fix: do not fail if coverage fails

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

.github/workflows/build.yml

@@ -42,6 +42,7 @@ jobs:
           go test -v -race -coverprofile=coverage.txt -covermode=atomic ./...
       
       - name: Upload coverage to Coveralls
+        continue-on-error: true
         uses: coverallsapp/github-action@v2
         with:
           github-token: ${{ secrets.GITHUB_TOKEN }}
@@ -81,6 +82,7 @@ jobs:
           go test -v -race -coverprofile=coverage.txt -covermode=atomic ./...
       
       - name: Upload coverage to Coveralls
+        continue-on-error: true
         uses: coverallsapp/github-action@v2
         with:
           github-token: ${{ secrets.GITHUB_TOKEN }}
@@ -106,6 +108,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Coveralls Finished
+        continue-on-error: true
         uses: coverallsapp/github-action@v2
         with:
           github-token: ${{ secrets.GITHUB_TOKEN }}

v2/context/readerioresult/file/file.go

@@ -83,6 +83,45 @@ var (
 		RIOE.WithContext[*os.File],
 	)
 
+	// Create creates or truncates a file for writing within the given context.
+	// If the file already exists, it is truncated. If it doesn't exist, it is created
+	// with mode 0666 (before umask).
+	//
+	// 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 WriteFile.
+	//
+	// Parameters:
+	//   - path: The path to the file to create or truncate
+	//
+	// Returns:
+	//   - ReaderIOResult[*os.File]: A context-aware computation that creates the file
+	//
+	// Example:
+	//
+	//	createFile := Create("output.txt")
+	//	result := createFile(ctx)()
+	//	either.Fold(
+	//	    result,
+	//	    func(err error) { log.Printf("Error: %v", err) },
+	//	    func(f *os.File) {
+	//	        defer f.Close()
+	//	        f.WriteString("Hello, World!")
+	//	    },
+	//	)
+	//
+	// See Also:
+	//   - WriteFile: For writing data to a file with automatic resource management
+	//   - Open: For opening files for reading
+	//   - Close: For closing file handles
+	Create = F.Flow3(
+		IOEF.Create,
+		RIOE.FromIOEither[*os.File],
+		RIOE.WithContext[*os.File],
+	)
+
 	// Remove removes a file by name.
 	// The operation returns the filename on success, allowing for easy composition
 	// with other file operations.
@@ -191,3 +230,48 @@ func ReadFile(path string) ReaderIOResult[[]byte] {
 		}
 	})
 }
+
+// WriteFile writes data to 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.
+//
+// If the file doesn't exist, it is created with mode 0666 (before umask).
+// If the file already exists, it is truncated before writing.
+//
+// The operation:
+//   - Creates or truncates the file for writing
+//   - Writes all data to the file
+//   - Automatically closes the file when done
+//   - Respects context cancellation during the write operation
+//
+// Parameters:
+//   - data: The byte slice to write to the file
+//
+// Returns:
+//   - Kleisli[string, []byte]: A function that takes a file path and returns a computation
+//     that writes the data and returns the written bytes on success
+//
+// Example:
+//
+//	writeOp := WriteFile([]byte("Hello, World!"))
+//	result := writeOp("output.txt")(ctx)()
+//	either.Fold(
+//	    result,
+//	    func(err error) { log.Printf("Write error: %v", err) },
+//	    func(data []byte) { log.Printf("Wrote %d bytes", len(data)) },
+//	)
+//
+// The function uses WithResource internally to ensure proper cleanup:
+//
+//	WriteFile(data) = Create >> WriteAll(data) >> Close
+//
+// See Also:
+//   - ReadFile: For reading file contents with automatic resource management
+//   - Create: For creating files without automatic writing
+//   - WriteAll: For writing to an already-open file handle
+func WriteFile(data []byte) Kleisli[string, []byte] {
+	return F.Flow2(
+		Create,
+		WriteAll[*os.File](data),
+	)
+}

v2/context/readerioresult/file/file_test.go

@@ -18,11 +18,16 @@ package file
 import (
 	"context"
 	"fmt"
+	"os"
+	"path/filepath"
+	"testing"
 
 	R "github.com/IBM/fp-go/v2/context/readerioresult"
+	E "github.com/IBM/fp-go/v2/either"
 	F "github.com/IBM/fp-go/v2/function"
 	"github.com/IBM/fp-go/v2/io"
 	J "github.com/IBM/fp-go/v2/json"
+	"github.com/stretchr/testify/assert"
 )
 
 type RecordType struct {
@@ -49,3 +54,267 @@ func ExampleReadFile() {
 	// Output:
 	// Right[string](Carsten)
 }
+
+func TestCreate(t *testing.T) {
+	ctx := context.Background()
+
+	t.Run("Success - creates new file", func(t *testing.T) {
+		tempFile := filepath.Join(t.TempDir(), "test_create.txt")
+
+		createOp := Create(tempFile)
+		result := createOp(ctx)()
+
+		assert.True(t, E.IsRight(result))
+
+		// Verify file was created
+		_, err := os.Stat(tempFile)
+		assert.NoError(t, err)
+
+		// Clean up file handle
+		E.MonadFold(result,
+			func(error) *os.File { return nil },
+			func(f *os.File) *os.File { f.Close(); return f },
+		)
+	})
+
+	t.Run("Success - truncates existing file", func(t *testing.T) {
+		tempFile := filepath.Join(t.TempDir(), "test_truncate.txt")
+
+		// Create file with initial content
+		err := os.WriteFile(tempFile, []byte("initial content"), 0644)
+		assert.NoError(t, err)
+
+		// Create should truncate
+		createOp := Create(tempFile)
+		result := createOp(ctx)()
+
+		assert.True(t, E.IsRight(result))
+
+		// Close the file
+		E.MonadFold(result,
+			func(error) *os.File { return nil },
+			func(f *os.File) *os.File { f.Close(); return f },
+		)
+
+		// Verify file was truncated
+		content, err := os.ReadFile(tempFile)
+		assert.NoError(t, err)
+		assert.Empty(t, content)
+	})
+
+	t.Run("Failure - invalid path", func(t *testing.T) {
+		// Try to create file in non-existent directory
+		invalidPath := filepath.Join(t.TempDir(), "nonexistent", "test.txt")
+
+		createOp := Create(invalidPath)
+		result := createOp(ctx)()
+
+		assert.True(t, E.IsLeft(result))
+	})
+
+	t.Run("Success - file can be written to", func(t *testing.T) {
+		tempFile := filepath.Join(t.TempDir(), "test_write.txt")
+
+		createOp := Create(tempFile)
+		result := createOp(ctx)()
+
+		assert.True(t, E.IsRight(result))
+
+		// Write to the file
+		E.MonadFold(result,
+			func(err error) *os.File { t.Fatalf("Unexpected error: %v", err); return nil },
+			func(f *os.File) *os.File {
+				defer f.Close()
+				_, err := f.WriteString("test content")
+				assert.NoError(t, err)
+				return f
+			},
+		)
+
+		// Verify content was written
+		content, err := os.ReadFile(tempFile)
+		assert.NoError(t, err)
+		assert.Equal(t, "test content", string(content))
+	})
+
+	t.Run("Context cancellation", func(t *testing.T) {
+		cancelCtx, cancel := context.WithCancel(context.Background())
+		cancel() // Cancel immediately
+
+		tempFile := filepath.Join(t.TempDir(), "test_cancel.txt")
+
+		createOp := Create(tempFile)
+		result := createOp(cancelCtx)()
+
+		// Note: File creation itself doesn't check context, but this tests the pattern
+		// In practice, context cancellation would affect subsequent operations
+		_ = result
+	})
+}
+
+func TestWriteFile(t *testing.T) {
+	ctx := context.Background()
+
+	t.Run("Success - writes data to new file", func(t *testing.T) {
+		tempFile := filepath.Join(t.TempDir(), "test_write.txt")
+		testData := []byte("Hello, World!")
+
+		writeOp := WriteFile(testData)
+		result := writeOp(tempFile)(ctx)()
+
+		assert.True(t, E.IsRight(result))
+
+		// Verify returned data
+		E.MonadFold(result,
+			func(err error) []byte { t.Fatalf("Unexpected error: %v", err); return nil },
+			func(data []byte) []byte {
+				assert.Equal(t, testData, data)
+				return data
+			},
+		)
+
+		// Verify file content
+		content, err := os.ReadFile(tempFile)
+		assert.NoError(t, err)
+		assert.Equal(t, testData, content)
+	})
+
+	t.Run("Success - overwrites existing file", func(t *testing.T) {
+		tempFile := filepath.Join(t.TempDir(), "test_overwrite.txt")
+
+		// Write initial content
+		err := os.WriteFile(tempFile, []byte("old content"), 0644)
+		assert.NoError(t, err)
+
+		// Overwrite with new content
+		newData := []byte("new content")
+		writeOp := WriteFile(newData)
+		result := writeOp(tempFile)(ctx)()
+
+		assert.True(t, E.IsRight(result))
+
+		// Verify file was overwritten
+		content, err := os.ReadFile(tempFile)
+		assert.NoError(t, err)
+		assert.Equal(t, newData, content)
+	})
+
+	t.Run("Success - writes empty data", func(t *testing.T) {
+		tempFile := filepath.Join(t.TempDir(), "test_empty.txt")
+		emptyData := []byte{}
+
+		writeOp := WriteFile(emptyData)
+		result := writeOp(tempFile)(ctx)()
+
+		assert.True(t, E.IsRight(result))
+
+		// Verify file is empty
+		content, err := os.ReadFile(tempFile)
+		assert.NoError(t, err)
+		assert.Empty(t, content)
+	})
+
+	t.Run("Success - writes large data", func(t *testing.T) {
+		tempFile := filepath.Join(t.TempDir(), "test_large.txt")
+		largeData := make([]byte, 1024*1024) // 1MB
+		for i := range largeData {
+			largeData[i] = byte(i % 256)
+		}
+
+		writeOp := WriteFile(largeData)
+		result := writeOp(tempFile)(ctx)()
+
+		assert.True(t, E.IsRight(result))
+
+		// Verify file content
+		content, err := os.ReadFile(tempFile)
+		assert.NoError(t, err)
+		assert.Equal(t, largeData, content)
+	})
+
+	t.Run("Failure - invalid path", func(t *testing.T) {
+		invalidPath := filepath.Join(t.TempDir(), "nonexistent", "test.txt")
+		testData := []byte("test")
+
+		writeOp := WriteFile(testData)
+		result := writeOp(invalidPath)(ctx)()
+
+		assert.True(t, E.IsLeft(result))
+	})
+
+	t.Run("Success - writes binary data", func(t *testing.T) {
+		tempFile := filepath.Join(t.TempDir(), "test_binary.bin")
+		binaryData := []byte{0x00, 0x01, 0x02, 0xFF, 0xFE, 0xFD}
+
+		writeOp := WriteFile(binaryData)
+		result := writeOp(tempFile)(ctx)()
+
+		assert.True(t, E.IsRight(result))
+
+		// Verify binary content
+		content, err := os.ReadFile(tempFile)
+		assert.NoError(t, err)
+		assert.Equal(t, binaryData, content)
+	})
+
+	t.Run("Integration - write then read", func(t *testing.T) {
+		tempFile := filepath.Join(t.TempDir(), "test_roundtrip.txt")
+		testData := []byte("Round trip test data")
+
+		// Write data
+		writeOp := WriteFile(testData)
+		writeResult := writeOp(tempFile)(ctx)()
+		assert.True(t, E.IsRight(writeResult))
+
+		// Read data back
+		readOp := ReadFile(tempFile)
+		readResult := readOp(ctx)()
+		assert.True(t, E.IsRight(readResult))
+
+		// Verify data matches
+		E.MonadFold(readResult,
+			func(err error) []byte { t.Fatalf("Unexpected error: %v", err); return nil },
+			func(data []byte) []byte {
+				assert.Equal(t, testData, data)
+				return data
+			},
+		)
+	})
+
+	t.Run("Composition with Map", func(t *testing.T) {
+		tempFile := filepath.Join(t.TempDir(), "test_compose.txt")
+		testData := []byte("test data")
+
+		// Write and transform result
+		pipeline := F.Pipe1(
+			WriteFile(testData)(tempFile),
+			R.Map(func(data []byte) int { return len(data) }),
+		)
+
+		result := pipeline(ctx)()
+		assert.True(t, E.IsRight(result))
+
+		E.MonadFold(result,
+			func(err error) int { t.Fatalf("Unexpected error: %v", err); return 0 },
+			func(length int) int {
+				assert.Equal(t, len(testData), length)
+				return length
+			},
+		)
+	})
+
+	t.Run("Context cancellation during write", func(t *testing.T) {
+		cancelCtx, cancel := context.WithCancel(context.Background())
+		cancel() // Cancel immediately
+
+		tempFile := filepath.Join(t.TempDir(), "test_cancel.txt")
+		testData := []byte("test")
+
+		writeOp := WriteFile(testData)
+		result := writeOp(tempFile)(cancelCtx)()
+
+		// Note: The actual write may complete before cancellation is checked
+		// This test verifies the pattern works with cancelled contexts
+		_ = result
+	})
+}

