a [ReaderIOResult] that represents a successful computation with the given value.
+//
+// Parameters:
+//   - r: The success value
+//
+// Returns a ReaderIOResult that always succeeds with the given value.
+//
+//go:inline
+func Right[A any](r A) ReaderIOResult[A] {
+	return RIOR.Right[context.Context](r)
+}
+
+// MonadMap transforms the success value of a [ReaderIOResult] using the provided function.
+// If the computation fails, the error is propagated unchanged.
+//
+// Parameters:
+//   - fa: The ReaderIOResult to transform
+//   - f: The transformation function
+//
+// Returns a new ReaderIOResult with the transformed value.
+//
+//go:inline
+func MonadMap[A, B any](fa ReaderIOResult[A], f func(A) B) ReaderIOResult[B] {
+	return RIOR.MonadMap(fa, f)
+}
+
+// Map transforms the success value of a [ReaderIOResult] using the provided function.
+// This is the curried version of [MonadMap], useful for composition.
+//
+// Parameters:
+//   - f: The transformation function
+//
+// Returns a function that transforms a ReaderIOResult.
+//
+//go:inline
+func Map[A, B any](f func(A) B) Operator[A, B] {
+	return RIOR.Map[context.Context](f)
+}
+
+// MonadMapTo replaces the success value of a [ReaderIOResult] with a constant value.
+// If the computation fails, the error is propagated unchanged.
+//
+// Parameters:
+//   - fa: The ReaderIOResult to transform
+//   - b: The constant value to use
+//
+// Returns a new ReaderIOResult with the constant value.
+//
+//go:inline
+func MonadMapTo[A, B any](fa ReaderIOResult[A], b B) ReaderIOResult[B] {
+	return RIOR.MonadMapTo(fa, b)
+}
+
+// MapTo replaces the success value of a [ReaderIOResult] with a constant value.
+// This is the curried version of [MonadMapTo].
+//
+// Parameters:
+//   - b: The constant value to use
+//
+// Returns a function that transforms a ReaderIOResult.
+//
+//go:inline
+func MapTo[A, B any](b B) Operator[A, B] {
+	return RIOR.MapTo[context.Context, A](b)
+}
+
+// MonadChain sequences two [ReaderIOResult] computations, where the second depends on the result of the first.
+// If the first computation fails, the second is not executed.
+//
+// Parameters:
+//   - ma: The first ReaderIOResult
+//   - f: Function that produces the second ReaderIOResult based on the first's result
+//
+// Returns a new ReaderIOResult representing the sequenced computation.
+//
+//go:inline
+func MonadChain[A, B any](ma ReaderIOResult[A], f Kleisli[A, B]) ReaderIOResult[B] {
+	return RIOR.MonadChain(ma, f)
+}
+
+// Chain sequences two [ReaderIOResult] computations, where the second depends on the result of the first.
+// This is the curried version of [MonadChain], useful for composition.
+//
+// Parameters:
+//   - f: Function that produces the second ReaderIOResult based on the first's result
+//
+// Returns a function that sequences ReaderIOResult computations.
+//
+//go:inline
+func Chain[A, B any](f Kleisli[A, B]) Operator[A, B] {
+	return RIOR.Chain(f)
+}
+
+// MonadChainFirst sequences two [ReaderIOResult] computations but returns the result of the first.
+// The second computation is executed for its side effects only.
+//
+// Parameters:
+//   - ma: The first ReaderIOResult
+//   - f: Function that produces the second ReaderIOResult
+//
+// Returns a ReaderIOResult with the result of the first computation.
+//
+//go:inline
+func MonadChainFirst[A, B any](ma ReaderIOResult[A], f Kleisli[A, B]) ReaderIOResult[A] {
+	return RIOR.MonadChainFirst(ma, f)
+}
+
+// ChainFirst sequences two [ReaderIOResult] computations but returns the result of the first.
+// This is the curried version of [MonadChainFirst].
+//
+// Parameters:
+//   - f: Function that produces the second ReaderIOResult
+//
+// Returns a function that sequences ReaderIOResult computations.
+//
+//go:inline
+func ChainFirst[A, B any](f Kleisli[A, B]) Operator[A, A] {
+	return RIOR.ChainFirst(f)
+}
+
+// Of creates a [ReaderIOResult] that always succeeds with the given value.
+// This is the same as [Right] and represents the monadic return operation.
+//
+// Parameters:
+//   - a: The value to wrap
+//
+// Returns a ReaderIOResult that always succeeds with the given value.
+//
+//go:inline
+func Of[A any](a A) ReaderIOResult[A] {
+	return RIOR.Of[context.Context](a)
+}
+
+func withCancelCauseFunc[A any](cancel context.CancelCauseFunc, ma IOResult[A]) IOResult[A] {
+	return function.Pipe3(
+		ma,
+		ioresult.Swap[A],
+		ioeither.ChainFirstIOK[A](func(err error) func() any {
+			return io.FromImpure(func() { cancel(err) })
+		}),
+		ioeither.Swap[A],
+	)
+}
+
+// MonadApPar implements parallel applicative application for [ReaderIOResult].
+// It executes both computations in parallel and creates a sub-context that will be canceled
+// if either operation fails. This provides automatic cancellation propagation.
+//
+// Parameters:
+//   - fab: ReaderIOResult containing a function
+//   - fa: ReaderIOResult containing a value
+//
+// Returns a ReaderIOResult with the function applied to the value.
+func MonadApPar[B, A any](fab ReaderIOResult[func(A) B], fa ReaderIOResult[A]) ReaderIOResult[B] {
+	// context sensitive input
+	cfab := WithContext(fab)
+	cfa := WithContext(fa)
+
+	return func(ctx context.Context) IOResult[B] {
+		// quick check for cancellation
+		if err := context.Cause(ctx); err != nil {
+			return ioeither.Left[B](err)
+		}
+
+		return func() Result[B] {
+			// quick check for cancellation
+			if err := context.Cause(ctx); err != nil {
+				return either.Left[B](err)
+			}
+
+			// create sub-contexts for fa and fab, so they can cancel one other
+			ctxSub, cancelSub := context.WithCancelCause(ctx)
+			defer cancelSub(nil) // cancel has to be called in all paths
+
+			fabIOE := withCancelCauseFunc(cancelSub, cfab(ctxSub))
+			faIOE := withCancelCauseFunc(cancelSub, cfa(ctxSub))
+
+			return ioresult.MonadApPar(fabIOE, faIOE)()
+		}
+	}
+}
+
+// MonadAp implements applicative application for [ReaderIOResult].
+// By default, it uses parallel execution ([MonadApPar]) but can be configured to use
+// sequential execution ([MonadApSeq]) via the useParallel constant.
+//
+// Parameters:
+//   - fab: ReaderIOResult containing a function
+//   - fa: ReaderIOResult containing a value
+//
+// Returns a ReaderIOResult with the function applied to the value.
+func MonadAp[B, A any](fab ReaderIOResult[func(A) B], fa ReaderIOResult[A]) ReaderIOResult[B] {
+	// dispatch to the configured version
+	if useParallel {
+		return MonadApPar(fab, fa)
+	}
+	return MonadApSeq(fab, fa)
+}
+
+// MonadApSeq implements sequential applicative application for [ReaderIOResult].
+// It executes the function computation first, then the value computation.
+//
+// Parameters:
+//   - fab: ReaderIOResult containing a function
+//   - fa: ReaderIOResult containing a value
+//
+// Returns a ReaderIOResult with the function applied to the value.
+//
+//go:inline
+func MonadApSeq[B, A any](fab ReaderIOResult[func(A) B], fa ReaderIOResult[A]) ReaderIOResult[B] {
+	return RIOR.MonadApSeq(fab, fa)
+}
+
+// Ap applies a function wrapped in a [ReaderIOResult] to a value wrapped in a ReaderIOResult.
+// This is the curried version of [MonadAp], using the default execution mode.
+//
+// Parameters:
+//   - fa: ReaderIOResult containing a value
+//
+// Returns a function that applies a ReaderIOResult function to the value.
+//
+//go:inline
+func Ap[B, A any](fa ReaderIOResult[A]) Operator[func(A) B, B] {
+	return function.Bind2nd(MonadAp[B, A], fa)
+}
+
+// ApSeq applies a function wrapped in a [ReaderIOResult] to a value sequentially.
+// This is the curried version of [MonadApSeq].
+//
+// Parameters:
+//   - fa: ReaderIOResult containing a value
+//
+// Returns a function that applies a ReaderIOResult function to the value sequentially.
+//
+//go:inline
+func ApSeq[B, A any](fa ReaderIOResult[A]) Operator[func(A) B, B] {
+	return function.Bind2nd(MonadApSeq[B, A], fa)
+}
+
+// ApPar applies a function wrapped in a [ReaderIOResult] to a value in parallel.
+// This is the curried version of [MonadApPar].
+//
+// Parameters:
+//   - fa: ReaderIOResult containing a value
+//
+// Returns a function that applies a ReaderIOResult function to the value in parallel.
+//
+//go:inline
+func ApPar[B, A any](fa ReaderIOResult[A]) Operator[func(A) B, B] {
+	return function.Bind2nd(MonadApPar[B, A], fa)
+}
+
+// FromPredicate creates a [ReaderIOResult] from a predicate function.
+// If the predicate returns true, the value is wrapped in Right; otherwise, Left with the error from onFalse.
+//
+// Parameters:
+//   - pred: Predicate function to test the value
+//   - onFalse: Function to generate an error when predicate fails
+//
+// Returns a function that converts a value to ReaderIOResult based on the predicate.
+//
+//go:inline
+func FromPredicate[A any](pred func(A) bool, onFalse func(A) error) Kleisli[A, A] {
+	return RIOR.FromPredicate[context.Context](pred, onFalse)
+}
+
+// OrElse provides an alternative [ReaderIOResult] computation if the first one fails.
+// The alternative is only executed if the first computation results in a Left (error).
+//
+// Parameters:
+//   - onLeft: Function that produces an alternative ReaderIOResult from the error
+//
+// Returns a function that provides fallback behavior for failed computations.
+//
+//go:inline
+func OrElse[A any](onLeft Kleisli[error, A]) Operator[A, A] {
+	return RIOR.OrElse(onLeft)
+}
+
+// Ask returns a [ReaderIOResult] that provides access to the context.
+// This is useful for accessing the [context.Context] within a computation.
+//
+// Returns a ReaderIOResult that produces the context.
+//
+//go:inline
+func Ask() ReaderIOResult[context.Context] {
+	return RIOR.Ask[context.Context]()
+}
+
+// MonadChainEitherK chains a function that returns an [Either] into a [ReaderIOResult] computation.
+// This is useful for integrating pure Either-returning functions into ReaderIOResult workflows.
+//
+// Parameters:
+//   - ma: The ReaderIOResult to chain from
+//   - f: Function that produces an Either
+//
+// Returns a new ReaderIOResult with the chained computation.
+//
+//go:inline
+func MonadChainEitherK[A, B any](ma ReaderIOResult[A], f func(A) Either[B]) ReaderIOResult[B] {
+	return RIOR.MonadChainEitherK(ma, f)
+}
+
+// ChainEitherK chains a function that returns an [Either] into a [ReaderIOResult] computation.
+// This is the curried version of [MonadChainEitherK].
+//
+// Parameters:
+//   - f: Function that produces an Either
+//
+// Returns a function that chains the Either-returning function.
+//
+//go:inline
+func ChainEitherK[A, B any](f func(A) Either[B]) Operator[A, B] {
+	return RIOR.ChainEitherK[context.Context](f)
+}
+
+// MonadChainFirstEitherK chains a function that returns an [Either] but keeps the original value.
+// The Either-returning function is executed for its validation/side effects only.
+//
+// Parameters:
+//   - ma: The ReaderIOResult to chain from
+//   - f: Function that produces an Either
+//
+// Returns a ReaderIOResult with the original value if both computations succeed.
+//
+//go:inline
+func MonadChainFirstEitherK[A, B any](ma ReaderIOResult[A], f func(A) Either[B]) ReaderIOResult[A] {
+	return RIOR.MonadChainFirstEitherK(ma, f)
+}
+
+// ChainFirstEitherK chains a function that returns an [Either] but keeps the original value.
+// This is the curried version of [MonadChainFirstEitherK].
+//
+// Parameters:
+//   - f: Function that produces an Either
+//
+// Returns a function that chains the Either-returning function.
+//
+//go:inline
+func ChainFirstEitherK[A, B any](f func(A) Either[B]) Operator[A, A] {
+	return RIOR.ChainFirstEitherK[context.Context](f)
+}
+
+// ChainOptionK chains a function that returns an [Option] into a [ReaderIOResult] computation.
+// If the Option is None, the provided error function is called.
+//
+// Parameters:
+//   - onNone: Function to generate an error when Option is None
+//
+// Returns a function that chains Option-returning functions into ReaderIOResult.
+//
+//go:inline
+func ChainOptionK[A, B any](onNone func() error) func(func(A) Option[B]) Operator[A, B] {
+	return RIOR.ChainOptionK[context.Context, A, B](onNone)
+}
+
+// FromIOEither converts an [IOResult] into a [ReaderIOResult].
+// The resulting computation ignores the context.
+//
+// Parameters:
+//   - t: The IOResult to convert
+//
+// Returns a ReaderIOResult that executes the IOResult.
+//
+//go:inline
+func FromIOEither[A any](t IOResult[A]) ReaderIOResult[A] {
+	return RIOR.FromIOEither[context.Context](t)
+}
+
+//go:inline
+func FromIOResult[A any](t IOResult[A]) ReaderIOResult[A] {
+	return RIOR.FromIOResult[context.Context](t)
+}
+
+// FromIO converts an [IO] into a [ReaderIOResult].
+// The IO computation always succeeds, so it's wrapped in Right.
+//
+// Parameters:
+//   - t: The IO to convert
+//
+// Returns a ReaderIOResult that executes the IO and wraps the result in Right.
+//
+//go:inline
+func FromIO[A any](t IO[A]) ReaderIOResult[A] {
+	return RIOR.FromIO[context.Context](t)
+}
+
+//go:inline
+func FromReader[A any](t Reader[context.Context, A]) ReaderIOResult[A] {
+	return RIOR.FromReader(t)
+}
+
+//go:inline
+func FromReaderIO[A any](t ReaderIO[A]) ReaderIOResult[A] {
+	return RIOR.FromReaderIO(t)
+}
+
+// FromLazy converts a [Lazy] computation into a [ReaderIOResult].
+// The Lazy computation always succeeds, so it's wrapped in Right.
+// This is an alias for [FromIO] since Lazy and IO have the same structure.
+//
+// Parameters:
+//   - t: The Lazy computation to convert
+//
+// Returns a ReaderIOResult that executes the Lazy computation and wraps the result in Right.
+//
+//go:inline
+func FromLazy[A any](t Lazy[A]) ReaderIOResult[A] {
+	return RIOR.FromIO[context.Context](t)
+}
+
+// Never returns a [ReaderIOResult] that blocks indefinitely until the context is canceled.
+// This is useful for creating computations that wait for external cancellation signals.
+//
+// Returns a ReaderIOResult that waits for context cancellation and returns the cancellation error.
+func Never[A any]() ReaderIOResult[A] {
+	return func(ctx context.Context) IOResult[A] {
+		return func() Either[A] {
+			<-ctx.Done()
+			return either.Left[A](context.Cause(ctx))
+		}
+	}
+}
+
+// MonadChainIOK chains a function that returns an [IO] into a [ReaderIOResult] computation.
+// The IO computation always succeeds, so it's wrapped in Right.
+//
+// Parameters:
+//   - ma: The ReaderIOResult to chain from
+//   - f: Function that produces an IO
+//
+// Returns a new ReaderIOResult with the chained IO computation.
+//
+//go:inline
+func MonadChainIOK[A, B any](ma ReaderIOResult[A], f func(A) IO[B]) ReaderIOResult[B] {
+	return RIOR.MonadChainIOK(ma, f)
+}
+
+// ChainIOK chains a function that returns an [IO] into a [ReaderIOResult] computation.
+// This is the curried version of [MonadChainIOK].
+//
+// Parameters:
+//   - f: Function that produces an IO
+//
+// Returns a function that chains the IO-returning function.
+//
+//go:inline
+func ChainIOK[A, B any](f func(A) IO[B]) Operator[A, B] {
+	return RIOR.ChainIOK[context.Context](f)
+}
+
+// MonadChainFirstIOK chains a function that returns an [IO] but keeps the original value.
+// The IO computation is executed for its side effects only.
+//
+// Parameters:
+//   - ma: The ReaderIOResult to chain from
+//   - f: Function that produces an IO
+//
+// Returns a ReaderIOResult with the original value after executing the IO.
+//
+//go:inline
+func MonadChainFirstIOK[A, B any](ma ReaderIOResult[A], f func(A) IO[B]) ReaderIOResult[A] {
+	return RIOR.MonadChainFirstIOK(ma, f)
+}
+
+// ChainFirstIOK chains a function that returns an [IO] but keeps the original value.
+// This is the curried version of [MonadChainFirstIOK].
+//
+// Parameters:
+//   - f: Function that produces an IO
+//
+// Returns a function that chains the IO-returning function.
+//
+//go:inline
+func ChainFirstIOK[A, B any](f func(A) IO[B]) Operator[A, A] {
+	return RIOR.ChainFirstIOK[context.Context](f)
+}
+
+// ChainIOEitherK chains a function that returns an [IOResult] into a [ReaderIOResult] computation.
+// This is useful for integrating IOResult-returning functions into ReaderIOResult workflows.
+//
+// Parameters:
+//   - f: Function that produces an IOResult
+//
+// Returns a function that chains the IOResult-returning function.
+//
+//go:inline
+func ChainIOEitherK[A, B any](f func(A) IOResult[B]) Operator[A, B] {
+	return RIOR.ChainIOEitherK[context.Context](f)
+}
+
+// Delay creates an operation that delays execution by the specified duration.
+// The computation waits for either the delay to expire or the context to be canceled.
+//
+// Parameters:
+//   - delay: The duration to wait before executing the computation
+//
+// Returns a function that delays a ReaderIOResult computation.
+func Delay[A any](delay time.Duration) Operator[A, A] {
+	return func(ma ReaderIOResult[A]) ReaderIOResult[A] {
+		return func(ctx context.Context) IOResult[A] {
+			return func() Either[A] {
+				// manage the timeout
+				timeoutCtx, cancelTimeout := context.WithTimeout(ctx, delay)
+				defer cancelTimeout()
+				// whatever comes first
+				select {
+				case <-timeoutCtx.Done():
+					return ma(ctx)()
+				case <-ctx.Done():
+					return either.Left[A](context.Cause(ctx))
+				}
+			}
+		}
+	}
+}
+
+// Timer returns the current time after waiting for the specified delay.
+// This is useful for creating time-based computations.
+//
+// Parameters:
+//   - delay: The duration to wait before returning the time
+//
+// Returns a ReaderIOResult that produces the current time after the delay.
+func Timer(delay time.Duration) ReaderIOResult[time.Time] {
+	return function.Pipe2(
+		io.Now,
+		FromIO[time.Time],
+		Delay[time.Time](delay),
+	)
+}
+
+// Defer creates a [ReaderIOResult] by lazily generating a new computation each time it's executed.
+// This is useful for creating computations that should be re-evaluated on each execution.
+//
+// Parameters:
+//   - gen: Lazy generator function that produces a ReaderIOResult
+//
+// Returns a ReaderIOResult that generates a fresh computation on each execution.
+//
+//go:inline
+func Defer[A any](gen Lazy[ReaderIOResult[A]]) ReaderIOResult[A] {
+	return RIOR.Defer(gen)
+}
+
+// TryCatch wraps a function that returns a tuple (value) into a [ReaderIOResult].
+// This is the standard way to convert Go error-returning functions into ReaderIOResult.
+//
+// Parameters:
+//   - f: Function that takes a context and returns a function producing (value)
+//
+// Returns a ReaderIOResult that wraps the error-returning function.
+//
+//go:inline
+func TryCatch[A any](f func(context.Context) func() (A, error)) ReaderIOResult[A] {
+	return RIOR.TryCatch(f, errors.IdentityError)
+}
+
+// MonadAlt provides an alternative [ReaderIOResult] if the first one fails.
+// The alternative is lazily evaluated only if needed.
+//
+// Parameters:
+//   - first: The primary ReaderIOResult to try
+//   - second: Lazy alternative ReaderIOResult to use if first fails
+//
+// Returns a ReaderIOResult that tries the first, then the second if first fails.
+//
+//go:inline
+func MonadAlt[A any](first ReaderIOResult[A], second Lazy[ReaderIOResult[A]]) ReaderIOResult[A] {
+	return RIOR.MonadAlt(first, second)
+}
+
+// Alt provides an alternative [ReaderIOResult] if the first one fails.
+// This is the curried version of [MonadAlt].
+//
+// Parameters:
+//   - second: Lazy alternative ReaderIOResult to use if first fails
+//
+// Returns a function that provides fallback behavior.
+//
+//go:inline
+func Alt[A any](second Lazy[ReaderIOResult[A]]) Operator[A, A] {
+	return RIOR.Alt(second)
+}
+
+// Memoize computes the value of the provided [ReaderIOResult] monad lazily but exactly once.
+// The context used to compute the value is the context of the first call, so do not use this
+// method if the value has a functional dependency on the content of the context.
+//
+// Parameters:
+//   - rdr: The ReaderIOResult to memoize
+//
+// Returns a ReaderIOResult that caches its result after the first execution.
+//
+//go:inline
+func Memoize[A any](rdr ReaderIOResult[A]) ReaderIOResult[A] {
+	return RIOR.Memoize(rdr)
+}
+
+// Flatten converts a nested [ReaderIOResult] into a flat [ReaderIOResult].
+// This is equivalent to [MonadChain] with the identity function.
+//
+// Parameters:
+//   - rdr: The nested ReaderIOResult to flatten
+//
+// Returns a flattened ReaderIOResult.
+//
+//go:inline
+func Flatten[A any](rdr ReaderIOResult[ReaderIOResult[A]]) ReaderIOResult[A] {
+	return RIOR.Flatten(rdr)
+}
+
+// MonadFlap applies a value to a function wrapped in a [ReaderIOResult].
+// This is the reverse of [MonadAp], useful in certain composition scenarios.
+//
+// Parameters:
+//   - fab: ReaderIOResult containing a function
+//   - a: The value to apply to the function
+//
+// Returns a ReaderIOResult with the function applied to the value.
+//
+//go:inline
+func MonadFlap[B, A any](fab ReaderIOResult[func(A) B], a A) ReaderIOResult[B] {
+	return RIOR.MonadFlap(fab, a)
+}
+
+// Flap applies a value to a function wrapped in a [ReaderIOResult].
+// This is the curried version of [MonadFlap].
+//
+// Parameters:
+//   - a: The value to apply to the function
+//
+// Returns a function that applies the value to a ReaderIOResult function.
+//
+//go:inline
+func Flap[B, A any](a A) Operator[func(A) B, B] {
+	return RIOR.Flap[context.Context, B](a)
+}
+
+// Fold handles both success and error cases of a [ReaderIOResult] by providing handlers for each.
+// Both handlers return ReaderIOResult, allowing for further composition.
+//
+// Parameters:
+//   - onLeft: Handler for error case
+//   - onRight: Handler for success case
+//
+// Returns a function that folds a ReaderIOResult into a new ReaderIOResult.
+//
+//go:inline
+func Fold[A, B any](onLeft Kleisli[error, B], onRight Kleisli[A, B]) Operator[A, B] {
+	return RIOR.Fold(onLeft, onRight)
+}
+
+// GetOrElse extracts the value from a [ReaderIOResult], providing a default via a function if it fails.
+// The result is a [ReaderIO] that always succeeds.
+//
+// Parameters:
+//   - onLeft: Function to provide a default value from the error
+//
+// Returns a function that converts a ReaderIOResult to a ReaderIO.
+//
+//go:inline
+func GetOrElse[A any](onLeft func(error) ReaderIO[A]) func(ReaderIOResult[A]) ReaderIO[A] {
+	return RIOR.GetOrElse(onLeft)
+}
+
+// OrLeft transforms the error of a [ReaderIOResult] using the provided function.
+// The success value is left unchanged.
+//
+// Parameters:
+//   - onLeft: Function to transform the error
+//
+// Returns a function that transforms the error of a ReaderIOResult.
+//
+//go:inline
+func OrLeft[A any](onLeft func(error) ReaderIO[error]) Operator[A, A] {
+	return RIOR.OrLeft[A](onLeft)
+}
+
+//go:inline
+func FromReaderEither[A any](ma ReaderEither[context.Context, error, A]) ReaderIOResult[A] {
+	return RIOR.FromReaderEither(ma)
+}
+
+//go:inline
+func FromReaderResult[A any](ma ReaderResult[A]) ReaderIOResult[A] {
+	return RIOR.FromReaderEither(ma)
+}
+
+//go:inline
+func FromReaderOption[A any](onNone func() error) Kleisli[ReaderOption[context.Context, A], A] {
+	return RIOR.FromReaderOption[context.Context, A](onNone)
+}
+
+//go:inline
+func MonadChainReaderK[A, B any](ma ReaderIOResult[A], f reader.Kleisli[context.Context, A, B]) ReaderIOResult[B] {
+	return RIOR.MonadChainReaderK(ma, f)
+}
+
+//go:inline
+func ChainReaderK[A, B any](f reader.Kleisli[context.Context, A, B]) Operator[A, B] {
+	return RIOR.ChainReaderK(f)
+}
+
+//go:inline
+func MonadChainFirstReaderK[A, B any](ma ReaderIOResult[A], f reader.Kleisli[context.Context, A, B]) ReaderIOResult[A] {
+	return RIOR.MonadChainFirstReaderK(ma, f)
+}
+
+//go:inline
+func ChainFirstReaderK[A, B any](f reader.Kleisli[context.Context, A, B]) Operator[A, A] {
+	return RIOR.ChainFirstReaderK(f)
+}
+
+//go:inline
+func MonadChainReaderResultK[A, B any](ma ReaderIOResult[A], f readerresult.Kleisli[A, B]) ReaderIOResult[B] {
+	return RIOR.MonadChainReaderResultK(ma, f)
+}
+
+//go:inline
+func ChainReaderResultK[A, B any](f readerresult.Kleisli[A, B]) Operator[A, B] {
+	return RIOR.ChainReaderResultK(f)
+}
+
+//go:inline
+func MonadChainFirstReaderResultK[A, B any](ma ReaderIOResult[A], f readerresult.Kleisli[A, B]) ReaderIOResult[A] {
+	return RIOR.MonadChainFirstReaderResultK(ma, f)
+}
+
+//go:inline
+func ChainFirstReaderResultK[A, B any](f readerresult.Kleisli[A, B]) Operator[A, A] {
+	return RIOR.ChainFirstReaderResultK(f)
+}
+
+//go:inline
+func MonadChainReaderIOK[A, B any](ma ReaderIOResult[A], f readerio.Kleisli[context.Context, A, B]) ReaderIOResult[B] {
+	return RIOR.MonadChainReaderIOK(ma, f)
+}
+
+//go:inline
+func ChainReaderIOK[A, B any](f readerio.Kleisli[context.Context, A, B]) Operator[A, B] {
+	return RIOR.ChainReaderIOK(f)
+}
+
+//go:inline
+func MonadChainFirstReaderIOK[A, B any](ma ReaderIOResult[A], f readerio.Kleisli[context.Context, A, B]) ReaderIOResult[A] {
+	return RIOR.MonadChainFirstReaderIOK(ma, f)
+}
+
+//go:inline
+func ChainFirstReaderIOK[A, B any](f readerio.Kleisli[context.Context, A, B]) Operator[A, A] {
+	return RIOR.ChainFirstReaderIOK(f)
+}
+
+//go:inline
+func ChainReaderOptionK[A, B any](onNone func() error) func(readeroption.Kleisli[context.Context, A, B]) Operator[A, B] {
+	return RIOR.ChainReaderOptionK[context.Context, A, B](onNone)
+}
+
+//go:inline
+func ChainFirstReaderOptionK[A, B any](onNone func() error) func(readeroption.Kleisli[context.Context, A, B]) Operator[A, A] {
+	return RIOR.ChainFirstReaderOptionK[context.Context, A, B](onNone)
+}
+
+//go:inline
+func Read[A any](r context.Context) func(ReaderIOResult[A]) IOResult[A] {
+	return RIOR.Read[A](r)
+}

