fix: add ChainThunkK

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

v2/cli/README.md

@@ -0,0 +1,273 @@
+# CLI Package - Functional Wrappers for urfave/cli/v3
+
+This package provides functional programming wrappers for the `github.com/urfave/cli/v3` library, enabling Effect-based command actions and type-safe flag handling through Prisms.
+
+## Features
+
+### 1. Effect-Based Command Actions
+
+Transform CLI command actions into composable Effects that follow functional programming principles.
+
+#### Key Functions
+
+- **`ToAction(effect CommandEffect) func(context.Context, *C.Command) error`**
+  - Converts a CommandEffect into a standard urfave/cli Action function
+  - Enables Effect-based command handlers to work with cli/v3 framework
+
+- **`FromAction(action func(context.Context, *C.Command) error) CommandEffect`**
+  - Lifts existing cli/v3 action handlers into the Effect type
+  - Allows gradual migration to functional style
+
+- **`MakeCommand(name, usage string, flags []C.Flag, effect CommandEffect) *C.Command`**
+  - Creates a new Command with an Effect-based action
+  - Convenience function combining command creation with Effect conversion
+
+- **`MakeCommandWithSubcommands(...) *C.Command`**
+  - Creates a Command with subcommands and an Effect-based action
+
+#### Example Usage
+
+```go
+import (
+    "context"
+    
+    E "github.com/IBM/fp-go/v2/effect"
+    F "github.com/IBM/fp-go/v2/function"
+    R "github.com/IBM/fp-go/v2/result"
+    "github.com/IBM/fp-go/v2/cli"
+    C "github.com/urfave/cli/v3"
+)
+
+// Define an Effect-based command action
+processEffect := func(cmd *C.Command) E.Thunk[F.Void] {
+    return func(ctx context.Context) E.IOResult[F.Void] {
+        return func() R.Result[F.Void] {
+            input := cmd.String("input")
+            // Process input...
+            return R.Of(F.Void{})
+        }
+    }
+}
+
+// Create command with Effect
+command := cli.MakeCommand(
+    "process",
+    "Process input files",
+    []C.Flag{
+        &C.StringFlag{Name: "input", Usage: "Input file path"},
+    },
+    processEffect,
+)
+
+// Or convert existing action to Effect
+existingAction := func(ctx context.Context, cmd *C.Command) error {
+    // Existing logic...
+    return nil
+}
+effect := cli.FromAction(existingAction)
+```
+
+### 2. Flag Type Prisms
+
+Type-safe extraction and manipulation of CLI flags using Prisms from the optics package.
+
+#### Available Prisms
+
+- `StringFlagPrism()` - Extract `*C.StringFlag` from `C.Flag`
+- `IntFlagPrism()` - Extract `*C.IntFlag` from `C.Flag`
+- `BoolFlagPrism()` - Extract `*C.BoolFlag` from `C.Flag`
+- `Float64FlagPrism()` - Extract `*C.Float64Flag` from `C.Flag`
+- `DurationFlagPrism()` - Extract `*C.DurationFlag` from `C.Flag`
+- `TimestampFlagPrism()` - Extract `*C.TimestampFlag` from `C.Flag`
+- `StringSliceFlagPrism()` - Extract `*C.StringSliceFlag` from `C.Flag`
+- `IntSliceFlagPrism()` - Extract `*C.IntSliceFlag` from `C.Flag`
+- `Float64SliceFlagPrism()` - Extract `*C.Float64SliceFlag` from `C.Flag`
+- `UintFlagPrism()` - Extract `*C.UintFlag` from `C.Flag`
+- `Uint64FlagPrism()` - Extract `*C.Uint64Flag` from `C.Flag`
+- `Int64FlagPrism()` - Extract `*C.Int64Flag` from `C.Flag`
+
+#### Example Usage
+
+```go
+import (
+    O "github.com/IBM/fp-go/v2/option"
+    "github.com/IBM/fp-go/v2/cli"
+    C "github.com/urfave/cli/v3"
+)
+
+// Extract a StringFlag from a Flag interface
+var flag C.Flag = &C.StringFlag{Name: "input", Value: "default"}
+prism := cli.StringFlagPrism()
+
+// Safe extraction returns Option
+result := prism.GetOption(flag)
+if O.IsSome(result) {
+    strFlag := O.MonadFold(result, 
+        func() *C.StringFlag { return nil },
+        func(f *C.StringFlag) *C.StringFlag { return f },
+    )
+    // Use strFlag...
+}
+
+// Type mismatch returns None
+var intFlag C.Flag = &C.IntFlag{Name: "count"}
+result = prism.GetOption(intFlag)  // Returns None
+
+// Convert back to Flag
+strFlag := &C.StringFlag{Name: "output"}
+flag = prism.ReverseGet(strFlag)
+```
+
+## Type Definitions
+
+### CommandEffect
+
+```go
+type CommandEffect = E.Effect[*C.Command, F.Void]
+```
+
+A CommandEffect represents a CLI command action as an Effect. It takes a `*C.Command` as context and produces a result wrapped in the Effect monad.
+
+The Effect structure is:
+```
+func(*C.Command) -> func(context.Context) -> func() -> Result[Void]
+```
+
+This allows for:
+- **Composability**: Effects can be composed using standard functional combinators
+- **Testability**: Pure functions are easier to test
+- **Error Handling**: Errors are explicitly represented in the Result type
+- **Context Management**: Context flows naturally through the Effect
+
+## Benefits
+
+### 1. Functional Composition
+
+Effects can be composed using standard functional programming patterns:
+
+```go
+import (
+    F "github.com/IBM/fp-go/v2/function"
+    RRIOE "github.com/IBM/fp-go/v2/context/readerreaderioresult"
+)
+
+// Compose multiple effects
+validateInput := func(cmd *C.Command) E.Thunk[F.Void] { /* ... */ }
+processData := func(cmd *C.Command) E.Thunk[F.Void] { /* ... */ }
+saveResults := func(cmd *C.Command) E.Thunk[F.Void] { /* ... */ }
+
+// Chain effects together
+pipeline := F.Pipe3(
+    validateInput,
+    RRIOE.Chain(func(F.Void) E.Effect[*C.Command, F.Void] { return processData }),
+    RRIOE.Chain(func(F.Void) E.Effect[*C.Command, F.Void] { return saveResults }),
+)
+```
+
+### 2. Type Safety
+
+Prisms provide compile-time type safety when working with flags:
+
+```go
+// Type-safe flag extraction
+flags := []C.Flag{
+    &C.StringFlag{Name: "input"},
+    &C.IntFlag{Name: "count"},
+}
+
+for _, flag := range flags {
+    // Safe extraction with pattern matching
+    O.MonadFold(
+        cli.StringFlagPrism().GetOption(flag),
+        func() { /* Not a string flag */ },
+        func(sf *C.StringFlag) { /* Handle string flag */ },
+    )
+}
+```
+
+### 3. Error Handling
+
+Errors are explicitly represented in the Result type:
+
+```go
+effect := func(cmd *C.Command) E.Thunk[F.Void] {
+    return func(ctx context.Context) E.IOResult[F.Void] {
+        return func() R.Result[F.Void] {
+            if err := validateInput(cmd); err != nil {
+                return R.Left[F.Void](err)  // Explicit error
+            }
+            return R.Of(F.Void{})  // Success
+        }
+    }
+}
+```
+
+### 4. Testability
+
+Pure functions are easier to test:
+
+```go
+func TestCommandEffect(t *testing.T) {
+    cmd := &C.Command{Name: "test"}
+    effect := myCommandEffect(cmd)
+    
+    // Execute effect
+    result := effect(context.Background())()
+    
+    // Assert on result
+    assert.True(t, R.IsRight(result))
+}
+```
+
+## Migration Guide
+
+### From Standard Actions to Effects
+
+**Before:**
+```go
+command := &C.Command{
+    Name: "process",
+    Action: func(ctx context.Context, cmd *C.Command) error {
+        input := cmd.String("input")
+        // Process...
+        return nil
+    },
+}
+```
+
+**After:**
+```go
+effect := func(cmd *C.Command) E.Thunk[F.Void] {
+    return func(ctx context.Context) E.IOResult[F.Void] {
+        return func() R.Result[F.Void] {
+            input := cmd.String("input")
+            // Process...
+            return R.Of(F.Void{})
+        }
+    }
+}
+
+command := cli.MakeCommand("process", "Process files", flags, effect)
+```
+
+### Gradual Migration
+
+You can mix both styles during migration:
+
+```go
+// Wrap existing action
+existingAction := func(ctx context.Context, cmd *C.Command) error {
+    // Legacy code...
+    return nil
+}
+
+// Use as Effect
+effect := cli.FromAction(existingAction)
+command := cli.MakeCommand("legacy", "Legacy command", flags, effect)
+```
+
+## See Also
+
+- [Effect Package](../effect/) - Core Effect type definitions
+- [Optics Package](../optics/) - Prism and other optics
+- [urfave/cli/v3](https://github.com/urfave/cli) - Underlying CLI framework

v2/cli/effect.go

@@ -0,0 +1,199 @@
+// 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 (
+	"context"
+
+	E "github.com/IBM/fp-go/v2/effect"
+	ET "github.com/IBM/fp-go/v2/either"
+	F "github.com/IBM/fp-go/v2/function"
+	"github.com/IBM/fp-go/v2/io"
+	R "github.com/IBM/fp-go/v2/result"
+	C "github.com/urfave/cli/v3"
+)
+
+// CommandEffect represents a CLI command action as an Effect.
+// The Effect takes a *C.Command as context and produces a result.
+type CommandEffect = E.Effect[*C.Command, F.Void]
+
+// ToAction converts a CommandEffect into a standard urfave/cli Action function.
+// This allows Effect-based command handlers to be used with the cli/v3 framework.
+//
+// The conversion process:
+//  1. Takes the Effect which expects a *C.Command context
+//  2. Executes it with the provided command
+//  3. Runs the resulting IO operation
+//  4. Converts the Result to either nil (success) or error (failure)
+//
+// # Parameters
+//
+//   - effect: The CommandEffect to convert
+//
+// # Returns
+//
+//   - A function compatible with C.Command.Action signature
+//
+// # Example Usage
+//
+//	effect := func(cmd *C.Command) E.Thunk[F.Void] {
+//	    return func(ctx context.Context) E.IOResult[F.Void] {
+//	        return func() R.Result[F.Void] {
+//	            // Command logic here
+//	            return R.Of(F.Void{})
+//	        }
+//	    }
+//	}
+//	action := ToAction(effect)
+//	command := &C.Command{
+//	    Name: "example",
+//	    Action: action,
+//	}
+func ToAction(effect CommandEffect) func(context.Context, *C.Command) error {
+	return func(ctx context.Context, cmd *C.Command) error {
+		// Execute the effect: cmd -> ctx -> IO -> Result
+		return F.Pipe3(
+			ctx,
+			effect(cmd),
+			io.Run,
+			// Convert Result[Void] to error
+			ET.Fold(F.Identity[error], F.Constant1[F.Void, error](nil)),
+		)
+	}
+}
+
+// FromAction converts a standard urfave/cli Action function into a CommandEffect.
+// This allows existing cli/v3 action handlers to be lifted into the Effect type.
+//
+// The conversion process:
+//  1. Takes a standard action function (context.Context, *C.Command) -> error
+//  2. Wraps it in the Effect structure
+//  3. Converts the error result to a Result type
+//
+// # Parameters
+//
+//   - action: The standard cli/v3 action function to convert
+//
+// # Returns
+//
+//   - A CommandEffect that wraps the original action
+//
+// # Example Usage
+//
+//	standardAction := func(ctx context.Context, cmd *C.Command) error {
+//	    // Existing command logic
+//	    return nil
+//	}
+//	effect := FromAction(standardAction)
+//	// Now can be composed with other Effects
+func FromAction(action func(context.Context, *C.Command) error) CommandEffect {
+	return func(cmd *C.Command) E.Thunk[F.Void] {
+		return func(ctx context.Context) E.IOResult[F.Void] {
+			return func() R.Result[F.Void] {
+				err := action(ctx, cmd)
+				if err != nil {
+					return R.Left[F.Void](err)
+				}
+				return R.Of(F.Void{})
+			}
+		}
+	}
+}
+
+// MakeCommand creates a new Command with an Effect-based action.
+// This is a convenience function that combines command creation with Effect conversion.
+//
+// # Parameters
+//
+//   - name: The command name
+//   - usage: The command usage description
+//   - flags: The command flags
+//   - effect: The CommandEffect to use as the action
+//
+// # Returns
+//
+//   - A *C.Command configured with the Effect-based action
+//
+// # Example Usage
+//
+//	cmd := MakeCommand(
+//	    "process",
+//	    "Process data files",
+//	    []C.Flag{
+//	        &C.StringFlag{Name: "input", Usage: "Input file"},
+//	    },
+//	    func(cmd *C.Command) E.Thunk[F.Void] {
+//	        return func(ctx context.Context) E.IOResult[F.Void] {
+//	            return func() R.Result[F.Void] {
+//	                input := cmd.String("input")
+//	                // Process input...
+//	                return R.Of(F.Void{})
+//	            }
+//	        }
+//	    },
+//	)
+func MakeCommand(
+	name string,
+	usage string,
+	flags []C.Flag,
+	effect CommandEffect,
+) *C.Command {
+	return &C.Command{
+		Name:   name,
+		Usage:  usage,
+		Flags:  flags,
+		Action: ToAction(effect),
+	}
+}
+
+// MakeCommandWithSubcommands creates a new Command with subcommands and an Effect-based action.
+//
+// # Parameters
+//
+//   - name: The command name
+//   - usage: The command usage description
+//   - flags: The command flags
+//   - commands: The subcommands
+//   - effect: The CommandEffect to use as the action
+//
+// # Returns
+//
+//   - A *C.Command configured with subcommands and the Effect-based action
+//
+// # Example Usage
+//
+//	cmd := MakeCommandWithSubcommands(
+//	    "app",
+//	    "Application commands",
+//	    []C.Flag{},
+//	    []*C.Command{subCmd1, subCmd2},
+//	    defaultEffect,
+//	)
+func MakeCommandWithSubcommands(
+	name string,
+	usage string,
+	flags []C.Flag,
+	commands []*C.Command,
+	effect CommandEffect,
+) *C.Command {
+	return &C.Command{
+		Name:     name,
+		Usage:    usage,
+		Flags:    flags,
+		Commands: commands,
+		Action:   ToAction(effect),
+	}
+}