v2/effect/common_test.go

@@ -26,7 +26,7 @@ type TestContext struct {
 
 // 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)
+	ioResult := Provide[A, C](ctx)(eff)
 	readerResult := RunSync(ioResult)
 	return readerResult(context.Background())
 }

v2/effect/dependencies.go

@@ -51,7 +51,7 @@ import (
 //	)(dbEffect)
 //
 //go:inline
-func Local[C1, C2, A any](acc Reader[C1, C2]) Kleisli[C1, Effect[C2, A], A] {
+func Local[A, C1, C2 any](acc Reader[C1, C2]) Kleisli[C1, Effect[C2, A], A] {
 	return readerreaderioresult.Local[A](acc)
 }
 
@@ -73,7 +73,7 @@ func Local[C1, C2, A any](acc Reader[C1, C2]) Kleisli[C1, Effect[C2, A], A] {
 //   - 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] {
+func Contramap[A, C1, C2 any](acc Reader[C1, C2]) Kleisli[C1, Effect[C2, A], A] {
 	return readerreaderioresult.Local[A](acc)
 }
 

v2/effect/dependencies_test.go

@@ -44,11 +44,11 @@ func TestLocal(t *testing.T) {
 		}
 
 		// Apply Local to transform the context
-		kleisli := Local[OuterContext, InnerContext, string](accessor)
+		kleisli := Local[string, OuterContext, InnerContext](accessor)
 		outerEffect := kleisli(innerEffect)
 
 		// Run with OuterContext
-		ioResult := Provide[OuterContext, string](OuterContext{
+		ioResult := Provide[string, OuterContext](OuterContext{
 			Value:  "test",
 			Number: 42,
 		})(outerEffect)
@@ -70,11 +70,11 @@ func TestLocal(t *testing.T) {
 			return InnerContext{Value: outer.Value + " transformed"}
 		}
 
-		kleisli := Local[OuterContext, InnerContext, string](accessor)
+		kleisli := Local[string, OuterContext, InnerContext](accessor)
 		outerEffect := kleisli(innerEffect)
 
 		// Run with OuterContext
-		ioResult := Provide[OuterContext, string](OuterContext{
+		ioResult := Provide[string, OuterContext](OuterContext{
 			Value:  "original",
 			Number: 100,
 		})(outerEffect)
@@ -93,10 +93,10 @@ func TestLocal(t *testing.T) {
 			return InnerContext{Value: outer.Value}
 		}
 
-		kleisli := Local[OuterContext, InnerContext, string](accessor)
+		kleisli := Local[string, OuterContext, InnerContext](accessor)
 		outerEffect := kleisli(innerEffect)
 
-		ioResult := Provide[OuterContext, string](OuterContext{
+		ioResult := Provide[string, OuterContext](OuterContext{
 			Value:  "test",
 			Number: 42,
 		})(outerEffect)
@@ -122,12 +122,12 @@ func TestLocal(t *testing.T) {
 		level3Effect := Of[Level3]("deep result")
 
 		// Transform Level2 -> Level3
-		local23 := Local[Level2, Level3, string](func(l2 Level2) Level3 {
+		local23 := Local[string, Level2, Level3](func(l2 Level2) Level3 {
 			return Level3{C: l2.B + "-c"}
 		})
 
 		// Transform Level1 -> Level2
-		local12 := Local[Level1, Level2, string](func(l1 Level1) Level2 {
+		local12 := Local[string, Level1, Level2](func(l1 Level1) Level2 {
 			return Level2{B: l1.A + "-b"}
 		})
 
@@ -136,7 +136,7 @@ func TestLocal(t *testing.T) {
 		level1Effect := local12(level2Effect)
 
 		// Run with Level1 context
-		ioResult := Provide[Level1, string](Level1{A: "a"})(level1Effect)
+		ioResult := Provide[string, Level1](Level1{A: "a"})(level1Effect)
 		readerResult := RunSync(ioResult)
 		result, err := readerResult(context.Background())
 
@@ -165,11 +165,11 @@ func TestLocal(t *testing.T) {
 			return app.DB
 		}
 
-		kleisli := Local[AppConfig, DatabaseConfig, string](accessor)
+		kleisli := Local[string, AppConfig, DatabaseConfig](accessor)
 		appEffect := kleisli(dbEffect)
 
 		// Run with full AppConfig
-		ioResult := Provide[AppConfig, string](AppConfig{
+		ioResult := Provide[string, AppConfig](AppConfig{
 			DB: DatabaseConfig{
 				Host:     "localhost",
 				Port:     5432,
@@ -195,21 +195,21 @@ func TestContramap(t *testing.T) {
 		}
 
 		// Test Local
-		localKleisli := Local[OuterContext, InnerContext, int](accessor)
+		localKleisli := Local[int, OuterContext, InnerContext](accessor)
 		localEffect := localKleisli(innerEffect)
 
 		// Test Contramap
-		contramapKleisli := Contramap[OuterContext, InnerContext, int](accessor)
+		contramapKleisli := Contramap[int, OuterContext, InnerContext](accessor)
 		contramapEffect := contramapKleisli(innerEffect)
 
 		outerCtx := OuterContext{Value: "test", Number: 100}
 
 		// Run both
-		localIO := Provide[OuterContext, int](outerCtx)(localEffect)
+		localIO := Provide[int, OuterContext](outerCtx)(localEffect)
 		localReader := RunSync(localIO)
 		localResult, localErr := localReader(context.Background())
 
-		contramapIO := Provide[OuterContext, int](outerCtx)(contramapEffect)
+		contramapIO := Provide[int, OuterContext](outerCtx)(contramapEffect)
 		contramapReader := RunSync(contramapIO)
 		contramapResult, contramapErr := contramapReader(context.Background())
 
@@ -225,10 +225,10 @@ func TestContramap(t *testing.T) {
 			return InnerContext{Value: outer.Value + " modified"}
 		}
 
-		kleisli := Contramap[OuterContext, InnerContext, string](accessor)
+		kleisli := Contramap[string, OuterContext, InnerContext](accessor)
 		outerEffect := kleisli(innerEffect)
 
-		ioResult := Provide[OuterContext, string](OuterContext{
+		ioResult := Provide[string, OuterContext](OuterContext{
 			Value:  "original",
 			Number: 50,
 		})(outerEffect)
@@ -247,10 +247,10 @@ func TestContramap(t *testing.T) {
 			return InnerContext{Value: outer.Value}
 		}
 
-		kleisli := Contramap[OuterContext, InnerContext, int](accessor)
+		kleisli := Contramap[int, OuterContext, InnerContext](accessor)
 		outerEffect := kleisli(innerEffect)
 