v2/context/readerioresult/reader_bench_test.go

@@ -0,0 +1,885 @@
+// 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 readerioresult
+
+import (
+	"context"
+	"errors"
+	"testing"
+	"time"
+
+	E "github.com/IBM/fp-go/v2/either"
+	F "github.com/IBM/fp-go/v2/function"
+	IOE "github.com/IBM/fp-go/v2/ioeither"
+)
+
+var (
+	benchErr    = errors.New("benchmark error")
+	benchCtx    = context.Background()
+	benchResult Either[int]
+	benchRIOE   ReaderIOResult[int]
+	benchInt    int
+)
+
+// Benchmark core constructors
+func BenchmarkLeft(b *testing.B) {
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = Left[int](benchErr)
+	}
+}
+
+func BenchmarkRight(b *testing.B) {
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = Right(42)
+	}
+}
+
+func BenchmarkOf(b *testing.B) {
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = Of(42)
+	}
+}
+
+func BenchmarkFromEither_Right(b *testing.B) {
+	either := E.Right[error](42)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = FromEither(either)
+	}
+}
+
+func BenchmarkFromEither_Left(b *testing.B) {
+	either := E.Left[int](benchErr)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = FromEither(either)
+	}
+}
+
+func BenchmarkFromIO(b *testing.B) {
+	io := func() int { return 42 }
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = FromIO(io)
+	}
+}
+
+func BenchmarkFromIOEither_Right(b *testing.B) {
+	ioe := IOE.Of[error](42)
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = FromIOEither(ioe)
+	}
+}
+
+func BenchmarkFromIOEither_Left(b *testing.B) {
+	ioe := IOE.Left[int](benchErr)
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = FromIOEither(ioe)
+	}
+}
+
+// Benchmark execution
+func BenchmarkExecute_Right(b *testing.B) {
+	rioe := Right(42)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchResult = rioe(benchCtx)()
+	}
+}
+
+func BenchmarkExecute_Left(b *testing.B) {
+	rioe := Left[int](benchErr)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchResult = rioe(benchCtx)()
+	}
+}
+
+func BenchmarkExecute_WithContext(b *testing.B) {
+	rioe := Right(42)
+	ctx, cancel := context.WithCancel(benchCtx)
+	defer cancel()
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchResult = rioe(ctx)()
+	}
+}
+
+// Benchmark functor operations
+func BenchmarkMonadMap_Right(b *testing.B) {
+	rioe := Right(42)
+	mapper := func(a int) int { return a * 2 }
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = MonadMap(rioe, mapper)
+	}
+}
+
+func BenchmarkMonadMap_Left(b *testing.B) {
+	rioe := Left[int](benchErr)
+	mapper := func(a int) int { return a * 2 }
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = MonadMap(rioe, mapper)
+	}
+}
+
+func BenchmarkMap_Right(b *testing.B) {
+	rioe := Right(42)
+	mapper := Map(func(a int) int { return a * 2 })
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = mapper(rioe)
+	}
+}
+
+func BenchmarkMap_Left(b *testing.B) {
+	rioe := Left[int](benchErr)
+	mapper := Map(func(a int) int { return a * 2 })
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = mapper(rioe)
+	}
+}
+
+func BenchmarkMapTo_Right(b *testing.B) {
+	rioe := Right(42)
+	mapper := MapTo[int](99)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = mapper(rioe)
+	}
+}
+
+// Benchmark monad operations
+func BenchmarkMonadChain_Right(b *testing.B) {
+	rioe := Right(42)
+	chainer := func(a int) ReaderIOResult[int] { return Right(a * 2) }
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = MonadChain(rioe, chainer)
+	}
+}
+
+func BenchmarkMonadChain_Left(b *testing.B) {
+	rioe := Left[int](benchErr)
+	chainer := func(a int) ReaderIOResult[int] { return Right(a * 2) }
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = MonadChain(rioe, chainer)
+	}
+}
+
+func BenchmarkChain_Right(b *testing.B) {
+	rioe := Right(42)
+	chainer := Chain(func(a int) ReaderIOResult[int] { return Right(a * 2) })
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = chainer(rioe)
+	}
+}
+
+func BenchmarkChain_Left(b *testing.B) {
+	rioe := Left[int](benchErr)
+	chainer := Chain(func(a int) ReaderIOResult[int] { return Right(a * 2) })
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = chainer(rioe)
+	}
+}
+
+func BenchmarkChainFirst_Right(b *testing.B) {
+	rioe := Right(42)
+	chainer := ChainFirst(func(a int) ReaderIOResult[string] { return Right("logged") })
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = chainer(rioe)
+	}
+}
+
+func BenchmarkChainFirst_Left(b *testing.B) {
+	rioe := Left[int](benchErr)
+	chainer := ChainFirst(func(a int) ReaderIOResult[string] { return Right("logged") })
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = chainer(rioe)
+	}
+}
+
+func BenchmarkFlatten_Right(b *testing.B) {
+	nested := Right(Right(42))
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = Flatten(nested)
+	}
+}
+
+func BenchmarkFlatten_Left(b *testing.B) {
+	nested := Left[ReaderIOResult[int]](benchErr)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = Flatten(nested)
+	}
+}
+
+// Benchmark applicative operations
+func BenchmarkMonadApSeq_RightRight(b *testing.B) {
+	fab := Right(func(a int) int { return a * 2 })
+	fa := Right(42)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = MonadApSeq(fab, fa)
+	}
+}
+
+func BenchmarkMonadApSeq_RightLeft(b *testing.B) {
+	fab := Right(func(a int) int { return a * 2 })
+	fa := Left[int](benchErr)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = MonadApSeq(fab, fa)
+	}
+}
+
+func BenchmarkMonadApSeq_LeftRight(b *testing.B) {
+	fab := Left[func(int) int](benchErr)
+	fa := Right(42)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = MonadApSeq(fab, fa)
+	}
+}
+
+func BenchmarkMonadApPar_RightRight(b *testing.B) {
+	fab := Right(func(a int) int { return a * 2 })
+	fa := Right(42)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = MonadApPar(fab, fa)
+	}
+}
+
+func BenchmarkMonadApPar_RightLeft(b *testing.B) {
+	fab := Right(func(a int) int { return a * 2 })
+	fa := Left[int](benchErr)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = MonadApPar(fab, fa)
+	}
+}
+
+func BenchmarkMonadApPar_LeftRight(b *testing.B) {
+	fab := Left[func(int) int](benchErr)
+	fa := Right(42)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = MonadApPar(fab, fa)
+	}
+}
+
+// Benchmark execution of applicative operations
+func BenchmarkExecuteApSeq_RightRight(b *testing.B) {
+	fab := Right(func(a int) int { return a * 2 })
+	fa := Right(42)
+	rioe := MonadApSeq(fab, fa)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchResult = rioe(benchCtx)()
+	}
+}
+
+func BenchmarkExecuteApPar_RightRight(b *testing.B) {
+	fab := Right(func(a int) int { return a * 2 })
+	fa := Right(42)
+	rioe := MonadApPar(fab, fa)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchResult = rioe(benchCtx)()
+	}
+}
+
+// Benchmark alternative operations
+func BenchmarkAlt_RightRight(b *testing.B) {
+	rioe := Right(42)
+	alternative := Alt(func() ReaderIOResult[int] { return Right(99) })
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = alternative(rioe)
+	}
+}
+
+func BenchmarkAlt_LeftRight(b *testing.B) {
+	rioe := Left[int](benchErr)
+	alternative := Alt(func() ReaderIOResult[int] { return Right(99) })
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = alternative(rioe)
+	}
+}
+
+func BenchmarkOrElse_Right(b *testing.B) {
+	rioe := Right(42)
+	recover := OrElse(func(e error) ReaderIOResult[int] { return Right(0) })
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = recover(rioe)
+	}
+}
+
+func BenchmarkOrElse_Left(b *testing.B) {
+	rioe := Left[int](benchErr)
+	recover := OrElse(func(e error) ReaderIOResult[int] { return Right(0) })
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = recover(rioe)
+	}
+}
+
+// Benchmark chain operations with different types
+func BenchmarkChainEitherK_Right(b *testing.B) {
+	rioe := Right(42)
+	chainer := ChainEitherK(func(a int) Either[int] { return E.Right[error](a * 2) })
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = chainer(rioe)
+	}
+}
+
+func BenchmarkChainEitherK_Left(b *testing.B) {
+	rioe := Left[int](benchErr)
+	chainer := ChainEitherK(func(a int) Either[int] { return E.Right[error](a * 2) })
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = chainer(rioe)
+	}
+}
+
+func BenchmarkChainIOK_Right(b *testing.B) {
+	rioe := Right(42)
+	chainer := ChainIOK(func(a int) func() int { return func() int { return a * 2 } })
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = chainer(rioe)
+	}
+}
+
+func BenchmarkChainIOK_Left(b *testing.B) {
+	rioe := Left[int](benchErr)
+	chainer := ChainIOK(func(a int) func() int { return func() int { return a * 2 } })
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = chainer(rioe)
+	}
+}
+
+func BenchmarkChainIOEitherK_Right(b *testing.B) {
+	rioe := Right(42)
+	chainer := ChainIOEitherK(func(a int) IOEither[int] { return IOE.Of[error](a * 2) })
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = chainer(rioe)
+	}
+}
+
+func BenchmarkChainIOEitherK_Left(b *testing.B) {
+	rioe := Left[int](benchErr)
+	chainer := ChainIOEitherK(func(a int) IOEither[int] { return IOE.Of[error](a * 2) })
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = chainer(rioe)
+	}
+}
+
+// Benchmark context operations
+func BenchmarkAsk(b *testing.B) {
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		_ = Ask()
+	}
+}
+
+func BenchmarkDefer(b *testing.B) {
+	gen := func() ReaderIOResult[int] { return Right(42) }
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = Defer(gen)
+	}
+}
+
+func BenchmarkMemoize(b *testing.B) {
+	rioe := Right(42)
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = Memoize(rioe)
+	}
+}
+
+// Benchmark delay operations
+func BenchmarkDelay_Construction(b *testing.B) {
+	rioe := Right(42)
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = Delay[int](time.Millisecond)(rioe)
+	}
+}
+
+func BenchmarkTimer_Construction(b *testing.B) {
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		_ = Timer(time.Millisecond)
+	}
+}
+
+// Benchmark TryCatch
+func BenchmarkTryCatch_Success(b *testing.B) {
+	f := func(ctx context.Context) func() (int, error) {
+		return func() (int, error) { return 42, nil }
+	}
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = TryCatch(f)
+	}
+}
+
+func BenchmarkTryCatch_Error(b *testing.B) {
+	f := func(ctx context.Context) func() (int, error) {
+		return func() (int, error) { return 0, benchErr }
+	}
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = TryCatch(f)
+	}
+}
+
+func BenchmarkExecuteTryCatch_Success(b *testing.B) {
+	f := func(ctx context.Context) func() (int, error) {
+		return func() (int, error) { return 42, nil }
+	}
+	rioe := TryCatch(f)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchResult = rioe(benchCtx)()
+	}
+}
+
+func BenchmarkExecuteTryCatch_Error(b *testing.B) {
+	f := func(ctx context.Context) func() (int, error) {
+		return func() (int, error) { return 0, benchErr }
+	}
+	rioe := TryCatch(f)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchResult = rioe(benchCtx)()
+	}
+}
+
+// Benchmark pipeline operations
+func BenchmarkPipeline_Map_Right(b *testing.B) {
+	rioe := Right(21)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = F.Pipe1(
+			rioe,
+			Map(func(x int) int { return x * 2 }),
+		)
+	}
+}
+
+func BenchmarkPipeline_Map_Left(b *testing.B) {
+	rioe := Left[int](benchErr)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = F.Pipe1(
+			rioe,
+			Map(func(x int) int { return x * 2 }),
+		)
+	}
+}
+
+func BenchmarkPipeline_Chain_Right(b *testing.B) {
+	rioe := Right(21)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = F.Pipe1(
+			rioe,
+			Chain(func(x int) ReaderIOResult[int] { return Right(x * 2) }),
+		)
+	}
+}
+
+func BenchmarkPipeline_Chain_Left(b *testing.B) {
+	rioe := Left[int](benchErr)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = F.Pipe1(
+			rioe,
+			Chain(func(x int) ReaderIOResult[int] { return Right(x * 2) }),
+		)
+	}
+}
+
+func BenchmarkPipeline_Complex_Right(b *testing.B) {
+	rioe := Right(10)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = F.Pipe3(
+			rioe,
+			Map(func(x int) int { return x * 2 }),
+			Chain(func(x int) ReaderIOResult[int] { return Right(x + 1) }),
+			Map(func(x int) int { return x * 2 }),
+		)
+	}
+}
+
+func BenchmarkPipeline_Complex_Left(b *testing.B) {
+	rioe := Left[int](benchErr)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchRIOE = F.Pipe3(
+			rioe,
+			Map(func(x int) int { return x * 2 }),
+			Chain(func(x int) ReaderIOResult[int] { return Right(x + 1) }),
+			Map(func(x int) int { return x * 2 }),
+		)
+	}
+}
+
+func BenchmarkExecutePipeline_Complex_Right(b *testing.B) {
+	rioe := F.Pipe3(
+		Right(10),
+		Map(func(x int) int { return x * 2 }),
+		Chain(func(x int) ReaderIOResult[int] { return Right(x + 1) }),
+		Map(func(x int) int { return x * 2 }),
+	)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchResult = rioe(benchCtx)()
+	}
+}
+
+// Benchmark do-notation operations
+func BenchmarkDo(b *testing.B) {
+	type State struct{ value int }
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		_ = Do(State{})
+	}
+}
+
+func BenchmarkBind_Right(b *testing.B) {
+	type State struct{ value int }
+	initial := Do(State{})
+	binder := Bind(
+		func(v int) func(State) State {
+			return func(s State) State { return State{value: v} }
+		},
+		func(s State) ReaderIOResult[int] {
+			return Right(42)
+		},
+	)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		_ = binder(initial)
+	}
+}
+
+func BenchmarkLet_Right(b *testing.B) {
+	type State struct{ value int }
+	initial := Right(State{value: 10})
+	letter := Let(
+		func(v int) func(State) State {
+			return func(s State) State { return State{value: s.value + v} }
+		},
+		func(s State) int { return 32 },
+	)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		_ = letter(initial)
+	}
+}
+
+func BenchmarkApS_Right(b *testing.B) {
+	type State struct{ value int }
+	initial := Right(State{value: 10})
+	aps := ApS(
+		func(v int) func(State) State {
+			return func(s State) State { return State{value: v} }
+		},
+		Right(42),
+	)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		_ = aps(initial)
+	}
+}
+
+// Benchmark traverse operations
+func BenchmarkTraverseArray_Empty(b *testing.B) {
+	arr := []int{}
+	traverser := TraverseArray(func(x int) ReaderIOResult[int] {
+		return Right(x * 2)
+	})
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		_ = traverser(arr)
+	}
+}
+
+func BenchmarkTraverseArray_Small(b *testing.B) {
+	arr := []int{1, 2, 3}
+	traverser := TraverseArray(func(x int) ReaderIOResult[int] {
+		return Right(x * 2)
+	})
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		_ = traverser(arr)
+	}
+}
+
+func BenchmarkTraverseArray_Medium(b *testing.B) {
+	arr := make([]int, 10)
+	for i := range arr {
+		arr[i] = i
+	}
+	traverser := TraverseArray(func(x int) ReaderIOResult[int] {
+		return Right(x * 2)
+	})
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		_ = traverser(arr)
+	}
+}
+
+func BenchmarkTraverseArraySeq_Small(b *testing.B) {
+	arr := []int{1, 2, 3}
+	traverser := TraverseArraySeq(func(x int) ReaderIOResult[int] {
+		return Right(x * 2)
+	})
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		_ = traverser(arr)
+	}
+}
+
+func BenchmarkTraverseArrayPar_Small(b *testing.B) {
+	arr := []int{1, 2, 3}
+	traverser := TraverseArrayPar(func(x int) ReaderIOResult[int] {
+		return Right(x * 2)
+	})
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		_ = traverser(arr)
+	}
+}
+
+func BenchmarkSequenceArray_Small(b *testing.B) {
+	arr := []ReaderIOResult[int]{
+		Right(1),
+		Right(2),
+		Right(3),
+	}
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		_ = SequenceArray(arr)
+	}
+}
+
+func BenchmarkExecuteTraverseArray_Small(b *testing.B) {
+	arr := []int{1, 2, 3}
+	rioe := TraverseArray(func(x int) ReaderIOResult[int] {
+		return Right(x * 2)
+	})(arr)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		_ = rioe(benchCtx)()
+	}
+}
+
+func BenchmarkExecuteTraverseArraySeq_Small(b *testing.B) {
+	arr := []int{1, 2, 3}
+	rioe := TraverseArraySeq(func(x int) ReaderIOResult[int] {
+		return Right(x * 2)
+	})(arr)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		_ = rioe(benchCtx)()
+	}
+}
+
+func BenchmarkExecuteTraverseArrayPar_Small(b *testing.B) {
+	arr := []int{1, 2, 3}
+	rioe := TraverseArrayPar(func(x int) ReaderIOResult[int] {
+		return Right(x * 2)
+	})(arr)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		_ = rioe(benchCtx)()
+	}
+}
+
+// Benchmark record operations
+func BenchmarkTraverseRecord_Small(b *testing.B) {
+	rec := map[string]int{"a": 1, "b": 2, "c": 3}
+	traverser := TraverseRecord[string](func(x int) ReaderIOResult[int] {
+		return Right(x * 2)
+	})
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		_ = traverser(rec)
+	}
+}
+
+func BenchmarkSequenceRecord_Small(b *testing.B) {
+	rec := map[string]ReaderIOResult[int]{
+		"a": Right(1),
+		"b": Right(2),
+		"c": Right(3),
+	}
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		_ = SequenceRecord(rec)
+	}
+}
+
+// Benchmark resource management
+func BenchmarkWithResource_Success(b *testing.B) {
+	acquire := Right(42)
+	release := func(int) ReaderIOResult[int] { return Right(0) }
+	body := func(x int) ReaderIOResult[int] { return Right(x * 2) }
+
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		_ = WithResource[int](acquire, release)(body)
+	}
+}
+
+func BenchmarkExecuteWithResource_Success(b *testing.B) {
+	acquire := Right(42)
+	release := func(int) ReaderIOResult[int] { return Right(0) }
+	body := func(x int) ReaderIOResult[int] { return Right(x * 2) }
+	rioe := WithResource[int](acquire, release)(body)
+
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchResult = rioe(benchCtx)()
+	}
+}
+
+func BenchmarkExecuteWithResource_ErrorInBody(b *testing.B) {
+	acquire := Right(42)
+	release := func(int) ReaderIOResult[int] { return Right(0) }
+	body := func(x int) ReaderIOResult[int] { return Left[int](benchErr) }
+	rioe := WithResource[int](acquire, release)(body)
+
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchResult = rioe(benchCtx)()
+	}
+}
+
+// Benchmark context cancellation
+func BenchmarkExecute_CanceledContext(b *testing.B) {
+	rioe := Right(42)
+	ctx, cancel := context.WithCancel(benchCtx)
+	cancel() // Cancel immediately
+
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchResult = rioe(ctx)()
+	}
+}
+
+func BenchmarkExecuteApPar_CanceledContext(b *testing.B) {
+	fab := Right(func(a int) int { return a * 2 })
+	fa := Right(42)
+	rioe := MonadApPar(fab, fa)
+	ctx, cancel := context.WithCancel(benchCtx)
+	cancel() // Cancel immediately
+
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		benchResult = rioe(ctx)()
+	}
+}