v2/cli/effect_test.go

@@ -0,0 +1,204 @@
+// 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 (
+	"context"
+	"errors"
+	"testing"
+
+	E "github.com/IBM/fp-go/v2/effect"
+	F "github.com/IBM/fp-go/v2/function"
+	R "github.com/IBM/fp-go/v2/result"
+	"github.com/stretchr/testify/assert"
+	C "github.com/urfave/cli/v3"
+)
+
+func TestToAction_Success(t *testing.T) {
+	t.Run("converts successful Effect to action", func(t *testing.T) {
+		// Arrange
+		effect := func(cmd *C.Command) E.Thunk[F.Void] {
+			return func(ctx context.Context) E.IOResult[F.Void] {
+				return func() R.Result[F.Void] {
+					return R.Of(F.Void{})
+				}
+			}
+		}
+		action := ToAction(effect)
+		cmd := &C.Command{Name: "test"}
+
+		// Act
+		err := action(context.Background(), cmd)
+
+		// Assert
+		assert.NoError(t, err)
+	})
+}
+
+func TestToAction_Failure(t *testing.T) {
+	t.Run("converts failed Effect to error", func(t *testing.T) {
+		// Arrange
+		expectedErr := errors.New("test error")
+		effect := func(cmd *C.Command) E.Thunk[F.Void] {
+			return func(ctx context.Context) E.IOResult[F.Void] {
+				return func() R.Result[F.Void] {
+					return R.Left[F.Void](expectedErr)
+				}
+			}
+		}
+		action := ToAction(effect)
+		cmd := &C.Command{Name: "test"}
+
+		// Act
+		err := action(context.Background(), cmd)
+
+		// Assert
+		assert.Error(t, err)
+		assert.Equal(t, expectedErr, err)
+	})
+}
+
+func TestFromAction_Success(t *testing.T) {
+	t.Run("converts successful action to Effect", func(t *testing.T) {
+		// Arrange
+		action := func(ctx context.Context, cmd *C.Command) error {
+			return nil
+		}
+		effect := FromAction(action)
+		cmd := &C.Command{Name: "test"}
+
+		// Act
+		result := effect(cmd)(context.Background())()
+
+		// Assert
+		assert.True(t, R.IsRight(result))
+	})
+}
+
+func TestFromAction_Failure(t *testing.T) {
+	t.Run("converts failed action to Effect", func(t *testing.T) {
+		// Arrange
+		expectedErr := errors.New("test error")
+		action := func(ctx context.Context, cmd *C.Command) error {
+			return expectedErr
+		}
+		effect := FromAction(action)
+		cmd := &C.Command{Name: "test"}
+
+		// Act
+		result := effect(cmd)(context.Background())()
+
+		// Assert
+		assert.True(t, R.IsLeft(result))
+		err := R.MonadFold(result, F.Identity[error], func(F.Void) error { return nil })
+		assert.Equal(t, expectedErr, err)
+	})
+}
+
+func TestMakeCommand(t *testing.T) {
+	t.Run("creates command with Effect-based action", func(t *testing.T) {
+		// Arrange
+		effect := func(cmd *C.Command) E.Thunk[F.Void] {
+			return func(ctx context.Context) E.IOResult[F.Void] {
+				return func() R.Result[F.Void] {
+					return R.Of(F.Void{})
+				}
+			}
+		}
+
+		// Act
+		cmd := MakeCommand(
+			"test",
+			"Test command",
+			[]C.Flag{},
+			effect,
+		)
+
+		// Assert
+		assert.NotNil(t, cmd)
+		assert.Equal(t, "test", cmd.Name)
+		assert.Equal(t, "Test command", cmd.Usage)
+		assert.NotNil(t, cmd.Action)
+
+		// Test the action
+		err := cmd.Action(context.Background(), cmd)
+		assert.NoError(t, err)
+	})
+}
+
+func TestMakeCommandWithSubcommands(t *testing.T) {
+	t.Run("creates command with subcommands and Effect-based action", func(t *testing.T) {
+		// Arrange
+		subCmd := &C.Command{Name: "sub"}
+		effect := func(cmd *C.Command) E.Thunk[F.Void] {
+			return func(ctx context.Context) E.IOResult[F.Void] {
+				return func() R.Result[F.Void] {
+					return R.Of(F.Void{})
+				}
+			}
+		}
+
+		// Act
+		cmd := MakeCommandWithSubcommands(
+			"parent",
+			"Parent command",
+			[]C.Flag{},
+			[]*C.Command{subCmd},
+			effect,
+		)
+
+		// Assert
+		assert.NotNil(t, cmd)
+		assert.Equal(t, "parent", cmd.Name)
+		assert.Equal(t, "Parent command", cmd.Usage)
+		assert.Len(t, cmd.Commands, 1)
+		assert.Equal(t, "sub", cmd.Commands[0].Name)
+		assert.NotNil(t, cmd.Action)
+	})
+}
+
+func TestToAction_Integration(t *testing.T) {
+	t.Run("Effect can access command flags", func(t *testing.T) {
+		// Arrange
+		var capturedValue string
+		effect := func(cmd *C.Command) E.Thunk[F.Void] {
+			return func(ctx context.Context) E.IOResult[F.Void] {
+				return func() R.Result[F.Void] {
+					capturedValue = cmd.String("input")
+					return R.Of(F.Void{})
+				}
+			}
+		}
+
+		cmd := &C.Command{
+			Name: "test",
+			Flags: []C.Flag{
+				&C.StringFlag{
+					Name:  "input",
+					Value: "default-value",
+				},
+			},
+			Action: ToAction(effect),
+		}
+
+		// Act
+		err := cmd.Action(context.Background(), cmd)
+
+		// Assert
+		assert.NoError(t, err)
+		assert.Equal(t, "default-value", capturedValue)
+	})
+}

v2/cli/flags.go

@@ -0,0 +1,359 @@
+// 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 (
+	P "github.com/IBM/fp-go/v2/optics/prism"
+	O "github.com/IBM/fp-go/v2/option"
+	C "github.com/urfave/cli/v3"
+)
+
+// StringFlagPrism creates a Prism for extracting a StringFlag from a Flag.
+// This provides a type-safe way to work with string flags, handling type
+// mismatches gracefully through the Option type.
+//
+// The prism's GetOption attempts to cast a Flag to *C.StringFlag.
+// If the cast succeeds, it returns Some(*C.StringFlag); if it fails, it returns None.
+//
+// The prism's ReverseGet converts a *C.StringFlag back to a Flag.
+//
+// # Returns
+//
+//   - A Prism[C.Flag, *C.StringFlag] for safe StringFlag extraction
+//
+// # Example Usage
+//
+//	prism := StringFlagPrism()
+//
+//	// Extract StringFlag from Flag
+//	var flag C.Flag = &C.StringFlag{Name: "input", Value: "default"}
+//	result := prism.GetOption(flag)  // Some(*C.StringFlag{...})
+//
+//	// Type mismatch returns None
+//	var intFlag C.Flag = &C.IntFlag{Name: "count"}
+//	result = prism.GetOption(intFlag)  // None[*C.StringFlag]()
+//
+//	// Convert back to Flag
+//	strFlag := &C.StringFlag{Name: "output"}
+//	flag = prism.ReverseGet(strFlag)
+func StringFlagPrism() P.Prism[C.Flag, *C.StringFlag] {
+	return P.MakePrism(
+		func(flag C.Flag) O.Option[*C.StringFlag] {
+			if sf, ok := flag.(*C.StringFlag); ok {
+				return O.Some(sf)
+			}
+			return O.None[*C.StringFlag]()
+		},
+		func(f *C.StringFlag) C.Flag { return f },
+	)
+}
+
+// IntFlagPrism creates a Prism for extracting an IntFlag from a Flag.
+// This provides a type-safe way to work with integer flags, handling type
+// mismatches gracefully through the Option type.
+//
+// # Returns
+//
+//   - A Prism[C.Flag, *C.IntFlag] for safe IntFlag extraction
+//
+// # Example Usage
+//
+//	prism := IntFlagPrism()
+//
+//	// Extract IntFlag from Flag
+//	var flag C.Flag = &C.IntFlag{Name: "count", Value: 10}
+//	result := prism.GetOption(flag)  // Some(*C.IntFlag{...})
+func IntFlagPrism() P.Prism[C.Flag, *C.IntFlag] {
+	return P.MakePrism(
+		func(flag C.Flag) O.Option[*C.IntFlag] {
+			if f, ok := flag.(*C.IntFlag); ok {
+				return O.Some(f)
+			}
+			return O.None[*C.IntFlag]()
+		},
+		func(f *C.IntFlag) C.Flag { return f },
+	)
+}
+
+// BoolFlagPrism creates a Prism for extracting a BoolFlag from a Flag.
+// This provides a type-safe way to work with boolean flags, handling type
+// mismatches gracefully through the Option type.
+//
+// # Returns
+//
+//   - A Prism[C.Flag, *C.BoolFlag] for safe BoolFlag extraction
+//
+// # Example Usage
+//
+//	prism := BoolFlagPrism()
+//
+//	// Extract BoolFlag from Flag
+//	var flag C.Flag = &C.BoolFlag{Name: "verbose", Value: true}
+//	result := prism.GetOption(flag)  // Some(*C.BoolFlag{...})
+func BoolFlagPrism() P.Prism[C.Flag, *C.BoolFlag] {
+	return P.MakePrism(
+		func(flag C.Flag) O.Option[*C.BoolFlag] {
+			if f, ok := flag.(*C.BoolFlag); ok {
+				return O.Some(f)
+			}
+			return O.None[*C.BoolFlag]()
+		},
+		func(f *C.BoolFlag) C.Flag { return f },
+	)
+}
+
+// Float64FlagPrism creates a Prism for extracting a Float64Flag from a Flag.
+// This provides a type-safe way to work with float64 flags, handling type
+// mismatches gracefully through the Option type.
+//
+// # Returns
+//
+//   - A Prism[C.Flag, *C.Float64Flag] for safe Float64Flag extraction
+//
+// # Example Usage
+//
+//	prism := Float64FlagPrism()
+//
+//	// Extract Float64Flag from Flag
+//	var flag C.Flag = &C.Float64Flag{Name: "ratio", Value: 0.5}
+//	result := prism.GetOption(flag)  // Some(*C.Float64Flag{...})
+func Float64FlagPrism() P.Prism[C.Flag, *C.Float64Flag] {
+	return P.MakePrism(
+		func(flag C.Flag) O.Option[*C.Float64Flag] {
+			if f, ok := flag.(*C.Float64Flag); ok {
+				return O.Some(f)
+			}
+			return O.None[*C.Float64Flag]()
+		},
+		func(f *C.Float64Flag) C.Flag { return f },
+	)
+}
+
+// DurationFlagPrism creates a Prism for extracting a DurationFlag from a Flag.
+// This provides a type-safe way to work with duration flags, handling type
+// mismatches gracefully through the Option type.
+//
+// # Returns
+//
+//   - A Prism[C.Flag, *C.DurationFlag] for safe DurationFlag extraction
+//
+// # Example Usage
+//
+//	prism := DurationFlagPrism()
+//
+//	// Extract DurationFlag from Flag
+//	var flag C.Flag = &C.DurationFlag{Name: "timeout", Value: 30 * time.Second}
+//	result := prism.GetOption(flag)  // Some(*C.DurationFlag{...})
+func DurationFlagPrism() P.Prism[C.Flag, *C.DurationFlag] {
+	return P.MakePrism(
+		func(flag C.Flag) O.Option[*C.DurationFlag] {
+			if f, ok := flag.(*C.DurationFlag); ok {
+				return O.Some(f)
+			}
+			return O.None[*C.DurationFlag]()
+		},
+		func(f *C.DurationFlag) C.Flag { return f },
+	)
+}
+
+// TimestampFlagPrism creates a Prism for extracting a TimestampFlag from a Flag.
+// This provides a type-safe way to work with timestamp flags, handling type
+// mismatches gracefully through the Option type.
+//
+// # Returns
+//
+//   - A Prism[C.Flag, *C.TimestampFlag] for safe TimestampFlag extraction
+//
+// # Example Usage
+//
+//	prism := TimestampFlagPrism()
+//
+//	// Extract TimestampFlag from Flag
+//	var flag C.Flag = &C.TimestampFlag{Name: "created"}
+//	result := prism.GetOption(flag)  // Some(*C.TimestampFlag{...})
+func TimestampFlagPrism() P.Prism[C.Flag, *C.TimestampFlag] {
+	return P.MakePrism(
+		func(flag C.Flag) O.Option[*C.TimestampFlag] {
+			if f, ok := flag.(*C.TimestampFlag); ok {
+				return O.Some(f)
+			}
+			return O.None[*C.TimestampFlag]()
+		},
+		func(f *C.TimestampFlag) C.Flag { return f },
+	)
+}
+
+// StringSliceFlagPrism creates a Prism for extracting a StringSliceFlag from a Flag.
+// This provides a type-safe way to work with string slice flags, handling type
+// mismatches gracefully through the Option type.
+//
+// # Returns
+//
+//   - A Prism[C.Flag, *C.StringSliceFlag] for safe StringSliceFlag extraction
+//
+// # Example Usage
+//
+//	prism := StringSliceFlagPrism()
+//
+//	// Extract StringSliceFlag from Flag
+//	var flag C.Flag = &C.StringSliceFlag{Name: "tags"}
+//	result := prism.GetOption(flag)  // Some(*C.StringSliceFlag{...})
+func StringSliceFlagPrism() P.Prism[C.Flag, *C.StringSliceFlag] {
+	return P.MakePrism(
+		func(flag C.Flag) O.Option[*C.StringSliceFlag] {
+			if f, ok := flag.(*C.StringSliceFlag); ok {
+				return O.Some(f)
+			}
+			return O.None[*C.StringSliceFlag]()
+		},
+		func(f *C.StringSliceFlag) C.Flag { return f },
+	)
+}
+
+// IntSliceFlagPrism creates a Prism for extracting an IntSliceFlag from a Flag.
+// This provides a type-safe way to work with int slice flags, handling type
+// mismatches gracefully through the Option type.
+//
+// # Returns
+//
+//   - A Prism[C.Flag, *C.IntSliceFlag] for safe IntSliceFlag extraction
+//
+// # Example Usage
+//
+//	prism := IntSliceFlagPrism()
+//
+//	// Extract IntSliceFlag from Flag
+//	var flag C.Flag = &C.IntSliceFlag{Name: "ports"}
+//	result := prism.GetOption(flag)  // Some(*C.IntSliceFlag{...})
+func IntSliceFlagPrism() P.Prism[C.Flag, *C.IntSliceFlag] {
+	return P.MakePrism(
+		func(flag C.Flag) O.Option[*C.IntSliceFlag] {
+			if f, ok := flag.(*C.IntSliceFlag); ok {
+				return O.Some(f)
+			}
+			return O.None[*C.IntSliceFlag]()
+		},
+		func(f *C.IntSliceFlag) C.Flag { return f },
+	)
+}
+
+// Float64SliceFlagPrism creates a Prism for extracting a Float64SliceFlag from a Flag.
+// This provides a type-safe way to work with float64 slice flags, handling type
+// mismatches gracefully through the Option type.
+//
+// # Returns
+//
+//   - A Prism[C.Flag, *C.Float64SliceFlag] for safe Float64SliceFlag extraction
+//
+// # Example Usage
+//
+//	prism := Float64SliceFlagPrism()
+//
+//	// Extract Float64SliceFlag from Flag
+//	var flag C.Flag = &C.Float64SliceFlag{Name: "ratios"}
+//	result := prism.GetOption(flag)  // Some(*C.Float64SliceFlag{...})
+func Float64SliceFlagPrism() P.Prism[C.Flag, *C.Float64SliceFlag] {
+	return P.MakePrism(
+		func(flag C.Flag) O.Option[*C.Float64SliceFlag] {
+			if f, ok := flag.(*C.Float64SliceFlag); ok {
+				return O.Some(f)
+			}
+			return O.None[*C.Float64SliceFlag]()
+		},
+		func(f *C.Float64SliceFlag) C.Flag { return f },
+	)
+}
+
+// UintFlagPrism creates a Prism for extracting a UintFlag from a Flag.
+// This provides a type-safe way to work with unsigned integer flags, handling type
+// mismatches gracefully through the Option type.
+//
+// # Returns
+//
+//   - A Prism[C.Flag, *C.UintFlag] for safe UintFlag extraction
+//
+// # Example Usage
+//
+//	prism := UintFlagPrism()
+//
+//	// Extract UintFlag from Flag
+//	var flag C.Flag = &C.UintFlag{Name: "workers", Value: 4}
+//	result := prism.GetOption(flag)  // Some(*C.UintFlag{...})
+func UintFlagPrism() P.Prism[C.Flag, *C.UintFlag] {
+	return P.MakePrism(
+		func(flag C.Flag) O.Option[*C.UintFlag] {
+			if f, ok := flag.(*C.UintFlag); ok {
+				return O.Some(f)
+			}
+			return O.None[*C.UintFlag]()
+		},
+		func(f *C.UintFlag) C.Flag { return f },
+	)
+}
+
+// Uint64FlagPrism creates a Prism for extracting a Uint64Flag from a Flag.
+// This provides a type-safe way to work with uint64 flags, handling type
+// mismatches gracefully through the Option type.
+//
+// # Returns
+//
+//   - A Prism[C.Flag, *C.Uint64Flag] for safe Uint64Flag extraction
+//
+// # Example Usage
+//
+//	prism := Uint64FlagPrism()
+//
+//	// Extract Uint64Flag from Flag
+//	var flag C.Flag = &C.Uint64Flag{Name: "size"}
+//	result := prism.GetOption(flag)  // Some(*C.Uint64Flag{...})
+func Uint64FlagPrism() P.Prism[C.Flag, *C.Uint64Flag] {
+	return P.MakePrism(
+		func(flag C.Flag) O.Option[*C.Uint64Flag] {
+			if f, ok := flag.(*C.Uint64Flag); ok {
+				return O.Some(f)
+			}
+			return O.None[*C.Uint64Flag]()
+		},
+		func(f *C.Uint64Flag) C.Flag { return f },
+	)
+}
+
+// Int64FlagPrism creates a Prism for extracting an Int64Flag from a Flag.
+// This provides a type-safe way to work with int64 flags, handling type
+// mismatches gracefully through the Option type.
+//
+// # Returns
+//
+//   - A Prism[C.Flag, *C.Int64Flag] for safe Int64Flag extraction
+//
+// # Example Usage
+//
+//	prism := Int64FlagPrism()
+//
+//	// Extract Int64Flag from Flag
+//	var flag C.Flag = &C.Int64Flag{Name: "offset"}
+//	result := prism.GetOption(flag)  // Some(*C.Int64Flag{...})
+func Int64FlagPrism() P.Prism[C.Flag, *C.Int64Flag] {
+	return P.MakePrism(
+		func(flag C.Flag) O.Option[*C.Int64Flag] {
+			if f, ok := flag.(*C.Int64Flag); ok {
+				return O.Some(f)
+			}
+			return O.None[*C.Int64Flag]()
+		},
+		func(f *C.Int64Flag) C.Flag { return f },
+	)
+}