-		ioResult := Provide[OuterContext, int](OuterContext{
+		ioResult := Provide[int, OuterContext](OuterContext{
 			Value:  "test",
 			Number: 42,
 		})(outerEffect)
@@ -278,12 +278,12 @@ func TestLocalAndContramapInteroperability(t *testing.T) {
 		effect3 := Of[Config3]("result")
 
 		// Use Local for first transformation
-		local23 := Local[Config2, Config3, string](func(c2 Config2) Config3 {
+		local23 := Local[string, Config2, Config3](func(c2 Config2) Config3 {
 			return Config3{Info: c2.Data}
 		})
 
 		// Use Contramap for second transformation
-		contramap12 := Contramap[Config1, Config2, string](func(c1 Config1) Config2 {
+		contramap12 := Contramap[string, Config1, Config2](func(c1 Config1) Config2 {
 			return Config2{Data: c1.Value}
 		})
 
@@ -292,7 +292,7 @@ func TestLocalAndContramapInteroperability(t *testing.T) {
 		effect1 := contramap12(effect2)
 
 		// Run
-		ioResult := Provide[Config1, string](Config1{Value: "test"})(effect1)
+		ioResult := Provide[string, Config1](Config1{Value: "test"})(effect1)
 		readerResult := RunSync(ioResult)
 		result, err := readerResult(context.Background())
 
@@ -326,7 +326,7 @@ func TestLocalEffectK(t *testing.T) {
 		appEffect := transform(dbEffect)
 
 		// Run with AppConfig
-		ioResult := Provide[AppConfig, string](AppConfig{
+		ioResult := Provide[string, AppConfig](AppConfig{
 			ConfigPath: "/etc/app.conf",
 		})(appEffect)
 		readerResult := RunSync(ioResult)
@@ -356,7 +356,7 @@ func TestLocalEffectK(t *testing.T) {
 		transform := LocalEffectK[string](failingTransform)
 		outerEffect := transform(innerEffect)
 
-		ioResult := Provide[OuterCtx, string](OuterCtx{Path: "test"})(outerEffect)
+		ioResult := Provide[string, OuterCtx](OuterCtx{Path: "test"})(outerEffect)
 		readerResult := RunSync(ioResult)
 		_, err := readerResult(context.Background())
 
@@ -384,7 +384,7 @@ func TestLocalEffectK(t *testing.T) {
 		transformK := LocalEffectK[string](transform)
 		outerEffect := transformK(innerEffect)
 
-		ioResult := Provide[OuterCtx, string](OuterCtx{Path: "test"})(outerEffect)
+		ioResult := Provide[string, OuterCtx](OuterCtx{Path: "test"})(outerEffect)
 		readerResult := RunSync(ioResult)
 		_, err := readerResult(context.Background())
 
@@ -417,7 +417,7 @@ func TestLocalEffectK(t *testing.T) {
 		transform := LocalEffectK[string](loadConfigEffect)
 		appEffect := transform(configEffect)
 
-		ioResult := Provide[AppContext, string](AppContext{
+		ioResult := Provide[string, AppContext](AppContext{
 			ConfigFile: "config.json",
 		})(appEffect)
 		readerResult := RunSync(ioResult)
@@ -456,7 +456,7 @@ func TestLocalEffectK(t *testing.T) {
 		level1Effect := transform12(level2Effect)
 
 		// Run with Level1 context
-		ioResult := Provide[Level1, string](Level1{A: "a"})(level1Effect)
+		ioResult := Provide[string, Level1](Level1{A: "a"})(level1Effect)
 		readerResult := RunSync(ioResult)
 		result, err := readerResult(context.Background())
 
@@ -497,7 +497,7 @@ func TestLocalEffectK(t *testing.T) {
 		transform := LocalEffectK[string](transformWithContext)
 		appEffect := transform(dbEffect)
 
-		ioResult := Provide[AppConfig, string](AppConfig{
+		ioResult := Provide[string, AppConfig](AppConfig{
 			Environment: "prod",
 			DBHost:      "localhost",
 			DBPort:      5432,
@@ -534,14 +534,14 @@ func TestLocalEffectK(t *testing.T) {
 		outerEffect := transform(innerEffect)
 
 		// Test with invalid config
-		ioResult := Provide[RawConfig, string](RawConfig{APIKey: ""})(outerEffect)
+		ioResult := Provide[string, RawConfig](RawConfig{APIKey: ""})(outerEffect)
 		readerResult := RunSync(ioResult)
 		_, err := readerResult(context.Background())
 
 		assert.Error(t, err)
 
 		// Test with valid config
-		ioResult2 := Provide[RawConfig, string](RawConfig{APIKey: "valid-key"})(outerEffect)
+		ioResult2 := Provide[string, RawConfig](RawConfig{APIKey: "valid-key"})(outerEffect)
 		readerResult2 := RunSync(ioResult2)
 		result, err2 := readerResult2(context.Background())
 
@@ -569,7 +569,7 @@ func TestLocalEffectK(t *testing.T) {
 		})
 
 		// Use Local for second transformation (pure)
-		local12 := Local[Level1, Level2, string](func(l1 Level1) Level2 {
+		local12 := Local[string, Level1, Level2](func(l1 Level1) Level2 {
 			return Level2{Data: l1.Value}
 		})
 
@@ -578,7 +578,7 @@ func TestLocalEffectK(t *testing.T) {
 		effect1 := local12(effect2)
 
 		// Run
-		ioResult := Provide[Level1, string](Level1{Value: "test"})(effect1)
+		ioResult := Provide[string, Level1](Level1{Value: "test"})(effect1)
 		readerResult := RunSync(ioResult)
 		result, err := readerResult(context.Background())
 
@@ -610,7 +610,7 @@ func TestLocalEffectK(t *testing.T) {
 		transform := LocalEffectK[int](complexTransform)
 		outerEffect := transform(innerEffect)
 
-		ioResult := Provide[OuterCtx, int](OuterCtx{Multiplier: 3})(outerEffect)
+		ioResult := Provide[int, OuterCtx](OuterCtx{Multiplier: 3})(outerEffect)
 		readerResult := RunSync(ioResult)
 		result, err := readerResult(context.Background())
 

v2/effect/effect.go

@@ -20,6 +20,7 @@ import (
 	"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/io"
 	"github.com/IBM/fp-go/v2/reader"
 	"github.com/IBM/fp-go/v2/readerio"
 	"github.com/IBM/fp-go/v2/result"
@@ -59,6 +60,11 @@ func FromThunk[C, A any](f Thunk[A]) Effect[C, A] {
 	return reader.Of[C](f)
 }
 
+//go:inline
+func FromResult[C, A any](r Result[A]) Effect[C, A] {
+	return readerreaderioresult.FromEither[C](r)
+}
+
 // Succeed creates a successful Effect that produces the given value.
 // This is the primary way to lift a pure value into the Effect context.
 //
@@ -187,10 +193,126 @@ func Map[C, A, B any](f func(A) B) Operator[C, A, B] {
 //		return effect.Of[MyContext](strconv.Itoa(x * 2))
 //	})(eff)
 //	// chained produces "84"
+//
+//go:inline
 func Chain[C, A, B any](f Kleisli[C, A, B]) Operator[C, A, B] {
 	return readerreaderioresult.Chain(f)
 }
 
+//go:inline
+func ChainFirst[C, A, B any](f Kleisli[C, A, B]) Operator[C, A, A] {
+	return readerreaderioresult.ChainFirst(f)
+}
+
+// ChainIOK chains an effect with a function that returns an IO action.
+// This is useful for integrating IO-based computations (synchronous side effects)
+// into effect chains. The IO action 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 IO[B]
+//
+// # Returns
+//
+//   - Operator[C, A, B]: A function that chains the IO-returning function with the effect
+//
+// # Example
+//
+//	performIO := func(n int) io.IO[string] {
+//	    return func() string {
+//	        // Perform synchronous side effect
+//	        return fmt.Sprintf("Value: %d", n)
+//	    }
+//	}
+//
+//	eff := effect.Of[MyContext](42)
+//	chained := effect.ChainIOK[MyContext](performIO)(eff)
+//	// chained produces "Value: 42"
+//
+//go:inline
+func ChainIOK[C, A, B any](f io.Kleisli[A, B]) Operator[C, A, B] {
+	return readerreaderioresult.ChainIOK[C](f)
+}
+
+// ChainFirstIOK chains an effect with a function that returns an IO action,
+// but discards the result and returns the original value.
+// This is useful for performing side effects (like logging) without changing the value.
+//
+// # Type Parameters
+//
+//   - C: The context type required by the effect
+//   - A: The value type (preserved)
+//   - B: The type produced by the IO action (discarded)
+//
+// # Parameters
+//
+//   - f: A function that takes A and returns IO[B] for side effects
+//
+// # Returns
+//
+//   - Operator[C, A, A]: A function that executes the IO action but preserves the original value
+//
+// # Example
+//
+//	logValue := func(n int) io.IO[any] {
+//	    return func() any {
+//	        fmt.Printf("Processing: %d\n", n)
+//	        return nil
+//	    }
+//	}
+//
+//	eff := effect.Of[MyContext](42)
+//	logged := effect.ChainFirstIOK[MyContext](logValue)(eff)
+//	// Prints "Processing: 42" but still produces 42
+//
+//go:inline
+func ChainFirstIOK[C, A, B any](f io.Kleisli[A, B]) Operator[C, A, A] {
+	return readerreaderioresult.ChainFirstIOK[C](f)
+}
+
+// TapIOK is an alias for ChainFirstIOK.
+// It chains an effect with a function that returns an IO action for side effects,
+// but preserves 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 effect
+//   - A: The value type (preserved)
+//   - B: The type produced by the IO action (discarded)
+//
+// # Parameters
+//
+//   - f: A function that takes A and returns IO[B] for side effects
+//
+// # Returns
+//
+//   - Operator[C, A, A]: A function that executes the IO action but preserves the original value
+//
+// # Example
+//
+//	logValue := func(n int) io.IO[any] {
+//	    return func() any {
+//	        fmt.Printf("Value: %d\n", n)
+//	        return nil
+//	    }
+//	}
+//
+//	eff := effect.Of[MyContext](42)
+//	tapped := effect.TapIOK[MyContext](logValue)(eff)
+//	// Prints "Value: 42" but still produces 42
+//
+//go:inline
+func TapIOK[C, A, B any](f io.Kleisli[A, B]) Operator[C, A, A] {
+	return readerreaderioresult.ChainFirstIOK[C](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.
 //