v2/context/readerioresult/reader_extended_test.go

@@ -0,0 +1,877 @@
+// 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 readerioresult
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"testing"
+	"time"
+
+	E "github.com/IBM/fp-go/v2/either"
+	IOG "github.com/IBM/fp-go/v2/io"
+	IOE "github.com/IBM/fp-go/v2/ioeither"
+	M "github.com/IBM/fp-go/v2/monoid"
+	O "github.com/IBM/fp-go/v2/option"
+	R "github.com/IBM/fp-go/v2/reader"
+	"github.com/stretchr/testify/assert"
+)
+
+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())())
+	})
+
+	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())())
+	})
+}
+
+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())())
+	})
+
+	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())())
+	})
+}
+
+func TestLeft(t *testing.T) {
+	err := errors.New("test error")
+	result := Left[string](err)
+	assert.Equal(t, E.Left[string](err), result(context.Background())())
+}
+
+func TestRight(t *testing.T) {
+	result := Right("success")
+	assert.Equal(t, E.Right[error]("success"), result(context.Background())())
+}
+
+func TestOf(t *testing.T) {
+	result := Of(42)
+	assert.Equal(t, E.Right[error](42), result(context.Background())())
+}
+
+func TestMonadMap(t *testing.T) {
+	t.Run("Map over Right", func(t *testing.T) {
+		result := MonadMap(Of(5), func(x int) int { return x * 2 })
+		assert.Equal(t, E.Right[error](10), result(context.Background())())
+	})
+
+	t.Run("Map over Left", func(t *testing.T) {
+		err := errors.New("test error")
+		result := MonadMap(Left[int](err), func(x int) int { return x * 2 })
+		assert.Equal(t, E.Left[int](err), result(context.Background())())
+	})
+}
+
+func TestMap(t *testing.T) {
+	t.Run("Map with success", func(t *testing.T) {
+		mapper := Map(func(x int) int { return x * 2 })
+		result := mapper(Of(5))
+		assert.Equal(t, E.Right[error](10), result(context.Background())())
+	})
+
+	t.Run("Map with error", func(t *testing.T) {
+		err := errors.New("test error")
+		mapper := Map(func(x int) int { return x * 2 })
+		result := mapper(Left[int](err))
+		assert.Equal(t, E.Left[int](err), result(context.Background())())
+	})
+}
+
+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())())
+	})
+
+	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())())
+	})
+}
+
+func TestMapTo(t *testing.T) {
+	mapper := MapTo[string](42)
+	result := mapper(Of("original"))
+	assert.Equal(t, E.Right[error](42), result(context.Background())())
+}
+
+func TestMonadChain(t *testing.T) {
+	t.Run("Chain with success", func(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())())
+	})
+
+	t.Run("Chain with error in first", func(t *testing.T) {
+		err := errors.New("test error")
+		result := MonadChain(Left[int](err), func(x int) ReaderIOResult[int] {
+			return Of(x * 2)
+		})
+		assert.Equal(t, E.Left[int](err), result(context.Background())())
+	})
+
+	t.Run("Chain with error in second", func(t *testing.T) {
+		err := errors.New("test error")
+		result := MonadChain(Of(5), func(x int) ReaderIOResult[int] {
+			return Left[int](err)
+		})
+		assert.Equal(t, E.Left[int](err), result(context.Background())())
+	})
+}
+
+func TestChain(t *testing.T) {
+	chainer := Chain(func(x int) ReaderIOResult[int] {
+		return Of(x * 2)
+	})
+	result := chainer(Of(5))
+	assert.Equal(t, E.Right[error](10), result(context.Background())())
+}
+
+func TestMonadChainFirst(t *testing.T) {
+	t.Run("ChainFirst keeps first value", func(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())())
+	})
+
+	t.Run("ChainFirst propagates error from second", func(t *testing.T) {
+		err := errors.New("test error")
+		result := MonadChainFirst(Of(5), func(x int) ReaderIOResult[string] {
+			return Left[string](err)
+		})
+		assert.Equal(t, E.Left[int](err), result(context.Background())())
+	})
+}
+
+func TestChainFirst(t *testing.T) {
+	chainer := ChainFirst(func(x int) ReaderIOResult[string] {
+		return Of("ignored")
+	})
+	result := chainer(Of(5))
+	assert.Equal(t, E.Right[error](5), result(context.Background())())
+}
+
+func TestMonadApSeq(t *testing.T) {
+	t.Run("ApSeq with success", func(t *testing.T) {
+		fab := Of(func(x int) int { return x * 2 })
+		fa := Of(5)
+		result := MonadApSeq(fab, fa)
+		assert.Equal(t, E.Right[error](10), result(context.Background())())
+	})
+
+	t.Run("ApSeq with error in function", func(t *testing.T) {
+		err := errors.New("test error")
+		fab := Left[func(int) int](err)
+		fa := Of(5)
+		result := MonadApSeq(fab, fa)
+		assert.Equal(t, E.Left[int](err), result(context.Background())())
+	})
+
+	t.Run("ApSeq with error in value", func(t *testing.T) {
+		err := errors.New("test error")
+		fab := Of(func(x int) int { return x * 2 })
+		fa := Left[int](err)
+		result := MonadApSeq(fab, fa)
+		assert.Equal(t, E.Left[int](err), result(context.Background())())
+	})
+}
+
+func TestApSeq(t *testing.T) {
+	fa := Of(5)
+	fab := Of(func(x int) int { return x * 2 })
+	result := MonadApSeq(fab, fa)
+	assert.Equal(t, E.Right[error](10), result(context.Background())())
+}
+
+func TestApPar(t *testing.T) {
+	t.Run("ApPar with success", func(t *testing.T) {
+		fa := Of(5)
+		fab := Of(func(x int) int { return x * 2 })
+		result := MonadApPar(fab, fa)
+		assert.Equal(t, E.Right[error](10), result(context.Background())())
+	})
+
+	t.Run("ApPar with cancelled context", func(t *testing.T) {
+		ctx, cancel := context.WithCancel(context.Background())
+		cancel()
+		fa := Of(5)
+		fab := Of(func(x int) int { return x * 2 })
+		result := MonadApPar(fab, fa)
+		res := result(ctx)()
+		assert.True(t, E.IsLeft(res))
+	})
+}
+
+func TestFromPredicate(t *testing.T) {
+	t.Run("Predicate true", func(t *testing.T) {
+		pred := FromPredicate(
+			func(x int) bool { return x > 0 },
+			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())())
+	})
+
+	t.Run("Predicate false", func(t *testing.T) {
+		pred := FromPredicate(
+			func(x int) bool { return x > 0 },
+			func(x int) error { return fmt.Errorf("value %d is not positive", x) },
+		)
+		result := pred(-5)
+		res := result(context.Background())()
+		assert.True(t, E.IsLeft(res))
+	})
+}
+
+func TestOrElse(t *testing.T) {
+	t.Run("OrElse with success", func(t *testing.T) {
+		fallback := OrElse(func(err error) ReaderIOResult[int] {
+			return Of(42)
+		})
+		result := fallback(Of(10))
+		assert.Equal(t, E.Right[error](10), result(context.Background())())
+	})
+
+	t.Run("OrElse with error", func(t *testing.T) {
+		err := errors.New("test error")
+		fallback := OrElse(func(err error) ReaderIOResult[int] {
+			return Of(42)
+		})
+		result := fallback(Left[int](err))
+		assert.Equal(t, E.Right[error](42), result(context.Background())())
+	})
+}
+
+func TestAsk(t *testing.T) {
+	result := Ask()
+	ctx := context.Background()
+	res := result(ctx)()
+	assert.True(t, E.IsRight(res))
+	ctxResult := E.ToOption(res)
+	assert.True(t, O.IsSome(ctxResult))
+}
+
+func TestMonadChainEitherK(t *testing.T) {
+	t.Run("ChainEitherK with success", func(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())())
+	})
+
+	t.Run("ChainEitherK with error", func(t *testing.T) {
+		err := errors.New("test error")
+		result := MonadChainEitherK(Of(5), func(x int) Either[int] {
+			return E.Left[int](err)
+		})
+		assert.Equal(t, E.Left[int](err), result(context.Background())())
+	})
+}
+
+func TestChainEitherK(t *testing.T) {
+	chainer := ChainEitherK(func(x int) Either[int] {
+		return E.Right[error](x * 2)
+	})
+	result := chainer(Of(5))
+	assert.Equal(t, E.Right[error](10), result(context.Background())())
+}
+
+func TestMonadChainFirstEitherK(t *testing.T) {
+	t.Run("ChainFirstEitherK keeps first value", func(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())())
+	})
+
+	t.Run("ChainFirstEitherK propagates error", func(t *testing.T) {
+		err := errors.New("test error")
+		result := MonadChainFirstEitherK(Of(5), func(x int) Either[string] {
+			return E.Left[string](err)
+		})
+		assert.Equal(t, E.Left[int](err), result(context.Background())())
+	})
+}
+
+func TestChainFirstEitherK(t *testing.T) {
+	chainer := ChainFirstEitherK(func(x int) Either[string] {
+		return E.Right[error]("ignored")
+	})
+	result := chainer(Of(5))
+	assert.Equal(t, E.Right[error](5), result(context.Background())())
+}
+
+func TestChainOptionK(t *testing.T) {
+	t.Run("ChainOptionK with Some", func(t *testing.T) {
+		chainer := ChainOptionK[int, int](func() error {
+			return errors.New("none error")
+		})(func(x int) Option[int] {
+			return O.Some(x * 2)
+		})
+		result := chainer(Of(5))
+		assert.Equal(t, E.Right[error](10), result(context.Background())())
+	})
+
+	t.Run("ChainOptionK with None", func(t *testing.T) {
+		chainer := ChainOptionK[int, int](func() error {
+			return errors.New("none error")
+		})(func(x int) Option[int] {
+			return O.None[int]()
+		})
+		result := chainer(Of(5))
+		res := result(context.Background())()
+		assert.True(t, E.IsLeft(res))
+	})
+}
+
+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())())
+	})
+
+	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())())
+	})
+}
+
+func TestFromIOResult(t *testing.T) {
+	ioe := IOE.Of[error](42)
+	result := FromIOResult(ioe)
+	assert.Equal(t, E.Right[error](42), result(context.Background())())
+}
+
+func TestFromIO(t *testing.T) {
+	io := IOG.Of(42)
+	result := FromIO(io)
+	assert.Equal(t, E.Right[error](42), result(context.Background())())
+}
+
+func TestFromReader(t *testing.T) {
+	reader := R.Of[context.Context](42)
+	result := FromReader(reader)
+	assert.Equal(t, E.Right[error](42), result(context.Background())())
+}
+
+func TestFromLazy(t *testing.T) {
+	lazy := func() int { return 42 }
+	result := FromLazy(lazy)
+	assert.Equal(t, E.Right[error](42), result(context.Background())())
+}
+
+func TestNever(t *testing.T) {
+	t.Run("Never with cancelled context", func(t *testing.T) {
+		ctx, cancel := context.WithCancel(context.Background())
+		result := Never[int]()
+
+		// Cancel immediately
+		cancel()
+
+		res := result(ctx)()
+		assert.True(t, E.IsLeft(res))
+	})
+
+	t.Run("Never with timeout", func(t *testing.T) {
+		ctx, cancel := context.WithTimeout(context.Background(), 100*time.Millisecond)
+		defer cancel()
+
+		result := Never[int]()
+		res := result(ctx)()
+		assert.True(t, E.IsLeft(res))
+	})
+}
+
+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())())
+}
+
+func TestChainIOK(t *testing.T) {
+	chainer := ChainIOK(func(x int) IOG.IO[int] {
+		return IOG.Of(x * 2)
+	})
+	result := chainer(Of(5))
+	assert.Equal(t, E.Right[error](10), result(context.Background())())
+}
+
+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())())
+}
+
+func TestChainFirstIOK(t *testing.T) {
+	chainer := ChainFirstIOK(func(x int) IOG.IO[string] {
+		return IOG.Of("ignored")
+	})
+	result := chainer(Of(5))
+	assert.Equal(t, E.Right[error](5), result(context.Background())())
+}
+
+func TestChainIOEitherK(t *testing.T) {
+	t.Run("ChainIOEitherK with success", func(t *testing.T) {
+		chainer := ChainIOEitherK(func(x int) IOResult[int] {
+			return IOE.Of[error](x * 2)
+		})
+		result := chainer(Of(5))
+		assert.Equal(t, E.Right[error](10), result(context.Background())())
+	})
+
+	t.Run("ChainIOEitherK with error", func(t *testing.T) {
+		err := errors.New("test error")
+		chainer := ChainIOEitherK(func(x int) IOResult[int] {
+			return IOE.Left[int](err)
+		})
+		result := chainer(Of(5))
+		assert.Equal(t, E.Left[int](err), result(context.Background())())
+	})
+}
+
+func TestDelay(t *testing.T) {
+	t.Run("Delay with success", func(t *testing.T) {
+		start := time.Now()
+		delayed := Delay[int](100 * time.Millisecond)
+		result := delayed(Of(42))
+		res := result(context.Background())()
+		elapsed := time.Since(start)
+
+		assert.True(t, E.IsRight(res))
+		assert.GreaterOrEqual(t, elapsed, 100*time.Millisecond)
+	})
+
+	t.Run("Delay with cancelled context", func(t *testing.T) {
+		ctx, cancel := context.WithCancel(context.Background())
+
+		delayed := Delay[int](100 * time.Millisecond)
+		result := delayed(Of(42))
+
+		// Cancel after starting but before delay completes
+		cancel()
+		res := result(ctx)()
+
+		// The result might be either Left (if cancelled) or Right (if completed before cancel)
+		// This is a race condition, so we just verify it completes
+		assert.True(t, E.IsLeft(res) || E.IsRight(res))
+	})
+}
+
+func TestDefer(t *testing.T) {
+	counter := 0
+	deferred := Defer(func() ReaderIOResult[int] {
+		counter++
+		return Of(counter)
+	})
+
+	// First execution
+	res1 := deferred(context.Background())()
+	assert.True(t, E.IsRight(res1))
+
+	// Second execution should generate a new computation
+	res2 := deferred(context.Background())()
+	assert.True(t, E.IsRight(res2))
+
+	// Counter should be incremented for each execution
+	assert.Equal(t, 2, counter)
+}
+
+func TestTryCatch(t *testing.T) {
+	t.Run("TryCatch with success", func(t *testing.T) {
+		result := TryCatch(func(ctx context.Context) func() (int, error) {
+			return func() (int, error) {
+				return 42, nil
+			}
+		})
+		assert.Equal(t, E.Right[error](42), result(context.Background())())
+	})
+
+	t.Run("TryCatch with error", func(t *testing.T) {
+		err := errors.New("test error")
+		result := TryCatch(func(ctx context.Context) func() (int, error) {
+			return func() (int, error) {
+				return 0, err
+			}
+		})
+		assert.Equal(t, E.Left[int](err), result(context.Background())())
+	})
+}
+
+func TestMonadAlt(t *testing.T) {
+	t.Run("Alt with first success", func(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())())
+	})
+
+	t.Run("Alt with first error", func(t *testing.T) {
+		err := errors.New("test error")
+		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())())
+	})
+}
+
+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())())
+}
+
+func TestMemoize(t *testing.T) {
+	counter := 0
+	computation := Memoize(FromLazy(func() int {
+		counter++
+		return counter
+	}))
+
+	// First execution
+	res1 := computation(context.Background())()
+	assert.True(t, E.IsRight(res1))
+	val1 := E.ToOption(res1)
+	v1, _ := O.Unwrap(val1)
+	assert.Equal(t, 1, v1)
+
+	// Second execution should return cached value
+	res2 := computation(context.Background())()
+	assert.True(t, E.IsRight(res2))
+	val2 := E.ToOption(res2)
+	v2, _ := O.Unwrap(val2)
+	assert.Equal(t, 1, v2)
+
+	// Counter should only be incremented once
+	assert.Equal(t, 1, counter)
+}
+
+func TestFlatten(t *testing.T) {
+	nested := Of(Of(42))
+	result := Flatten(nested)
+	assert.Equal(t, E.Right[error](42), result(context.Background())())
+}
+
+func TestMonadFlap(t *testing.T) {
+	fab := Of(func(x int) int { return x * 2 })
+	result := MonadFlap(fab, 5)
+	assert.Equal(t, E.Right[error](10), result(context.Background())())
+}
+
+func TestFlap(t *testing.T) {
+	flapper := Flap[int](5)
+	result := flapper(Of(func(x int) int { return x * 2 }))
+	assert.Equal(t, E.Right[error](10), result(context.Background())())
+}
+
+func TestFold(t *testing.T) {
+	t.Run("Fold with success", func(t *testing.T) {
+		folder := Fold(
+			func(err error) ReaderIOResult[string] {
+				return Of("error: " + err.Error())
+			},
+			func(x int) ReaderIOResult[string] {
+				return Of(fmt.Sprintf("success: %d", x))
+			},
+		)
+		result := folder(Of(42))
+		assert.Equal(t, E.Right[error]("success: 42"), result(context.Background())())
+	})
+
+	t.Run("Fold with error", func(t *testing.T) {
+		err := errors.New("test error")
+		folder := Fold(
+			func(err error) ReaderIOResult[string] {
+				return Of("error: " + err.Error())
+			},
+			func(x int) ReaderIOResult[string] {
+				return Of(fmt.Sprintf("success: %d", x))
+			},
+		)
+		result := folder(Left[int](err))
+		assert.Equal(t, E.Right[error]("error: test error"), result(context.Background())())
+	})
+}
+
+func TestGetOrElse(t *testing.T) {
+	t.Run("GetOrElse with success", func(t *testing.T) {
+		getter := GetOrElse(func(err error) ReaderIO[int] {
+			return func(ctx context.Context) IOG.IO[int] {
+				return IOG.Of(0)
+			}
+		})
+		result := getter(Of(42))
+		assert.Equal(t, 42, result(context.Background())())
+	})
+
+	t.Run("GetOrElse with error", func(t *testing.T) {
+		err := errors.New("test error")
+		getter := GetOrElse(func(err error) ReaderIO[int] {
+			return func(ctx context.Context) IOG.IO[int] {
+				return IOG.Of(0)
+			}
+		})
+		result := getter(Left[int](err))
+		assert.Equal(t, 0, result(context.Background())())
+	})
+}
+
+func TestWithContext(t *testing.T) {
+	t.Run("WithContext with valid context", func(t *testing.T) {
+		computation := WithContext(Of(42))
+		result := computation(context.Background())()
+		assert.Equal(t, E.Right[error](42), result)
+	})
+
+	t.Run("WithContext with cancelled context", func(t *testing.T) {
+		ctx, cancel := context.WithCancel(context.Background())
+		cancel()
+
+		computation := WithContext(Of(42))
+		result := computation(ctx)()
+		assert.True(t, E.IsLeft(result))
+	})
+}
+
+func TestEitherize0(t *testing.T) {
+	f := func(ctx context.Context) (int, error) {
+		return 42, nil
+	}
+	eitherized := Eitherize0(f)
+	result := eitherized()
+	assert.Equal(t, E.Right[error](42), result(context.Background())())
+}
+
+func TestUneitherize0(t *testing.T) {
+	f := func() ReaderIOResult[int] {
+		return Of(42)
+	}
+	uneitherized := Uneitherize0(f)
+	result, err := uneitherized(context.Background())
+	assert.NoError(t, err)
+	assert.Equal(t, 42, result)
+}
+
+func TestEitherize1(t *testing.T) {
+	f := func(ctx context.Context, x int) (int, error) {
+		return x * 2, nil
+	}
+	eitherized := Eitherize1(f)
+	result := eitherized(5)
+	assert.Equal(t, E.Right[error](10), result(context.Background())())
+}
+
+func TestUneitherize1(t *testing.T) {
+	f := func(x int) ReaderIOResult[int] {
+		return Of(x * 2)
+	}
+	uneitherized := Uneitherize1(f)
+	result, err := uneitherized(context.Background(), 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())()
+	assert.True(t, E.IsRight(res))
+	tuple := E.ToOption(res)
+	assert.True(t, O.IsSome(tuple))
+	t1, _ := O.Unwrap(tuple)
+	assert.Equal(t, 1, t1.F1)
+	assert.Equal(t, 2, t1.F2)
+}
+
+func TestSequenceSeqT2(t *testing.T) {
+	result := SequenceSeqT2(Of(1), Of(2))
+	res := result(context.Background())()
+	assert.True(t, E.IsRight(res))
+}
+
+func TestSequenceParT2(t *testing.T) {
+	result := SequenceParT2(Of(1), Of(2))
+	res := result(context.Background())()
+	assert.True(t, E.IsRight(res))
+}
+
+func TestTraverseArray(t *testing.T) {
+	t.Run("TraverseArray with success", func(t *testing.T) {
+		arr := []int{1, 2, 3}
+		traverser := TraverseArray(func(x int) ReaderIOResult[int] {
+			return Of(x * 2)
+		})
+		result := traverser(arr)
+		res := result(context.Background())()
+		assert.True(t, E.IsRight(res))
+		arrOpt := E.ToOption(res)
+		assert.True(t, O.IsSome(arrOpt))
+		resultArr, _ := O.Unwrap(arrOpt)
+		assert.Equal(t, []int{2, 4, 6}, resultArr)
+	})
+
+	t.Run("TraverseArray with error", func(t *testing.T) {
+		arr := []int{1, 2, 3}
+		err := errors.New("test error")
+		traverser := TraverseArray(func(x int) ReaderIOResult[int] {
+			if x == 2 {
+				return Left[int](err)
+			}
+			return Of(x * 2)
+		})
+		result := traverser(arr)
+		res := result(context.Background())()
+		assert.True(t, E.IsLeft(res))
+	})
+}
+
+func TestSequenceArray(t *testing.T) {
+	arr := []ReaderIOResult[int]{Of(1), Of(2), Of(3)}
+	result := SequenceArray(arr)
+	res := result(context.Background())()
+	assert.True(t, E.IsRight(res))
+	arrOpt := E.ToOption(res)
+	assert.True(t, O.IsSome(arrOpt))
+	resultArr, _ := O.Unwrap(arrOpt)
+	assert.Equal(t, []int{1, 2, 3}, resultArr)
+}
+
+func TestTraverseRecord(t *testing.T) {
+	rec := map[string]int{"a": 1, "b": 2}
+	result := TraverseRecord[string](func(x int) ReaderIOResult[int] {
+		return Of(x * 2)
+	})(rec)
+	res := result(context.Background())()
+	assert.True(t, E.IsRight(res))
+	recOpt := E.ToOption(res)
+	assert.True(t, O.IsSome(recOpt))
+	resultRec, _ := O.Unwrap(recOpt)
+	assert.Equal(t, 2, resultRec["a"])
+	assert.Equal(t, 4, resultRec["b"])
+}
+
+func TestSequenceRecord(t *testing.T) {
+	rec := map[string]ReaderIOResult[int]{
+		"a": Of(1),
+		"b": Of(2),
+	}
+	result := SequenceRecord(rec)
+	res := result(context.Background())()
+	assert.True(t, E.IsRight(res))
+	recOpt := E.ToOption(res)
+	assert.True(t, O.IsSome(recOpt))
+	resultRec, _ := O.Unwrap(recOpt)
+	assert.Equal(t, 1, resultRec["a"])
+	assert.Equal(t, 2, resultRec["b"])
+}
+
+func TestAltSemigroup(t *testing.T) {
+	sg := AltSemigroup[int]()
+	err := errors.New("test error")
+
+	result := sg.Concat(Left[int](err), Of(42))
+	res := result(context.Background())()
+	assert.Equal(t, E.Right[error](42), res)
+}
+
+func TestApplicativeMonoid(t *testing.T) {
+	// Test with int addition monoid
+	intAddMonoid := ApplicativeMonoid(M.MakeMonoid(
+		func(a, b int) int { return a + b },
+		0,
+	))
+
+	result := intAddMonoid.Concat(Of(5), Of(10))
+	res := result(context.Background())()
+	assert.Equal(t, E.Right[error](15), res)
+}
+
+func TestBracket(t *testing.T) {
+	t.Run("Bracket with success", func(t *testing.T) {
+		var acquired, released bool
+
+		acquire := FromLazy(func() int {
+			acquired = true
+			return 42
+		})
+
+		use := func(x int) ReaderIOResult[int] {
+			return Of(x * 2)
+		}
+
+		release := func(x int, result Either[int]) ReaderIOResult[any] {
+			return FromLazy(func() any {
+				released = true
+				return nil
+			})
+		}
+
+		result := Bracket(acquire, use, release)
+		res := result(context.Background())()
+
+		assert.True(t, acquired)
+		assert.True(t, released)
+		assert.Equal(t, E.Right[error](84), res)
+	})
+
+	t.Run("Bracket with error in use", func(t *testing.T) {
+		var acquired, released bool
+		err := errors.New("use error")
+
+		acquire := FromLazy(func() int {
+			acquired = true
+			return 42
+		})
+
+		use := func(x int) ReaderIOResult[int] {
+			return Left[int](err)
+		}
+
+		release := func(x int, result Either[int]) ReaderIOResult[any] {
+			return FromLazy(func() any {
+				released = true
+				return nil
+			})
+		}
+
+		result := Bracket(acquire, use, release)
+		res := result(context.Background())()
+
+		assert.True(t, acquired)
+		assert.True(t, released)
+		assert.Equal(t, E.Left[int](err), res)
+	})
+}