v2/cli/flags_test.go

@@ -0,0 +1,287 @@
+// 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 (
+	"testing"
+	"time"
+
+	O "github.com/IBM/fp-go/v2/option"
+	"github.com/stretchr/testify/assert"
+	C "github.com/urfave/cli/v3"
+)
+
+func TestStringFlagPrism_Success(t *testing.T) {
+	t.Run("extracts StringFlag from Flag", func(t *testing.T) {
+		// Arrange
+		prism := StringFlagPrism()
+		var flag C.Flag = &C.StringFlag{Name: "input", Value: "test"}
+
+		// Act
+		result := prism.GetOption(flag)
+
+		// Assert
+		assert.True(t, O.IsSome(result))
+		extracted := O.MonadFold(result, func() *C.StringFlag { return nil }, func(f *C.StringFlag) *C.StringFlag { return f })
+		assert.NotNil(t, extracted)
+		assert.Equal(t, "input", extracted.Name)
+		assert.Equal(t, "test", extracted.Value)
+	})
+}
+
+func TestStringFlagPrism_Failure(t *testing.T) {
+	t.Run("returns None for non-StringFlag", func(t *testing.T) {
+		// Arrange
+		prism := StringFlagPrism()
+		var flag C.Flag = &C.IntFlag{Name: "count"}
+
+		// Act
+		result := prism.GetOption(flag)
+
+		// Assert
+		assert.True(t, O.IsNone(result))
+	})
+}
+
+func TestStringFlagPrism_ReverseGet(t *testing.T) {
+	t.Run("converts StringFlag back to Flag", func(t *testing.T) {
+		// Arrange
+		prism := StringFlagPrism()
+		strFlag := &C.StringFlag{Name: "output", Value: "result"}
+
+		// Act
+		flag := prism.ReverseGet(strFlag)
+
+		// Assert
+		assert.NotNil(t, flag)
+		assert.IsType(t, &C.StringFlag{}, flag)
+	})
+}
+
+func TestIntFlagPrism_Success(t *testing.T) {
+	t.Run("extracts IntFlag from Flag", func(t *testing.T) {
+		// Arrange
+		prism := IntFlagPrism()
+		var flag C.Flag = &C.IntFlag{Name: "count", Value: 42}
+
+		// Act
+		result := prism.GetOption(flag)
+
+		// Assert
+		assert.True(t, O.IsSome(result))
+		extracted := O.MonadFold(result, func() *C.IntFlag { return nil }, func(f *C.IntFlag) *C.IntFlag { return f })
+		assert.NotNil(t, extracted)
+		assert.Equal(t, "count", extracted.Name)
+		assert.Equal(t, 42, extracted.Value)
+	})
+}
+
+func TestBoolFlagPrism_Success(t *testing.T) {
+	t.Run("extracts BoolFlag from Flag", func(t *testing.T) {
+		// Arrange
+		prism := BoolFlagPrism()
+		var flag C.Flag = &C.BoolFlag{Name: "verbose", Value: true}
+
+		// Act
+		result := prism.GetOption(flag)
+
+		// Assert
+		assert.True(t, O.IsSome(result))
+		extracted := O.MonadFold(result, func() *C.BoolFlag { return nil }, func(f *C.BoolFlag) *C.BoolFlag { return f })
+		assert.NotNil(t, extracted)
+		assert.Equal(t, "verbose", extracted.Name)
+		assert.Equal(t, true, extracted.Value)
+	})
+}
+
+func TestFloat64FlagPrism_Success(t *testing.T) {
+	t.Run("extracts Float64Flag from Flag", func(t *testing.T) {
+		// Arrange
+		prism := Float64FlagPrism()
+		var flag C.Flag = &C.Float64Flag{Name: "ratio", Value: 0.5}
+
+		// Act
+		result := prism.GetOption(flag)
+
+		// Assert
+		assert.True(t, O.IsSome(result))
+		extracted := O.MonadFold(result, func() *C.Float64Flag { return nil }, func(f *C.Float64Flag) *C.Float64Flag { return f })
+		assert.NotNil(t, extracted)
+		assert.Equal(t, "ratio", extracted.Name)
+		assert.Equal(t, 0.5, extracted.Value)
+	})
+}
+
+func TestDurationFlagPrism_Success(t *testing.T) {
+	t.Run("extracts DurationFlag from Flag", func(t *testing.T) {
+		// Arrange
+		prism := DurationFlagPrism()
+		duration := 30 * time.Second
+		var flag C.Flag = &C.DurationFlag{Name: "timeout", Value: duration}
+
+		// Act
+		result := prism.GetOption(flag)
+
+		// Assert
+		assert.True(t, O.IsSome(result))
+		extracted := O.MonadFold(result, func() *C.DurationFlag { return nil }, func(f *C.DurationFlag) *C.DurationFlag { return f })
+		assert.NotNil(t, extracted)
+		assert.Equal(t, "timeout", extracted.Name)
+		assert.Equal(t, duration, extracted.Value)
+	})
+}
+
+func TestTimestampFlagPrism_Success(t *testing.T) {
+	t.Run("extracts TimestampFlag from Flag", func(t *testing.T) {
+		// Arrange
+		prism := TimestampFlagPrism()
+		var flag C.Flag = &C.TimestampFlag{Name: "created"}
+
+		// Act
+		result := prism.GetOption(flag)
+
+		// Assert
+		assert.True(t, O.IsSome(result))
+		extracted := O.MonadFold(result, func() *C.TimestampFlag { return nil }, func(f *C.TimestampFlag) *C.TimestampFlag { return f })
+		assert.NotNil(t, extracted)
+		assert.Equal(t, "created", extracted.Name)
+	})
+}
+
+func TestStringSliceFlagPrism_Success(t *testing.T) {
+	t.Run("extracts StringSliceFlag from Flag", func(t *testing.T) {
+		// Arrange
+		prism := StringSliceFlagPrism()
+		var flag C.Flag = &C.StringSliceFlag{Name: "tags"}
+
+		// Act
+		result := prism.GetOption(flag)
+
+		// Assert
+		assert.True(t, O.IsSome(result))
+		extracted := O.MonadFold(result, func() *C.StringSliceFlag { return nil }, func(f *C.StringSliceFlag) *C.StringSliceFlag { return f })
+		assert.NotNil(t, extracted)
+		assert.Equal(t, "tags", extracted.Name)
+	})
+}
+
+func TestIntSliceFlagPrism_Success(t *testing.T) {
+	t.Run("extracts IntSliceFlag from Flag", func(t *testing.T) {
+		// Arrange
+		prism := IntSliceFlagPrism()
+		var flag C.Flag = &C.IntSliceFlag{Name: "ports"}
+
+		// Act
+		result := prism.GetOption(flag)
+
+		// Assert
+		assert.True(t, O.IsSome(result))
+		extracted := O.MonadFold(result, func() *C.IntSliceFlag { return nil }, func(f *C.IntSliceFlag) *C.IntSliceFlag { return f })
+		assert.NotNil(t, extracted)
+		assert.Equal(t, "ports", extracted.Name)
+	})
+}
+
+func TestFloat64SliceFlagPrism_Success(t *testing.T) {
+	t.Run("extracts Float64SliceFlag from Flag", func(t *testing.T) {
+		// Arrange
+		prism := Float64SliceFlagPrism()
+		var flag C.Flag = &C.Float64SliceFlag{Name: "ratios"}
+
+		// Act
+		result := prism.GetOption(flag)
+
+		// Assert
+		assert.True(t, O.IsSome(result))
+		extracted := O.MonadFold(result, func() *C.Float64SliceFlag { return nil }, func(f *C.Float64SliceFlag) *C.Float64SliceFlag { return f })
+		assert.NotNil(t, extracted)
+		assert.Equal(t, "ratios", extracted.Name)
+	})
+}
+
+func TestUintFlagPrism_Success(t *testing.T) {
+	t.Run("extracts UintFlag from Flag", func(t *testing.T) {
+		// Arrange
+		prism := UintFlagPrism()
+		var flag C.Flag = &C.UintFlag{Name: "workers", Value: 4}
+
+		// Act
+		result := prism.GetOption(flag)
+
+		// Assert
+		assert.True(t, O.IsSome(result))
+		extracted := O.MonadFold(result, func() *C.UintFlag { return nil }, func(f *C.UintFlag) *C.UintFlag { return f })
+		assert.NotNil(t, extracted)
+		assert.Equal(t, "workers", extracted.Name)
+		assert.Equal(t, uint(4), extracted.Value)
+	})
+}
+
+func TestUint64FlagPrism_Success(t *testing.T) {
+	t.Run("extracts Uint64Flag from Flag", func(t *testing.T) {
+		// Arrange
+		prism := Uint64FlagPrism()
+		var flag C.Flag = &C.Uint64Flag{Name: "size", Value: 1024}
+
+		// Act
+		result := prism.GetOption(flag)
+
+		// Assert
+		assert.True(t, O.IsSome(result))
+		extracted := O.MonadFold(result, func() *C.Uint64Flag { return nil }, func(f *C.Uint64Flag) *C.Uint64Flag { return f })
+		assert.NotNil(t, extracted)
+		assert.Equal(t, "size", extracted.Name)
+		assert.Equal(t, uint64(1024), extracted.Value)
+	})
+}
+
+func TestInt64FlagPrism_Success(t *testing.T) {
+	t.Run("extracts Int64Flag from Flag", func(t *testing.T) {
+		// Arrange
+		prism := Int64FlagPrism()
+		var flag C.Flag = &C.Int64Flag{Name: "offset", Value: -100}
+
+		// Act
+		result := prism.GetOption(flag)
+
+		// Assert
+		assert.True(t, O.IsSome(result))
+		extracted := O.MonadFold(result, func() *C.Int64Flag { return nil }, func(f *C.Int64Flag) *C.Int64Flag { return f })
+		assert.NotNil(t, extracted)
+		assert.Equal(t, "offset", extracted.Name)
+		assert.Equal(t, int64(-100), extracted.Value)
+	})
+}
+
+func TestPrisms_EdgeCases(t *testing.T) {
+	t.Run("all prisms return None for wrong type", func(t *testing.T) {
+		// Arrange
+		var flag C.Flag = &C.StringFlag{Name: "test"}
+
+		// Act & Assert
+		assert.True(t, O.IsNone(IntFlagPrism().GetOption(flag)))
+		assert.True(t, O.IsNone(BoolFlagPrism().GetOption(flag)))
+		assert.True(t, O.IsNone(Float64FlagPrism().GetOption(flag)))
+		assert.True(t, O.IsNone(DurationFlagPrism().GetOption(flag)))
+		assert.True(t, O.IsNone(TimestampFlagPrism().GetOption(flag)))
+		assert.True(t, O.IsNone(StringSliceFlagPrism().GetOption(flag)))
+		assert.True(t, O.IsNone(IntSliceFlagPrism().GetOption(flag)))
+		assert.True(t, O.IsNone(Float64SliceFlagPrism().GetOption(flag)))
+		assert.True(t, O.IsNone(UintFlagPrism().GetOption(flag)))
+		assert.True(t, O.IsNone(Uint64FlagPrism().GetOption(flag)))
+		assert.True(t, O.IsNone(Int64FlagPrism().GetOption(flag)))
+	})
+}

v2/context/readerioresult/cancel.go

@@ -21,6 +21,7 @@ import (
 	CIOE "github.com/IBM/fp-go/v2/context/ioresult"
 	F "github.com/IBM/fp-go/v2/function"
 	"github.com/IBM/fp-go/v2/ioeither"
+	"github.com/IBM/fp-go/v2/pair"
 )
 
 // WithContext wraps an existing [ReaderIOResult] and performs a context check for cancellation before delegating.
@@ -85,3 +86,7 @@ func WithContextK[A, B any](f Kleisli[A, B]) Kleisli[A, B] {
 		WithContext,
 	)
 }
+
+func pairFromContextCancel(newCtx context.Context, cancelFct context.CancelFunc) ContextCancel {
+	return pair.MakePair(cancelFct, newCtx)
+}

v2/context/readerioresult/file/file.go

@@ -13,6 +13,25 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// Package file provides context-aware file operations that integrate with the ReaderIOResult monad.
+// It offers safe, composable file I/O operations that respect context cancellation and properly
+// manage resources using the RAII pattern.
+//
+// All operations in this package:
+//   - Respect context.Context for cancellation and timeouts
+//   - Return ReaderIOResult for composable error handling
+//   - Automatically manage resource cleanup
+//   - Are safe to use in concurrent environments
+//
+// # Example Usage
+//
+//	// Read a file with automatic resource management
+//	readOp := ReadFile("data.txt")
+//	result := readOp(ctx)()
+//
+//	// Open and manually manage a file
+//	fileOp := Open("config.json")
+//	fileResult := fileOp(ctx)()
 package file
 
 import (
@@ -29,32 +48,142 @@ import (
 )
 
 var (
-	// Open opens a file for reading within the given context
+	// Open opens a file for reading within the given context.
+	// The operation respects context cancellation and returns a ReaderIOResult
+	// that produces an os.File handle on success.
+	//
+	// The returned file handle should be closed using the Close function when no longer needed,
+	// or managed automatically using WithResource or ReadFile.
+	//
+	// Parameters:
+	//   - path: The path to the file to open
+	//
+	// Returns:
+	//   - ReaderIOResult[*os.File]: A context-aware computation that opens the file
+	//
+	// Example:
+	//
+	//	openFile := Open("data.txt")
+	//	result := openFile(ctx)()
+	//	either.Fold(
+	//	    result,
+	//	    func(err error) { log.Printf("Error: %v", err) },
+	//	    func(f *os.File) {
+	//	        defer f.Close()
+	//	        // Use file...
+	//	    },
+	//	)
+	//
+	// See Also:
+	//   - ReadFile: For reading entire file contents with automatic resource management
+	//   - Close: For closing file handles
 	Open = F.Flow3(
 		IOEF.Open,
 		RIOE.FromIOEither[*os.File],
 		RIOE.WithContext[*os.File],
 	)
 
-	// Remove removes a file by name
+	// Remove removes a file by name.
+	// The operation returns the filename on success, allowing for easy composition
+	// with other file operations.
+	//
+	// Parameters:
+	//   - name: The path to the file to remove
+	//
+	// Returns:
+	//   - ReaderIOResult[string]: A computation that removes the file and returns its name
+	//
+	// Example:
+	//
+	//	removeOp := Remove("temp.txt")
+	//	result := removeOp(ctx)()
+	//	either.Fold(
+	//	    result,
+	//	    func(err error) { log.Printf("Failed to remove: %v", err) },
+	//	    func(name string) { log.Printf("Removed: %s", name) },
+	//	)
+	//
+	// See Also:
+	//   - Open: For opening files
+	//   - ReadFile: For reading file contents
 	Remove = F.Flow2(
 		IOEF.Remove,
 		RIOE.FromIOEither[string],
 	)
 )
 
-// Close closes an object
-func Close[C io.Closer](c C) RIOE.ReaderIOResult[struct{}] {
+// Close closes an io.Closer resource and returns a ReaderIOResult.
+// This function is generic and works with any type that implements io.Closer,
+// including os.File, network connections, and other closeable resources.
+//
+// The function captures any error that occurs during closing and returns it
+// as part of the ReaderIOResult. On success, it returns Void (empty struct).
+//
+// Type Parameters:
+//   - C: Any type that implements io.Closer
+//
+// Parameters:
+//   - c: The resource to close
+//
+// Returns:
+//   - ReaderIOResult[Void]: A computation that closes the resource
+//
+// Example:
+//
+//	file, _ := os.Open("data.txt")
+//	closeOp := Close(file)
+//	result := closeOp(ctx)()
+//
+// Note: This function is typically used with WithResource for automatic resource management
+// rather than being called directly.
+//
+// See Also:
+//   - Open: For opening files
+//   - ReadFile: For reading files with automatic closing
+func Close[C io.Closer](c C) ReaderIOResult[Void] {
 	return F.Pipe2(
 		c,
 		IOEF.Close[C],
-		RIOE.FromIOEither[struct{}],
+		RIOE.FromIOEither[Void],
 	)
 }
 