v2/effect/effect_additional_test.go

@@ -0,0 +1,649 @@
+// 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"
+	"fmt"
+	"strconv"
+	"testing"
+
+	F "github.com/IBM/fp-go/v2/function"
+	"github.com/IBM/fp-go/v2/io"
+	"github.com/IBM/fp-go/v2/reader"
+	"github.com/IBM/fp-go/v2/result"
+	"github.com/stretchr/testify/assert"
+)
+
+// TestSucceed tests the Succeed function
+func TestSucceed_Success(t *testing.T) {
+	t.Run("creates successful effect with int", func(t *testing.T) {
+		eff := Succeed[TestConfig](42)
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Of(42), outcome)
+	})
+
+	t.Run("creates successful effect with string", func(t *testing.T) {
+		eff := Succeed[TestConfig]("hello")
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Of("hello"), outcome)
+	})
+
+	t.Run("creates successful effect with zero value", func(t *testing.T) {
+		eff := Succeed[TestConfig](0)
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Of(0), outcome)
+	})
+}
+
+// TestFail tests the Fail function
+func TestFail_Failure(t *testing.T) {
+	t.Run("creates failed effect with error", func(t *testing.T) {
+		testErr := errors.New("test error")
+		eff := Fail[TestConfig, int](testErr)
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Left[int](testErr), outcome)
+	})
+
+	t.Run("preserves error message", func(t *testing.T) {
+		testErr := errors.New("specific error message")
+		eff := Fail[TestConfig, string](testErr)
+		outcome := eff(testConfig)(context.Background())()
+		assert.True(t, result.IsLeft(outcome))
+		extractedErr := result.MonadFold(outcome,
+			F.Identity[error],
+			func(string) error { return nil },
+		)
+		assert.Equal(t, testErr, extractedErr)
+	})
+}
+
+// TestOf tests the Of function
+func TestOf_Success(t *testing.T) {
+	t.Run("creates successful effect with value", func(t *testing.T) {
+		eff := Of[TestConfig](100)
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Of(100), outcome)
+	})
+
+	t.Run("is equivalent to Succeed", func(t *testing.T) {
+		value := "test"
+		eff1 := Of[TestConfig](value)
+		eff2 := Succeed[TestConfig](value)
+		outcome1 := eff1(testConfig)(context.Background())()
+		outcome2 := eff2(testConfig)(context.Background())()
+		assert.Equal(t, outcome1, outcome2)
+	})
+}
+
+// TestMap tests the Map function
+func TestMap_Success(t *testing.T) {
+	t.Run("transforms success value", func(t *testing.T) {
+		eff := F.Pipe1(
+			Of[TestConfig](42),
+			Map[TestConfig](func(x int) int { return x * 2 }),
+		)
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Of(84), outcome)
+	})
+
+	t.Run("transforms type", func(t *testing.T) {
+		eff := F.Pipe1(
+			Of[TestConfig](42),
+			Map[TestConfig](func(x int) string { return strconv.Itoa(x) }),
+		)
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Of("42"), outcome)
+	})
+
+	t.Run("chains multiple maps", func(t *testing.T) {
+		eff := F.Pipe2(
+			Of[TestConfig](10),
+			Map[TestConfig](func(x int) int { return x + 5 }),
+			Map[TestConfig](func(x int) int { return x * 2 }),
+		)
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Of(30), outcome)
+	})
+}
+
+func TestMap_Failure(t *testing.T) {
+	t.Run("propagates error unchanged", func(t *testing.T) {
+		testErr := errors.New("test error")
+		eff := F.Pipe1(
+			Fail[TestConfig, int](testErr),
+			Map[TestConfig](func(x int) int { return x * 2 }),
+		)
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Left[int](testErr), outcome)
+	})
+}
+
+// TestChain tests the Chain function
+func TestChain_Success(t *testing.T) {
+	t.Run("sequences two effects", func(t *testing.T) {
+		eff := F.Pipe1(
+			Of[TestConfig](42),
+			Chain[TestConfig](func(x int) Effect[TestConfig, string] {
+				return Of[TestConfig](strconv.Itoa(x))
+			}),
+		)
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Of("42"), outcome)
+	})
+
+	t.Run("chains multiple effects", func(t *testing.T) {
+		eff := F.Pipe2(
+			Of[TestConfig](10),
+			Chain[TestConfig](func(x int) Effect[TestConfig, int] {
+				return Of[TestConfig](x + 5)
+			}),
+			Chain[TestConfig](func(x int) Effect[TestConfig, int] {
+				return Of[TestConfig](x * 2)
+			}),
+		)
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Of(30), outcome)
+	})
+}
+
+func TestChain_Failure(t *testing.T) {
+	t.Run("propagates error from first effect", func(t *testing.T) {
+		testErr := errors.New("first error")
+		eff := F.Pipe1(
+			Fail[TestConfig, int](testErr),
+			Chain[TestConfig](func(x int) Effect[TestConfig, string] {
+				return Of[TestConfig]("should not execute")
+			}),
+		)
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Left[string](testErr), outcome)
+	})
+
+	t.Run("propagates error from second effect", func(t *testing.T) {
+		testErr := errors.New("second error")
+		eff := F.Pipe1(
+			Of[TestConfig](42),
+			Chain[TestConfig](func(x int) Effect[TestConfig, string] {
+				return Fail[TestConfig, string](testErr)
+			}),
+		)
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Left[string](testErr), outcome)
+	})
+}
+
+// TestChainIOK tests the ChainIOK function
+func TestChainIOK_Success(t *testing.T) {
+	t.Run("chains with IO action", func(t *testing.T) {
+		counter := 0
+		eff := F.Pipe1(
+			Of[TestConfig](42),
+			ChainIOK[TestConfig](func(x int) io.IO[string] {
+				return func() string {
+					counter++
+					return fmt.Sprintf("Value: %d", x)
+				}
+			}),
+		)
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Of("Value: 42"), outcome)
+		assert.Equal(t, 1, counter)
+	})
+
+	t.Run("chains multiple IO actions", func(t *testing.T) {
+		log := []string{}
+		eff := F.Pipe2(
+			Of[TestConfig](10),
+			ChainIOK[TestConfig](func(x int) io.IO[int] {
+				return func() int {
+					log = append(log, "first")
+					return x + 5
+				}
+			}),
+			ChainIOK[TestConfig](func(x int) io.IO[int] {
+				return func() int {
+					log = append(log, "second")
+					return x * 2
+				}
+			}),
+		)
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Of(30), outcome)
+		assert.Equal(t, []string{"first", "second"}, log)
+	})
+}
+
+func TestChainIOK_Failure(t *testing.T) {
+	t.Run("propagates error from previous effect", func(t *testing.T) {
+		testErr := errors.New("test error")
+		executed := false
+		eff := F.Pipe1(
+			Fail[TestConfig, int](testErr),
+			ChainIOK[TestConfig](func(x int) io.IO[string] {
+				return func() string {
+					executed = true
+					return "should not execute"
+				}
+			}),
+		)
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Left[string](testErr), outcome)
+		assert.False(t, executed)
+	})
+}
+
+// TestChainFirstIOK tests the ChainFirstIOK function
+func TestChainFirstIOK_Success(t *testing.T) {
+	t.Run("executes IO but preserves value", func(t *testing.T) {
+		log := []string{}
+		eff := F.Pipe1(
+			Of[TestConfig](42),
+			ChainFirstIOK[TestConfig](func(x int) io.IO[any] {
+				return func() any {
+					log = append(log, fmt.Sprintf("logged: %d", x))
+					return nil
+				}
+			}),
+		)
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Of(42), outcome)
+		assert.Equal(t, []string{"logged: 42"}, log)
+	})
+
+	t.Run("chains multiple side effects", func(t *testing.T) {
+		log := []string{}
+		eff := F.Pipe2(
+			Of[TestConfig](10),
+			ChainFirstIOK[TestConfig](func(x int) io.IO[any] {
+				return func() any {
+					log = append(log, "first")
+					return nil
+				}
+			}),
+			ChainFirstIOK[TestConfig](func(x int) io.IO[any] {
+				return func() any {
+					log = append(log, "second")
+					return nil
+				}
+			}),
+		)
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Of(10), outcome)
+		assert.Equal(t, []string{"first", "second"}, log)
+	})
+}
+
+func TestChainFirstIOK_Failure(t *testing.T) {
+	t.Run("propagates error without executing IO", func(t *testing.T) {
+		testErr := errors.New("test error")
+		executed := false
+		eff := F.Pipe1(
+			Fail[TestConfig, int](testErr),
+			ChainFirstIOK[TestConfig](func(x int) io.IO[any] {
+				return func() any {
+					executed = true
+					return nil
+				}
+			}),
+		)
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Left[int](testErr), outcome)
+		assert.False(t, executed)
+	})
+}
+
+// TestTapIOK tests the TapIOK function
+func TestTapIOK_Success(t *testing.T) {
+	t.Run("executes IO but preserves value", func(t *testing.T) {
+		log := []string{}
+		eff := F.Pipe1(
+			Of[TestConfig](42),
+			TapIOK[TestConfig](func(x int) io.IO[any] {
+				return func() any {
+					log = append(log, fmt.Sprintf("tapped: %d", x))
+					return nil
+				}
+			}),
+		)
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Of(42), outcome)
+		assert.Equal(t, []string{"tapped: 42"}, log)
+	})
+
+	t.Run("is equivalent to ChainFirstIOK", func(t *testing.T) {
+		log1 := []string{}
+		log2 := []string{}
+
+		eff1 := F.Pipe1(
+			Of[TestConfig](10),
+			TapIOK[TestConfig](func(x int) io.IO[any] {
+				return func() any {
+					log1 = append(log1, "tap")
+					return nil
+				}
+			}),
+		)
+
+		eff2 := F.Pipe1(
+			Of[TestConfig](10),
+			ChainFirstIOK[TestConfig](func(x int) io.IO[any] {
+				return func() any {
+					log2 = append(log2, "tap")
+					return nil
+				}
+			}),
+		)
+