v2/context/readerioresult/reader_test.go

@@ -13,7 +13,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package readerioeither
+package readerioresult
 
 import (
 	"context"
@@ -143,7 +143,7 @@ func TestCanceledApply(t *testing.T) {
 
 	applied := F.Pipe1(
 		fct,
-		Ap[string, string](errValue),
+		Ap[string](errValue),
 	)
 
 	res := applied(context.Background())()
@@ -156,7 +156,7 @@ func TestRegularApply(t *testing.T) {
 
 	applied := F.Pipe1(
 		fct,
-		Ap[string, string](value),
+		Ap[string](value),
 	)
 
 	res := applied(context.Background())()
@@ -171,14 +171,14 @@ func TestWithResourceNoErrors(t *testing.T) {
 		return countAcquire
 	})
 
-	release := func(int) ReaderIOEither[int] {
+	release := func(int) ReaderIOResult[int] {
 		return FromLazy(func() int {
 			countRelease++
 			return countRelease
 		})
 	}
 
-	body := func(int) ReaderIOEither[int] {
+	body := func(int) ReaderIOResult[int] {
 		return FromLazy(func() int {
 			countBody++
 			return countBody
@@ -203,7 +203,7 @@ func TestWithResourceErrorInBody(t *testing.T) {
 		return countAcquire
 	})
 
-	release := func(int) ReaderIOEither[int] {
+	release := func(int) ReaderIOResult[int] {
 		return FromLazy(func() int {
 			countRelease++
 			return countRelease
@@ -211,7 +211,7 @@ func TestWithResourceErrorInBody(t *testing.T) {
 	}
 
 	err := fmt.Errorf("error in body")
-	body := func(int) ReaderIOEither[int] {
+	body := func(int) ReaderIOResult[int] {
 		return Left[int](err)
 	}
 
@@ -231,14 +231,14 @@ func TestWithResourceErrorInAcquire(t *testing.T) {
 	err := fmt.Errorf("error in acquire")
 	acquire := Left[int](err)
 
-	release := func(int) ReaderIOEither[int] {
+	release := func(int) ReaderIOResult[int] {
 		return FromLazy(func() int {
 			countRelease++
 			return countRelease
 		})
 	}
 
-	body := func(int) ReaderIOEither[int] {
+	body := func(int) ReaderIOResult[int] {
 		return FromLazy(func() int {
 			countBody++
 			return countBody
@@ -264,11 +264,11 @@ func TestWithResourceErrorInRelease(t *testing.T) {
 	})
 
 	err := fmt.Errorf("error in release")
-	release := func(int) ReaderIOEither[int] {
+	release := func(int) ReaderIOResult[int] {
 		return Left[int](err)
 	}
 
-	body := func(int) ReaderIOEither[int] {
+	body := func(int) ReaderIOResult[int] {
 		return FromLazy(func() int {
 			countBody++
 			return countBody

v2/context/readerioresult/resource.go

@@ -13,13 +13,10 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package readerioeither
+package readerioresult
 
 import (
-	"context"
+	RIOR "github.com/IBM/fp-go/v2/readerioresult"
-
-	"github.com/IBM/fp-go/v2/function"
-	RIE "github.com/IBM/fp-go/v2/readerioeither"
 )
 
 // WithResource constructs a function that creates a resource, then operates on it and then releases the resource.
@@ -32,22 +29,22 @@ import (
 //   - onRelease: Releases the resource (always called, even on error)
 //
 // Parameters:
-//   - onCreate: ReaderIOEither that creates the resource
+//   - onCreate: ReaderIOResult that creates the resource
 //   - onRelease: Function to release the resource
 //
-// Returns a function that takes a resource-using function and returns a ReaderIOEither.
+// Returns a function that takes a resource-using function and returns a ReaderIOResult.
 //
 // Example:
 //
 //	file := WithResource(
 //	    openFile("data.txt"),
-//	    func(f *os.File) ReaderIOEither[any] {
+//	    func(f *os.File) ReaderIOResult[any] {
 //	        return TryCatch(func(ctx context.Context) func() (any, error) {
 //	            return func() (any, error) { return nil, f.Close() }
 //	        })
 //	    },
 //	)
-//	result := file(func(f *os.File) ReaderIOEither[string] {
+//	result := file(func(f *os.File) ReaderIOResult[string] {
 //	    return TryCatch(func(ctx context.Context) func() (string, error) {
 //	        return func() (string, error) {
 //	            data, err := io.ReadAll(f)
@@ -55,9 +52,6 @@ import (
 //	        }
 //	    })
 //	})
-func WithResource[A, R, ANY any](onCreate ReaderIOEither[R], onRelease func(R) ReaderIOEither[ANY]) func(func(R) ReaderIOEither[A]) ReaderIOEither[A] {
+func WithResource[A, R, ANY any](onCreate ReaderIOResult[R], onRelease Kleisli[R, ANY]) Kleisli[Kleisli[R, A], A] {
-	return function.Flow2(
+	return RIOR.WithResource[A](onCreate, onRelease)
-		function.Bind2nd(function.Flow2[func(R) ReaderIOEither[A], Operator[A, A], R, ReaderIOEither[A], ReaderIOEither[A]], WithContext[A]),
-		RIE.WithResource[A, context.Context, error, R](WithContext(onCreate), onRelease),
-	)
 }

v2/context/readerioresult/resource_test.go

@@ -13,7 +13,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package readerioeither
+package readerioresult
 
 import (
 	"context"
@@ -37,7 +37,7 @@ var (
 	)
 )
 
-func closeFile(f *os.File) ReaderIOEither[string] {
+func closeFile(f *os.File) ReaderIOResult[string] {
 	return F.Pipe1(
 		TryCatch(func(_ context.Context) func() (string, error) {
 			return func() (string, error) {
@@ -52,7 +52,7 @@ func ExampleWithResource() {
 
 	stringReader := WithResource[string](openFile("data/file.txt"), closeFile)
 
-	rdr := stringReader(func(f *os.File) ReaderIOEither[string] {
+	rdr := stringReader(func(f *os.File) ReaderIOResult[string] {
 		return F.Pipe2(
 			TryCatch(func(_ context.Context) func() ([]byte, error) {
 				return func() ([]byte, error) {

v2/context/readerioresult/semigroup.go

@@ -13,21 +13,21 @@
 //   See the License for the specific language governing permissions and
 //   limitations under the License.
 
-package readerioeither
+package readerioresult
 
 import (
 	"github.com/IBM/fp-go/v2/semigroup"
 )
 
 type (
-	Semigroup[A any] = semigroup.Semigroup[ReaderIOEither[A]]
+	Semigroup[A any] = semigroup.Semigroup[ReaderIOResult[A]]
 )
 
 // AltSemigroup is a [Semigroup] that tries the first item and then the second one using an alternative.
-// This creates a semigroup where combining two ReaderIOEither values means trying the first one,
+// This creates a semigroup where combining two ReaderIOResult values means trying the first one,
 // and if it fails, trying the second one. This is useful for implementing fallback behavior.
 //
-// Returns a Semigroup for ReaderIOEither[A] with Alt-based combination.
+// Returns a Semigroup for ReaderIOResult[A] with Alt-based combination.
 //
 // Example:
 //

v2/context/readerioresult/sync.go

@@ -13,7 +13,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package readerioeither
+package readerioresult
 
 import (
 	"context"
@@ -29,9 +29,9 @@ import (
 // The lock parameter should return a CancelFunc that releases the lock when called.
 //
 // Parameters:
-//   - lock: ReaderIOEither that acquires a lock and returns a CancelFunc to release it
+//   - lock: ReaderIOResult that acquires a lock and returns a CancelFunc to release it
 //
-// Returns a function that wraps a ReaderIOEither with lock protection.
+// Returns a function that wraps a ReaderIOResult with lock protection.
 //
 // Example:
 //
@@ -43,9 +43,9 @@ import (
 //	    }
 //	})
 //	protectedOp := WithLock(lock)(myOperation)
-func WithLock[A any](lock ReaderIOEither[context.CancelFunc]) Operator[A, A] {
+func WithLock[A any](lock ReaderIOResult[context.CancelFunc]) Operator[A, A] {
 	return function.Flow2(
-		function.Constant1[context.CancelFunc, ReaderIOEither[A]],
+		function.Constant1[context.CancelFunc, ReaderIOResult[A]],
 		WithResource[A](lock, function.Flow2(
 			io.FromImpure[context.CancelFunc],
 			FromIO[any],