-// ReadFile reads a file in the scope of a context
-func ReadFile(path string) RIOE.ReaderIOResult[[]byte] {
-	return RIOE.WithResource[[]byte](Open(path), Close[*os.File])(func(r *os.File) RIOE.ReaderIOResult[[]byte] {
+// ReadFile reads the entire contents of a file in a context-aware manner.
+// This function automatically manages the file resource using the RAII pattern,
+// ensuring the file is properly closed even if an error occurs or the context is canceled.
+//
+// The operation:
+//   - Opens the file for reading
+//   - Reads all contents into a byte slice
+//   - Automatically closes the file when done
+//   - Respects context cancellation during the read operation
+//
+// Parameters:
+//   - path: The path to the file to read
+//
+// Returns:
+//   - ReaderIOResult[[]byte]: A computation that reads the file contents
+//
+// Example:
+//
+//	readOp := ReadFile("config.json")
+//	result := readOp(ctx)()
+//	either.Fold(
+//	    result,
+//	    func(err error) { log.Printf("Read error: %v", err) },
+//	    func(data []byte) { log.Printf("Read %d bytes", len(data)) },
+//	)
+//
+// The function uses WithResource internally to ensure proper cleanup:
+//
+//	ReadFile(path) = WithResource(Open(path), Close)(readAllBytes)
+//
+// See Also:
+//   - Open: For opening files without automatic reading
+//   - Close: For closing file handles
+//   - WithResource: For custom resource management patterns
+func ReadFile(path string) ReaderIOResult[[]byte] {
+	return RIOE.WithResource[[]byte](Open(path), Close[*os.File])(func(r *os.File) 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/tempfile.go

@@ -38,7 +38,7 @@ var (
 )
 
 // CreateTemp created a temp file with proper parametrization
-func CreateTemp(dir, pattern string) RIOE.ReaderIOResult[*os.File] {
+func CreateTemp(dir, pattern string) ReaderIOResult[*os.File] {
 	return F.Pipe2(
 		IOEF.CreateTemp(dir, pattern),
 		RIOE.FromIOEither[*os.File],
@@ -47,6 +47,6 @@ func CreateTemp(dir, pattern string) RIOE.ReaderIOResult[*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.ReaderIOResult[A]) RIOE.ReaderIOResult[A] {
+func WithTempFile[A any](f Kleisli[*os.File, A]) ReaderIOResult[A] {
 	return RIOE.WithResource[A](onCreateTempFile, onReleaseTempFile)(f)
 }

v2/context/readerioresult/file/tempfile_test.go

@@ -34,7 +34,7 @@ func TestWithTempFile(t *testing.T) {
 
 func TestWithTempFileOnClosedFile(t *testing.T) {
 
-	res := WithTempFile(func(f *os.File) RIOE.ReaderIOResult[[]byte] {
+	res := WithTempFile(func(f *os.File) ReaderIOResult[[]byte] {
 		return F.Pipe2(
 			f,
 			onWriteAll[*os.File]([]byte("Carsten")),

v2/context/readerioresult/file/types.go

@@ -0,0 +1,90 @@
+// 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 file
+
+import (
+	"github.com/IBM/fp-go/v2/context/readerioresult"
+	"github.com/IBM/fp-go/v2/function"
+)
+
+type (
+	// ReaderIOResult represents a context-aware computation that performs side effects
+	// and can fail with an error. This is the main type used throughout the file package
+	// for all file operations.
+	//
+	// ReaderIOResult[A] is equivalent to:
+	//   func(context.Context) func() Either[error, A]
+	//
+	// The computation:
+	//   - Takes a context.Context for cancellation and timeouts
+	//   - Performs side effects (IO operations)
+	//   - Returns Either an error or a value of type A
+	//
+	// See Also:
+	//   - readerioresult.ReaderIOResult: The underlying type definition
+	ReaderIOResult[A any] = readerioresult.ReaderIOResult[A]
+
+	// Void represents the absence of a meaningful value, similar to unit type in other languages.
+	// It is used when a function performs side effects but doesn't return a meaningful result.
+	//
+	// Void is typically used as the success type in operations like Close that perform
+	// an action but don't produce a useful value.
+	//
+	// Example:
+	//   Close[*os.File](file) // Returns ReaderIOResult[Void]
+	//
+	// See Also:
+	//   - function.Void: The underlying type definition
+	Void = function.Void
+
+	// Kleisli represents a Kleisli arrow for ReaderIOResult.
+	// It is a function that takes a value of type A and returns a ReaderIOResult[B].
+	//
+	// Kleisli arrows are used for monadic composition, allowing you to chain operations
+	// that produce ReaderIOResults. They are particularly useful with Chain and Bind operations.
+	//
+	// Kleisli[A, B] is equivalent to:
+	//   func(A) ReaderIOResult[B]
+	//
+	// Example:
+	//   // A Kleisli arrow that reads a file given its path
+	//   var readFileK Kleisli[string, []byte] = ReadFile
+	//
+	// See Also:
+	//   - readerioresult.Kleisli: The underlying type definition
+	//   - Operator: For transforming ReaderIOResults
+	Kleisli[A, B any] = readerioresult.Kleisli[A, 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(ReaderIOResult[A]) ReaderIOResult[B]
+	//
+	// Operators are used to transform computations without executing them, enabling
+	// powerful composition patterns.
+	//
+	// Example:
+	//   // An operator that maps over file contents
+	//   var toUpper Operator[[]byte, string] = Map(func(data []byte) string {
+	//       return strings.ToUpper(string(data))
+	//   })
+	//
+	// See Also:
+	//   - readerioresult.Operator: The underlying type definition
+	//   - Kleisli: For functions that produce ReaderIOResults
+	Operator[A, B any] = readerioresult.Operator[A, B]
+)

v2/context/readerioresult/file/write.go

@@ -23,8 +23,8 @@ import (
 	F "github.com/IBM/fp-go/v2/function"
 )
 
-func onWriteAll[W io.Writer](data []byte) func(w W) RIOE.ReaderIOResult[[]byte] {
-	return func(w W) RIOE.ReaderIOResult[[]byte] {
+func onWriteAll[W io.Writer](data []byte) Kleisli[W, []byte] {
+	return func(w W) 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.ReaderIOResult[[]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.ReaderIOResult[W]) RIOE.ReaderIOResult[[]byte] {
+func WriteAll[W io.WriteCloser](data []byte) Operator[W, []byte] {
 	onWrite := onWriteAll[W](data)
-	return func(onCreate RIOE.ReaderIOResult[W]) RIOE.ReaderIOResult[[]byte] {
+	return func(onCreate ReaderIOResult[W]) ReaderIOResult[[]byte] {
 		return RIOE.WithResource[[]byte](
 			onCreate,
 			Close[W])(
@@ -50,7 +50,7 @@ func WriteAll[W io.WriteCloser](data []byte) func(acquire RIOE.ReaderIOResult[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.ReaderIOResult[W]) func(use func(W) RIOE.ReaderIOResult[R]) RIOE.ReaderIOResult[R] {
+func Write[R any, W io.WriteCloser](acquire ReaderIOResult[W]) Kleisli[Kleisli[W, R], R] {
 	return RIOE.WithResource[R](
 		acquire,
 		Close[W])

v2/context/readerioresult/profunctor.go

@@ -19,6 +19,10 @@ import (
 	"context"
 
 	"github.com/IBM/fp-go/v2/function"
+	"github.com/IBM/fp-go/v2/io"
+	"github.com/IBM/fp-go/v2/ioresult"
+	"github.com/IBM/fp-go/v2/pair"
+	"github.com/IBM/fp-go/v2/result"
 )
 
 // Promap is the profunctor map operation that transforms both the input and output of a context-based ReaderIOResult.
@@ -45,7 +49,7 @@ import (
 //   - An Operator that takes a ReaderIOResult[A] and returns a ReaderIOResult[B]
 //
 //go:inline
-func Promap[A, B any](f func(context.Context) (context.Context, context.CancelFunc), g func(A) B) Operator[A, B] {
+func Promap[A, B any](f pair.Kleisli[context.CancelFunc, context.Context, context.Context], g func(A) B) Operator[A, B] {
 	return function.Flow2(
 		Local[A](f),
 		Map(g),
@@ -70,6 +74,139 @@ func Promap[A, B any](f func(context.Context) (context.Context, context.CancelFu
 //   - An Operator that takes a ReaderIOResult[A] and returns a ReaderIOResult[A]
 //
 //go:inline
-func Contramap[A any](f func(context.Context) (context.Context, context.CancelFunc)) Operator[A, A] {
+func Contramap[A any](f pair.Kleisli[context.CancelFunc, context.Context, context.Context]) Operator[A, A] {
 	return Local[A](f)
 }
+
+func ContramapIOK[A any](f io.Kleisli[context.Context, ContextCancel]) Operator[A, A] {
+	return LocalIOK[A](f)
+}
+
+// LocalIOK transforms the context using an IO-based function before passing it to a ReaderIOResult.
+// This is similar to Local but the context transformation itself is wrapped in an IO effect.
+//
+// The function f takes a context and returns an IO effect that produces a ContextCancel
+// (a pair of CancelFunc and the new Context). This allows the context transformation to
+// perform side effects.
+//
+// # Use Cases
+//
+// This function is useful for sharing information via the Context that is computed through
+// side effects that cannot fail, such as:
+//   - Generating unique request IDs or trace IDs
+//   - Recording timestamps or metrics
+//   - Logging context information
+//   - Computing derived values from existing context data
+//
+// The side effect is executed during the context transformation, and the resulting data is
+// stored in the context for downstream computations to access.
+//
+// # Type Parameters
+//
+//   - A: The success type (unchanged through the transformation)
+//
+// # Parameters
+//
+//   - f: An IO-based Kleisli function that transforms the context
+//
+// # Returns
+//
+//   - An Operator that applies the context transformation before executing the ReaderIOResult
+//
+// # Example Usage
+//
+//	// Generate a request ID via side effect and add to context
+//	addRequestID := func(ctx context.Context) io.IO[ContextCancel] {
+//	    return func() ContextCancel {
+//	        // Side effect: generate unique ID
+//	        requestID := uuid.New().String()
+//	        // Share the ID via context
+//	        newCtx := context.WithValue(ctx, "requestID", requestID)
+//	        return pair.MakePair(func() {}, newCtx)
+//	    }
+//	}
+//	adapted := LocalIOK[int](addRequestID)(computation)
+//
+// # See Also
+//
+//   - Local: For pure context transformations
+//   - LocalIOResultK: For context transformations that can fail
+//
+//go:inline
+func LocalIOK[A any](f io.Kleisli[context.Context, ContextCancel]) Operator[A, A] {
+	return LocalIOResultK[A](function.Flow2(f, ioresult.FromIO))
+}
+
+// LocalIOResultK transforms the context using an IOResult-based function before passing it to a ReaderIOResult.
+// This is similar to Local but the context transformation can fail with an error.
+//
+// The function f takes a context and returns an IOResult that produces either an error or a ContextCancel
+// (a pair of CancelFunc and the new Context). If the transformation fails, the error is propagated
+// and the original ReaderIOResult is not executed.
+//
+// # Use Cases
+//
+// This function is particularly useful for sharing information via the Context that is computed
+// through side effects, such as:
+//   - Loading configuration from a file or database
+//   - Fetching authentication tokens from an external service
+//   - Computing derived values that require I/O operations
+//   - Validating and enriching context with data from external sources
+//
+// The side effect is executed during the context transformation, and the resulting data is
+// stored in the context for downstream computations to access.
+//
+// # Type Parameters
+//
+//   - A: The success type (unchanged through the transformation)
+//
+// # Parameters
+//
+//   - f: An IOResult-based Kleisli function that transforms the context and may fail
+//
+// # Returns
+//
+//   - An Operator that applies the context transformation before executing the ReaderIOResult
+//
+// # Example Usage
+//
+//	// Load configuration via side effect and add to context
+//	loadConfig := func(ctx context.Context) ioresult.IOResult[ContextCancel] {
+//	    return func() result.Result[ContextCancel] {
+//	        // Side effect: read from file system
+//	        config, err := os.ReadFile("config.json")
+//	        if err != nil {
+//	            return result.Left[ContextCancel](err)
+//	        }
+//	        // Share the loaded config via context
+//	        newCtx := context.WithValue(ctx, "config", config)
+//	        return result.Of(pair.MakePair(func() {}, newCtx))
+//	    }
+//	}
+//	adapted := LocalIOResultK[int](loadConfig)(computation)
+//
+// # See Also
+//
+//   - Local: For pure context transformations
+//   - LocalIOK: For context transformations with side effects that cannot fail
+//
+//go:inline
+func LocalIOResultK[A any](f ioresult.Kleisli[context.Context, ContextCancel]) Operator[A, A] {
+	return func(rr ReaderIOResult[A]) ReaderIOResult[A] {
+		return func(ctx context.Context) IOResult[A] {
+			return func() Result[A] {
+				if ctx.Err() != nil {
+					return result.Left[A](context.Cause(ctx))
+				}
+				p, err := result.Unwrap(f(ctx)())
+				if err != nil {
+					return result.Left[A](err)
+				}
+				// unwrap
+				otherCancel, otherCtx := pair.Unpack(p)
+				defer otherCancel()
+				return rr(otherCtx)()
+			}
+		}
+	}
+}

v2/context/readerioresult/profunctor_test.go

@@ -20,6 +20,10 @@ import (
 	"strconv"
 	"testing"
 
+	"github.com/IBM/fp-go/v2/context/ioresult"
+	F "github.com/IBM/fp-go/v2/function"
+	"github.com/IBM/fp-go/v2/io"
+	"github.com/IBM/fp-go/v2/pair"
 	R "github.com/IBM/fp-go/v2/result"
 	"github.com/stretchr/testify/assert"
 )
@@ -36,9 +40,9 @@ func TestPromapBasic(t *testing.T) {
 			}
 		}
 
-		addKey := func(ctx context.Context) (context.Context, context.CancelFunc) {
+		addKey := func(ctx context.Context) pair.Pair[context.CancelFunc, context.Context] {
 			newCtx := context.WithValue(ctx, "key", 42)
-			return newCtx, func() {}
+			return pair.MakePair(context.CancelFunc(func() {}), newCtx)
 		}
 		toString := strconv.Itoa
 
@@ -61,9 +65,9 @@ func TestContramapBasic(t *testing.T) {
 			}
 		}
 
-		addKey := func(ctx context.Context) (context.Context, context.CancelFunc) {
+		addKey := func(ctx context.Context) pair.Pair[context.CancelFunc, context.Context] {
 			newCtx := context.WithValue(ctx, "key", 100)
-			return newCtx, func() {}
+			return pair.MakePair(context.CancelFunc(func() {}), newCtx)
 		}
 
 		adapted := Contramap[int](addKey)(getValue)
@@ -85,9 +89,9 @@ func TestLocalBasic(t *testing.T) {
 			}
 		}
 