+		outcome1 := eff1(testConfig)(context.Background())()
+		outcome2 := eff2(testConfig)(context.Background())()
+
+		assert.Equal(t, outcome1, outcome2)
+		assert.Equal(t, log1, log2)
+	})
+}
+
+func TestTapIOK_Failure(t *testing.T) {
+	t.Run("propagates error without executing IO", func(t *testing.T) {
+		testErr := errors.New("test error")
+		executed := false
+		eff := F.Pipe1(
+			Fail[TestConfig, int](testErr),
+			TapIOK[TestConfig](func(x int) io.IO[any] {
+				return func() any {
+					executed = true
+					return nil
+				}
+			}),
+		)
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Left[int](testErr), outcome)
+		assert.False(t, executed)
+	})
+}
+
+// TestChainResultK tests the ChainResultK function
+func TestChainResultK_Success(t *testing.T) {
+	t.Run("chains with Result-returning function", func(t *testing.T) {
+		parseIntResult := result.Eitherize1(strconv.Atoi)
+		eff := F.Pipe1(
+			Of[TestConfig]("42"),
+			ChainResultK[TestConfig](parseIntResult),
+		)
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Of(42), outcome)
+	})
+
+	t.Run("chains multiple Result operations", func(t *testing.T) {
+		parseIntResult := result.Eitherize1(strconv.Atoi)
+		eff := F.Pipe2(
+			Of[TestConfig]("10"),
+			ChainResultK[TestConfig](parseIntResult),
+			ChainResultK[TestConfig](func(x int) result.Result[string] {
+				return result.Of(fmt.Sprintf("Value: %d", x*2))
+			}),
+		)
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Of("Value: 20"), outcome)
+	})
+}
+
+func TestChainResultK_Failure(t *testing.T) {
+	t.Run("propagates error from previous effect", func(t *testing.T) {
+		testErr := errors.New("test error")
+		parseIntResult := result.Eitherize1(strconv.Atoi)
+		eff := F.Pipe1(
+			Fail[TestConfig, string](testErr),
+			ChainResultK[TestConfig](parseIntResult),
+		)
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Left[int](testErr), outcome)
+	})
+
+	t.Run("propagates error from Result function", func(t *testing.T) {
+		parseIntResult := result.Eitherize1(strconv.Atoi)
+		eff := F.Pipe1(
+			Of[TestConfig]("not a number"),
+			ChainResultK[TestConfig](parseIntResult),
+		)
+		outcome := eff(testConfig)(context.Background())()
+		assert.True(t, result.IsLeft(outcome))
+	})
+}
+
+// TestAp tests the Ap function
+func TestAp_Success(t *testing.T) {
+	t.Run("applies function effect to value effect", func(t *testing.T) {
+		fnEff := Of[TestConfig](func(x int) int { return x * 2 })
+		valEff := Of[TestConfig](21)
+		eff := Ap[int](valEff)(fnEff)
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Of(42), outcome)
+	})
+
+	t.Run("applies function with different types", func(t *testing.T) {
+		fnEff := Of[TestConfig](func(x int) string { return strconv.Itoa(x) })
+		valEff := Of[TestConfig](42)
+		eff := Ap[string](valEff)(fnEff)
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Of("42"), outcome)
+	})
+}
+
+func TestAp_Failure(t *testing.T) {
+	t.Run("propagates error from function effect", func(t *testing.T) {
+		testErr := errors.New("function error")
+		fnEff := Fail[TestConfig, func(int) int](testErr)
+		valEff := Of[TestConfig](42)
+		eff := Ap[int](valEff)(fnEff)
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Left[int](testErr), outcome)
+	})
+
+	t.Run("propagates error from value effect", func(t *testing.T) {
+		testErr := errors.New("value error")
+		fnEff := Of[TestConfig](func(x int) int { return x * 2 })
+		valEff := Fail[TestConfig, int](testErr)
+		eff := Ap[int](valEff)(fnEff)
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Left[int](testErr), outcome)
+	})
+}
+
+// TestSuspend tests the Suspend function
+func TestSuspend_Success(t *testing.T) {
+	t.Run("delays evaluation of effect", func(t *testing.T) {
+		counter := 0
+		eff := Suspend(func() Effect[TestConfig, int] {
+			counter++
+			return Of[TestConfig](42)
+		})
+		assert.Equal(t, 0, counter, "should not evaluate immediately")
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, 1, counter, "should evaluate when run")
+		assert.Equal(t, result.Of(42), outcome)
+	})
+
+	t.Run("enables recursive effects", func(t *testing.T) {
+		var factorial func(int) Effect[TestConfig, int]
+		factorial = func(n int) Effect[TestConfig, int] {
+			if n <= 1 {
+				return Of[TestConfig](1)
+			}
+			return Suspend(func() Effect[TestConfig, int] {
+				return F.Pipe1(
+					factorial(n-1),
+					Map[TestConfig](func(x int) int { return x * n }),
+				)
+			})
+		}
+
+		outcome := factorial(5)(testConfig)(context.Background())()
+		assert.Equal(t, result.Of(120), outcome)
+	})
+}
+
+// TestTap tests the Tap function
+func TestTap_Success(t *testing.T) {
+	t.Run("executes side effect but preserves value", func(t *testing.T) {
+		log := []string{}
+		eff := F.Pipe1(
+			Of[TestConfig](42),
+			Tap[TestConfig](func(x int) Effect[TestConfig, any] {
+				log = append(log, fmt.Sprintf("tapped: %d", x))
+				return Of[TestConfig, any](nil)
+			}),
+		)
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Of(42), outcome)
+		assert.Equal(t, []string{"tapped: 42"}, log)
+	})
+
+	t.Run("chains multiple taps", func(t *testing.T) {
+		log := []string{}
+		eff := F.Pipe2(
+			Of[TestConfig](10),
+			Tap[TestConfig](func(x int) Effect[TestConfig, any] {
+				log = append(log, "first")
+				return Of[TestConfig, any](nil)
+			}),
+			Tap[TestConfig](func(x int) Effect[TestConfig, any] {
+				log = append(log, "second")
+				return Of[TestConfig, any](nil)
+			}),
+		)
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Of(10), outcome)
+		assert.Equal(t, []string{"first", "second"}, log)
+	})
+}
+
+func TestTap_Failure(t *testing.T) {
+	t.Run("propagates error without executing tap", func(t *testing.T) {
+		testErr := errors.New("test error")
+		executed := false
+		eff := F.Pipe1(
+			Fail[TestConfig, int](testErr),
+			Tap[TestConfig](func(x int) Effect[TestConfig, any] {
+				executed = true
+				return Of[TestConfig, any](nil)
+			}),
+		)
+		outcome := eff(testConfig)(context.Background())()
+		assert.Equal(t, result.Left[int](testErr), outcome)
+		assert.False(t, executed)
+	})
+}
+
+// TestTernary tests the Ternary function
+func TestTernary_Success(t *testing.T) {
+	t.Run("executes onTrue when predicate is true", func(t *testing.T) {
+		kleisli := Ternary(
+			func(x int) bool { return x > 10 },
+			func(x int) Effect[TestConfig, string] {
+				return Of[TestConfig]("large")
+			},
+			func(x int) Effect[TestConfig, string] {
+				return Of[TestConfig]("small")
+			},
+		)
+		outcome := kleisli(15)(testConfig)(context.Background())()
+		assert.Equal(t, result.Of("large"), outcome)
+	})
+
+	t.Run("executes onFalse when predicate is false", func(t *testing.T) {
+		kleisli := Ternary(
+			func(x int) bool { return x > 10 },
+			func(x int) Effect[TestConfig, string] {
+				return Of[TestConfig]("large")
+			},
+			func(x int) Effect[TestConfig, string] {
+				return Of[TestConfig]("small")
+			},
+		)
+		outcome := kleisli(5)(testConfig)(context.Background())()
+		assert.Equal(t, result.Of("small"), outcome)
+	})
+
+	t.Run("works with boundary value", func(t *testing.T) {
+		kleisli := Ternary(
+			func(x int) bool { return x >= 10 },
+			func(x int) Effect[TestConfig, string] {
+				return Of[TestConfig]("gte")
+			},
+			func(x int) Effect[TestConfig, string] {
+				return Of[TestConfig]("lt")
+			},
+		)
+		outcome := kleisli(10)(testConfig)(context.Background())()
+		assert.Equal(t, result.Of("gte"), outcome)
+	})
+}
+
+// TestRead tests the Read function
+func TestRead_Success(t *testing.T) {
+	t.Run("provides context to effect", func(t *testing.T) {
+		eff := Of[TestConfig](42)
+		thunk := Read[int](testConfig)(eff)
+		outcome := thunk(context.Background())()
+		assert.Equal(t, result.Of(42), outcome)
+	})
+
+	t.Run("converts effect to thunk", func(t *testing.T) {
+		eff := F.Pipe1(
+			Of[TestConfig](10),
+			Map[TestConfig](func(x int) int { return x * testConfig.Multiplier }),
+		)
+		thunk := Read[int](testConfig)(eff)
+		outcome := thunk(context.Background())()
+		assert.Equal(t, result.Of(30), outcome)
+	})
+
+	t.Run("works with different contexts", func(t *testing.T) {
+		cfg1 := TestConfig{Multiplier: 2, Prefix: "A", DatabaseURL: ""}
+		cfg2 := TestConfig{Multiplier: 5, Prefix: "B", DatabaseURL: ""}
+
+		// Create an effect that uses the context's Multiplier
+		eff := F.Pipe1(
+			Of[TestConfig](10),
+			ChainReaderK[TestConfig](func(x int) reader.Reader[TestConfig, int] {
+				return func(cfg TestConfig) int {
+					return x * cfg.Multiplier
+				}
+			}),
+		)
+
+		thunk1 := Read[int](cfg1)(eff)
+		thunk2 := Read[int](cfg2)(eff)
+
+		outcome1 := thunk1(context.Background())()
+		outcome2 := thunk2(context.Background())()
+
+		assert.Equal(t, result.Of(20), outcome1)
+		assert.Equal(t, result.Of(50), outcome2)
+	})
+}
+
+func TestRead_Failure(t *testing.T) {
+	t.Run("propagates error from effect", func(t *testing.T) {
+		testErr := errors.New("test error")
+		eff := Fail[TestConfig, int](testErr)
+		thunk := Read[int](testConfig)(eff)
+		outcome := thunk(context.Background())()
+		assert.Equal(t, result.Left[int](testErr), outcome)
+	})
+}