v2/context/readerioresult/traverse.go

@@ -0,0 +1,306 @@
+// 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 readerioresult
+
+import (
+	"github.com/IBM/fp-go/v2/function"
+	"github.com/IBM/fp-go/v2/internal/array"
+	"github.com/IBM/fp-go/v2/internal/record"
+)
+
+// TraverseArray transforms an array [[]A] into [[]ReaderIOResult[B]] and then resolves that into a [ReaderIOResult[[]B]].
+// This uses the default applicative behavior (parallel or sequential based on useParallel flag).
+//
+// Parameters:
+//   - f: Function that transforms each element into a ReaderIOResult
+//
+// Returns a function that transforms an array into a ReaderIOResult of an array.
+func TraverseArray[A, B any](f Kleisli[A, B]) Kleisli[[]A, []B] {
+	return array.Traverse[[]A](
+		Of[[]B],
+		Map[[]B, func(B) []B],
+		Ap[[]B, B],
+
+		f,
+	)
+}
+
+// TraverseArrayWithIndex transforms an array [[]A] into [[]ReaderIOResult[B]] and then resolves that into a [ReaderIOResult[[]B]].
+// The transformation function receives both the index and the element.
+//
+// Parameters:
+//   - f: Function that transforms each element with its index into a ReaderIOResult
+//
+// Returns a function that transforms an array into a ReaderIOResult of an array.
+func TraverseArrayWithIndex[A, B any](f func(int, A) ReaderIOResult[B]) Kleisli[[]A, []B] {
+	return array.TraverseWithIndex[[]A](
+		Of[[]B],
+		Map[[]B, func(B) []B],
+		Ap[[]B, B],
+
+		f,
+	)
+}
+
+// SequenceArray converts a homogeneous sequence of ReaderIOResult into a ReaderIOResult of sequence.
+// This is equivalent to TraverseArray with the identity function.
+//
+// Parameters:
+//   - ma: Array of ReaderIOResult values
+//
+// Returns a ReaderIOResult containing an array of values.
+func SequenceArray[A any](ma []ReaderIOResult[A]) ReaderIOResult[[]A] {
+	return TraverseArray(function.Identity[ReaderIOResult[A]])(ma)
+}
+
+// TraverseRecord transforms a record [map[K]A] into [map[K]ReaderIOResult[B]] and then resolves that into a [ReaderIOResult[map[K]B]].
+//
+// Parameters:
+//   - f: Function that transforms each value into a ReaderIOResult
+//
+// Returns a function that transforms a map into a ReaderIOResult of a map.
+func TraverseRecord[K comparable, A, B any](f Kleisli[A, B]) Kleisli[map[K]A, map[K]B] {
+	return record.Traverse[map[K]A](
+		Of[map[K]B],
+		Map[map[K]B, func(B) map[K]B],
+		Ap[map[K]B, B],
+
+		f,
+	)
+}
+
+// TraverseRecordWithIndex transforms a record [map[K]A] into [map[K]ReaderIOResult[B]] and then resolves that into a [ReaderIOResult[map[K]B]].
+// The transformation function receives both the key and the value.
+//
+// Parameters:
+//   - f: Function that transforms each key-value pair into a ReaderIOResult
+//
+// Returns a function that transforms a map into a ReaderIOResult of a map.
+func TraverseRecordWithIndex[K comparable, A, B any](f func(K, A) ReaderIOResult[B]) Kleisli[map[K]A, map[K]B] {
+	return record.TraverseWithIndex[map[K]A](
+		Of[map[K]B],
+		Map[map[K]B, func(B) map[K]B],
+		Ap[map[K]B, B],
+
+		f,
+	)
+}
+
+// SequenceRecord converts a homogeneous map of ReaderIOResult into a ReaderIOResult of map.
+//
+// Parameters:
+//   - ma: Map of ReaderIOResult values
+//
+// Returns a ReaderIOResult containing a map of values.
+func SequenceRecord[K comparable, A any](ma map[K]ReaderIOResult[A]) ReaderIOResult[map[K]A] {
+	return TraverseRecord[K](function.Identity[ReaderIOResult[A]])(ma)
+}
+
+// MonadTraverseArraySeq transforms an array [[]A] into [[]ReaderIOResult[B]] and then resolves that into a [ReaderIOResult[[]B]].
+// This explicitly uses sequential execution.
+//
+// Parameters:
+//   - as: The array to traverse
+//   - f: Function that transforms each element into a ReaderIOResult
+//
+// Returns a ReaderIOResult containing an array of transformed values.
+func MonadTraverseArraySeq[A, B any](as []A, f Kleisli[A, B]) ReaderIOResult[[]B] {
+	return array.MonadTraverse(
+		Of[[]B],
+		Map[[]B, func(B) []B],
+		ApSeq[[]B, B],
+		as,
+		f,
+	)
+}
+
+// TraverseArraySeq transforms an array [[]A] into [[]ReaderIOResult[B]] and then resolves that into a [ReaderIOResult[[]B]].
+// This is the curried version of [MonadTraverseArraySeq] with sequential execution.
+//
+// Parameters:
+//   - f: Function that transforms each element into a ReaderIOResult
+//
+// Returns a function that transforms an array into a ReaderIOResult of an array.
+func TraverseArraySeq[A, B any](f Kleisli[A, B]) Kleisli[[]A, []B] {
+	return array.Traverse[[]A](
+		Of[[]B],
+		Map[[]B, func(B) []B],
+		ApSeq[[]B, B],
+
+		f,
+	)
+}
+
+// TraverseArrayWithIndexSeq uses transforms an array [[]A] into [[]ReaderIOResult[B]] and then resolves that into a [ReaderIOResult[[]B]]
+func TraverseArrayWithIndexSeq[A, B any](f func(int, A) ReaderIOResult[B]) Kleisli[[]A, []B] {
+	return array.TraverseWithIndex[[]A](
+		Of[[]B],
+		Map[[]B, func(B) []B],
+		ApSeq[[]B, B],
+
+		f,
+	)
+}
+
+// SequenceArraySeq converts a homogeneous sequence of ReaderIOResult into a ReaderIOResult of sequence.
+// This explicitly uses sequential execution.
+//
+// Parameters:
+//   - ma: Array of ReaderIOResult values
+//
+// Returns a ReaderIOResult containing an array of values.
+func SequenceArraySeq[A any](ma []ReaderIOResult[A]) ReaderIOResult[[]A] {
+	return MonadTraverseArraySeq(ma, function.Identity[ReaderIOResult[A]])
+}
+
+// MonadTraverseRecordSeq uses transforms a record [map[K]A] into [map[K]ReaderIOResult[B]] and then resolves that into a [ReaderIOResult[map[K]B]]
+func MonadTraverseRecordSeq[K comparable, A, B any](as map[K]A, f Kleisli[A, B]) ReaderIOResult[map[K]B] {
+	return record.MonadTraverse(
+		Of[map[K]B],
+		Map[map[K]B, func(B) map[K]B],
+		ApSeq[map[K]B, B],
+		as,
+		f,
+	)
+}
+
+// TraverseRecordSeq uses transforms a record [map[K]A] into [map[K]ReaderIOResult[B]] and then resolves that into a [ReaderIOResult[map[K]B]]
+func TraverseRecordSeq[K comparable, A, B any](f Kleisli[A, B]) Kleisli[map[K]A, map[K]B] {
+	return record.Traverse[map[K]A](
+		Of[map[K]B],
+		Map[map[K]B, func(B) map[K]B],
+		ApSeq[map[K]B, B],
+
+		f,
+	)
+}
+
+// TraverseRecordWithIndexSeq uses transforms a record [map[K]A] into [map[K]ReaderIOResult[B]] and then resolves that into a [ReaderIOResult[map[K]B]]
+func TraverseRecordWithIndexSeq[K comparable, A, B any](f func(K, A) ReaderIOResult[B]) Kleisli[map[K]A, map[K]B] {
+	return record.TraverseWithIndex[map[K]A](
+		Of[map[K]B],
+		Map[map[K]B, func(B) map[K]B],
+		ApSeq[map[K]B, B],
+
+		f,
+	)
+}
+
+// SequenceRecordSeq converts a homogeneous sequence of either into an either of sequence
+func SequenceRecordSeq[K comparable, A any](ma map[K]ReaderIOResult[A]) ReaderIOResult[map[K]A] {
+	return MonadTraverseRecordSeq(ma, function.Identity[ReaderIOResult[A]])
+}
+
+// MonadTraverseArrayPar transforms an array [[]A] into [[]ReaderIOResult[B]] and then resolves that into a [ReaderIOResult[[]B]].
+// This explicitly uses parallel execution.
+//
+// Parameters:
+//   - as: The array to traverse
+//   - f: Function that transforms each element into a ReaderIOResult
+//
+// Returns a ReaderIOResult containing an array of transformed values.
+func MonadTraverseArrayPar[A, B any](as []A, f Kleisli[A, B]) ReaderIOResult[[]B] {
+	return array.MonadTraverse(
+		Of[[]B],
+		Map[[]B, func(B) []B],
+		ApPar[[]B, B],
+		as,
+		f,
+	)
+}
+
+// TraverseArrayPar transforms an array [[]A] into [[]ReaderIOResult[B]] and then resolves that into a [ReaderIOResult[[]B]].
+// This is the curried version of [MonadTraverseArrayPar] with parallel execution.
+//
+// Parameters:
+//   - f: Function that transforms each element into a ReaderIOResult
+//
+// Returns a function that transforms an array into a ReaderIOResult of an array.
+func TraverseArrayPar[A, B any](f Kleisli[A, B]) Kleisli[[]A, []B] {
+	return array.Traverse[[]A](
+		Of[[]B],
+		Map[[]B, func(B) []B],
+		ApPar[[]B, B],
+
+		f,
+	)
+}
+
+// TraverseArrayWithIndexPar uses transforms an array [[]A] into [[]ReaderIOResult[B]] and then resolves that into a [ReaderIOResult[[]B]]
+func TraverseArrayWithIndexPar[A, B any](f func(int, A) ReaderIOResult[B]) Kleisli[[]A, []B] {
+	return array.TraverseWithIndex[[]A](
+		Of[[]B],
+		Map[[]B, func(B) []B],
+		ApPar[[]B, B],
+
+		f,
+	)
+}
+
+// SequenceArrayPar converts a homogeneous sequence of ReaderIOResult into a ReaderIOResult of sequence.
+// This explicitly uses parallel execution.
+//
+// Parameters:
+//   - ma: Array of ReaderIOResult values
+//
+// Returns a ReaderIOResult containing an array of values.
+func SequenceArrayPar[A any](ma []ReaderIOResult[A]) ReaderIOResult[[]A] {
+	return MonadTraverseArrayPar(ma, function.Identity[ReaderIOResult[A]])
+}
+
+// TraverseRecordPar uses transforms a record [map[K]A] into [map[K]ReaderIOResult[B]] and then resolves that into a [ReaderIOResult[map[K]B]]
+func TraverseRecordPar[K comparable, A, B any](f Kleisli[A, B]) Kleisli[map[K]A, map[K]B] {
+	return record.Traverse[map[K]A](
+		Of[map[K]B],
+		Map[map[K]B, func(B) map[K]B],
+		ApPar[map[K]B, B],
+
+		f,
+	)
+}
+
+// TraverseRecordWithIndexPar uses transforms a record [map[K]A] into [map[K]ReaderIOResult[B]] and then resolves that into a [ReaderIOResult[map[K]B]]
+func TraverseRecordWithIndexPar[K comparable, A, B any](f func(K, A) ReaderIOResult[B]) Kleisli[map[K]A, map[K]B] {
+	return record.TraverseWithIndex[map[K]A](
+		Of[map[K]B],
+		Map[map[K]B, func(B) map[K]B],
+		ApPar[map[K]B, B],
+
+		f,
+	)
+}
+
+// MonadTraverseRecordPar uses transforms a record [map[K]A] into [map[K]ReaderIOResult[B]] and then resolves that into a [ReaderIOResult[map[K]B]]
+func MonadTraverseRecordPar[K comparable, A, B any](as map[K]A, f Kleisli[A, B]) ReaderIOResult[map[K]B] {
+	return record.MonadTraverse(
+		Of[map[K]B],
+		Map[map[K]B, func(B) map[K]B],
+		ApPar[map[K]B, B],
+		as,
+		f,
+	)
+}
+
+// SequenceRecordPar converts a homogeneous map of ReaderIOResult into a ReaderIOResult of map.
+// This explicitly uses parallel execution.
+//
+// Parameters:
+//   - ma: Map of ReaderIOResult values
+//
+// Returns a ReaderIOResult containing a map of values.
+func SequenceRecordPar[K comparable, A any](ma map[K]ReaderIOResult[A]) ReaderIOResult[map[K]A] {
+	return MonadTraverseRecordPar(ma, function.Identity[ReaderIOResult[A]])
+}

v2/context/readerioresult/type.go

@@ -13,19 +13,24 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package readerioeither
+package readerioresult
 
 import (
 	"context"
 
+	"github.com/IBM/fp-go/v2/context/ioresult"
+	"github.com/IBM/fp-go/v2/context/readerresult"
 	"github.com/IBM/fp-go/v2/either"
 	"github.com/IBM/fp-go/v2/io"
 	"github.com/IBM/fp-go/v2/ioeither"
 	"github.com/IBM/fp-go/v2/lazy"
 	"github.com/IBM/fp-go/v2/option"
 	"github.com/IBM/fp-go/v2/reader"
+	"github.com/IBM/fp-go/v2/readereither"
 	"github.com/IBM/fp-go/v2/readerio"
-	"github.com/IBM/fp-go/v2/readerioeither"
+	RIOR "github.com/IBM/fp-go/v2/readerioresult"
+	"github.com/IBM/fp-go/v2/readeroption"
+	"github.com/IBM/fp-go/v2/result"
 )
 
 type (
@@ -40,6 +45,8 @@ type (
 	// Either[A] is equivalent to Either[error, A] from the either package.
 	Either[A any] = either.Either[error, A]
 
+	Result[A any] = result.Result[A]
+
 	// Lazy represents a deferred computation that produces a value of type A when executed.
 	// The computation is not executed until explicitly invoked.
 	Lazy[A any] = lazy.Lazy[A]
@@ -56,6 +63,8 @@ type (
 	// IOEither[A] is equivalent to func() Either[error, A]
 	IOEither[A any] = ioeither.IOEither[error, A]
 
+	IOResult[A any] = ioresult.IOResult[A]
+
 	// Reader represents a computation that depends on a context of type R.
 	// This is used for dependency injection and accessing shared context.
 	//
@@ -68,21 +77,21 @@ type (
 	// ReaderIO[A] is equivalent to func(context.Context) func() A
 	ReaderIO[A any] = readerio.ReaderIO[context.Context, A]
 
-	// ReaderIOEither is the main type of this package. It represents a computation that:
+	// ReaderIOResult is the main type of this package. It represents a computation that:
 	//   - Depends on a [context.Context] (Reader aspect)
 	//   - Performs side effects (IO aspect)
 	//   - Can fail with an [error] (Either aspect)
 	//   - Produces a value of type A on success
 	//
-	// This is a specialization of [readerioeither.ReaderIOEither] with:
+	// This is a specialization of [readerioeither.ReaderIOResult] with:
 	//   - Context type fixed to [context.Context]
 	//   - Error type fixed to [error]
 	//
 	// The type is defined as:
-	//   ReaderIOEither[A] = func(context.Context) func() Either[error, A]
+	//   ReaderIOResult[A] = func(context.Context) func() Either[error, A]
 	//
 	// Example usage:
-	//   func fetchUser(id string) ReaderIOEither[User] {
+	//   func fetchUser(id string) ReaderIOResult[User] {
 	//       return func(ctx context.Context) func() Either[error, User] {
 	//           return func() Either[error, User] {
 	//               user, err := userService.Get(ctx, id)
@@ -97,12 +106,14 @@ type (
 	// The computation is executed by providing a context and then invoking the result:
 	//   ctx := context.Background()
 	//   result := fetchUser("123")(ctx)()
-	ReaderIOEither[A any] = readerioeither.ReaderIOEither[context.Context, error, A]
+	ReaderIOResult[A any] = RIOR.ReaderIOResult[context.Context, A]
 
-	// Operator represents a transformation from one ReaderIOEither to another.
+	Kleisli[A, B any] = reader.Reader[A, ReaderIOResult[B]]
+
+	// Operator represents a transformation from one ReaderIOResult to another.
 	// This is useful for point-free style composition and building reusable transformations.
 	//
-	// Operator[A, B] is equivalent to func(ReaderIOEither[A]) ReaderIOEither[B]
+	// Operator[A, B] is equivalent to Kleisli[ReaderIOResult[A], B]
 	//
 	// Example usage:
 	//   // Define a reusable transformation
@@ -110,5 +121,9 @@ type (
 	//
 	//   // Apply the transformation
 	//   result := toUpper(computation)
-	Operator[A, B any] = Reader[ReaderIOEither[A], ReaderIOEither[B]]
+	Operator[A, B any] = Kleisli[ReaderIOResult[A], B]
+
+	ReaderResult[A any]       = readerresult.ReaderResult[A]
+	ReaderEither[R, E, A any] = readereither.ReaderEither[R, E, A]
+	ReaderOption[R, A any]    = readeroption.ReaderOption[R, A]
 )

v2/context/readerresult/array.go

@@ -13,21 +13,21 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package readereither
+package readerresult
 
 import "github.com/IBM/fp-go/v2/readereither"
 
 // TraverseArray transforms an array
-func TraverseArray[A, B any](f func(A) ReaderEither[B]) func([]A) ReaderEither[[]B] {
+func TraverseArray[A, B any](f Kleisli[A, B]) Kleisli[[]A, []B] {
 	return readereither.TraverseArray(f)
 }
 
 // TraverseArrayWithIndex transforms an array
-func TraverseArrayWithIndex[A, B any](f func(int, A) ReaderEither[B]) func([]A) ReaderEither[[]B] {
+func TraverseArrayWithIndex[A, B any](f func(int, A) ReaderResult[B]) Kleisli[[]A, []B] {
 	return readereither.TraverseArrayWithIndex(f)
 }
 
 // SequenceArray converts a homogeneous sequence of either into an either of sequence
-func SequenceArray[A any](ma []ReaderEither[A]) ReaderEither[[]A] {
+func SequenceArray[A any](ma []ReaderResult[A]) ReaderResult[[]A] {
 	return readereither.SequenceArray(ma)
 }

v2/context/readerresult/bind.go

@@ -0,0 +1,304 @@
+// 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 (
+	F "github.com/IBM/fp-go/v2/function"
+	L "github.com/IBM/fp-go/v2/optics/lens"
+	G "github.com/IBM/fp-go/v2/readereither/generic"
+)
+
+// 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.
+//
+// Example:
+//
+//	type State struct {
+//	    UserID   string
+//	    TenantID string
+//	}
+//	result := readereither.Do(State{})
+func Do[S any](
+	empty S,
+) ReaderResult[S] {
+	return G.Do[ReaderResult[S]](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 the context.Context from the environment.
+//
+// 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 {
+//	    UserID   string
+//	    TenantID string
+//	}
+//
+//	result := F.Pipe2(
+//	    readereither.Do(State{}),
+//	    readereither.Bind(
+//	        func(uid string) func(State) State {
+//	            return func(s State) State { s.UserID = uid; return s }
+//	        },
+//	        func(s State) readereither.ReaderResult[string] {
+//	            return func(ctx context.Context) either.Either[error, string] {
+//	                if uid, ok := ctx.Value("userID").(string); ok {
+//	                    return either.Right[error](uid)
+//	                }
+//	                return either.Left[string](errors.New("no userID"))
+//	            }
+//	        },
+//	    ),
+//	    readereither.Bind(
+//	        func(tid string) func(State) State {
+//	            return func(s State) State { s.TenantID = tid; return s }
+//	        },
+//	        func(s State) readereither.ReaderResult[string] {
+//	            // This can access s.UserID from the previous step
+//	            return func(ctx context.Context) either.Either[error, string] {
+//	                return either.Right[error]("tenant-" + s.UserID)
+//	            }
+//	        },
+//	    ),
+//	)
+func Bind[S1, S2, T any](
+	setter func(T) func(S1) S2,
+	f Kleisli[S1, T],
+) Kleisli[ReaderResult[S1], S2] {
+	return G.Bind[ReaderResult[S1], ReaderResult[S2]](setter, f)
+}
+
+// Let attaches the result of a computation to a context [S1] to produce a context [S2]
+func Let[S1, S2, T any](
+	setter func(T) func(S1) S2,
+	f func(S1) T,
+) Kleisli[ReaderResult[S1], S2] {
+	return G.Let[ReaderResult[S1], ReaderResult[S2]](setter, f)
+}
+
+// LetTo attaches the a value to a context [S1] to produce a context [S2]
+func LetTo[S1, S2, T any](
+	setter func(T) func(S1) S2,
+	b T,
+) Kleisli[ReaderResult[S1], S2] {
+	return G.LetTo[ReaderResult[S1], ReaderResult[S2]](setter, b)
+}
+
+// BindTo initializes a new state [S1] from a value [T]
+func BindTo[S1, T any](
+	setter func(T) S1,
+) Kleisli[ReaderResult[T], S1] {
+	return G.BindTo[ReaderResult[S1], ReaderResult[T]](setter)
+}
+
+// ApS attaches a value to a context [S1] to produce a context [S2] by considering
+// the context and the value concurrently (using Applicative rather than Monad).
+// This allows independent computations to be combined without one depending on the result of the other.
+//
+// Unlike Bind, which sequences operations, ApS can be used when operations are independent
+// and can conceptually run in parallel.
+//
+// Example:
+//
+//	type State struct {
+//	    UserID   string
+//	    TenantID string
+//	}
+//
+//	// These operations are independent and can be combined with ApS
+//	getUserID := func(ctx context.Context) either.Either[error, string] {
+//	    return either.Right[error](ctx.Value("userID").(string))
+//	}
+//	getTenantID := func(ctx context.Context) either.Either[error, string] {
+//	    return either.Right[error](ctx.Value("tenantID").(string))
+//	}
+//
+//	result := F.Pipe2(
+//	    readereither.Do(State{}),
+//	    readereither.ApS(
+//	        func(uid string) func(State) State {
+//	            return func(s State) State { s.UserID = uid; return s }
+//	        },
+//	        getUserID,
+//	    ),
+//	    readereither.ApS(
+//	        func(tid string) func(State) State {
+//	            return func(s State) State { s.TenantID = tid; return s }
+//	        },
+//	        getTenantID,
+//	    ),
+//	)
+func ApS[S1, S2, T any](
+	setter func(T) func(S1) S2,
+	fa ReaderResult[T],
+) Kleisli[ReaderResult[S1], S2] {
+	return G.ApS[ReaderResult[S1], ReaderResult[S2]](setter, fa)
+}
+
+// ApSL is a variant of ApS that uses a lens to focus on a specific field in the state.
+// Instead of providing a setter function, you provide a lens that knows how to get and set
+// the field. This is more convenient when working with nested structures.
+//
+// Parameters:
+//   - lens: A lens that focuses on a field of type T within state S
+//   - fa: A ReaderResult computation that produces a value of type T
+//
+// Returns:
+//   - A function that transforms ReaderResult[S] to ReaderResult[S] by setting the focused field
+//
+// Example:
+//
+//	type Person struct {
+//	    Name string
+//	    Age  int
+//	}
+//
+//	ageLens := lens.MakeLens(
+//	    func(p Person) int { return p.Age },
+//	    func(p Person, a int) Person { p.Age = a; return p },
+//	)
+//
+//	getAge := func(ctx context.Context) either.Either[error, int] {
+//	    return either.Right[error](30)
+//	}
+//
+//	result := F.Pipe1(
+//	    readereither.Do(Person{Name: "Alice", Age: 25}),
+//	    readereither.ApSL(ageLens, getAge),
+//	)
+func ApSL[S, T any](
+	lens L.Lens[S, T],
+	fa ReaderResult[T],
+) Kleisli[ReaderResult[S], S] {
+	return ApS(lens.Set, fa)
+}
+
+// BindL is a variant of Bind that uses a lens to focus on a specific field in the state.
+// It combines the lens-based field access with monadic composition, allowing you to:
+// 1. Extract a field value using the lens
+// 2. Use that value in a computation that may fail
+// 3. Update the field with the result
+//
+// Parameters:
+//   - lens: A lens that focuses on a field of type T within state S
+//   - f: A function that takes the current field value and returns a ReaderResult computation
+//
+// Returns:
+//   - A function that transforms ReaderResult[S] to ReaderResult[S]
+//
+// Example:
+//
+//	type Counter struct {
+//	    Value int
+//	}
+//
+//	valueLens := lens.MakeLens(
+//	    func(c Counter) int { return c.Value },
+//	    func(c Counter, v int) Counter { c.Value = v; return c },
+//	)
+//
+//	increment := func(v int) readereither.ReaderResult[int] {
+//	    return func(ctx context.Context) either.Either[error, int] {
+//	        if v >= 100 {
+//	            return either.Left[int](errors.New("value too large"))
+//	        }
+//	        return either.Right[error](v + 1)
+//	    }
+//	}
+//
+//	result := F.Pipe1(
+//	    readereither.Of[error](Counter{Value: 42}),
+//	    readereither.BindL(valueLens, increment),
+//	)
+func BindL[S, T any](
+	lens L.Lens[S, T],
+	f Kleisli[T, T],
+) Kleisli[ReaderResult[S], S] {
+	return Bind(lens.Set, F.Flow2(lens.Get, f))
+}
+
+// LetL is a variant of Let that uses a lens to focus on a specific field in the state.
+// It applies a pure transformation to the focused field without any effects.
+//
+// Parameters:
+//   - lens: A lens that focuses on a field of type T within state S
+//   - f: A pure function that transforms the field value
+//
+// Returns:
+//   - A function that transforms ReaderResult[S] to ReaderResult[S]
+//
+// Example:
+//
+//	type Counter struct {
+//	    Value int
+//	}
+//
+//	valueLens := lens.MakeLens(
+//	    func(c Counter) int { return c.Value },
+//	    func(c Counter, v int) Counter { c.Value = v; return c },
+//	)
+//
+//	double := func(v int) int { return v * 2 }
+//
+//	result := F.Pipe1(
+//	    readereither.Of[error](Counter{Value: 21}),
+//	    readereither.LetL(valueLens, double),
+//	)
+//	// result when executed will be Right(Counter{Value: 42})
+func LetL[S, T any](
+	lens L.Lens[S, T],
+	f func(T) T,
+) Kleisli[ReaderResult[S], S] {
+	return Let(lens.Set, F.Flow2(lens.Get, f))
+}
+
+// LetToL is a variant of LetTo that uses a lens to focus on a specific field in the state.
+// It sets the focused field to a constant value.
+//
+// Parameters:
+//   - lens: A lens that focuses on a field of type T within state S
+//   - b: The constant value to set
+//
+// Returns:
+//   - A function that transforms ReaderResult[S] to ReaderResult[S]
+//
+// Example:
+//
+//	type Config struct {
+//	    Debug   bool
+//	    Timeout int
+//	}
+//
+//	debugLens := lens.MakeLens(
+//	    func(c Config) bool { return c.Debug },
+//	    func(c Config, d bool) Config { c.Debug = d; return c },
+//	)
+//
+//	result := F.Pipe1(
+//	    readereither.Of[error](Config{Debug: true, Timeout: 30}),
+//	    readereither.LetToL(debugLens, false),
+//	)
+//	// result when executed will be Right(Config{Debug: false, Timeout: 30})
+func LetToL[S, T any](
+	lens L.Lens[S, T],
+	b T,
+) Kleisli[ReaderResult[S], S] {
+	return LetTo(lens.Set, b)
+}

v2/context/readerresult/bind_test.go

@@ -13,7 +13,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package readereither
+package readerresult
 
 import (
 	"context"
@@ -25,11 +25,11 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-func getLastName(s utils.Initial) ReaderEither[string] {
+func getLastName(s utils.Initial) ReaderResult[string] {
 	return Of("Doe")
 }
 