-		addUser := func(ctx context.Context) (context.Context, context.CancelFunc) {
+		addUser := func(ctx context.Context) pair.Pair[context.CancelFunc, context.Context] {
 			newCtx := context.WithValue(ctx, "user", "Alice")
-			return newCtx, func() {}
+			return pair.MakePair(context.CancelFunc(func() {}), newCtx)
 		}
 
 		adapted := Local[string](addUser)(getValue)
@@ -96,3 +100,311 @@ func TestLocalBasic(t *testing.T) {
 		assert.Equal(t, R.Of("Alice"), result)
 	})
 }
+
+// TestLocalIOK_Success tests LocalIOK with successful context transformation
+func TestLocalIOK_Success(t *testing.T) {
+	t.Run("transforms context with IO effect", func(t *testing.T) {
+		getValue := func(ctx context.Context) IOResult[string] {
+			return func() R.Result[string] {
+				if v := ctx.Value("user"); v != nil {
+					return R.Of(v.(string))
+				}
+				return R.Of("unknown")
+			}
+		}
+
+		addUser := func(ctx context.Context) io.IO[ContextCancel] {
+			return func() ContextCancel {
+				newCtx := context.WithValue(ctx, "user", "Bob")
+				return pair.MakePair(context.CancelFunc(func() {}), newCtx)
+			}
+		}
+
+		adapted := LocalIOK[string](addUser)(getValue)
+		result := adapted(t.Context())()
+
+		assert.Equal(t, R.Of("Bob"), result)
+	})
+
+	t.Run("preserves original value type", func(t *testing.T) {
+		getValue := func(ctx context.Context) IOResult[int] {
+			return func() R.Result[int] {
+				if v := ctx.Value("count"); v != nil {
+					return R.Of(v.(int))
+				}
+				return R.Of(0)
+			}
+		}
+
+		addCount := func(ctx context.Context) io.IO[ContextCancel] {
+			return func() ContextCancel {
+				newCtx := context.WithValue(ctx, "count", 42)
+				return pair.MakePair(context.CancelFunc(func() {}), newCtx)
+			}
+		}
+
+		adapted := LocalIOK[int](addCount)(getValue)
+		result := adapted(t.Context())()
+
+		assert.Equal(t, R.Of(42), result)
+	})
+}
+
+// TestLocalIOK_CancelledContext tests LocalIOK with cancelled context
+func TestLocalIOK_CancelledContext(t *testing.T) {
+	t.Run("returns error when context is cancelled", func(t *testing.T) {
+		getValue := func(ctx context.Context) IOResult[string] {
+			return func() R.Result[string] {
+				return R.Of("should not reach here")
+			}
+		}
+
+		addUser := func(ctx context.Context) io.IO[ContextCancel] {
+			return func() ContextCancel {
+				newCtx := context.WithValue(ctx, "user", "Charlie")
+				return pair.MakePair(context.CancelFunc(func() {}), newCtx)
+			}
+		}
+
+		ctx, cancel := context.WithCancel(t.Context())
+		cancel()
+
+		adapted := LocalIOK[string](addUser)(getValue)
+		result := adapted(ctx)()
+
+		assert.True(t, R.IsLeft(result))
+	})
+}
+
+// TestLocalIOK_CancelFuncCalled tests that CancelFunc is properly called
+func TestLocalIOK_CancelFuncCalled(t *testing.T) {
+	t.Run("calls cancel function after execution", func(t *testing.T) {
+		cancelCalled := false
+
+		getValue := func(ctx context.Context) IOResult[string] {
+			return func() R.Result[string] {
+				return R.Of("test")
+			}
+		}
+
+		addUser := func(ctx context.Context) io.IO[ContextCancel] {
+			return func() ContextCancel {
+				newCtx := context.WithValue(ctx, "user", "Dave")
+				cancelFunc := context.CancelFunc(func() {
+					cancelCalled = true
+				})
+				return pair.MakePair(cancelFunc, newCtx)
+			}
+		}
+
+		adapted := LocalIOK[string](addUser)(getValue)
+		_ = adapted(t.Context())()
+
+		assert.True(t, cancelCalled, "cancel function should be called")
+	})
+}
+
+// TestLocalIOResultK_Success tests LocalIOResultK with successful context transformation
+func TestLocalIOResultK_Success(t *testing.T) {
+	t.Run("transforms context with IOResult effect", func(t *testing.T) {
+		getValue := func(ctx context.Context) IOResult[string] {
+			return func() R.Result[string] {
+				if v := ctx.Value("role"); v != nil {
+					return R.Of(v.(string))
+				}
+				return R.Of("guest")
+			}
+		}
+
+		addRole := func(ctx context.Context) ioresult.IOResult[ContextCancel] {
+			return func() R.Result[ContextCancel] {
+				newCtx := context.WithValue(ctx, "role", "admin")
+				return R.Of(pair.MakePair(context.CancelFunc(func() {}), newCtx))
+			}
+		}
+
+		adapted := LocalIOResultK[string](addRole)(getValue)
+		result := adapted(t.Context())()
+
+		assert.Equal(t, R.Of("admin"), result)
+	})
+
+	t.Run("preserves original value type", func(t *testing.T) {
+		getValue := func(ctx context.Context) IOResult[int] {
+			return func() R.Result[int] {
+				if v := ctx.Value("score"); v != nil {
+					return R.Of(v.(int))
+				}
+				return R.Of(0)
+			}
+		}
+
+		addScore := func(ctx context.Context) ioresult.IOResult[ContextCancel] {
+			return func() R.Result[ContextCancel] {
+				newCtx := context.WithValue(ctx, "score", 100)
+				return R.Of(pair.MakePair(context.CancelFunc(func() {}), newCtx))
+			}
+		}
+
+		adapted := LocalIOResultK[int](addScore)(getValue)
+		result := adapted(t.Context())()
+
+		assert.Equal(t, R.Of(100), result)
+	})
+}
+
+// TestLocalIOResultK_Failure tests LocalIOResultK with failed context transformation
+func TestLocalIOResultK_Failure(t *testing.T) {
+	t.Run("propagates transformation error", func(t *testing.T) {
+		getValue := func(ctx context.Context) IOResult[string] {
+			return func() R.Result[string] {
+				return R.Of("should not reach here")
+			}
+		}
+
+		failTransform := func(ctx context.Context) ioresult.IOResult[ContextCancel] {
+			return func() R.Result[ContextCancel] {
+				return R.Left[ContextCancel](assert.AnError)
+			}
+		}
+
+		adapted := LocalIOResultK[string](failTransform)(getValue)
+		result := adapted(t.Context())()
+
+		assert.True(t, R.IsLeft(result))
+		_, err := R.UnwrapError(result)
+		assert.Equal(t, assert.AnError, err)
+	})
+
+	t.Run("does not execute original computation on transformation failure", func(t *testing.T) {
+		executed := false
+
+		getValue := func(ctx context.Context) IOResult[string] {
+			return func() R.Result[string] {
+				executed = true
+				return R.Of("should not execute")
+			}
+		}
+
+		failTransform := func(ctx context.Context) ioresult.IOResult[ContextCancel] {
+			return func() R.Result[ContextCancel] {
+				return R.Left[ContextCancel](assert.AnError)
+			}
+		}
+
+		adapted := LocalIOResultK[string](failTransform)(getValue)
+		_ = adapted(t.Context())()
+
+		assert.False(t, executed, "original computation should not execute")
+	})
+}
+
+// TestLocalIOResultK_CancelledContext tests LocalIOResultK with cancelled context
+func TestLocalIOResultK_CancelledContext(t *testing.T) {
+	t.Run("returns error when context is cancelled", func(t *testing.T) {
+		getValue := func(ctx context.Context) IOResult[string] {
+			return func() R.Result[string] {
+				return R.Of("should not reach here")
+			}
+		}
+
+		addRole := func(ctx context.Context) ioresult.IOResult[ContextCancel] {
+			return func() R.Result[ContextCancel] {
+				newCtx := context.WithValue(ctx, "role", "user")
+				return R.Of(pair.MakePair(context.CancelFunc(func() {}), newCtx))
+			}
+		}
+
+		ctx, cancel := context.WithCancel(t.Context())
+		cancel()
+
+		adapted := LocalIOResultK[string](addRole)(getValue)
+		result := adapted(ctx)()
+
+		assert.True(t, R.IsLeft(result))
+	})
+}
+
+// TestLocalIOResultK_CancelFuncCalled tests that CancelFunc is properly called
+func TestLocalIOResultK_CancelFuncCalled(t *testing.T) {
+	t.Run("calls cancel function after successful execution", func(t *testing.T) {
+		cancelCalled := false
+
+		getValue := func(ctx context.Context) IOResult[string] {
+			return func() R.Result[string] {
+				return R.Of("test")
+			}
+		}
+
+		addRole := func(ctx context.Context) ioresult.IOResult[ContextCancel] {
+			return func() R.Result[ContextCancel] {
+				newCtx := context.WithValue(ctx, "role", "user")
+				cancelFunc := context.CancelFunc(func() {
+					cancelCalled = true
+				})
+				return R.Of(pair.MakePair(cancelFunc, newCtx))
+			}
+		}
+
+		adapted := LocalIOResultK[string](addRole)(getValue)
+		_ = adapted(t.Context())()
+
+		assert.True(t, cancelCalled, "cancel function should be called")
+	})
+
+	t.Run("does not call cancel function on transformation failure", func(t *testing.T) {
+		cancelCalled := false
+
+		getValue := func(ctx context.Context) IOResult[string] {
+			return func() R.Result[string] {
+				return R.Of("test")
+			}
+		}
+
+		failTransform := func(ctx context.Context) ioresult.IOResult[ContextCancel] {
+			return func() R.Result[ContextCancel] {
+				cancelFunc := context.CancelFunc(func() {
+					cancelCalled = true
+				})
+				_ = cancelFunc // avoid unused warning
+				return R.Left[ContextCancel](assert.AnError)
+			}
+		}
+
+		adapted := LocalIOResultK[string](failTransform)(getValue)
+		_ = adapted(t.Context())()
+
+		assert.False(t, cancelCalled, "cancel function should not be called on failure")
+	})
+}
+
+// TestLocalIOResultK_Integration tests integration with other operations
+func TestLocalIOResultK_Integration(t *testing.T) {
+	t.Run("composes with Map", func(t *testing.T) {
+		getValue := func(ctx context.Context) IOResult[int] {
+			return func() R.Result[int] {
+				if v := ctx.Value("value"); v != nil {
+					return R.Of(v.(int))
+				}
+				return R.Of(0)
+			}
+		}
+
+		addValue := func(ctx context.Context) ioresult.IOResult[ContextCancel] {
+			return func() R.Result[ContextCancel] {
+				newCtx := context.WithValue(ctx, "value", 10)
+				return R.Of(pair.MakePair(context.CancelFunc(func() {}), newCtx))
+			}
+		}
+
+		double := func(x int) int { return x * 2 }
+
+		adapted := F.Flow2(
+			LocalIOResultK[int](addValue),
+			Map(double),
+		)(getValue)
+		result := adapted(t.Context())()
+
+		assert.Equal(t, R.Of(20), result)
+	})
+}

v2/context/readerioresult/reader.go

@@ -28,6 +28,7 @@ import (
 	"github.com/IBM/fp-go/v2/ioeither"
 	"github.com/IBM/fp-go/v2/ioresult"
 	"github.com/IBM/fp-go/v2/option"
+	"github.com/IBM/fp-go/v2/pair"
 	"github.com/IBM/fp-go/v2/reader"
 	RIOR "github.com/IBM/fp-go/v2/readerioresult"
 	"github.com/IBM/fp-go/v2/readeroption"
@@ -1054,14 +1055,14 @@ func TapLeftIOK[A, B any](f io.Kleisli[error, B]) Operator[A, A] {
 //	    fetchData,
 //	    withTimeout,
 //	)
-func Local[A any](f func(context.Context) (context.Context, context.CancelFunc)) Operator[A, A] {
+func Local[A any](f pair.Kleisli[context.CancelFunc, context.Context, context.Context]) Operator[A, A] {
 	return func(rr ReaderIOResult[A]) ReaderIOResult[A] {
 		return func(ctx context.Context) IOResult[A] {
 			return func() Result[A] {
 				if ctx.Err() != nil {
 					return result.Left[A](context.Cause(ctx))
 				}
-				otherCtx, otherCancel := f(ctx)
+				otherCancel, otherCtx := pair.Unpack(f(ctx))
 				defer otherCancel()
 				return rr(otherCtx)()
 			}
@@ -1123,9 +1124,10 @@ func Local[A any](f func(context.Context) (context.Context, context.CancelFunc))
 //	)
 //	value, err := result(t.Context())()  // Returns (Data{Value: "quick"}, nil)
 func WithTimeout[A any](timeout time.Duration) Operator[A, A] {
-	return Local[A](func(ctx context.Context) (context.Context, context.CancelFunc) {
-		return context.WithTimeout(ctx, timeout)
-	})
+	return Local[A](
+		func(ctx context.Context) ContextCancel {
+			return pairFromContextCancel(context.WithTimeout(ctx, timeout))
+		})
 }
 
 // WithDeadline adds an absolute deadline to the context for a ReaderIOResult computation.
@@ -1188,7 +1190,7 @@ func WithTimeout[A any](timeout time.Duration) Operator[A, A] {
 //	)
 //	value, err := result(parentCtx)()  // Will use parent's 1-hour deadline
 func WithDeadline[A any](deadline time.Time) Operator[A, A] {
-	return Local[A](func(ctx context.Context) (context.Context, context.CancelFunc) {
-		return context.WithDeadline(ctx, deadline)
+	return Local[A](func(ctx context.Context) ContextCancel {
+		return pairFromContextCancel(context.WithDeadline(ctx, deadline))
 	})
 }

v2/context/readerioresult/type.go

@@ -55,6 +55,10 @@ type (
 	// Either[A] is equivalent to Either[error, A] from the either package.
 	Either[A any] = either.Either[error, A]
 
+	// Result represents a computation that can either succeed with a value of type A
+	// or fail with an error. This is an alias for result.Result[A].
+	//
+	// Result[A] is equivalent to Either[error, A]
 	Result[A any] = result.Result[A]
 
 	// Lazy represents a deferred computation that produces a value of type A when executed.
@@ -73,6 +77,10 @@ type (
 	// IOEither[A] is equivalent to func() Either[error, A]
 	IOEither[A any] = ioeither.IOEither[error, A]
 
+	// IOResult represents a side-effectful computation that can fail with an error.
+	// This combines IO (side effects) with Result (error handling).
+	//
+	// IOResult[A] is equivalent to func() Result[A]
 	IOResult[A any] = ioresult.IOResult[A]
 
 	// Reader represents a computation that depends on a context of type R.
@@ -118,6 +126,13 @@ type (
 	//   result := fetchUser("123")(ctx)()
 	ReaderIOResult[A any] = RIOR.ReaderIOResult[context.Context, A]
 
+	// Kleisli represents a Kleisli arrow for ReaderIOResult.
+	// It is a function that takes a value of type A and returns a ReaderIOResult[B].
+	//
+	// Kleisli arrows are used for monadic composition, allowing you to chain operations
+	// that produce ReaderIOResults. They are particularly useful with Chain operations.
+	//
+	// Kleisli[A, B] is equivalent to func(A) ReaderIOResult[B]
 	Kleisli[A, B any] = reader.Reader[A, ReaderIOResult[B]]
 
 	// Operator represents a transformation from one ReaderIOResult to another.
@@ -133,26 +148,76 @@ type (
 	//   result := toUpper(computation)
 	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]
+	// ReaderResult represents a context-dependent computation that can fail.
+	// This is specialized to use context.Context as the context type.
+	//
+	// ReaderResult[A] is equivalent to func(context.Context) Result[A]
+	ReaderResult[A any] = readerresult.ReaderResult[A]
 
+	// ReaderEither represents a context-dependent computation that can fail.
+	// It takes a context of type R and produces an Either[E, A].
+	//
+	// ReaderEither[R, E, A] is equivalent to func(R) Either[E, A]
+	ReaderEither[R, E, A any] = readereither.ReaderEither[R, E, A]
+
+	// ReaderOption represents a context-dependent computation that may not produce a value.
+	// It takes a context of type R and produces an Option[A].
+	//
+	// ReaderOption[R, A] is equivalent to func(R) Option[A]
+	ReaderOption[R, A any] = readeroption.ReaderOption[R, A]
+
+	// Endomorphism represents a function from a type to itself.
+	// It is used for transformations that preserve the type.
+	//
+	// Endomorphism[A] is equivalent to func(A) A
 	Endomorphism[A any] = endomorphism.Endomorphism[A]
 
+	// Consumer represents a function that consumes a value without producing a result.
+	// It is used for side effects like logging or updating state.
+	//
+	// Consumer[A] is equivalent to func(A)
 	Consumer[A any] = consumer.Consumer[A]
 
+	// Prism represents an optic for working with sum types (tagged unions).
+	// It provides a way to focus on a specific variant of a sum type.
 	Prism[S, T any] = prism.Prism[S, T]
-	Lens[S, T any]  = lens.Lens[S, T]
 
+	// Lens represents an optic for working with product types (records/structs).
+	// It provides a way to focus on a specific field of a product type.
+	Lens[S, T any] = lens.Lens[S, T]
+
+	// Trampoline represents a computation that can be executed in a stack-safe manner.
+	// It is used for tail-recursive computations that would otherwise overflow the stack.
 	Trampoline[B, L any] = tailrec.Trampoline[B, L]
 
+	// Predicate represents a function that tests a value of type A.
+	// It returns true if the value satisfies the predicate, false otherwise.
+	//
+	// Predicate[A] is equivalent to func(A) bool
 	Predicate[A any] = predicate.Predicate[A]
 
+	// Pair represents a tuple of two values of types A and B.
+	// It is used to group two related values together.
 	Pair[A, B any] = pair.Pair[A, B]
 
+	// IORef represents a mutable reference that can be safely accessed in IO computations.
+	// It provides thread-safe read and write operations.
 	IORef[A any] = ioref.IORef[A]
 
+	// State represents a stateful computation that transforms a state of type S
+	// and produces a value of type A.
+	//
+	// State[S, A] is equivalent to func(S) Pair[A, S]
 	State[S, A any] = state.State[S, A]
 
+	// Void represents the absence of a value, similar to unit type in other languages.
+	// It is used when a function performs side effects but doesn't return a meaningful value.
 	Void = function.Void
+
+	// ContextCancel represents a pair of a cancel function and a context.
+	// It is used in operations that create new contexts with cancellation capabilities.
+	//
+	// The first element is the CancelFunc that should be called to release resources.
+	// The second element is the new Context that was created.
+	ContextCancel = Pair[context.CancelFunc, context.Context]
 )

v2/effect/bind.go

@@ -25,6 +25,31 @@ import (
 	"github.com/IBM/fp-go/v2/readerio"
 )
 