v2/effect/run.go

@@ -46,7 +46,7 @@ import (
 //	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] {
+func Provide[A, C any](c C) func(Effect[C, A]) ReaderIOResult[A] {
 	return readerreaderioresult.Read[A](c)
 }
 

v2/effect/run_test.go

@@ -28,7 +28,7 @@ func TestProvide(t *testing.T) {
 		ctx := TestContext{Value: "test-value"}
 		eff := Of[TestContext]("result")
 
-		ioResult := Provide[TestContext, string](ctx)(eff)
+		ioResult := Provide[string, TestContext](ctx)(eff)
 		readerResult := RunSync(ioResult)
 		result, err := readerResult(context.Background())
 
@@ -45,7 +45,7 @@ func TestProvide(t *testing.T) {
 		cfg := Config{Host: "localhost", Port: 8080}
 		eff := Of[Config]("connected")
 
-		ioResult := Provide[Config, string](cfg)(eff)
+		ioResult := Provide[string, Config](cfg)(eff)
 		readerResult := RunSync(ioResult)
 		result, err := readerResult(context.Background())
 
@@ -58,7 +58,7 @@ func TestProvide(t *testing.T) {
 		ctx := TestContext{Value: "test"}
 		eff := Fail[TestContext, string](expectedErr)
 
-		ioResult := Provide[TestContext, string](ctx)(eff)
+		ioResult := Provide[string, TestContext](ctx)(eff)
 		readerResult := RunSync(ioResult)
 		_, err := readerResult(context.Background())
 
@@ -74,7 +74,7 @@ func TestProvide(t *testing.T) {
 		ctx := SimpleContext{ID: 42}
 		eff := Of[SimpleContext](100)
 
-		ioResult := Provide[SimpleContext, int](ctx)(eff)
+		ioResult := Provide[int, SimpleContext](ctx)(eff)
 		readerResult := RunSync(ioResult)
 		result, err := readerResult(context.Background())
 
@@ -89,7 +89,7 @@ func TestProvide(t *testing.T) {
 			return Of[TestContext]("result")
 		})(Of[TestContext](42))
 
-		ioResult := Provide[TestContext, string](ctx)(eff)
+		ioResult := Provide[string, TestContext](ctx)(eff)
 		readerResult := RunSync(ioResult)
 		result, err := readerResult(context.Background())
 
@@ -104,7 +104,7 @@ func TestProvide(t *testing.T) {
 			return "mapped"
 		})(Of[TestContext](42))
 
-		ioResult := Provide[TestContext, string](ctx)(eff)
+		ioResult := Provide[string, TestContext](ctx)(eff)
 		readerResult := RunSync(ioResult)
 		result, err := readerResult(context.Background())
 
@@ -118,7 +118,7 @@ func TestRunSync(t *testing.T) {
 		ctx := TestContext{Value: "test"}
 		eff := Of[TestContext](42)
 
-		ioResult := Provide[TestContext, int](ctx)(eff)
+		ioResult := Provide[int, TestContext](ctx)(eff)
 		readerResult := RunSync(ioResult)
 		result, err := readerResult(context.Background())
 
@@ -130,7 +130,7 @@ func TestRunSync(t *testing.T) {
 		ctx := TestContext{Value: "test"}
 		eff := Of[TestContext]("hello")
 
-		ioResult := Provide[TestContext, string](ctx)(eff)
+		ioResult := Provide[string, TestContext](ctx)(eff)
 		readerResult := RunSync(ioResult)
 
 		bgCtx := context.Background()
@@ -145,7 +145,7 @@ func TestRunSync(t *testing.T) {
 		ctx := TestContext{Value: "test"}
 		eff := Fail[TestContext, int](expectedErr)
 
-		ioResult := Provide[TestContext, int](ctx)(eff)
+		ioResult := Provide[int, TestContext](ctx)(eff)
 		readerResult := RunSync(ioResult)
 		_, err := readerResult(context.Background())
 
@@ -162,7 +162,7 @@ func TestRunSync(t *testing.T) {
 			return Of[TestContext](x + 10)
 		})(Of[TestContext](5)))
 
-		ioResult := Provide[TestContext, int](ctx)(eff)
+		ioResult := Provide[int, TestContext](ctx)(eff)
 		readerResult := RunSync(ioResult)
 		result, err := readerResult(context.Background())
 
@@ -174,7 +174,7 @@ func TestRunSync(t *testing.T) {
 		ctx := TestContext{Value: "test"}
 		eff := Of[TestContext](42)
 
-		ioResult := Provide[TestContext, int](ctx)(eff)
+		ioResult := Provide[int, TestContext](ctx)(eff)
 		readerResult := RunSync(ioResult)
 
 		// Run multiple times
@@ -200,7 +200,7 @@ func TestRunSync(t *testing.T) {
 		user := User{Name: "Alice", Age: 30}
 		eff := Of[TestContext](user)
 
-		ioResult := Provide[TestContext, User](ctx)(eff)
+		ioResult := Provide[User, TestContext](ctx)(eff)
 		readerResult := RunSync(ioResult)
 		result, err := readerResult(context.Background())
 
@@ -222,7 +222,7 @@ func TestProvideAndRunSyncIntegration(t *testing.T) {
 		eff := Of[AppConfig]("API call successful")
 
 		// Provide config and run
-		result, err := RunSync(Provide[AppConfig, string](cfg)(eff))(context.Background())
+		result, err := RunSync(Provide[string, AppConfig](cfg)(eff))(context.Background())
 
 		assert.NoError(t, err)
 		assert.Equal(t, "API call successful", result)
@@ -238,7 +238,7 @@ func TestProvideAndRunSyncIntegration(t *testing.T) {
 
 		eff := Fail[AppConfig, string](expectedErr)
 
-		_, err := RunSync(Provide[AppConfig, string](cfg)(eff))(context.Background())
+		_, err := RunSync(Provide[string, AppConfig](cfg)(eff))(context.Background())
 
 		assert.Error(t, err)
 		assert.Equal(t, expectedErr, err)
@@ -253,7 +253,7 @@ func TestProvideAndRunSyncIntegration(t *testing.T) {
 			return Of[TestContext](x * 2)
 		})(Of[TestContext](21)))
 
-		result, err := RunSync(Provide[TestContext, string](ctx)(eff))(context.Background())
+		result, err := RunSync(Provide[string, TestContext](ctx)(eff))(context.Background())
 
 		assert.NoError(t, err)
 		assert.Equal(t, "final", result)
@@ -281,7 +281,7 @@ func TestProvideAndRunSyncIntegration(t *testing.T) {
 			return State{X: x}
 		})(Of[TestContext](10)))
 
-		result, err := RunSync(Provide[TestContext, State](ctx)(eff))(context.Background())
+		result, err := RunSync(Provide[State, TestContext](ctx)(eff))(context.Background())
 
 		assert.NoError(t, err)
 		assert.Equal(t, 10, result.X)
@@ -300,11 +300,11 @@ func TestProvideAndRunSyncIntegration(t *testing.T) {
 		innerEff := Of[InnerCtx]("inner result")
 
 		// Transform context
-		transformedEff := Local[OuterCtx, InnerCtx, string](func(outer OuterCtx) InnerCtx {
+		transformedEff := Local[string, OuterCtx, InnerCtx](func(outer OuterCtx) InnerCtx {
 			return InnerCtx{Data: outer.Value + "-transformed"}
 		})(innerEff)
 
-		result, err := RunSync(Provide[OuterCtx, string](outerCtx)(transformedEff))(context.Background())
+		result, err := RunSync(Provide[string, OuterCtx](outerCtx)(transformedEff))(context.Background())
 
 		assert.NoError(t, err)
 		assert.Equal(t, "inner result", result)
@@ -318,7 +318,7 @@ func TestProvideAndRunSyncIntegration(t *testing.T) {
 			return Of[TestContext](x * 2)
 		})(input)
 
-		result, err := RunSync(Provide[TestContext, []int](ctx)(eff))(context.Background())
+		result, err := RunSync(Provide[[]int, TestContext](ctx)(eff))(context.Background())
 
 		assert.NoError(t, err)
 		assert.Equal(t, []int{2, 4, 6, 8, 10}, result)

v2/readerioeither/reader.go

@@ -37,11 +37,46 @@ import (
 	"github.com/IBM/fp-go/v2/readeroption"
 )
 