-func getGivenName(s utils.WithLastName) ReaderEither[string] {
+func getGivenName(s utils.WithLastName) ReaderResult[string] {
 	return Of("John")
 }
 

v2/context/readerresult/cancel.go

@@ -13,7 +13,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package readereither
+package readerresult
 
 import (
 	"context"
@@ -21,8 +21,8 @@ import (
 	E "github.com/IBM/fp-go/v2/either"
 )
 
-// withContext wraps an existing ReaderEither and performs a context check for cancellation before deletating
+// withContext wraps an existing ReaderResult and performs a context check for cancellation before deletating
-func WithContext[A any](ma ReaderEither[A]) ReaderEither[A] {
+func WithContext[A any](ma ReaderResult[A]) ReaderResult[A] {
 	return func(ctx context.Context) E.Either[error, A] {
 		if err := context.Cause(ctx); err != nil {
 			return E.Left[A](err)

v2/context/readerresult/curry.go

@@ -13,7 +13,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package readereither
+package readerresult
 
 import (
 	"context"
@@ -24,30 +24,30 @@ import (
 // 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
 
-func Curry0[A any](f func(context.Context) (A, error)) ReaderEither[A] {
+func Curry0[A any](f func(context.Context) (A, error)) ReaderResult[A] {
 	return readereither.Curry0(f)
 }
 
-func Curry1[T1, A any](f func(context.Context, T1) (A, error)) func(T1) ReaderEither[A] {
+func Curry1[T1, A any](f func(context.Context, T1) (A, error)) Kleisli[T1, A] {
 	return readereither.Curry1(f)
 }
 
-func Curry2[T1, T2, A any](f func(context.Context, T1, T2) (A, error)) func(T1) func(T2) ReaderEither[A] {
+func Curry2[T1, T2, A any](f func(context.Context, T1, T2) (A, error)) func(T1) Kleisli[T2, A] {
 	return readereither.Curry2(f)
 }
 
-func Curry3[T1, T2, T3, A any](f func(context.Context, T1, T2, T3) (A, error)) func(T1) func(T2) func(T3) ReaderEither[A] {
+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)
 }
 
-func Uncurry1[T1, A any](f func(T1) ReaderEither[A]) func(context.Context, T1) (A, error) {
+func Uncurry1[T1, A any](f Kleisli[T1, A]) func(context.Context, T1) (A, error) {
 	return readereither.Uncurry1(f)
 }
 
-func Uncurry2[T1, T2, A any](f func(T1) func(T2) ReaderEither[A]) func(context.Context, T1, T2) (A, error) {
+func Uncurry2[T1, T2, A any](f func(T1) Kleisli[T2, A]) func(context.Context, T1, T2) (A, error) {
 	return readereither.Uncurry2(f)
 }
 
-func Uncurry3[T1, T2, T3, A any](f func(T1) func(T2) func(T3) ReaderEither[A]) func(context.Context, T1, T2, T3) (A, error) {
+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/exec/exec.go

@@ -18,11 +18,10 @@ package exec
 import (
 	"context"
 
-	"github.com/IBM/fp-go/v2/context/readereither"
-	"github.com/IBM/fp-go/v2/either"
 	"github.com/IBM/fp-go/v2/exec"
 	"github.com/IBM/fp-go/v2/function"
 	INTE "github.com/IBM/fp-go/v2/internal/exec"
+	"github.com/IBM/fp-go/v2/result"
 )
 
 var (
@@ -32,8 +31,8 @@ var (
 	Command = function.Curry3(command)
 )
 
-func command(name string, args []string, in []byte) readereither.ReaderEither[exec.CommandOutput] {
+func command(name string, args []string, in []byte) ReaderResult[exec.CommandOutput] {
-	return func(ctx context.Context) either.Either[error, exec.CommandOutput] {
+	return func(ctx context.Context) Result[exec.CommandOutput] {
-		return either.TryCatchError(INTE.Exec(ctx, name, args, in))
+		return result.TryCatchError(INTE.Exec(ctx, name, args, in))
 	}
 }

v2/context/readerresult/exec/type.go

@@ -0,0 +1,27 @@
+// 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 implements a specialization of the Reader monad assuming a golang context as the context of the monad and a standard golang error
+package exec
+
+import (
+	"github.com/IBM/fp-go/v2/context/readerresult"
+	"github.com/IBM/fp-go/v2/result"
+)
+
+type (
+	Result[T any]       = result.Result[T]
+	ReaderResult[T any] = readerresult.ReaderResult[T]
+)

v2/context/readerresult/from.go

@@ -13,7 +13,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package readereither
+package readerresult
 
 import (
 	"context"
@@ -24,18 +24,18 @@ import (
 // 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
 
-func From0[A any](f func(context.Context) (A, error)) func() ReaderEither[A] {
+func From0[A any](f func(context.Context) (A, error)) func() ReaderResult[A] {
 	return readereither.From0(f)
 }
 
-func From1[T1, A any](f func(context.Context, T1) (A, error)) func(T1) ReaderEither[A] {
+func From1[T1, A any](f func(context.Context, T1) (A, error)) Kleisli[T1, A] {
 	return readereither.From1(f)
 }
 
-func From2[T1, T2, A any](f func(context.Context, T1, T2) (A, error)) func(T1, T2) ReaderEither[A] {
+func From2[T1, T2, A any](f func(context.Context, T1, T2) (A, error)) func(T1, T2) ReaderResult[A] {
 	return readereither.From2(f)
 }
 
-func From3[T1, T2, T3, A any](f func(context.Context, T1, T2, T3) (A, error)) func(T1, T2, T3) ReaderEither[A] {
+func From3[T1, T2, T3, A any](f func(context.Context, T1, T2, T3) (A, error)) func(T1, T2, T3) ReaderResult[A] {
 	return readereither.From3(f)
 }

v2/context/readerresult/reader.go

@@ -13,7 +13,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package readereither
+package readerresult
 
 import (
 	"context"
@@ -21,19 +21,19 @@ import (
 	"github.com/IBM/fp-go/v2/readereither"
 )
 
-func FromEither[A any](e Either[A]) ReaderEither[A] {
+func FromEither[A any](e Either[A]) ReaderResult[A] {
 	return readereither.FromEither[context.Context](e)
 }
 
-func Left[A any](l error) ReaderEither[A] {
+func Left[A any](l error) ReaderResult[A] {
 	return readereither.Left[context.Context, A](l)
 }
 
-func Right[A any](r A) ReaderEither[A] {
+func Right[A any](r A) ReaderResult[A] {
 	return readereither.Right[context.Context, error](r)
 }
 
-func MonadMap[A, B any](fa ReaderEither[A], f func(A) B) ReaderEither[B] {
+func MonadMap[A, B any](fa ReaderResult[A], f func(A) B) ReaderResult[B] {
 	return readereither.MonadMap(fa, f)
 }
 
@@ -41,43 +41,43 @@ func Map[A, B any](f func(A) B) Operator[A, B] {
 	return readereither.Map[context.Context, error](f)
 }
 
-func MonadChain[A, B any](ma ReaderEither[A], f func(A) ReaderEither[B]) ReaderEither[B] {
+func MonadChain[A, B any](ma ReaderResult[A], f Kleisli[A, B]) ReaderResult[B] {
 	return readereither.MonadChain(ma, f)
 }
 
-func Chain[A, B any](f func(A) ReaderEither[B]) Operator[A, B] {
+func Chain[A, B any](f Kleisli[A, B]) Operator[A, B] {
 	return readereither.Chain(f)
 }
 
-func Of[A any](a A) ReaderEither[A] {
+func Of[A any](a A) ReaderResult[A] {
 	return readereither.Of[context.Context, error](a)
 }
 
-func MonadAp[A, B any](fab ReaderEither[func(A) B], fa ReaderEither[A]) ReaderEither[B] {
+func MonadAp[A, B any](fab ReaderResult[func(A) B], fa ReaderResult[A]) ReaderResult[B] {
 	return readereither.MonadAp(fab, fa)
 }
 
-func Ap[A, B any](fa ReaderEither[A]) func(ReaderEither[func(A) B]) ReaderEither[B] {
+func Ap[A, B any](fa ReaderResult[A]) func(ReaderResult[func(A) B]) ReaderResult[B] {
 	return readereither.Ap[B](fa)
 }
 
-func FromPredicate[A any](pred func(A) bool, onFalse func(A) error) func(A) ReaderEither[A] {
+func FromPredicate[A any](pred func(A) bool, onFalse func(A) error) Kleisli[A, A] {
 	return readereither.FromPredicate[context.Context](pred, onFalse)
 }
 
-func OrElse[A any](onLeft func(error) ReaderEither[A]) func(ReaderEither[A]) ReaderEither[A] {
+func OrElse[A any](onLeft Kleisli[error, A]) Kleisli[ReaderResult[A], A] {
 	return readereither.OrElse(onLeft)
 }
 
-func Ask() ReaderEither[context.Context] {
+func Ask() ReaderResult[context.Context] {
 	return readereither.Ask[context.Context, error]()
 }
 
-func MonadChainEitherK[A, B any](ma ReaderEither[A], f func(A) Either[B]) ReaderEither[B] {
+func MonadChainEitherK[A, B any](ma ReaderResult[A], f func(A) Either[B]) ReaderResult[B] {
 	return readereither.MonadChainEitherK(ma, f)
 }
 
-func ChainEitherK[A, B any](f func(A) Either[B]) func(ma ReaderEither[A]) ReaderEither[B] {
+func ChainEitherK[A, B any](f func(A) Either[B]) func(ma ReaderResult[A]) ReaderResult[B] {
 	return readereither.ChainEitherK[context.Context](f)
 }
 
@@ -85,10 +85,15 @@ func ChainOptionK[A, B any](onNone func() error) func(func(A) Option[B]) Operato
 	return readereither.ChainOptionK[context.Context, A, B](onNone)
 }
 
-func MonadFlap[B, A any](fab ReaderEither[func(A) B], a A) ReaderEither[B] {
+func MonadFlap[B, A any](fab ReaderResult[func(A) B], a A) ReaderResult[B] {
 	return readereither.MonadFlap(fab, a)
 }
 
 func Flap[B, A any](a A) Operator[func(A) B, B] {
 	return readereither.Flap[context.Context, error, B](a)
 }
+
+//go:inline
+func Read[A any](r context.Context) func(ReaderResult[A]) Result[A] {
+	return readereither.Read[error, A](r)
+}

v2/context/readerresult/sequence.go

@@ -13,7 +13,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package readereither
+package readerresult
 
 import (
 	"github.com/IBM/fp-go/v2/readereither"
@@ -22,18 +22,18 @@ import (
 
 // SequenceT converts n inputs of higher kinded types into a higher kinded types of n strongly typed values, represented as a tuple
 
-func SequenceT1[A any](a ReaderEither[A]) ReaderEither[tuple.Tuple1[A]] {
+func SequenceT1[A any](a ReaderResult[A]) ReaderResult[tuple.Tuple1[A]] {
 	return readereither.SequenceT1(a)
 }
 
-func SequenceT2[A, B any](a ReaderEither[A], b ReaderEither[B]) ReaderEither[tuple.Tuple2[A, B]] {
+func SequenceT2[A, B any](a ReaderResult[A], b ReaderResult[B]) ReaderResult[tuple.Tuple2[A, B]] {
 	return readereither.SequenceT2(a, b)
 }
 
-func SequenceT3[A, B, C any](a ReaderEither[A], b ReaderEither[B], c ReaderEither[C]) ReaderEither[tuple.Tuple3[A, B, C]] {
+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)
 }
 
-func SequenceT4[A, B, C, D any](a ReaderEither[A], b ReaderEither[B], c ReaderEither[C], d ReaderEither[D]) ReaderEither[tuple.Tuple4[A, B, C, D]] {
+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/type.go

@@ -13,8 +13,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// Package readereither implements a specialization of the Reader monad assuming a golang context as the context of the monad and a standard golang error
+// package readerresult implements a specialization of the Reader monad assuming a golang context as the context of the monad and a standard golang error
-package readereither
+package readerresult
 
 import (
 	"context"
@@ -23,13 +23,16 @@ import (
 	"github.com/IBM/fp-go/v2/option"
 	"github.com/IBM/fp-go/v2/reader"
 	"github.com/IBM/fp-go/v2/readereither"
+	"github.com/IBM/fp-go/v2/result"
 )
 
 type (
 	Option[A any] = option.Option[A]
 	Either[A any] = either.Either[error, A]
-	// ReaderEither is a specialization of the Reader monad for the typical golang scenario
+	Result[A any] = result.Result[A]
-	ReaderEither[A any] = readereither.ReaderEither[context.Context, error, A]
+	// ReaderResult is a specialization of the Reader monad for the typical golang scenario
+	ReaderResult[A any] = readereither.ReaderEither[context.Context, error, A]
 
-	Operator[A, B any] = reader.Reader[ReaderEither[A], ReaderEither[B]]
+	Kleisli[A, B any]  = reader.Reader[A, ReaderResult[B]]
+	Operator[A, B any] = Kleisli[ReaderResult[A], B]
 )

v2/di/app.go

@@ -19,7 +19,7 @@ import (
 	DIE "github.com/IBM/fp-go/v2/di/erasure"
 	F "github.com/IBM/fp-go/v2/function"
 	IO "github.com/IBM/fp-go/v2/io"
-	IOE "github.com/IBM/fp-go/v2/ioeither"
+	IOR "github.com/IBM/fp-go/v2/ioresult"
 )
 
 var (
@@ -34,5 +34,5 @@ var (
 var RunMain = F.Flow3(
 	DIE.MakeInjector,
 	Main,
-	IOE.Fold(IO.Of[error], F.Constant1[any](IO.Of[error](nil))),
+	IOR.Fold(IO.Of[error], F.Constant1[any](IO.Of[error](nil))),
 )

v2/di/doc.go

@@ -64,8 +64,8 @@ Creating and using dependencies:
 	dbProvider := di.MakeProvider1(
 		DBToken,
 		ConfigToken.Identity(),
-		func(cfg Config) IOE.IOEither[error, Database] {
+		func(cfg Config) IOResult[Database] {
-			return IOE.Of[error](NewDatabase(cfg))
+			return ioresult.Of(NewDatabase(cfg))
 		},
 	)
 
@@ -73,8 +73,8 @@ Creating and using dependencies:
 		APIToken,
 		ConfigToken.Identity(),
 		DBToken.Identity(),
-		func(cfg Config, db Database) IOE.IOEither[error, APIService] {
+		func(cfg Config, db Database) IOResult[APIService] {
-			return IOE.Of[error](NewAPIService(cfg, db))
+			return ioresult.Of(NewAPIService(cfg, db))
 		},
 	)
 
@@ -116,7 +116,7 @@ MakeProvider0 - No dependencies:
 
 	provider := di.MakeProvider0(
 		token,
-		IOE.Of[error](value),
+		ioresult.Of(value),
 	)
 
 MakeProvider1 - One dependency:
@@ -124,8 +124,8 @@ MakeProvider1 - One dependency:
 	provider := di.MakeProvider1(
 		resultToken,
 		dep1Token.Identity(),
-		func(dep1 Dep1Type) IOE.IOEither[error, ResultType] {
+		func(dep1 Dep1Type) IOResult[ResultType] {
-			return IOE.Of[error](createResult(dep1))
+			return ioresult.Of(createResult(dep1))
 		},
 	)
 
@@ -135,8 +135,8 @@ MakeProvider2 - Two dependencies:
 		resultToken,
 		dep1Token.Identity(),
 		dep2Token.Identity(),
-		func(dep1 Dep1Type, dep2 Dep2Type) IOE.IOEither[error, ResultType] {
+		func(dep1 Dep1Type, dep2 Dep2Type) IOResult[ResultType] {
-			return IOE.Of[error](createResult(dep1, dep2))
+			return ioresult.Of(createResult(dep1, dep2))
 		},
 	)
 
@@ -153,7 +153,7 @@ provider is registered:
 
 	token := di.MakeTokenWithDefault0(
 		"ServiceName",
-		IOE.Of[error](defaultImplementation),
+		ioresult.Of(defaultImplementation),
 	)
 
 	// Or with dependencies
@@ -161,8 +161,8 @@ provider is registered:
 		"ServiceName",
 		dep1Token.Identity(),
 		dep2Token.Identity(),
-		func(dep1 Dep1Type, dep2 Dep2Type) IOE.IOEither[error, ResultType] {
+		func(dep1 Dep1Type, dep2 Dep2Type) IOResult[ResultType] {
-			return IOE.Of[error](createDefault(dep1, dep2))
+			return ioresult.Of(createDefault(dep1, dep2))
 		},
 	)
 
@@ -208,8 +208,8 @@ The framework provides a convenient pattern for running applications:
 	mainProvider := di.MakeProvider1(
 		di.InjMain,
 		APIToken.Identity(),
-		func(api APIService) IOE.IOEither[error, any] {
+		func(api APIService) IOResult[any] {
-			return IOE.Of[error](api.Start())
+			return ioresult.Of(api.Start())
 		},
 	)
 
@@ -247,8 +247,8 @@ Example 1: Configuration-based Service
 	clientProvider := di.MakeProvider1(
 		ClientToken,
 		ConfigToken.Identity(),
-		func(cfg Config) IOE.IOEither[error, HTTPClient] {
+		func(cfg Config) IOResult[HTTPClient] {
-			return IOE.Of[error](HTTPClient{config: cfg})
+			return ioresult.Of(HTTPClient{config: cfg})
 		},
 	)
 
@@ -263,8 +263,8 @@ Example 2: Optional Dependencies
 	serviceProvider := di.MakeProvider1(
 		ServiceToken,
 		CacheToken.Option(), // Optional dependency
-		func(cache O.Option[Cache]) IOE.IOEither[error, Service] {
+		func(cache Option[Cache]) IOResult[Service] {
-			return IOE.Of[error](NewService(cache))
+			return ioresult.Of(NewService(cache))
 		},
 	)
 
@@ -279,8 +279,8 @@ Example 3: Lazy Dependencies
 	reporterProvider := di.MakeProvider1(
 		ReporterToken,
 		DBToken.IOEither(), // Lazy dependency
-		func(dbIO IOE.IOEither[error, Database]) IOE.IOEither[error, Reporter] {
+		func(dbIO IOResult[Database]) IOResult[Reporter] {
-			return IOE.Of[error](NewReporter(dbIO))
+			return ioresult.Of(NewReporter(dbIO))
 		},
 	)
 

v2/di/erasure/injector.go

@@ -20,7 +20,7 @@ import (
 	"github.com/IBM/fp-go/v2/errors"
 	F "github.com/IBM/fp-go/v2/function"
 	I "github.com/IBM/fp-go/v2/identity"
-	IOE "github.com/IBM/fp-go/v2/ioeither"
+	IOR "github.com/IBM/fp-go/v2/ioresult"
 	L "github.com/IBM/fp-go/v2/lazy"
 	O "github.com/IBM/fp-go/v2/option"
 	R "github.com/IBM/fp-go/v2/record"
@@ -42,8 +42,8 @@ var (
 	missingProviderError = F.Flow4(
 		Dependency.String,
 		errors.OnSome[string]("no provider for dependency [%s]"),
-		IOE.Left[any, error],
+		IOR.Left[any],
-		F.Constant1[InjectableFactory, IOE.IOEither[error, any]],
+		F.Constant1[InjectableFactory, IOResult[any]],
 	)
 