+// Do creates an Effect with an initial state value.
+// This is the starting point for do-notation style effect composition,
+// allowing you to build up complex state transformations step by step.
+//
+// # Type Parameters
+//
+//   - C: The context type required by the effect
+//   - S: The state type
+//
+// # Parameters
+//
+//   - empty: The initial state value
+//
+// # Returns
+//
+//   - Effect[C, S]: An effect that produces the initial state
+//
+// # Example
+//
+//	type State struct {
+//		Name string
+//		Age  int
+//	}
+//	eff := effect.Do[MyContext](State{})
+//
 //go:inline
 func Do[C, S any](
 	empty S,
@@ -32,6 +57,40 @@ func Do[C, S any](
 	return readerreaderioresult.Of[C](empty)
 }
 
+// Bind executes an effectful computation and binds its result to the state.
+// This is the core operation for do-notation, allowing you to sequence effects
+// while accumulating results in a state structure.
+//
+// # Type Parameters
+//
+//   - C: The context type required by the effects
+//   - S1: The input state type
+//   - S2: The output state type
+//   - T: The type of value produced by the effect
+//
+// # Parameters
+//
+//   - setter: A function that takes the effect result and returns a state updater
+//   - f: An effectful computation that depends on the current state
+//
+// # Returns
+//
+//   - Operator[C, S1, S2]: A function that transforms the state effect
+//
+// # Example
+//
+//	eff := effect.Bind(
+//		func(age int) func(State) State {
+//			return func(s State) State {
+//				s.Age = age
+//				return s
+//			}
+//		},
+//		func(s State) Effect[MyContext, int] {
+//			return effect.Of[MyContext](30)
+//		},
+//	)(effect.Do[MyContext](State{}))
+//
 //go:inline
 func Bind[C, S1, S2, T any](
 	setter func(T) func(S1) S2,
@@ -40,6 +99,39 @@ func Bind[C, S1, S2, T any](
 	return readerreaderioresult.Bind(setter, f)
 }
 
+// Let computes a pure value from the current state and binds it to the state.
+// Unlike Bind, this doesn't perform any effects - it's for pure computations.
+//
+// # Type Parameters
+//
+//   - C: The context type required by the effect
+//   - S1: The input state type
+//   - S2: The output state type
+//   - T: The type of computed value
+//
+// # Parameters
+//
+//   - setter: A function that takes the computed value and returns a state updater
+//   - f: A pure function that computes a value from the current state
+//
+// # Returns
+//
+//   - Operator[C, S1, S2]: A function that transforms the state effect
+//
+// # Example
+//
+//	eff := effect.Let[MyContext](
+//		func(nameLen int) func(State) State {
+//			return func(s State) State {
+//				s.NameLength = nameLen
+//				return s
+//			}
+//		},
+//		func(s State) int {
+//			return len(s.Name)
+//		},
+//	)(stateEff)
+//
 //go:inline
 func Let[C, S1, S2, T any](
 	setter func(T) func(S1) S2,
@@ -48,6 +140,37 @@ func Let[C, S1, S2, T any](
 	return readerreaderioresult.Let[C](setter, f)
 }
 
+// LetTo binds a constant value to the state.
+// This is useful for setting fixed values in your state structure.
+//
+// # Type Parameters
+//
+//   - C: The context type required by the effect
+//   - S1: The input state type
+//   - S2: The output state type
+//   - T: The type of the constant value
+//
+// # Parameters
+//
+//   - setter: A function that takes the constant and returns a state updater
+//   - b: The constant value to bind
+//
+// # Returns
+//
+//   - Operator[C, S1, S2]: A function that transforms the state effect
+//
+// # Example
+//
+//	eff := effect.LetTo[MyContext](
+//		func(age int) func(State) State {
+//			return func(s State) State {
+//				s.Age = age
+//				return s
+//			}
+//		},
+//		42,
+//	)(stateEff)
+//
 //go:inline
 func LetTo[C, S1, S2, T any](
 	setter func(T) func(S1) S2,
@@ -56,6 +179,30 @@ func LetTo[C, S1, S2, T any](
 	return readerreaderioresult.LetTo[C](setter, b)
 }
 
+// BindTo wraps a value in an initial state structure.
+// This is typically used to start a bind chain by converting a simple value
+// into a state structure.
+//
+// # Type Parameters
+//
+//   - C: The context type required by the effect
+//   - S1: The state type to create
+//   - T: The type of the input value
+//
+// # Parameters
+//
+//   - setter: A function that creates a state from the value
+//
+// # Returns
+//
+//   - Operator[C, T, S1]: A function that wraps the value in state
+//
+// # Example
+//
+//	eff := effect.BindTo[MyContext](func(name string) State {
+//		return State{Name: name}
+//	})(effect.Of[MyContext]("Alice"))
+//
 //go:inline
 func BindTo[C, S1, T any](
 	setter func(T) S1,
@@ -63,6 +210,39 @@ func BindTo[C, S1, T any](
 	return readerreaderioresult.BindTo[C](setter)
 }
 
+// ApS applies an effect and binds its result to the state using a setter function.
+// This is similar to Bind but takes a pre-existing effect rather than a function
+// that creates an effect from the state.
+//
+// # Type Parameters
+//
+//   - C: The context type required by the effects
+//   - S1: The input state type
+//   - S2: The output state type
+//   - T: The type of value produced by the effect
+//
+// # Parameters
+//
+//   - setter: A function that takes the effect result and returns a state updater
+//   - fa: The effect to apply
+//
+// # Returns
+//
+//   - Operator[C, S1, S2]: A function that transforms the state effect
+//
+// # Example
+//
+//	ageEffect := effect.Of[MyContext](30)
+//	eff := effect.ApS(
+//		func(age int) func(State) State {
+//			return func(s State) State {
+//				s.Age = age
+//				return s
+//			}
+//		},
+//		ageEffect,
+//	)(stateEff)
+//
 //go:inline
 func ApS[C, S1, S2, T any](
 	setter func(T) func(S1) S2,
@@ -71,6 +251,33 @@ func ApS[C, S1, S2, T any](
 	return readerreaderioresult.ApS(setter, fa)
 }
 
+// ApSL applies an effect and updates a field in the state using a lens.
+// This provides a more ergonomic way to update nested state structures.
+//
+// # Type Parameters
+//
+//   - C: The context type required by the effects
+//   - S: The state type
+//   - T: The type of the field being updated
+//
+// # Parameters
+//
+//   - lens: A lens focusing on the field to update
+//   - fa: The effect producing the new field value
+//
+// # Returns
+//
+//   - Operator[C, S, S]: A function that updates the state field
+//
+// # Example
+//
+//	ageLens := lens.MakeLens(
+//		func(s State) int { return s.Age },
+//		func(s State, age int) State { s.Age = age; return s },
+//	)
+//	ageEffect := effect.Of[MyContext](30)
+//	eff := effect.ApSL(ageLens, ageEffect)(stateEff)
+//
 //go:inline
 func ApSL[C, S, T any](
 	lens Lens[S, T],
@@ -79,6 +286,37 @@ func ApSL[C, S, T any](
 	return readerreaderioresult.ApSL(lens, fa)
 }
 
+// BindL executes an effectful computation on a field and updates it using a lens.
+// The effect function receives the current field value and produces a new value.
+//
+// # Type Parameters
+//
+//   - C: The context type required by the effects
+//   - S: The state type
+//   - T: The type of the field being updated
+//
+// # Parameters
+//
+//   - lens: A lens focusing on the field to update
+//   - f: An effectful function that transforms the field value
+//
+// # Returns
+//
+//   - Operator[C, S, S]: A function that updates the state field
+//
+// # Example
+//
+//	ageLens := lens.MakeLens(
+//		func(s State) int { return s.Age },
+//		func(s State, age int) State { s.Age = age; return s },
+//	)
+//	eff := effect.BindL(
+//		ageLens,
+//		func(age int) Effect[MyContext, int] {
+//			return effect.Of[MyContext](age + 1)
+//		},
+//	)(stateEff)
+//
 //go:inline
 func BindL[C, S, T any](
 	lens Lens[S, T],
@@ -87,6 +325,35 @@ func BindL[C, S, T any](
 	return readerreaderioresult.BindL(lens, f)
 }
 
+// LetL computes a new field value from the current value using a lens.
+// This is a pure transformation of a field within the state.
+//
+// # Type Parameters
+//
+//   - C: The context type required by the effect
+//   - S: The state type
+//   - T: The type of the field being updated
+//
+// # Parameters
+//
+//   - lens: A lens focusing on the field to update
+//   - f: A pure function that transforms the field value
+//
+// # Returns
+//
+//   - Operator[C, S, S]: A function that updates the state field
+//
+// # Example
+//
+//	ageLens := lens.MakeLens(
+//		func(s State) int { return s.Age },
+//		func(s State, age int) State { s.Age = age; return s },
+//	)
+//	eff := effect.LetL[MyContext](
+//		ageLens,
+//		func(age int) int { return age * 2 },
+//	)(stateEff)
+//
 //go:inline
 func LetL[C, S, T any](
 	lens Lens[S, T],
@@ -95,6 +362,31 @@ func LetL[C, S, T any](
 	return readerreaderioresult.LetL[C](lens, f)
 }
 
+// LetToL sets a field to a constant value using a lens.
+//
+// # Type Parameters
+//
+//   - C: The context type required by the effect
+//   - S: The state type
+//   - T: The type of the field being updated
+//
+// # Parameters
+//
+//   - lens: A lens focusing on the field to update
+//   - b: The constant value to set
+//
+// # Returns
+//
+//   - Operator[C, S, S]: A function that updates the state field
+//
+// # Example
+//
+//	ageLens := lens.MakeLens(
+//		func(s State) int { return s.Age },
+//		func(s State, age int) State { s.Age = age; return s },
+//	)
+//	eff := effect.LetToL[MyContext](ageLens, 42)(stateEff)
+//
 //go:inline
 func LetToL[C, S, T any](
 	lens Lens[S, T],

v2/effect/common_test.go

@@ -0,0 +1,32 @@
+// 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 effect
+
+import (
+	"context"
+)
+
+// TestContext is a common test context type used across effect tests
+type TestContext struct {
+	Value string
+}
+
+// runEffect is a helper function to run an effect with a context and return the result
+func runEffect[C, A any](eff Effect[C, A], ctx C) (A, error) {
+	ioResult := Provide[C, A](ctx)(eff)
+	readerResult := RunSync(ioResult)
+	return readerResult(context.Background())
+}

v2/effect/dependencies.go

@@ -1,3 +1,18 @@
+// 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 effect
 
 import (
@@ -8,31 +23,182 @@ import (
 	"github.com/IBM/fp-go/v2/result"
 )
 
+// Local transforms the context required by an effect using a pure function.
+// This allows you to adapt an effect that requires one context type to work
+// with a different context type by providing a transformation function.
+//
+// # Type Parameters
+//
+//   - C1: The outer context type (what you have)
+//   - C2: The inner context type (what the effect needs)
+//   - A: The value type produced by the effect
+//
+// # Parameters
+//
+//   - acc: A pure function that transforms C1 to C2
+//
+// # Returns
+//
+//   - Kleisli[C1, Effect[C2, A], A]: A function that adapts the effect to use C1
+//
+// # Example
+//
+//	type AppConfig struct { DB DatabaseConfig }
+//	type DatabaseConfig struct { Host string }
+//	dbEffect := effect.Of[DatabaseConfig]("connected")
+//	appEffect := effect.Local[AppConfig, DatabaseConfig, string](
+//		func(app AppConfig) DatabaseConfig { return app.DB },
+//	)(dbEffect)
+//
 //go:inline
 func Local[C1, C2, A any](acc Reader[C1, C2]) Kleisli[C1, Effect[C2, A], A] {
 	return readerreaderioresult.Local[A](acc)
 }
 
+// Contramap is an alias for Local, following the contravariant functor naming convention.
+// It transforms the context required by an effect using a pure function.
+//
+// # Type Parameters
+//
+//   - C1: The outer context type (what you have)
+//   - C2: The inner context type (what the effect needs)
+//   - A: The value type produced by the effect
+//
+// # Parameters
+//
+//   - acc: A pure function that transforms C1 to C2
+//
+// # Returns
+//
+//   - Kleisli[C1, Effect[C2, A], A]: A function that adapts the effect to use C1
+//
 //go:inline
 func Contramap[C1, C2, A any](acc Reader[C1, C2]) Kleisli[C1, Effect[C2, A], A] {
 	return readerreaderioresult.Local[A](acc)
 }
 
+// LocalIOK transforms the context using an IO-based function.
+// This allows the context transformation itself to perform I/O operations.
+//
+// # Type Parameters
+//
+//   - A: The value type produced by the effect
+//   - C1: The inner context type (what the effect needs)
+//   - C2: The outer context type (what you have)
+//
+// # Parameters
+//
+//   - f: An IO function that transforms C2 to C1
+//
+// # Returns
+//
+//   - func(Effect[C1, A]) Effect[C2, A]: A function that adapts the effect
+//
+// # Example
+//
+//	loadConfig := func(path string) io.IO[Config] {
+//		return func() Config { /* load from file */ }
+//	}
+//	transform := effect.LocalIOK[string](loadConfig)
+//	adapted := transform(configEffect)
+//
 //go:inline
 func LocalIOK[A, C1, C2 any](f io.Kleisli[C2, C1]) func(Effect[C1, A]) Effect[C2, A] {
 	return readerreaderioresult.LocalIOK[A](f)
 }
 
+// LocalIOResultK transforms the context using an IOResult-based function.
+// This allows the context transformation to perform I/O and handle errors.
+//
+// # Type Parameters
+//
+//   - A: The value type produced by the effect
+//   - C1: The inner context type (what the effect needs)
+//   - C2: The outer context type (what you have)
+//
+// # Parameters
+//
+//   - f: An IOResult function that transforms C2 to C1
+//
+// # Returns
+//
+//   - func(Effect[C1, A]) Effect[C2, A]: A function that adapts the effect
+//
+// # Example
+//
+//	loadConfig := func(path string) ioresult.IOResult[Config] {
+//		return func() result.Result[Config] {
+//			// load from file, may fail
+//		}
+//	}
+//	transform := effect.LocalIOResultK[string](loadConfig)
+//	adapted := transform(configEffect)
+//
 //go:inline
 func LocalIOResultK[A, C1, C2 any](f ioresult.Kleisli[C2, C1]) func(Effect[C1, A]) Effect[C2, A] {
 	return readerreaderioresult.LocalIOResultK[A](f)
 }
 
+// LocalResultK transforms the context using a Result-based function.
+// This allows the context transformation to fail with an error.
+//
+// # Type Parameters
+//
+//   - A: The value type produced by the effect
+//   - C1: The inner context type (what the effect needs)
+//   - C2: The outer context type (what you have)
+//
+// # Parameters
+//
+//   - f: A Result function that transforms C2 to C1
+//
+// # Returns
+//
+//   - func(Effect[C1, A]) Effect[C2, A]: A function that adapts the effect
+//
+// # Example
+//
+//	validateConfig := func(raw RawConfig) result.Result[Config] {
+//		if raw.IsValid() {
+//			return result.Of(raw.ToConfig())
+//		}
+//		return result.Left[Config](errors.New("invalid"))
+//	}
+//	transform := effect.LocalResultK[string](validateConfig)
+//	adapted := transform(configEffect)
+//
 //go:inline
 func LocalResultK[A, C1, C2 any](f result.Kleisli[C2, C1]) func(Effect[C1, A]) Effect[C2, A] {
 	return readerreaderioresult.LocalResultK[A](f)
 }
 
+// LocalThunkK transforms the context using a Thunk (ReaderIOResult) function.
+// This allows the context transformation to depend on context.Context, perform I/O, and handle errors.
+//
+// # Type Parameters
+//
+//   - A: The value type produced by the effect
+//   - C1: The inner context type (what the effect needs)
+//   - C2: The outer context type (what you have)
+//
+// # Parameters
+//
+//   - f: A Thunk function that transforms C2 to C1
+//
+// # Returns
+//
+//   - func(Effect[C1, A]) Effect[C2, A]: A function that adapts the effect
+//
+// # Example
+//
+//	loadConfig := func(path string) readerioresult.ReaderIOResult[Config] {
+//		return func(ctx context.Context) ioresult.IOResult[Config] {
+//			// load from file with context, may fail
+//		}
+//	}
+//	transform := effect.LocalThunkK[string](loadConfig)
+//	adapted := transform(configEffect)
+//
 //go:inline
 func LocalThunkK[A, C1, C2 any](f thunk.Kleisli[C2, C1]) func(Effect[C1, A]) Effect[C2, A] {
 	return readerreaderioresult.LocalReaderIOResultK[A](f)

v2/effect/effect.go

@@ -1,51 +1,492 @@
+// 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 effect
 
 import (
+	thunk "github.com/IBM/fp-go/v2/context/readerioresult"
 	"github.com/IBM/fp-go/v2/context/readerreaderioresult"
 	"github.com/IBM/fp-go/v2/function"
+	"github.com/IBM/fp-go/v2/internal/fromreader"
+	"github.com/IBM/fp-go/v2/reader"
+	"github.com/IBM/fp-go/v2/readerio"
 	"github.com/IBM/fp-go/v2/result"
 )
 