+// FromReaderOption converts a ReaderOption to a Kleisli arrow that handles None cases.
+// When the Option is None, the provided lazy error value is used.
+//
+// # Type Parameters
+//
+//   - R: The context/environment type
+//   - A: The value type
+//   - E: The error type
+//
+// # Parameters
+//
+//   - onNone: Lazy function that provides the error value when Option is None
+//
+// # Returns
+//
+//   - Kleisli arrow that converts ReaderOption to ReaderIOEither
+//
 //go:inline
 func FromReaderOption[R, A, E any](onNone Lazy[E]) Kleisli[R, E, ReaderOption[R, A], A] {
 	return function.Bind2nd(function.Flow2[ReaderOption[R, A], IOE.Kleisli[E, Option[A], A]], IOE.FromOption[A](onNone))
 }
 
+// FromReaderIO lifts a ReaderIO into a ReaderIOEither, placing the result in the Right side.
+// This is an alias for RightReaderIO, converting a computation that cannot fail into one
+// that can fail but never does.
+//
+// # Type Parameters
+//
+//   - E: The error type (will never actually contain an error)
+//   - R: The context/environment type
+//   - A: The value type
+//
+// # Parameters
+//
+//   - ma: The ReaderIO to lift
+//
+// # Returns
+//
+//   - ReaderIOEither with the ReaderIO result in the Right side
+//
 //go:inline
 func FromReaderIO[E, R, A any](ma ReaderIO[R, A]) ReaderIOEither[R, E, A] {
 	return RightReaderIO[E](ma)
@@ -121,6 +156,26 @@ func MonadChainFirst[R, E, A, B any](fa ReaderIOEither[R, E, A], f Kleisli[R, E,
 		f)
 }
 
+// MonadTap is an alias for MonadChainFirst.
+// It sequences two computations but keeps the result of the first, emphasizing the
+// side-effect nature of the operation (like "tapping" into a pipeline).
+//
+// # Type Parameters
+//
+//   - R: The context/environment type
+//   - E: The error type
+//   - A: The input value type (preserved in output)
+//   - B: The side effect result type (discarded)
+//
+// # Parameters
+//
+//   - fa: The ReaderIOEither computation
+//   - f: The side effect Kleisli arrow
+//
+// # Returns
+//
+//   - ReaderIOEither with the original value preserved
+//
 //go:inline
 func MonadTap[R, E, A, B any](fa ReaderIOEither[R, E, A], f Kleisli[R, E, A, B]) ReaderIOEither[R, E, A] {
 	return MonadChainFirst(fa, f)
@@ -165,6 +220,26 @@ func MonadChainFirstEitherK[R, E, A, B any](ma ReaderIOEither[R, E, A], f either
 	)
 }
 
+// MonadTapEitherK is an alias for MonadChainFirstEitherK.
+// It chains an Either-returning computation while preserving the original value,
+// emphasizing the side-effect nature of the operation.
+//
+// # Type Parameters
+//
+//   - R: The context/environment type
+//   - E: The error type
+//   - A: The input value type (preserved in output)
+//   - B: The side effect result type (discarded)
+//
+// # Parameters
+//
+//   - ma: The ReaderIOEither computation
+//   - f: The Either-returning side effect function
+//
+// # Returns
+//
+//   - ReaderIOEither with the original value preserved
+//
 //go:inline
 func MonadTapEitherK[R, E, A, B any](ma ReaderIOEither[R, E, A], f either.Kleisli[E, A, B]) ReaderIOEither[R, E, A] {
 	return MonadChainFirstEitherK(ma, f)
@@ -183,6 +258,25 @@ func ChainFirstEitherK[R, E, A, B any](f either.Kleisli[E, A, B]) Operator[R, E,
 	)
 }
 
+// TapEitherK is an alias for ChainFirstEitherK.
+// It returns a function that chains an Either-returning side effect while preserving
+// the original value, emphasizing the "tap" pattern for observing values.
+//
+// # Type Parameters
+//
+//   - R: The context/environment type
+//   - E: The error type
+//   - A: The input value type (preserved in output)
+//   - B: The side effect result type (discarded)
+//
+// # Parameters
+//
+//   - f: The Either-returning side effect function
+//
+// # Returns
+//
+//   - Operator that executes the side effect while preserving the original value
+//
 //go:inline
 func TapEitherK[R, E, A, B any](f either.Kleisli[E, A, B]) Operator[R, E, A, A] {
 	return ChainFirstEitherK[R](f)
@@ -213,6 +307,26 @@ func ChainReaderK[E, R, A, B any](f reader.Kleisli[R, A, B]) Operator[R, E, A, B
 	)
 }
 
+// MonadChainFirstReaderK chains a Reader-returning computation while preserving the original value.
+// Useful for performing Reader-based side effects (like logging with context) while keeping
+// the original value.
+//
+// # Type Parameters
+//
+//   - E: The error type
+//   - R: The context/environment type
+//   - A: The input value type (preserved in output)
+//   - B: The side effect result type (discarded)
+//
+// # Parameters
+//
+//   - ma: The ReaderIOEither computation
+//   - f: The Reader-returning side effect function
+//
+// # Returns
+//
+//   - ReaderIOEither with the original value preserved
+//
 //go:inline
 func MonadChainFirstReaderK[E, R, A, B any](ma ReaderIOEither[R, E, A], f reader.Kleisli[R, A, B]) ReaderIOEither[R, E, A] {
 	return fromreader.MonadChainFirstReaderK(
@@ -223,6 +337,25 @@ func MonadChainFirstReaderK[E, R, A, B any](ma ReaderIOEither[R, E, A], f reader
 	)
 }
 
+// MonadTapReaderK is an alias for MonadChainFirstReaderK.
+// It chains a Reader-returning side effect while preserving the original value.
+//
+// # Type Parameters
+//
+//   - E: The error type
+//   - R: The context/environment type
+//   - A: The input value type (preserved in output)
+//   - B: The side effect result type (discarded)
+//
+// # Parameters
+//
+//   - ma: The ReaderIOEither computation
+//   - f: The Reader-returning side effect function
+//
+// # Returns
+//
+//   - ReaderIOEither with the original value preserved
+//
 //go:inline
 func MonadTapReaderK[E, R, A, B any](ma ReaderIOEither[R, E, A], f reader.Kleisli[R, A, B]) ReaderIOEither[R, E, A] {
 	return MonadChainFirstReaderK(ma, f)
@@ -240,11 +373,49 @@ func ChainFirstReaderK[E, R, A, B any](f reader.Kleisli[R, A, B]) Operator[R, E,
 	)
 }
 
+// TapReaderK is an alias for ChainFirstReaderK.
+// It returns a function that chains a Reader-returning side effect while preserving
+// the original value.
+//
+// # Type Parameters
+//
+//   - E: The error type
+//   - R: The context/environment type
+//   - A: The input value type (preserved in output)
+//   - B: The side effect result type (discarded)
+//
+// # Parameters
+//
+//   - f: The Reader-returning side effect function
+//
+// # Returns
+//
+//   - Operator that executes the side effect while preserving the original value
+//
 //go:inline
 func TapReaderK[E, R, A, B any](f reader.Kleisli[R, A, B]) Operator[R, E, A, A] {
 	return ChainFirstReaderK[E](f)
 }
 
+// MonadChainReaderIOK chains a ReaderIO-returning computation into a ReaderIOEither.
+// The ReaderIO is automatically lifted into the ReaderIOEither context.
+//
+// # Type Parameters
+//
+//   - E: The error type
+//   - R: The context/environment type
+//   - A: The input value type
+//   - B: The output value type
+//
+// # Parameters
+//
+//   - ma: The ReaderIOEither computation
+//   - f: The ReaderIO-returning function
+//
+// # Returns
+//
+//   - ReaderIOEither with the result of the ReaderIO computation
+//
 //go:inline
 func MonadChainReaderIOK[E, R, A, B any](ma ReaderIOEither[R, E, A], f readerio.Kleisli[R, A, B]) ReaderIOEither[R, E, B] {
 	return fromreader.MonadChainReaderK(
@@ -255,6 +426,24 @@ func MonadChainReaderIOK[E, R, A, B any](ma ReaderIOEither[R, E, A], f readerio.
 	)
 }
 
+// ChainReaderIOK returns a function that chains a ReaderIO-returning function into ReaderIOEither.
+// This is the curried version of MonadChainReaderIOK.
+//
+// # Type Parameters
+//
+//   - E: The error type
+//   - R: The context/environment type
+//   - A: The input value type
+//   - B: The output value type
+//
+// # Parameters
+//
+//   - f: The ReaderIO-returning function
+//
+// # Returns
+//
+//   - Operator that chains the ReaderIO computation
+//
 //go:inline
 func ChainReaderIOK[E, R, A, B any](f readerio.Kleisli[R, A, B]) Operator[R, E, A, B] {
 	return fromreader.ChainReaderK(
@@ -264,6 +453,25 @@ func ChainReaderIOK[E, R, A, B any](f readerio.Kleisli[R, A, B]) Operator[R, E,
 	)
 }
 
+// MonadChainFirstReaderIOK chains a ReaderIO-returning computation while preserving the original value.
+// Useful for performing ReaderIO-based side effects while keeping the original value.
+//
+// # Type Parameters
+//
+//   - E: The error type
+//   - R: The context/environment type
+//   - A: The input value type (preserved in output)
+//   - B: The side effect result type (discarded)
+//
+// # Parameters
+//
+//   - ma: The ReaderIOEither computation
+//   - f: The ReaderIO-returning side effect function
+//
+// # Returns
+//
+//   - ReaderIOEither with the original value preserved
+//
 //go:inline
 func MonadChainFirstReaderIOK[E, R, A, B any](ma ReaderIOEither[R, E, A], f readerio.Kleisli[R, A, B]) ReaderIOEither[R, E, A] {
 	return fromreader.MonadChainFirstReaderK(
@@ -274,11 +482,48 @@ func MonadChainFirstReaderIOK[E, R, A, B any](ma ReaderIOEither[R, E, A], f read
 	)
 }
 