 	// missingProviderErrorOrDefault returns the default [ProviderFactory] or an error
@@ -56,7 +56,7 @@ var (
 	emptyMulti any = A.Empty[any]()
 
 	// emptyMultiDependency returns a [ProviderFactory] for an empty, multi dependency
-	emptyMultiDependency = F.Constant1[Dependency](F.Constant1[InjectableFactory](IOE.Of[error](emptyMulti)))
+	emptyMultiDependency = F.Constant1[Dependency](F.Constant1[InjectableFactory](IOR.Of(emptyMulti)))
 
 	// handleMissingProvider covers the case of a missing provider. It either
 	// returns an error or an empty multi value provider
@@ -93,21 +93,21 @@ var (
 
 // isMultiDependency tests if a dependency is a container dependency
 func isMultiDependency(dep Dependency) bool {
-	return dep.Flag()&Multi == Multi
+	return dep.Flag()&MULTI == MULTI
 }
 
 // isItemProvider tests if a provivder provides a single item
 func isItemProvider(provider Provider) bool {
-	return provider.Provides().Flag()&Item == Item
+	return provider.Provides().Flag()&ITEM == ITEM
 }
 
 // itemProviderFactory combines multiple factories into one, returning an array
 func itemProviderFactory(fcts []ProviderFactory) ProviderFactory {
-	return func(inj InjectableFactory) IOE.IOEither[error, any] {
+	return func(inj InjectableFactory) IOResult[any] {
 		return F.Pipe2(
 			fcts,
-			IOE.TraverseArray(I.Flap[IOE.IOEither[error, any]](inj)),
+			IOR.TraverseArray(I.Flap[IOResult[any]](inj)),
-			IOE.Map[error](F.ToAny[[]any]),
+			IOR.Map(F.ToAny[[]any]),
 		)
 	}
 }
@@ -118,7 +118,7 @@ func itemProviderFactory(fcts []ProviderFactory) ProviderFactory {
 // makes sure to transitively resolve the required dependencies.
 func MakeInjector(providers []Provider) InjectableFactory {
 
-	type Result = IOE.IOEither[error, any]
+	type Result = IOResult[any]
 	type LazyResult = L.Lazy[Result]
 
 	// resolved stores the values resolved so far, key is the string ID
@@ -148,11 +148,11 @@ func MakeInjector(providers []Provider) InjectableFactory {
 					T.Map2(F.Flow3(
 						Dependency.Id,
 						R.Lookup[ProviderFactory, string],
-						I.Ap[O.Option[ProviderFactory]](factoryByID),
+						I.Ap[Option[ProviderFactory]](factoryByID),
 					), handleMissingProvider),
 					T.Tupled2(O.MonadGetOrElse[ProviderFactory]),
-					I.Ap[IOE.IOEither[error, any]](injFct),
+					I.Ap[IOResult[any]](injFct),
-					IOE.Memoize[error, any],
+					IOR.Memoize[any],
 				)
 			}
 

v2/di/erasure/provider.go

@@ -19,25 +19,23 @@ import (
 	"fmt"
 
 	A "github.com/IBM/fp-go/v2/array"
-	E "github.com/IBM/fp-go/v2/either"
 	F "github.com/IBM/fp-go/v2/function"
 	I "github.com/IBM/fp-go/v2/identity"
 	IO "github.com/IBM/fp-go/v2/io"
 	IOE "github.com/IBM/fp-go/v2/ioeither"
-	IOO "github.com/IBM/fp-go/v2/iooption"
 	Int "github.com/IBM/fp-go/v2/number/integer"
-	O "github.com/IBM/fp-go/v2/option"
 	R "github.com/IBM/fp-go/v2/record"
+	"github.com/IBM/fp-go/v2/result"
 )
 
 type (
 	// InjectableFactory is a factory function that can create an untyped instance of a service based on its [Dependency] identifier
-	InjectableFactory = func(Dependency) IOE.IOEither[error, any]
+	InjectableFactory = func(Dependency) IOResult[any]
-	ProviderFactory   = func(InjectableFactory) IOE.IOEither[error, any]
+	ProviderFactory   = func(InjectableFactory) IOResult[any]
 
 	paramIndex = map[int]int
 	paramValue = map[int]any
-	handler    = func(paramIndex) func([]IOE.IOEither[error, any]) IOE.IOEither[error, paramValue]
+	handler    = func(paramIndex) func([]IOResult[any]) IOResult[paramValue]
 	mapping    = map[int]paramIndex
 
 	Provider interface {
@@ -83,50 +81,50 @@ var (
 	mergeMaps      = R.UnionLastMonoid[int, any]()
 	collectParams  = R.CollectOrd[any, any](Int.Ord)(F.SK[int, any])
 
-	mapDeps = F.Curry2(A.MonadMap[Dependency, IOE.IOEither[error, any]])
+	mapDeps = F.Curry2(A.MonadMap[Dependency, IOResult[any]])
 
 	handlers = map[int]handler{
-		Identity: func(mp paramIndex) func([]IOE.IOEither[error, any]) IOE.IOEither[error, paramValue] {
+		IDENTITY: func(mp paramIndex) func([]IOResult[any]) IOResult[paramValue] {
-			return func(res []IOE.IOEither[error, any]) IOE.IOEither[error, paramValue] {
+			return func(res []IOResult[any]) IOResult[paramValue] {
 				return F.Pipe1(
 					mp,
 					IOE.TraverseRecord[int](getAt(res)),
 				)
 			}
 		},
-		Option: func(mp paramIndex) func([]IOE.IOEither[error, any]) IOE.IOEither[error, paramValue] {
+		OPTION: func(mp paramIndex) func([]IOResult[any]) IOResult[paramValue] {
-			return func(res []IOE.IOEither[error, any]) IOE.IOEither[error, paramValue] {
+			return func(res []IOResult[any]) IOResult[paramValue] {
 				return F.Pipe3(
 					mp,
 					IO.TraverseRecord[int](getAt(res)),
 					IO.Map(R.Map[int](F.Flow2(
-						E.ToOption[error, any],
+						result.ToOption[any],
-						F.ToAny[O.Option[any]],
+						F.ToAny[Option[any]],
 					))),
 					IOE.FromIO[error, paramValue],
 				)
 			}
 		},
-		IOEither: func(mp paramIndex) func([]IOE.IOEither[error, any]) IOE.IOEither[error, paramValue] {
+		IOEITHER: func(mp paramIndex) func([]IOResult[any]) IOResult[paramValue] {
-			return func(res []IOE.IOEither[error, any]) IOE.IOEither[error, paramValue] {
+			return func(res []IOResult[any]) IOResult[paramValue] {
 				return F.Pipe2(
 					mp,
 					R.Map[int](F.Flow2(
 						getAt(res),
-						F.ToAny[IOE.IOEither[error, any]],
+						F.ToAny[IOResult[any]],
 					)),
 					IOE.Of[error, paramValue],
 				)
 			}
 		},
-		IOOption: func(mp paramIndex) func([]IOE.IOEither[error, any]) IOE.IOEither[error, paramValue] {
+		IOOPTION: func(mp paramIndex) func([]IOResult[any]) IOResult[paramValue] {
-			return func(res []IOE.IOEither[error, any]) IOE.IOEither[error, paramValue] {
+			return func(res []IOResult[any]) IOResult[paramValue] {
 				return F.Pipe2(
 					mp,
 					R.Map[int](F.Flow3(
 						getAt(res),
 						IOE.ToIOOption[error, any],
-						F.ToAny[IOO.IOOption[any]],
+						F.ToAny[IOOption[any]],
 					)),
 					IOE.Of[error, paramValue],
 				)
@@ -141,23 +139,23 @@ func getAt[T any](ar []T) func(idx int) T {
 	}
 }
 
-func handleMapping(mp mapping) func(res []IOE.IOEither[error, any]) IOE.IOEither[error, []any] {
+func handleMapping(mp mapping) func(res []IOResult[any]) IOResult[[]any] {
 	preFct := F.Pipe1(
 		mp,
-		R.Collect(func(idx int, p paramIndex) func([]IOE.IOEither[error, any]) IOE.IOEither[error, paramValue] {
+		R.Collect(func(idx int, p paramIndex) func([]IOResult[any]) IOResult[paramValue] {
 			return handlers[idx](p)
 		}),
 	)
 	doFct := F.Flow2(
-		I.Flap[IOE.IOEither[error, paramValue], []IOE.IOEither[error, any]],
+		I.Flap[IOResult[paramValue], []IOResult[any]],
-		IOE.TraverseArray[error, func([]IOE.IOEither[error, any]) IOE.IOEither[error, paramValue], paramValue],
+		IOE.TraverseArray[error, func([]IOResult[any]) IOResult[paramValue], paramValue],
 	)
 	postFct := IOE.Map[error](F.Flow2(
 		A.Fold(mergeMaps),
 		collectParams,
 	))
 
-	return func(res []IOE.IOEither[error, any]) IOE.IOEither[error, []any] {
+	return func(res []IOResult[any]) IOResult[[]any] {
 		return F.Pipe2(
 			preFct,
 			doFct(res),
@@ -170,7 +168,7 @@ func handleMapping(mp mapping) func(res []IOE.IOEither[error, any]) IOE.IOEither
 // a function that accepts the resolved dependencies to return a result
 func MakeProviderFactory(
 	deps []Dependency,
-	fct func(param ...any) IOE.IOEither[error, any]) ProviderFactory {
+	fct func(param ...any) IOResult[any]) ProviderFactory {
 
 	return F.Flow3(
 		mapDeps(deps),

v2/di/erasure/token.go

@@ -17,20 +17,18 @@ package erasure
 
 import (
 	"fmt"
-
-	O "github.com/IBM/fp-go/v2/option"
 )
 
 const (
 	BehaviourMask = 0x0f
-	Identity      = 0 // required dependency
+	IDENTITY      = 0 // required dependency
-	Option        = 1 // optional dependency
+	OPTION        = 1 // optional dependency
-	IOEither      = 2 // lazy and required
+	IOEITHER      = 2 // lazy and required
-	IOOption      = 3 // lazy and optional
+	IOOPTION      = 3 // lazy and optional
 
 	TypeMask = 0xf0
-	Multi    = 1 << 4 // array of implementations
+	MULTI    = 1 << 4 // array of implementations
-	Item     = 2 << 4 // item of a multi token
+	ITEM     = 2 << 4 // item of a multi token
 )
 
 // Dependency describes the relationship to a service
@@ -41,5 +39,5 @@ type Dependency interface {
 	// Flag returns a tag that identifies the behaviour of the dependency
 	Flag() int
 	// ProviderFactory optionally returns an attached [ProviderFactory] that represents the default for this dependency
-	ProviderFactory() O.Option[ProviderFactory]
+	ProviderFactory() Option[ProviderFactory]
 }

v2/di/erasure/types.go

@@ -0,0 +1,13 @@
+package erasure
+
+import (
+	"github.com/IBM/fp-go/v2/iooption"
+	"github.com/IBM/fp-go/v2/ioresult"
+	"github.com/IBM/fp-go/v2/option"
+)
+
+type (
+	Option[T any]   = option.Option[T]
+	IOResult[T any] = ioresult.IOResult[T]
+	IOOption[T any] = iooption.IOOption[T]
+)

v2/di/injector.go

@@ -19,14 +19,14 @@ import (
 	DIE "github.com/IBM/fp-go/v2/di/erasure"
 	F "github.com/IBM/fp-go/v2/function"
 	"github.com/IBM/fp-go/v2/identity"
-	IOE "github.com/IBM/fp-go/v2/ioeither"
+	IOR "github.com/IBM/fp-go/v2/ioresult"
-	RIOE "github.com/IBM/fp-go/v2/readerioeither"
+	RIOR "github.com/IBM/fp-go/v2/readerioresult"
 )
 
 // Resolve performs a type safe resolution of a dependency
-func Resolve[T any](token InjectionToken[T]) RIOE.ReaderIOEither[DIE.InjectableFactory, error, T] {
+func Resolve[T any](token InjectionToken[T]) RIOR.ReaderIOResult[DIE.InjectableFactory, T] {
 	return F.Flow2(
-		identity.Ap[IOE.IOEither[error, any]](asDependency(token)),
+		identity.Ap[IOResult[any]](asDependency(token)),
-		IOE.ChainEitherK(token.Unerase),
+		IOR.ChainResultK(token.Unerase),
 	)
 }

v2/di/provider.go

@@ -22,9 +22,10 @@ import (
 	"github.com/IBM/fp-go/v2/errors"
 	F "github.com/IBM/fp-go/v2/function"
 	IOE "github.com/IBM/fp-go/v2/ioeither"
+	"github.com/IBM/fp-go/v2/ioresult"
 )
 
-func lookupAt[T any](idx int, token Dependency[T]) func(params []any) E.Either[error, T] {
+func lookupAt[T any](idx int, token Dependency[T]) func(params []any) Result[T] {
 	return F.Flow3(
 		A.Lookup[any](idx),
 		E.FromOption[any](errors.OnNone("No parameter at position %d", idx)),
@@ -32,7 +33,7 @@ func lookupAt[T any](idx int, token Dependency[T]) func(params []any) E.Either[e
 	)
 }
 
-func eraseTuple[A, R any](f func(A) IOE.IOEither[error, R]) func(E.Either[error, A]) IOE.IOEither[error, any] {
+func eraseTuple[A, R any](f func(A) IOResult[R]) func(Result[A]) IOResult[any] {
 	return F.Flow3(
 		IOE.FromEither[error, A],
 		IOE.Chain(f),
@@ -40,8 +41,8 @@ func eraseTuple[A, R any](f func(A) IOE.IOEither[error, R]) func(E.Either[error,
 	)
 }
 
-func eraseProviderFactory0[R any](f IOE.IOEither[error, R]) func(params ...any) IOE.IOEither[error, any] {
+func eraseProviderFactory0[R any](f IOResult[R]) func(params ...any) IOResult[any] {
-	return func(_ ...any) IOE.IOEither[error, any] {
+	return func(_ ...any) IOResult[any] {
 		return F.Pipe1(
 			f,
 			IOE.Map[error](F.ToAny[R]),
@@ -50,7 +51,7 @@ func eraseProviderFactory0[R any](f IOE.IOEither[error, R]) func(params ...any)
 }
 
 func MakeProviderFactory0[R any](
-	fct IOE.IOEither[error, R],
+	fct IOResult[R],
 ) DIE.ProviderFactory {
 	return DIE.MakeProviderFactory(
 		A.Empty[DIE.Dependency](),
@@ -59,13 +60,13 @@ func MakeProviderFactory0[R any](
 }
 
 // MakeTokenWithDefault0 creates a unique [InjectionToken] for a specific type with an attached default [DIE.Provider]
-func MakeTokenWithDefault0[R any](name string, fct IOE.IOEither[error, R]) InjectionToken[R] {
+func MakeTokenWithDefault0[R any](name string, fct IOResult[R]) InjectionToken[R] {
 	return MakeTokenWithDefault[R](name, MakeProviderFactory0(fct))
 }
 
 func MakeProvider0[R any](
 	token InjectionToken[R],
-	fct IOE.IOEither[error, R],
+	fct IOResult[R],
 ) DIE.Provider {
 	return DIE.MakeProvider(
 		token,
@@ -75,5 +76,5 @@ func MakeProvider0[R any](
 
 // ConstProvider simple implementation for a provider with a constant value
 func ConstProvider[R any](token InjectionToken[R], value R) DIE.Provider {
-	return MakeProvider0[R](token, IOE.Of[error](value))
+	return MakeProvider0(token, ioresult.Of(value))
 }

v2/di/provider_test.go

@@ -25,7 +25,8 @@ import (
 	E "github.com/IBM/fp-go/v2/either"
 	F "github.com/IBM/fp-go/v2/function"
 	IOE "github.com/IBM/fp-go/v2/ioeither"
-	O "github.com/IBM/fp-go/v2/option"
+	"github.com/IBM/fp-go/v2/ioresult"
+	"github.com/IBM/fp-go/v2/result"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -39,19 +40,19 @@ func TestSimpleProvider(t *testing.T) {
 
 	var staticCount int
 
-	staticValue := func(value string) IOE.IOEither[error, string] {
+	staticValue := func(value string) IOResult[string] {
-		return func() E.Either[error, string] {
+		return func() Result[string] {
 			staticCount++
-			return E.Of[error](fmt.Sprintf("Static based on [%s], at [%s]", value, time.Now()))
+			return result.Of(fmt.Sprintf("Static based on [%s], at [%s]", value, time.Now()))
 		}
 	}
 
 	var dynamicCount int
 
-	dynamicValue := func(value string) IOE.IOEither[error, string] {
+	dynamicValue := func(value string) IOResult[string] {
-		return func() E.Either[error, string] {
+		return func() Result[string] {
 			dynamicCount++
-			return E.Of[error](fmt.Sprintf("Dynamic based on [%s] at [%s]", value, time.Now()))
+			return result.Of(fmt.Sprintf("Dynamic based on [%s] at [%s]", value, time.Now()))
 		}
 	}
 
@@ -81,19 +82,19 @@ func TestOptionalProvider(t *testing.T) {
 
 	var staticCount int
 
-	staticValue := func(value string) IOE.IOEither[error, string] {
+	staticValue := func(value string) IOResult[string] {
-		return func() E.Either[error, string] {
+		return func() Result[string] {
 			staticCount++
-			return E.Of[error](fmt.Sprintf("Static based on [%s], at [%s]", value, time.Now()))
+			return result.Of(fmt.Sprintf("Static based on [%s], at [%s]", value, time.Now()))
 		}
 	}
 
 	var dynamicCount int
 
-	dynamicValue := func(value O.Option[string]) IOE.IOEither[error, string] {
+	dynamicValue := func(value Option[string]) IOResult[string] {
-		return func() E.Either[error, string] {
+		return func() Result[string] {
 			dynamicCount++
-			return E.Of[error](fmt.Sprintf("Dynamic based on [%s] at [%s]", value, time.Now()))
+			return result.Of(fmt.Sprintf("Dynamic based on [%s] at [%s]", value, time.Now()))
 		}
 	}
 
@@ -123,10 +124,10 @@ func TestOptionalProviderMissingDependency(t *testing.T) {
 
 	var dynamicCount int
 
-	dynamicValue := func(value O.Option[string]) IOE.IOEither[error, string] {
+	dynamicValue := func(value Option[string]) IOResult[string] {
-		return func() E.Either[error, string] {
+		return func() Result[string] {
 			dynamicCount++
-			return E.Of[error](fmt.Sprintf("Dynamic based on [%s] at [%s]", value, time.Now()))
+			return result.Of(fmt.Sprintf("Dynamic based on [%s] at [%s]", value, time.Now()))
 		}
 	}
 
@@ -151,10 +152,10 @@ func TestProviderMissingDependency(t *testing.T) {
 
 	var dynamicCount int
 
-	dynamicValue := func(value string) IOE.IOEither[error, string] {
+	dynamicValue := func(value string) IOResult[string] {
-		return func() E.Either[error, string] {
+		return func() Result[string] {
 			dynamicCount++
-			return E.Of[error](fmt.Sprintf("Dynamic based on [%s] at [%s]", value, time.Now()))
+			return result.Of(fmt.Sprintf("Dynamic based on [%s] at [%s]", value, time.Now()))
 		}
 	}
 
@@ -179,31 +180,31 @@ func TestEagerAndLazyProvider(t *testing.T) {
 
 	var staticCount int
 
-	staticValue := func(value string) IOE.IOEither[error, string] {
+	staticValue := func(value string) IOResult[string] {
-		return func() E.Either[error, string] {
+		return func() Result[string] {
 			staticCount++
-			return E.Of[error](fmt.Sprintf("Static based on [%s], at [%s]", value, time.Now()))
+			return result.Of(fmt.Sprintf("Static based on [%s], at [%s]", value, time.Now()))
 		}
 	}
 
 	var dynamicCount int
 
-	dynamicValue := func(value string) IOE.IOEither[error, string] {
+	dynamicValue := func(value string) IOResult[string] {
-		return func() E.Either[error, string] {
+		return func() Result[string] {
 			dynamicCount++
-			return E.Of[error](fmt.Sprintf("Dynamic based on [%s] at [%s]", value, time.Now()))
+			return result.Of(fmt.Sprintf("Dynamic based on [%s] at [%s]", value, time.Now()))
 		}
 	}
 
 	var lazyEagerCount int
 
-	lazyEager := func(laz IOE.IOEither[error, string], eager string) IOE.IOEither[error, string] {
+	lazyEager := func(laz IOResult[string], eager string) IOResult[string] {
 		return F.Pipe1(
 			laz,
-			IOE.Chain(func(lazValue string) IOE.IOEither[error, string] {
+			IOE.Chain(func(lazValue string) IOResult[string] {
-				return func() E.Either[error, string] {
+				return func() Result[string] {
 					lazyEagerCount++
-					return E.Of[error](fmt.Sprintf("Dynamic based on [%s], [%s] at [%s]", lazValue, eager, time.Now()))
+					return result.Of(fmt.Sprintf("Dynamic based on [%s], [%s] at [%s]", lazValue, eager, time.Now()))
 				}
 			}),
 		)
@@ -248,7 +249,7 @@ func TestItemProvider(t *testing.T) {
 
 	value := multiInj()
 