+// FromThunk lifts a Thunk (context-independent IO computation with error handling) into an Effect.
+// This allows you to integrate computations that don't need the effect's context type C
+// into effect chains. The Thunk will be executed with the runtime context when the effect runs.
+//
+// # Type Parameters
+//
+//   - C: The context type required by the effect (not used by the thunk)
+//   - A: The type of the success value
+//
+// # Parameters
+//
+//   - f: A Thunk[A] that performs IO with error handling
+//
+// # Returns
+//
+//   - Effect[C, A]: An effect that ignores its context and executes the thunk
+//
+// # Example
+//
+//	thunk := func(ctx context.Context) io.IO[result.Result[int]] {
+//	    return func() result.Result[int] {
+//	        // Perform IO operation
+//	        return result.Of(42)
+//	    }
+//	}
+//
+//	eff := effect.FromThunk[MyContext](thunk)
+//	// eff can be used in any context but executes the thunk
+//
+//go:inline
+func FromThunk[C, A any](f Thunk[A]) Effect[C, A] {
+	return reader.Of[C](f)
+}
+
+// Succeed creates a successful Effect that produces the given value.
+// This is the primary way to lift a pure value into the Effect context.
+//
+// # Type Parameters
+//
+//   - C: The context type required by the effect
+//   - A: The type of the success value
+//
+// # Parameters
+//
+//   - a: The value to wrap in a successful effect
+//
+// # Returns
+//
+//   - Effect[C, A]: An effect that always succeeds with the given value
+//
+// # Example
+//
+//	eff := effect.Succeed[MyContext](42)
+//	result, err := runEffect(eff, myContext)
+//	// result == 42, err == nil
 func Succeed[C, A any](a A) Effect[C, A] {
 	return readerreaderioresult.Of[C](a)
 }
 
+// Fail creates a failed Effect with the given error.
+// This is used to represent computations that have failed.
+//
+// # Type Parameters
+//
+//   - C: The context type required by the effect
+//   - A: The type of the success value (never produced)
+//
+// # Parameters
+//
+//   - err: The error that caused the failure
+//
+// # Returns
+//
+//   - Effect[C, A]: An effect that always fails with the given error
+//
+// # Example
+//
+//	eff := effect.Fail[MyContext, int](errors.New("failed"))
+//	_, err := runEffect(eff, myContext)
+//	// err == errors.New("failed")
 func Fail[C, A any](err error) Effect[C, A] {
 	return readerreaderioresult.Left[C, A](err)
 }
 
+// Of creates a successful Effect that produces the given value.
+// This is an alias for Succeed and follows the pointed functor convention.
+//
+// # Type Parameters
+//
+//   - C: The context type required by the effect
+//   - A: The type of the success value
+//
+// # Parameters
+//
+//   - a: The value to wrap in a successful effect
+//
+// # Returns
+//
+//   - Effect[C, A]: An effect that always succeeds with the given value
+//
+// # Example
+//
+//	eff := effect.Of[MyContext]("hello")
+//	result, err := runEffect(eff, myContext)
+//	// result == "hello", err == nil
 func Of[C, A any](a A) Effect[C, A] {
 	return readerreaderioresult.Of[C](a)
 }
 
+// Map transforms the success value of an Effect using the provided function.
+// If the effect fails, the error is propagated unchanged.
+//
+// # Type Parameters
+//
+//   - C: The context type required by the effect
+//   - A: The input value type
+//   - B: The output value type
+//
+// # Parameters
+//
+//   - f: The transformation function to apply to the success value
+//
+// # Returns
+//
+//   - Operator[C, A, B]: A function that transforms Effect[C, A] to Effect[C, B]
+//
+// # Example
+//
+//	eff := effect.Of[MyContext](42)
+//	mapped := effect.Map[MyContext](func(x int) string {
+//		return strconv.Itoa(x)
+//	})(eff)
+//	// mapped produces "42"
 func Map[C, A, B any](f func(A) B) Operator[C, A, B] {
 	return readerreaderioresult.Map[C](f)
 }
 
+// Chain sequences two effects, where the second effect depends on the result of the first.
+// This is the monadic bind operation (flatMap) for effects.
+// If the first effect fails, the second is not executed.
+//
+// # Type Parameters
+//
+//   - C: The context type required by the effects
+//   - A: The input value type
+//   - B: The output value type
+//
+// # Parameters
+//
+//   - f: A function that takes the result of the first effect and returns a new effect
+//
+// # Returns
+//
+//   - Operator[C, A, B]: A function that transforms Effect[C, A] to Effect[C, B]
+//
+// # Example
+//
+//	eff := effect.Of[MyContext](42)
+//	chained := effect.Chain[MyContext](func(x int) Effect[MyContext, string] {
+//		return effect.Of[MyContext](strconv.Itoa(x * 2))
+//	})(eff)
+//	// chained produces "84"
 func Chain[C, A, B any](f Kleisli[C, A, B]) Operator[C, A, B] {
 	return readerreaderioresult.Chain(f)
 }
 
+// Ap applies a function wrapped in an Effect to a value wrapped in an Effect.
+// This is the applicative apply operation, useful for applying effects in parallel.
+//
+// # Type Parameters
+//
+//   - B: The output value type
+//   - C: The context type required by the effects
+//   - A: The input value type
+//
+// # Parameters
+//
+//   - fa: The effect containing the value to apply the function to
+//
+// # Returns
+//
+//   - Operator[C, func(A) B, B]: A function that applies the function effect to the value effect
+//
+// # Example
+//
+//	fnEff := effect.Of[MyContext](func(x int) int { return x * 2 })
+//	valEff := effect.Of[MyContext](21)
+//	result := effect.Ap[int](valEff)(fnEff)
+//	// result produces 42
 func Ap[B, C, A any](fa Effect[C, A]) Operator[C, func(A) B, B] {
 	return readerreaderioresult.Ap[B](fa)
 }
 
+// Suspend delays the evaluation of an effect until it is run.
+// This is useful for recursive effects or when you need lazy evaluation.
+//
+// # Type Parameters
+//
+//   - C: The context type required by the effect
+//   - A: The type of the success value
+//
+// # Parameters
+//
+//   - fa: A lazy computation that produces an effect
+//
+// # Returns
+//
+//   - Effect[C, A]: An effect that evaluates the lazy computation when run
+//
+// # Example
+//
+//	var recursiveEff func(int) Effect[MyContext, int]
+//	recursiveEff = func(n int) Effect[MyContext, int] {
+//		if n <= 0 {
+//			return effect.Of[MyContext](0)
+//		}
+//		return effect.Suspend(func() Effect[MyContext, int] {
+//			return effect.Map[MyContext](func(x int) int {
+//				return x + n
+//			})(recursiveEff(n - 1))
+//		})
+//	}
 func Suspend[C, A any](fa Lazy[Effect[C, A]]) Effect[C, A] {
 	return readerreaderioresult.Defer(fa)
 }
 
+// Tap executes a side effect for its effect, but returns the original value.
+// This is useful for logging, debugging, or performing actions without changing the result.
+//
+// # Type Parameters
+//
+//   - C: The context type required by the effects
+//   - A: The value type
+//   - ANY: The type produced by the side effect (ignored)
+//
+// # Parameters
+//
+//   - f: A function that performs a side effect based on the value
+//
+// # Returns
+//
+//   - Operator[C, A, A]: A function that executes the side effect but preserves the original value
+//
+// # Example
+//
+//	eff := effect.Of[MyContext](42)
+//	tapped := effect.Tap[MyContext](func(x int) Effect[MyContext, any] {
+//		fmt.Println("Value:", x)
+//		return effect.Of[MyContext, any](nil)
+//	})(eff)
+//	// Prints "Value: 42" but still produces 42
 func Tap[C, A, ANY any](f Kleisli[C, A, ANY]) Operator[C, A, A] {
 	return readerreaderioresult.Tap(f)
 }
 
+// Ternary creates a conditional effect based on a predicate.
+// If the predicate returns true, onTrue is executed; otherwise, onFalse is executed.
+//
+// # Type Parameters
+//
+//   - C: The context type required by the effects
+//   - A: The input value type
+//   - B: The output value type
+//
+// # Parameters
+//
+//   - pred: A predicate function to test the input value
+//   - onTrue: The effect to execute if the predicate is true
+//   - onFalse: The effect to execute if the predicate is false
+//
+// # Returns
+//
+//   - Kleisli[C, A, B]: A function that conditionally executes one of two effects
+//
+// # Example
+//
+//	kleisli := effect.Ternary(
+//		func(x int) bool { return x > 10 },
+//		func(x int) Effect[MyContext, string] {
+//			return effect.Of[MyContext]("large")
+//		},
+//		func(x int) Effect[MyContext, string] {
+//			return effect.Of[MyContext]("small")
+//		},
+//	)
+//	result := kleisli(15) // produces "large"
 func Ternary[C, A, B any](pred Predicate[A], onTrue, onFalse Kleisli[C, A, B]) Kleisli[C, A, B] {
 	return function.Ternary(pred, onTrue, onFalse)
 }
 
+// ChainResultK chains an effect with a function that returns a Result.
+// This is useful for integrating Result-based computations into effect chains.
+//
+// # Type Parameters
+//
+//   - C: The context type required by the effect
+//   - A: The input value type
+//   - B: The output value type
+//
+// # Parameters
+//
+//   - f: A function that takes A and returns Result[B]
+//
+// # Returns
+//
+//   - Operator[C, A, B]: A function that chains the Result-returning function with the effect
+//
+// # Example
+//
+//	parseIntResult := result.Eitherize1(strconv.Atoi)
+//	eff := effect.Of[MyContext]("42")
+//	chained := effect.ChainResultK[MyContext](parseIntResult)(eff)
+//	// chained produces 42 as an int
+//
+//go:inline
 func ChainResultK[C, A, B any](f result.Kleisli[A, B]) Operator[C, A, B] {
 	return readerreaderioresult.ChainResultK[C](f)
 }
 
+// ChainReaderK chains an effect with a function that returns a Reader.
+// This is useful for integrating Reader-based computations (pure context-dependent functions)
+// into effect chains. The Reader is automatically lifted into the Effect context.
+//
+// # Type Parameters
+//
+//   - C: The context type required by the effect
+//   - A: The input value type
+//   - B: The output value type
+//
+// # Parameters
+//
+//   - f: A function that takes A and returns Reader[C, B]
+//
+// # Returns
+//
+//   - Operator[C, A, B]: A function that chains the Reader-returning function with the effect
+//
+// # Example
+//
+//	type Config struct { Multiplier int }
+//
+//	getMultiplied := func(n int) reader.Reader[Config, int] {
+//	    return func(cfg Config) int {
+//	        return n * cfg.Multiplier
+//	    }
+//	}
+//
+//	eff := effect.Of[Config](5)
+//	chained := effect.ChainReaderK[Config](getMultiplied)(eff)
+//	// With Config{Multiplier: 3}, produces 15
+//
+//go:inline
+func ChainReaderK[C, A, B any](f reader.Kleisli[C, A, B]) Operator[C, A, B] {
+	return readerreaderioresult.ChainReaderK(f)
+}
+
+// ChainThunkK chains an effect with a function that returns a Thunk.
+// This is useful for integrating Thunk-based computations (context-independent IO with error handling)
+// into effect chains. The Thunk is automatically lifted into the Effect context.
+//
+// # Type Parameters
+//
+//   - C: The context type required by the effect
+//   - A: The input value type
+//   - B: The output value type
+//
+// # Parameters
+//
+//   - f: A function that takes A and returns Thunk[B] (readerioresult.Kleisli[A, B])
+//
+// # Returns
+//
+//   - Operator[C, A, B]: A function that chains the Thunk-returning function with the effect
+//
+// # Example
+//
+//	performIO := func(n int) readerioresult.ReaderIOResult[string] {
+//	    return func(ctx context.Context) io.IO[result.Result[string]] {
+//	        return func() result.Result[string] {
+//	            // Perform IO operation that doesn't need effect context
+//	            return result.Of(fmt.Sprintf("Processed: %d", n))
+//	        }
+//	    }
+//	}
+//
+//	eff := effect.Of[MyContext](42)
+//	chained := effect.ChainThunkK[MyContext](performIO)(eff)
+//	// chained produces "Processed: 42"
+//
+//go:inline
+func ChainThunkK[C, A, B any](f thunk.Kleisli[A, B]) Operator[C, A, B] {
+	return fromreader.ChainReaderK(
+		Chain[C, A, B],
+		FromThunk[C, B],
+		f,
+	)
+}
+
+// ChainReaderIOK chains an effect with a function that returns a ReaderIO.
+// This is useful for integrating ReaderIO-based computations (context-dependent IO operations)
+// into effect chains. The ReaderIO is automatically lifted into the Effect context.
+//
+// # Type Parameters
+//
+//   - C: The context type required by the effect
+//   - A: The input value type
+//   - B: The output value type
+//
+// # Parameters
+//
+//   - f: A function that takes A and returns ReaderIO[C, B]
+//
+// # Returns
+//
+//   - Operator[C, A, B]: A function that chains the ReaderIO-returning function with the effect
+//
+// # Example
+//
+//	type Config struct { LogPrefix string }
+//
+//	logAndDouble := func(n int) readerio.ReaderIO[Config, int] {
+//	    return func(cfg Config) io.IO[int] {
+//	        return func() int {
+//	            fmt.Printf("%s: %d\n", cfg.LogPrefix, n)
+//	            return n * 2
+//	        }
+//	    }
+//	}
+//
+//	eff := effect.Of[Config](21)
+//	chained := effect.ChainReaderIOK[Config](logAndDouble)(eff)
+//	// Logs "prefix: 21" and produces 42
+//
+//go:inline
+func ChainReaderIOK[C, A, B any](f readerio.Kleisli[C, A, B]) Operator[C, A, B] {
+	return readerreaderioresult.ChainReaderIOK(f)
+}
+
+// Read provides a context to an effect, partially applying it.
+// This converts an Effect[C, A] to a Thunk[A] by supplying the required context.
+//
+// # Type Parameters
+//
+//   - A: The type of the success value
+//   - C: The context type
+//
+// # Parameters
+//
+//   - c: The context to provide to the effect
+//
+// # Returns
+//
+//   - func(Effect[C, A]) Thunk[A]: A function that converts an effect to a thunk
+//
+// # Example
+//
+//	ctx := MyContext{Value: "test"}
+//	eff := effect.Of[MyContext](42)
+//	thunk := effect.Read[int](ctx)(eff)
+//	// thunk is now a Thunk[int] that can be run without context
+//
+//go:inline
 func Read[A, C any](c C) func(Effect[C, A]) Thunk[A] {
 	return readerreaderioresult.Read[A](c)
 }