-	assert.Equal(t, E.Of[error](A.From("Value1", "Value2")), value)
+	assert.Equal(t, result.Of(A.From("Value1", "Value2")), value)
 }
 
 func TestEmptyItemProvider(t *testing.T) {
@@ -269,7 +270,7 @@ func TestEmptyItemProvider(t *testing.T) {
 
 	value := multiInj()
 
-	assert.Equal(t, E.Of[error](A.Empty[string]()), value)
+	assert.Equal(t, result.Of(A.Empty[string]()), value)
 }
 
 func TestDependencyOnMultiProvider(t *testing.T) {
@@ -283,8 +284,8 @@ func TestDependencyOnMultiProvider(t *testing.T) {
 	p1 := ConstProvider(INJ_KEY1, "Value3")
 	p2 := ConstProvider(INJ_KEY2, "Value4")
 
-	fromMulti := func(val string, multi []string) IOE.IOEither[error, string] {
+	fromMulti := func(val string, multi []string) IOResult[string] {
-		return IOE.Of[error](fmt.Sprintf("Val: %s, Multi: %s", val, multi))
+		return ioresult.Of(fmt.Sprintf("Val: %s, Multi: %s", val, multi))
 	}
 	p3 := MakeProvider2(INJ_KEY3, INJ_KEY1.Identity(), injMulti.Container().Identity(), fromMulti)
 
@@ -295,19 +296,19 @@ func TestDependencyOnMultiProvider(t *testing.T) {
 
 	v := r3(inj)()
 
-	assert.Equal(t, E.Of[error]("Val: Value3, Multi: [Value1 Value2]"), v)
+	assert.Equal(t, result.Of("Val: Value3, Multi: [Value1 Value2]"), v)
 }
 
 func TestTokenWithDefaultProvider(t *testing.T) {
 	// token without a default
 	injToken1 := MakeToken[string]("Token1")
 	// token with a default
-	injToken2 := MakeTokenWithDefault0("Token2", IOE.Of[error]("Carsten"))
+	injToken2 := MakeTokenWithDefault0("Token2", ioresult.Of("Carsten"))
 	// dependency
 	injToken3 := MakeToken[string]("Token3")
 
-	p3 := MakeProvider1(injToken3, injToken2.Identity(), func(data string) IOE.IOEither[error, string] {
+	p3 := MakeProvider1(injToken3, injToken2.Identity(), func(data string) IOResult[string] {
-		return IOE.Of[error](fmt.Sprintf("Token: %s", data))
+		return ioresult.Of(fmt.Sprintf("Token: %s", data))
 	})
 
 	// populate the injector
@@ -320,19 +321,19 @@ func TestTokenWithDefaultProvider(t *testing.T) {
 	// inj1 should not be available
 	assert.True(t, E.IsLeft(r1(inj)()))
 	// r3 should work
-	assert.Equal(t, E.Of[error]("Token: Carsten"), r3(inj)())
+	assert.Equal(t, result.Of("Token: Carsten"), r3(inj)())
 }
 
 func TestTokenWithDefaultProviderAndOverride(t *testing.T) {
 	// token with a default
-	injToken2 := MakeTokenWithDefault0("Token2", IOE.Of[error]("Carsten"))
+	injToken2 := MakeTokenWithDefault0("Token2", ioresult.Of("Carsten"))
 	// dependency
 	injToken3 := MakeToken[string]("Token3")
 
 	p2 := ConstProvider(injToken2, "Override")
 
-	p3 := MakeProvider1(injToken3, injToken2.Identity(), func(data string) IOE.IOEither[error, string] {
+	p3 := MakeProvider1(injToken3, injToken2.Identity(), func(data string) IOResult[string] {
-		return IOE.Of[error](fmt.Sprintf("Token: %s", data))
+		return ioresult.Of(fmt.Sprintf("Token: %s", data))
 	})
 
 	// populate the injector
@@ -342,5 +343,5 @@ func TestTokenWithDefaultProviderAndOverride(t *testing.T) {
 	r3 := Resolve(injToken3)
 
 	// r3 should work
-	assert.Equal(t, E.Of[error]("Token: Override"), r3(inj)())
+	assert.Equal(t, result.Of("Token: Override"), r3(inj)())
 }

v2/di/token.go

@@ -21,10 +21,7 @@ import (
 	"sync/atomic"
 
 	DIE "github.com/IBM/fp-go/v2/di/erasure"
-	E "github.com/IBM/fp-go/v2/either"
 	IO "github.com/IBM/fp-go/v2/io"
-	IOE "github.com/IBM/fp-go/v2/ioeither"
-	IOO "github.com/IBM/fp-go/v2/iooption"
 	O "github.com/IBM/fp-go/v2/option"
 )
 
@@ -33,7 +30,7 @@ import (
 type Dependency[T any] interface {
 	DIE.Dependency
 	// Unerase converts a value with erased type signature into a strongly typed value
-	Unerase(val any) E.Either[error, T]
+	Unerase(val any) Result[T]
 }
 
 // InjectionToken uniquely identifies a dependency by giving it an Id, Type and name
@@ -42,17 +39,17 @@ type InjectionToken[T any] interface {
 	// Identity idenifies this dependency as a mandatory, required dependency, it will be resolved eagerly and injected as `T`.
 	// If the dependency cannot be resolved, the resolution process fails
 	Identity() Dependency[T]
-	// Option identifies this dependency as optional, it will be resolved eagerly and injected as [O.Option[T]].
+	// Option identifies this dependency as optional, it will be resolved eagerly and injected as [Option[T]].
 	// If the dependency cannot be resolved, the resolution process continues and the dependency is represented as [O.None[T]]
-	Option() Dependency[O.Option[T]]
+	Option() Dependency[Option[T]]
-	// IOEither identifies this dependency as mandatory but it will be resolved lazily as a [IOE.IOEither[error, T]]. This
+	// IOEither identifies this dependency as mandatory but it will be resolved lazily as a [IOResult[T]]. This
 	// value is memoized to make sure the dependency is a singleton.
 	// If the dependency cannot be resolved, the resolution process fails
-	IOEither() Dependency[IOE.IOEither[error, T]]
+	IOEither() Dependency[IOResult[T]]
-	// IOOption identifies this dependency as optional but it will be resolved lazily as a [IOO.IOOption[T]]. This
+	// IOOption identifies this dependency as optional but it will be resolved lazily as a [IOOption[T]]. This
 	// value is memoized to make sure the dependency is a singleton.
 	// If the dependency cannot be resolved, the resolution process continues and the dependency is represented as the none value.
-	IOOption() Dependency[IOO.IOOption[T]]
+	IOOption() Dependency[IOOption[T]]
 }
 
 // MultiInjectionToken uniquely identifies a dependency by giving it an Id, Type and name that can have multiple implementations.
@@ -79,12 +76,12 @@ type tokenBase struct {
 	name            string
 	id              string
 	flag            int
-	providerFactory O.Option[DIE.ProviderFactory]
+	providerFactory Option[DIE.ProviderFactory]
 }
 
 type token[T any] struct {
 	base   *tokenBase
-	toType func(val any) E.Either[error, T]
+	toType func(val any) Result[T]
 }
 
 func (t *token[T]) Id() string {
@@ -99,26 +96,26 @@ func (t *token[T]) String() string {
 	return t.base.name
 }
 
-func (t *token[T]) Unerase(val any) E.Either[error, T] {
+func (t *token[T]) Unerase(val any) Result[T] {
 	return t.toType(val)
 }
 
-func (t *token[T]) ProviderFactory() O.Option[DIE.ProviderFactory] {
+func (t *token[T]) ProviderFactory() Option[DIE.ProviderFactory] {
 	return t.base.providerFactory
 }
-func makeTokenBase(name string, id string, typ int, providerFactory O.Option[DIE.ProviderFactory]) *tokenBase {
+func makeTokenBase(name string, id string, typ int, providerFactory Option[DIE.ProviderFactory]) *tokenBase {
 	return &tokenBase{name, id, typ, providerFactory}
 }
 
-func makeToken[T any](name string, id string, typ int, unerase func(val any) E.Either[error, T], providerFactory O.Option[DIE.ProviderFactory]) Dependency[T] {
+func makeToken[T any](name string, id string, typ int, unerase func(val any) Result[T], providerFactory Option[DIE.ProviderFactory]) Dependency[T] {
 	return &token[T]{makeTokenBase(name, id, typ, providerFactory), unerase}
 }
 
 type injectionToken[T any] struct {
 	token[T]
-	option   Dependency[O.Option[T]]
+	option   Dependency[Option[T]]
-	ioeither Dependency[IOE.IOEither[error, T]]
+	ioeither Dependency[IOResult[T]]
-	iooption Dependency[IOO.IOOption[T]]
+	iooption Dependency[IOOption[T]]
 }
 
 type multiInjectionToken[T any] struct {
@@ -130,19 +127,19 @@ func (i *injectionToken[T]) Identity() Dependency[T] {
 	return i
 }
 
-func (i *injectionToken[T]) Option() Dependency[O.Option[T]] {
+func (i *injectionToken[T]) Option() Dependency[Option[T]] {
 	return i.option
 }
 
-func (i *injectionToken[T]) IOEither() Dependency[IOE.IOEither[error, T]] {
+func (i *injectionToken[T]) IOEither() Dependency[IOResult[T]] {
 	return i.ioeither
 }
 
-func (i *injectionToken[T]) IOOption() Dependency[IOO.IOOption[T]] {
+func (i *injectionToken[T]) IOOption() Dependency[IOOption[T]] {
 	return i.iooption
 }
 
-func (i *injectionToken[T]) ProviderFactory() O.Option[DIE.ProviderFactory] {
+func (i *injectionToken[T]) ProviderFactory() Option[DIE.ProviderFactory] {
 	return i.base.providerFactory
 }
 
@@ -155,14 +152,14 @@ func (m *multiInjectionToken[T]) Item() InjectionToken[T] {
 }
 
 // makeToken create a unique [InjectionToken] for a specific type
-func makeInjectionToken[T any](name string, providerFactory O.Option[DIE.ProviderFactory]) InjectionToken[T] {
+func makeInjectionToken[T any](name string, providerFactory Option[DIE.ProviderFactory]) InjectionToken[T] {
 	id := genID()
 	toIdentity := toType[T]()
 	return &injectionToken[T]{
-		token[T]{makeTokenBase(name, id, DIE.Identity, providerFactory), toIdentity},
+		token[T]{makeTokenBase(name, id, DIE.IDENTITY, providerFactory), toIdentity},
-		makeToken[O.Option[T]](fmt.Sprintf("Option[%s]", name), id, DIE.Option, toOptionType(toIdentity), providerFactory),
+		makeToken(fmt.Sprintf("Option[%s]", name), id, DIE.OPTION, toOptionType(toIdentity), providerFactory),
-		makeToken[IOE.IOEither[error, T]](fmt.Sprintf("IOEither[%s]", name), id, DIE.IOEither, toIOEitherType(toIdentity), providerFactory),
+		makeToken(fmt.Sprintf("IOEither[%s]", name), id, DIE.IOEITHER, toIOEitherType(toIdentity), providerFactory),
-		makeToken[IOO.IOOption[T]](fmt.Sprintf("IOOption[%s]", name), id, DIE.IOOption, toIOOptionType(toIdentity), providerFactory),
+		makeToken(fmt.Sprintf("IOOption[%s]", name), id, DIE.IOOPTION, toIOOptionType(toIdentity), providerFactory),
 	}
 }
 
@@ -187,17 +184,17 @@ func MakeMultiToken[T any](name string) MultiInjectionToken[T] {
 	providerFactory := O.None[DIE.ProviderFactory]()
 	// container
 	container := &injectionToken[[]T]{
-		token[[]T]{makeTokenBase(containerName, id, DIE.Multi|DIE.Identity, providerFactory), toContainer},
+		token[[]T]{makeTokenBase(containerName, id, DIE.MULTI|DIE.IDENTITY, providerFactory), toContainer},
-		makeToken[O.Option[[]T]](fmt.Sprintf("Option[%s]", containerName), id, DIE.Multi|DIE.Option, toOptionType(toContainer), providerFactory),
+		makeToken(fmt.Sprintf("Option[%s]", containerName), id, DIE.MULTI|DIE.OPTION, toOptionType(toContainer), providerFactory),
-		makeToken[IOE.IOEither[error, []T]](fmt.Sprintf("IOEither[%s]", containerName), id, DIE.Multi|DIE.IOEither, toIOEitherType(toContainer), providerFactory),
+		makeToken(fmt.Sprintf("IOEither[%s]", containerName), id, DIE.OPTION|DIE.IOEITHER, toIOEitherType(toContainer), providerFactory),
-		makeToken[IOO.IOOption[[]T]](fmt.Sprintf("IOOption[%s]", containerName), id, DIE.Multi|DIE.IOOption, toIOOptionType(toContainer), providerFactory),
+		makeToken(fmt.Sprintf("IOOption[%s]", containerName), id, DIE.OPTION|DIE.IOOPTION, toIOOptionType(toContainer), providerFactory),
 	}
 	// item
 	item := &injectionToken[T]{
-		token[T]{makeTokenBase(itemName, id, DIE.Item|DIE.Identity, providerFactory), toItem},
+		token[T]{makeTokenBase(itemName, id, DIE.ITEM|DIE.IDENTITY, providerFactory), toItem},
-		makeToken[O.Option[T]](fmt.Sprintf("Option[%s]", itemName), id, DIE.Item|DIE.Option, toOptionType(toItem), providerFactory),
+		makeToken(fmt.Sprintf("Option[%s]", itemName), id, DIE.ITEM|DIE.OPTION, toOptionType(toItem), providerFactory),
-		makeToken[IOE.IOEither[error, T]](fmt.Sprintf("IOEither[%s]", itemName), id, DIE.Item|DIE.IOEither, toIOEitherType(toItem), providerFactory),
+		makeToken(fmt.Sprintf("IOEither[%s]", itemName), id, DIE.ITEM|DIE.IOEITHER, toIOEitherType(toItem), providerFactory),
-		makeToken[IOO.IOOption[T]](fmt.Sprintf("IOOption[%s]", itemName), id, DIE.Item|DIE.IOOption, toIOOptionType(toItem), providerFactory),
+		makeToken(fmt.Sprintf("IOOption[%s]", itemName), id, DIE.ITEM|DIE.IOOPTION, toIOOptionType(toItem), providerFactory),
 	}
 	// returns the token
 	return &multiInjectionToken[T]{container, item}

v2/di/token_test.go

@@ -23,7 +23,9 @@ import (
 	F "github.com/IBM/fp-go/v2/function"
 	IOE "github.com/IBM/fp-go/v2/ioeither"
 	IOO "github.com/IBM/fp-go/v2/iooption"
+	"github.com/IBM/fp-go/v2/ioresult"
 	O "github.com/IBM/fp-go/v2/option"
+	"github.com/IBM/fp-go/v2/result"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -75,9 +77,9 @@ func TestTokenUnerase(t *testing.T) {
 	token := MakeToken[int]("IntToken")
 
 	// Test successful unerase
-	result := token.Unerase(42)
+	res := token.Unerase(42)
-	assert.True(t, E.IsRight(result))
+	assert.True(t, E.IsRight(res))
-	assert.Equal(t, E.Of[error](42), result)
+	assert.Equal(t, result.Of(42), res)
 
 	// Test failed unerase (wrong type)
 	result2 := token.Unerase("not an int")
@@ -104,7 +106,7 @@ func TestTokenProviderFactory(t *testing.T) {
 	assert.True(t, O.IsNone(token1.ProviderFactory()))
 
 	// Token with default
-	token2 := MakeTokenWithDefault0("Token2", IOE.Of[error](42))
+	token2 := MakeTokenWithDefault0("Token2", ioresult.Of(42))
 	assert.True(t, O.IsSome(token2.ProviderFactory()))
 }
 
@@ -148,13 +150,13 @@ func TestOptionTokenUnerase(t *testing.T) {
 	optionToken := token.Option()
 
 	// Test successful unerase with Some
-	result := optionToken.Unerase(O.Of[any](42))
+	res := optionToken.Unerase(O.Of[any](42))
-	assert.True(t, E.IsRight(result))
+	assert.True(t, E.IsRight(res))
 
 	// Test successful unerase with None
 	noneResult := optionToken.Unerase(O.None[any]())
 	assert.True(t, E.IsRight(noneResult))
-	assert.Equal(t, E.Of[error](O.None[int]()), noneResult)
+	assert.Equal(t, result.Of(O.None[int]()), noneResult)
 
 	// Test failed unerase (wrong type)
 	badResult := optionToken.Unerase(42) // Not an Option
@@ -166,7 +168,7 @@ func TestIOEitherTokenUnerase(t *testing.T) {
 	ioeitherToken := token.IOEither()
 
 	// Test successful unerase
-	ioValue := IOE.Of[error](any(42))
+	ioValue := ioresult.Of(any(42))
 	result := ioeitherToken.Unerase(ioValue)
 	assert.True(t, E.IsRight(result))
 
@@ -222,7 +224,7 @@ func TestMultiTokenContainerUnerase(t *testing.T) {
 }
 
 func TestMakeTokenWithDefault(t *testing.T) {
-	factory := MakeProviderFactory0(IOE.Of[error](42))
+	factory := MakeProviderFactory0(ioresult.Of(42))
 	token := MakeTokenWithDefault[int]("TokenWithDefault", factory)
 
 	assert.NotNil(t, token)

v2/di/types.go

@@ -0,0 +1,15 @@
+package di
+
+import (
+	"github.com/IBM/fp-go/v2/context/ioresult"
+	"github.com/IBM/fp-go/v2/iooption"
+	"github.com/IBM/fp-go/v2/option"
+	"github.com/IBM/fp-go/v2/result"
+)
+
+type (
+	Option[T any]   = option.Option[T]
+	Result[T any]   = result.Result[T]
+	IOResult[T any] = ioresult.IOResult[T]
+	IOOption[T any] = iooption.IOOption[T]
+)

v2/di/utils.go

@@ -23,12 +23,13 @@ import (
 	IOE "github.com/IBM/fp-go/v2/ioeither"
 	IOO "github.com/IBM/fp-go/v2/iooption"
 	O "github.com/IBM/fp-go/v2/option"
+	"github.com/IBM/fp-go/v2/result"
 )
 
 var (
-	toOptionAny   = toType[O.Option[any]]()
+	toOptionAny   = toType[Option[any]]()
-	toIOEitherAny = toType[IOE.IOEither[error, any]]()
+	toIOEitherAny = toType[IOResult[any]]()
-	toIOOptionAny = toType[IOO.IOOption[any]]()
+	toIOOptionAny = toType[IOOption[any]]()
 	toArrayAny    = toType[[]any]()
 )
 
@@ -38,45 +39,45 @@ func asDependency[T DIE.Dependency](t T) DIE.Dependency {
 }
 
 // toType converts an any to a T
-func toType[T any]() func(t any) E.Either[error, T] {
+func toType[T any]() result.Kleisli[any, T] {
 	return E.ToType[T](errors.OnSome[any]("Value of type [%T] cannot be converted."))
 }
 
 // toOptionType converts an any to an Option[any] and then to an Option[T]
-func toOptionType[T any](item func(any) E.Either[error, T]) func(t any) E.Either[error, O.Option[T]] {
+func toOptionType[T any](item result.Kleisli[any, T]) result.Kleisli[any, Option[T]] {
 	return F.Flow2(
 		toOptionAny,
 		E.Chain(O.Fold(
-			F.Nullary2(O.None[T], E.Of[error, O.Option[T]]),
+			F.Nullary2(O.None[T], E.Of[error, Option[T]]),
 			F.Flow2(
 				item,
-				E.Map[error](O.Of[T]),
+				result.Map(O.Of[T]),
 			),
 		)),
 	)
 }
 
 // toIOEitherType converts an any to an IOEither[error, any] and then to an IOEither[error, T]
-func toIOEitherType[T any](item func(any) E.Either[error, T]) func(t any) E.Either[error, IOE.IOEither[error, T]] {
+func toIOEitherType[T any](item result.Kleisli[any, T]) result.Kleisli[any, IOResult[T]] {
 	return F.Flow2(
 		toIOEitherAny,
-		E.Map[error](IOE.ChainEitherK(item)),
+		result.Map(IOE.ChainEitherK(item)),
 	)
 }
 
 // toIOOptionType converts an any to an IOOption[any] and then to an IOOption[T]
-func toIOOptionType[T any](item func(any) E.Either[error, T]) func(t any) E.Either[error, IOO.IOOption[T]] {
+func toIOOptionType[T any](item result.Kleisli[any, T]) result.Kleisli[any, IOOption[T]] {
 	return F.Flow2(
 		toIOOptionAny,
-		E.Map[error](IOO.ChainOptionK(F.Flow2(
+		result.Map(IOO.ChainOptionK(F.Flow2(
 			item,
-			E.ToOption[error, T],
+			result.ToOption[T],
 		))),
 	)
 }
 
 // toArrayType converts an any to a []T
-func toArrayType[T any](item func(any) E.Either[error, T]) func(t any) E.Either[error, []T] {
+func toArrayType[T any](item result.Kleisli[any, T]) result.Kleisli[any, []T] {
 	return F.Flow2(
 		toArrayAny,
 		E.Chain(E.TraverseArray(item)),