v2/effect/effect_missing_test.go

@@ -0,0 +1,213 @@
+// 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 effect
+
+import (
+	"context"
+	"errors"
+	"strconv"
+	"testing"
+
+	"github.com/IBM/fp-go/v2/result"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestRead(t *testing.T) {
+	t.Run("provides context to effect", func(t *testing.T) {
+		ctx := TestContext{Value: "test-context"}
+		eff := Of[TestContext](42)
+
+		thunk := Read[int](ctx)(eff)
+		ioResult := thunk(context.Background())
+		res := ioResult()
+
+		assert.True(t, result.IsRight(res))
+		value, err := result.Unwrap(res)
+		assert.NoError(t, err)
+		assert.Equal(t, 42, value)
+	})
+
+	t.Run("provides context to failing effect", func(t *testing.T) {
+		expectedErr := errors.New("read error")
+		ctx := TestContext{Value: "test"}
+		eff := Fail[TestContext, string](expectedErr)
+
+		thunk := Read[string](ctx)(eff)
+		ioResult := thunk(context.Background())
+		res := ioResult()
+
+		assert.True(t, result.IsLeft(res))
+		_, err := result.Unwrap(res)
+		assert.Error(t, err)
+		assert.Equal(t, expectedErr, err)
+	})
+
+	t.Run("provides context to chained effects", func(t *testing.T) {
+		ctx := TestContext{Value: "base"}
+		eff := Chain(func(x int) Effect[TestContext, string] {
+			return Of[TestContext](strconv.Itoa(x * 2))
+		})(Of[TestContext](21))
+
+		thunk := Read[string](ctx)(eff)
+		ioResult := thunk(context.Background())
+		res := ioResult()
+
+		assert.True(t, result.IsRight(res))
+		value, err := result.Unwrap(res)
+		assert.NoError(t, err)
+		assert.Equal(t, "42", value)
+	})
+
+	t.Run("works with different context types", func(t *testing.T) {
+		type CustomContext struct {
+			ID   int
+			Name string
+		}
+
+		ctx := CustomContext{ID: 100, Name: "custom"}
+		eff := Of[CustomContext]("result")
+
+		thunk := Read[string](ctx)(eff)
+		ioResult := thunk(context.Background())
+		res := ioResult()
+
+		assert.True(t, result.IsRight(res))
+		value, err := result.Unwrap(res)
+		assert.NoError(t, err)
+		assert.Equal(t, "result", value)
+	})
+
+	t.Run("can be composed with RunSync", func(t *testing.T) {
+		ctx := TestContext{Value: "test"}
+		eff := Of[TestContext](100)
+
+		thunk := Read[int](ctx)(eff)
+		readerResult := RunSync(thunk)
+		value, err := readerResult(context.Background())
+
+		assert.NoError(t, err)
+		assert.Equal(t, 100, value)
+	})
+}
+
+func TestChainResultK(t *testing.T) {
+	t.Run("chains successful Result function", func(t *testing.T) {
+		parseIntResult := result.Eitherize1(strconv.Atoi)
+		eff := Of[TestContext]("42")
+		chained := ChainResultK[TestContext](parseIntResult)(eff)
+
+		result, err := runEffect(chained, TestContext{Value: "test"})
+
+		assert.NoError(t, err)
+		assert.Equal(t, 42, result)
+	})
+
+	t.Run("chains failing Result function", func(t *testing.T) {
+		parseIntResult := result.Eitherize1(strconv.Atoi)
+		eff := Of[TestContext]("not-a-number")
+		chained := ChainResultK[TestContext](parseIntResult)(eff)
+
+		_, err := runEffect(chained, TestContext{Value: "test"})
+
+		assert.Error(t, err)
+		assert.Contains(t, err.Error(), "invalid syntax")
+	})
+
+	t.Run("propagates error from original effect", func(t *testing.T) {
+		expectedErr := errors.New("original error")
+		parseIntResult := result.Eitherize1(strconv.Atoi)
+		eff := Fail[TestContext, string](expectedErr)
+		chained := ChainResultK[TestContext](parseIntResult)(eff)
+
+		_, err := runEffect(chained, TestContext{Value: "test"})
+
+		assert.Error(t, err)
+		assert.Equal(t, expectedErr, err)
+	})
+
+	t.Run("chains multiple Result functions", func(t *testing.T) {
+		parseIntResult := result.Eitherize1(strconv.Atoi)
+		formatResult := func(x int) result.Result[string] {
+			return result.Of("value: " + strconv.Itoa(x))
+		}
+
+		eff := Of[TestContext]("42")
+		chained := ChainResultK[TestContext](formatResult)(
+			ChainResultK[TestContext](parseIntResult)(eff),
+		)
+
+		result, err := runEffect(chained, TestContext{Value: "test"})
+
+		assert.NoError(t, err)
+		assert.Equal(t, "value: 42", result)
+	})
+
+	t.Run("integrates with other effect operations", func(t *testing.T) {
+		parseIntResult := result.Eitherize1(strconv.Atoi)
+
+		eff := Map[TestContext](func(x int) string {
+			return "final: " + strconv.Itoa(x)
+		})(ChainResultK[TestContext](parseIntResult)(Of[TestContext]("100")))
+
+		result, err := runEffect(eff, TestContext{Value: "test"})
+
+		assert.NoError(t, err)
+		assert.Equal(t, "final: 100", result)
+	})
+
+	t.Run("works with custom Result functions", func(t *testing.T) {
+		validatePositive := func(x int) result.Result[int] {
+			if x > 0 {
+				return result.Of(x)
+			}
+			return result.Left[int](errors.New("must be positive"))
+		}
+
+		parseIntResult := result.Eitherize1(strconv.Atoi)
+
+		// Test with positive number
+		eff1 := ChainResultK[TestContext](validatePositive)(
+			ChainResultK[TestContext](parseIntResult)(Of[TestContext]("42")),
+		)
+		result1, err1 := runEffect(eff1, TestContext{Value: "test"})
+		assert.NoError(t, err1)
+		assert.Equal(t, 42, result1)
+
+		// Test with negative number
+		eff2 := ChainResultK[TestContext](validatePositive)(
+			ChainResultK[TestContext](parseIntResult)(Of[TestContext]("-5")),
+		)
+		_, err2 := runEffect(eff2, TestContext{Value: "test"})
+		assert.Error(t, err2)
+		assert.Contains(t, err2.Error(), "must be positive")
+	})
+
+	t.Run("preserves error context", func(t *testing.T) {
+		customError := errors.New("custom validation error")
+		validateFunc := func(s string) result.Result[string] {
+			if len(s) > 0 {
+				return result.Of(s)
+			}
+			return result.Left[string](customError)
+		}
+
+		eff := ChainResultK[TestContext](validateFunc)(Of[TestContext](""))
+		_, err := runEffect(eff, TestContext{Value: "test"})
+
+		assert.Error(t, err)
+		assert.Equal(t, customError, err)
+	})
+}

v2/effect/monoid.go

@@ -1,3 +1,18 @@
+// 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 effect
 
 import (
@@ -5,10 +20,66 @@ import (
 	"github.com/IBM/fp-go/v2/monoid"
 )
 
+// ApplicativeMonoid creates a monoid for effects using applicative semantics.
+// This combines effects by running both and combining their results using the provided monoid.
+// If either effect fails, the combined effect fails.
+//
+// # Type Parameters
+//
+//   - C: The context type required by the effects
+//   - A: The value type that has a monoid instance
+//
+// # Parameters
+//
+//   - m: The monoid instance for combining values of type A
+//
+// # Returns
+//
+//   - Monoid[Effect[C, A]]: A monoid for combining effects
+//
+// # Example
+//
+//	stringMonoid := monoid.MakeMonoid(
+//		func(a, b string) string { return a + b },
+//		"",
+//	)
+//	effectMonoid := effect.ApplicativeMonoid[MyContext](stringMonoid)
+//	eff1 := effect.Of[MyContext]("Hello")
+//	eff2 := effect.Of[MyContext](" World")
+//	combined := effectMonoid.Concat(eff1, eff2)
+//	// combined produces "Hello World"
 func ApplicativeMonoid[C, A any](m monoid.Monoid[A]) Monoid[Effect[C, A]] {
 	return readerreaderioresult.ApplicativeMonoid[C](m)
 }
 
+// AlternativeMonoid creates a monoid for effects using alternative semantics.
+// This tries the first effect, and if it fails, tries the second effect.
+// If both succeed, their results are combined using the provided monoid.
+//
+// # Type Parameters
+//
+//   - C: The context type required by the effects
+//   - A: The value type that has a monoid instance
+//
+// # Parameters
+//
+//   - m: The monoid instance for combining values of type A
+//
+// # Returns
+//
+//   - Monoid[Effect[C, A]]: A monoid for combining effects with fallback behavior
+//
+// # Example
+//
+//	stringMonoid := monoid.MakeMonoid(
+//		func(a, b string) string { return a + b },
+//		"",
+//	)
+//	effectMonoid := effect.AlternativeMonoid[MyContext](stringMonoid)
+//	eff1 := effect.Fail[MyContext, string](errors.New("failed"))
+//	eff2 := effect.Of[MyContext]("fallback")
+//	combined := effectMonoid.Concat(eff1, eff2)
+//	// combined produces "fallback" (first failed, so second is used)
 func AlternativeMonoid[C, A any](m monoid.Monoid[A]) Monoid[Effect[C, A]] {
 	return readerreaderioresult.AlternativeMonoid[C](m)
 }

v2/effect/retry.go

@@ -1,3 +1,18 @@
+// 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 effect
 
 import (
@@ -5,6 +20,39 @@ import (
 	"github.com/IBM/fp-go/v2/retry"
 )
 
+// Retrying executes an effect with retry logic based on a policy and check predicate.
+// The effect is retried according to the policy until either:
+//   - The effect succeeds and the check predicate returns false
+//   - The retry policy is exhausted
+//
+// # Type Parameters
+//
+//   - C: The context type required by the effect
+//   - A: The type of the success value
+//
+// # Parameters
+//
+//   - policy: The retry policy defining retry limits and delays
+//   - action: An effectful computation that receives retry status and produces a value
+//   - check: A predicate that determines if the result should trigger a retry
+//
+// # Returns
+//
+//   - Effect[C, A]: An effect that retries according to the policy
+//
+// # Example
+//
+//	policy := retry.LimitRetries(3)
+//	eff := effect.Retrying[MyContext, string](
+//		policy,
+//		func(status retry.RetryStatus) Effect[MyContext, string] {
+//			return fetchData() // may fail
+//		},
+//		func(result Result[string]) bool {
+//			return result.IsLeft() // retry on error
+//		},
+//	)
+//	// Retries up to 3 times if fetchData fails
 func Retrying[C, A any](
 	policy retry.RetryPolicy,
 	action Kleisli[C, retry.RetryStatus, A],

v2/effect/run.go

@@ -1,3 +1,18 @@
+// 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 effect
 
 import (
@@ -8,10 +23,64 @@ import (
 	"github.com/IBM/fp-go/v2/result"
 )
 
+// Provide supplies a context to an effect, converting it to a Thunk.
+// This is the first step in running an effect - it eliminates the context dependency
+// by providing the required context value.
+//
+// # Type Parameters
+//
+//   - C: The context type required by the effect
+//   - A: The type of the success value
+//
+// # Parameters
+//
+//   - c: The context value to provide to the effect
+//
+// # Returns
+//
+//   - func(Effect[C, A]) ReaderIOResult[A]: A function that converts an effect to a thunk
+//
+// # Example
+//
+//	ctx := MyContext{APIKey: "secret"}
+//	eff := effect.Of[MyContext](42)
+//	thunk := effect.Provide[MyContext, int](ctx)(eff)
+//	// thunk is now a ReaderIOResult[int] that can be run
 func Provide[C, A any](c C) func(Effect[C, A]) ReaderIOResult[A] {
 	return readerreaderioresult.Read[A](c)
 }
 
+// RunSync executes a Thunk synchronously, converting it to a standard Go function.
+// This is the final step in running an effect - it executes the IO operations
+// and returns the result as a standard (value, error) tuple.
+//
+// # Type Parameters
+//
+//   - A: The type of the success value
+//
+// # Parameters
+//
+//   - fa: The thunk to execute
+//
+// # Returns
+//
+//   - readerresult.ReaderResult[A]: A function that takes a context.Context and returns (A, error)
+//
+// # Example
+//
+//	ctx := MyContext{APIKey: "secret"}
+//	eff := effect.Of[MyContext](42)
+//	thunk := effect.Provide[MyContext, int](ctx)(eff)
+//	readerResult := effect.RunSync(thunk)
+//	value, err := readerResult(context.Background())
+//	// value == 42, err == nil
+//
+// # Complete Example
+//
+//	// Typical usage pattern:
+//	result, err := effect.RunSync(
+//		effect.Provide[MyContext, string](myContext)(myEffect),
+//	)(context.Background())
 func RunSync[A any](fa ReaderIOResult[A]) readerresult.ReaderResult[A] {
 	return func(ctx context.Context) (A, error) {
 		return result.Unwrap(fa(ctx)())

v2/effect/traverse.go

@@ -1,7 +1,55 @@
+// 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 effect
 
 import "github.com/IBM/fp-go/v2/context/readerreaderioresult"
 
+// TraverseArray applies an effectful function to each element of an array,
+// collecting the results into a new array. If any effect fails, the entire
+// traversal fails and returns the first error encountered.
+//
+// This is useful for performing effectful operations on collections while
+// maintaining the sequential order of results.
+//
+// # Type Parameters
+//
+//   - C: The context type required by the effects
+//   - A: The input element type
+//   - B: The output element type
+//
+// # Parameters
+//
+//   - f: An effectful function to apply to each element
+//
+// # Returns
+//
+//   - Kleisli[C, []A, []B]: A function that transforms an array of A to an effect producing an array of B
+//
+// # Example
+//
+//	parseIntEff := func(s string) Effect[MyContext, int] {
+//		val, err := strconv.Atoi(s)
+//		if err != nil {
+//			return effect.Fail[MyContext, int](err)
+//		}
+//		return effect.Of[MyContext](val)
+//	}
+//	input := []string{"1", "2", "3"}
+//	eff := effect.TraverseArray[MyContext](parseIntEff)(input)
+//	// eff produces []int{1, 2, 3}
 func TraverseArray[C, A, B any](f Kleisli[C, A, B]) Kleisli[C, []A, []B] {
 	return readerreaderioresult.TraverseArray(f)
 }

v2/effect/types.go

@@ -1,3 +1,18 @@
+// 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 effect
 
 import (
@@ -17,21 +32,61 @@ import (
 )
 
 type (
-	Either[E, A any]      = either.Either[E, A]
-	Reader[R, A any]      = reader.Reader[R, A]
-	ReaderIO[R, A any]    = readerio.ReaderIO[R, A]
-	IO[A any]             = io.IO[A]
-	IOEither[E, A any]    = ioeither.IOEither[E, A]
-	Lazy[A any]           = lazy.Lazy[A]
-	IOResult[A any]       = ioresult.IOResult[A]
-	ReaderIOResult[A any] = readerioresult.ReaderIOResult[A]
-	Monoid[A any]         = monoid.Monoid[A]
-	Effect[C, A any]      = readerreaderioresult.ReaderReaderIOResult[C, A]
-	Thunk[A any]          = ReaderIOResult[A]
-	Predicate[A any]      = predicate.Predicate[A]
-	Result[A any]         = result.Result[A]
-	Lens[S, T any]        = lens.Lens[S, T]
+	// Either represents a value that can be either a Left (error) or Right (success).
+	Either[E, A any] = either.Either[E, A]
 
-	Kleisli[C, A, B any]  = readerreaderioresult.Kleisli[C, A, B]
+	// Reader represents a computation that depends on a context R and produces a value A.
+	Reader[R, A any] = reader.Reader[R, A]
+
+	// ReaderIO represents a computation that depends on a context R and produces an IO action returning A.
+	ReaderIO[R, A any] = readerio.ReaderIO[R, A]
+
+	// IO represents a synchronous side effect that produces a value A.
+	IO[A any] = io.IO[A]
+
+	// IOEither represents a synchronous side effect that can fail with error E or succeed with value A.
+	IOEither[E, A any] = ioeither.IOEither[E, A]
+
+	// Lazy represents a lazily evaluated computation that produces a value A.
+	Lazy[A any] = lazy.Lazy[A]
+
+	// IOResult represents a synchronous side effect that can fail with an error or succeed with value A.
+	IOResult[A any] = ioresult.IOResult[A]
+
+	// ReaderIOResult represents a computation that depends on context and performs IO with error handling.
+	ReaderIOResult[A any] = readerioresult.ReaderIOResult[A]
+
+	// Monoid represents an algebraic structure with an associative binary operation and an identity element.
+	Monoid[A any] = monoid.Monoid[A]
+
+	// Effect represents an effectful computation that:
+	//   - Requires a context of type C
+	//   - Can perform I/O operations
+	//   - Can fail with an error
+	//   - Produces a value of type A on success
+	//
+	// This is the core type of the effect package, providing a complete effect system
+	// for managing dependencies, errors, and side effects in a composable way.
+	Effect[C, A any] = readerreaderioresult.ReaderReaderIOResult[C, A]
+
+	// Thunk represents a computation that performs IO with error handling but doesn't require context.
+	// It's equivalent to ReaderIOResult and is used as an intermediate step when providing context to an Effect.
+	Thunk[A any] = ReaderIOResult[A]
+
+	// Predicate represents a function that tests a value of type A and returns a boolean.
+	Predicate[A any] = predicate.Predicate[A]
+
+	// Result represents a computation result that can be either an error (Left) or a success value (Right).
+	Result[A any] = result.Result[A]
+
+	// Lens represents an optic for focusing on a field T within a structure S.
+	Lens[S, T any] = lens.Lens[S, T]
+
+	// Kleisli represents a function from A to Effect[C, B], enabling monadic composition.
+	// It's the fundamental building block for chaining effectful computations.
+	Kleisli[C, A, B any] = readerreaderioresult.Kleisli[C, A, B]
+
+	// Operator represents a function that transforms Effect[C, A] to Effect[C, B].
+	// It's used for lifting operations over effects.
 	Operator[C, A, B any] = readerreaderioresult.Operator[C, A, B]
 )

v2/optics/codec/validate/from_test.go

@@ -480,5 +480,3 @@ func BenchmarkFromReaderResult_WithContext(b *testing.B) {
 		_ = validator(42)(ctx)
 	}
 }
-
-// Made with Bob