+// MonadTapReaderIOK is an alias for MonadChainFirstReaderIOK.
+// It chains a ReaderIO-returning side effect while preserving the original value.
+//
+// # Type Parameters
+//
+//   - E: The error type
+//   - R: The context/environment type
+//   - A: The input value type (preserved in output)
+//   - B: The side effect result type (discarded)
+//
+// # Parameters
+//
+//   - ma: The ReaderIOEither computation
+//   - f: The ReaderIO-returning side effect function
+//
+// # Returns
+//
+//   - ReaderIOEither with the original value preserved
+//
 //go:inline
 func MonadTapReaderIOK[E, R, A, B any](ma ReaderIOEither[R, E, A], f readerio.Kleisli[R, A, B]) ReaderIOEither[R, E, A] {
 	return MonadChainFirstReaderIOK(ma, f)
 }
 
+// ChainFirstReaderIOK returns a function that chains a ReaderIO-returning function while
+// preserving the original value. This is the curried version of MonadChainFirstReaderIOK.
+//
+// # Type Parameters
+//
+//   - E: The error type
+//   - R: The context/environment type
+//   - A: The input value type (preserved in output)
+//   - B: The side effect result type (discarded)
+//
+// # Parameters
+//
+//   - f: The ReaderIO-returning side effect function
+//
+// # Returns
+//
+//   - Operator that executes the side effect while preserving the original value
+//
 //go:inline
 func ChainFirstReaderIOK[E, R, A, B any](f readerio.Kleisli[R, A, B]) Operator[R, E, A, A] {
 	return fromreader.ChainFirstReaderK(
@@ -288,11 +533,49 @@ func ChainFirstReaderIOK[E, R, A, B any](f readerio.Kleisli[R, A, B]) Operator[R
 	)
 }
 
+// TapReaderIOK is an alias for ChainFirstReaderIOK.
+// It returns a function that chains a ReaderIO-returning side effect while preserving
+// the original value.
+//
+// # Type Parameters
+//
+//   - E: The error type
+//   - R: The context/environment type
+//   - A: The input value type (preserved in output)
+//   - B: The side effect result type (discarded)
+//
+// # Parameters
+//
+//   - f: The ReaderIO-returning side effect function
+//
+// # Returns
+//
+//   - Operator that executes the side effect while preserving the original value
+//
 //go:inline
 func TapReaderIOK[E, R, A, B any](f readerio.Kleisli[R, A, B]) Operator[R, E, A, A] {
 	return ChainFirstReaderIOK[E](f)
 }
 
+// MonadChainReaderEitherK chains a ReaderEither-returning computation into a ReaderIOEither.
+// The ReaderEither is automatically lifted into the ReaderIOEither context.
+//
+// # Type Parameters
+//
+//   - R: The context/environment type
+//   - E: The error type
+//   - A: The input value type
+//   - B: The output value type
+//
+// # Parameters
+//
+//   - ma: The ReaderIOEither computation
+//   - f: The ReaderEither-returning function
+//
+// # Returns
+//
+//   - ReaderIOEither with the result of the ReaderEither computation
+//
 //go:inline
 func MonadChainReaderEitherK[R, E, A, B any](ma ReaderIOEither[R, E, A], f RE.Kleisli[R, E, A, B]) ReaderIOEither[R, E, B] {
 	return fromreader.MonadChainReaderK(
@@ -315,6 +598,25 @@ func ChainReaderEitherK[E, R, A, B any](f RE.Kleisli[R, E, A, B]) Operator[R, E,
 	)
 }
 
+// MonadChainFirstReaderEitherK chains a ReaderEither-returning computation while preserving the original value.
+// Useful for performing ReaderEither-based side effects while keeping the original value.
+//
+// # Type Parameters
+//
+//   - R: The context/environment type
+//   - E: The error type
+//   - A: The input value type (preserved in output)
+//   - B: The side effect result type (discarded)
+//
+// # Parameters
+//
+//   - ma: The ReaderIOEither computation
+//   - f: The ReaderEither-returning side effect function
+//
+// # Returns
+//
+//   - ReaderIOEither with the original value preserved
+//
 //go:inline
 func MonadChainFirstReaderEitherK[R, E, A, B any](ma ReaderIOEither[R, E, A], f RE.Kleisli[R, E, A, B]) ReaderIOEither[R, E, A] {
 	return fromreader.MonadChainFirstReaderK(
@@ -325,6 +627,25 @@ func MonadChainFirstReaderEitherK[R, E, A, B any](ma ReaderIOEither[R, E, A], f
 	)
 }
 
+// MonadTapReaderEitherK is an alias for MonadChainFirstReaderEitherK.
+// It chains a ReaderEither-returning side effect while preserving the original value.
+//
+// # Type Parameters
+//
+//   - R: The context/environment type
+//   - E: The error type
+//   - A: The input value type (preserved in output)
+//   - B: The side effect result type (discarded)
+//
+// # Parameters
+//
+//   - ma: The ReaderIOEither computation
+//   - f: The ReaderEither-returning side effect function
+//
+// # Returns
+//
+//   - ReaderIOEither with the original value preserved
+//
 //go:inline
 func MonadTapReaderEitherK[R, E, A, B any](ma ReaderIOEither[R, E, A], f RE.Kleisli[R, E, A, B]) ReaderIOEither[R, E, A] {
 	return MonadChainFirstReaderEitherK(ma, f)
@@ -342,11 +663,48 @@ func ChainFirstReaderEitherK[E, R, A, B any](f RE.Kleisli[R, E, A, B]) Operator[
 	)
 }
 
+// TapReaderEitherK is an alias for ChainFirstReaderEitherK.
+// It returns a function that chains a ReaderEither-returning side effect while preserving
+// the original value.
+//
+// # Type Parameters
+//
+//   - E: The error type
+//   - R: The context/environment type
+//   - A: The input value type (preserved in output)
+//   - B: The side effect result type (discarded)
+//
+// # Parameters
+//
+//   - f: The ReaderEither-returning side effect function
+//
+// # Returns
+//
+//   - Operator that executes the side effect while preserving the original value
+//
 //go:inline
 func TapReaderEitherK[E, R, A, B any](f RE.Kleisli[R, E, A, B]) Operator[R, E, A, A] {
 	return ChainFirstReaderEitherK(f)
 }
 
+// ChainReaderOptionK returns a function that chains a ReaderOption-returning function into ReaderIOEither.
+// When the Option is None, the provided error value is used.
+//
+// # Type Parameters
+//
+//   - R: The context/environment type
+//   - A: The input value type
+//   - B: The output value type
+//   - E: The error type
+//
+// # Parameters
+//
+//   - onNone: Lazy function that provides the error value when Option is None
+//
+// # Returns
+//
+//   - Function that takes a ReaderOption Kleisli and returns an Operator
+//
 //go:inline
 func ChainReaderOptionK[R, A, B, E any](onNone Lazy[E]) func(readeroption.Kleisli[R, A, B]) Operator[R, E, A, B] {
 	fro := FromReaderOption[R, B](onNone)
@@ -359,6 +717,24 @@ func ChainReaderOptionK[R, A, B, E any](onNone Lazy[E]) func(readeroption.Kleisl
 	}
 }
 
+// ChainFirstReaderOptionK returns a function that chains a ReaderOption-returning function
+// while preserving the original value. When the Option is None, the provided error value is used.
+//
+// # Type Parameters
+//
+//   - R: The context/environment type
+//   - A: The input value type (preserved in output)
+//   - B: The side effect result type (discarded)
+//   - E: The error type
+//
+// # Parameters
+//
+//   - onNone: Lazy function that provides the error value when Option is None
+//
+// # Returns
+//
+//   - Function that takes a ReaderOption Kleisli and returns an Operator
+//
 //go:inline
 func ChainFirstReaderOptionK[R, A, B, E any](onNone Lazy[E]) func(readeroption.Kleisli[R, A, B]) Operator[R, E, A, A] {
 	fro := FromReaderOption[R, B](onNone)
@@ -371,6 +747,25 @@ func ChainFirstReaderOptionK[R, A, B, E any](onNone Lazy[E]) func(readeroption.K
 	}
 }
 
+// TapReaderOptionK is an alias for ChainFirstReaderOptionK.
+// It returns a function that chains a ReaderOption-returning side effect while preserving
+// the original value.
+//
+// # Type Parameters
+//
+//   - R: The context/environment type
+//   - A: The input value type (preserved in output)
+//   - B: The side effect result type (discarded)
+//   - E: The error type
+//
+// # Parameters
+//
+//   - onNone: Lazy function that provides the error value when Option is None
+//
+// # Returns
+//
+//   - Function that takes a ReaderOption Kleisli and returns an Operator
+//
 //go:inline
 func TapReaderOptionK[R, A, B, E any](onNone Lazy[E]) func(readeroption.Kleisli[R, A, B]) Operator[R, E, A, A] {
 	return ChainFirstReaderOptionK[R, A, B](onNone)
@@ -401,6 +796,110 @@ func ChainIOEitherK[R, E, A, B any](f IOE.Kleisli[E, A, B]) Operator[R, E, A, B]
 	)
 }
 
+// ChainFirstIOEitherK chains an IOEither computation while preserving the original value.
+// This is useful for performing side effects that may fail (like logging, validation, or
+// external API calls) while keeping the original value in the success case.
+//
+// The function executes the IOEither computation but discards its result, returning the
+// original value if both computations succeed. If either computation fails, the error
+// is propagated.
+//
+// This is the curried version that returns an Operator for use in function composition.
+//
+// # Type Parameters
+//
+//   - R: The context/environment type
+//   - E: The error type
+//   - A: The input value type (preserved in output)
+//   - B: The side effect result type (discarded)
+//
+// # Parameters
+//
+//   - f: IOEither.Kleisli function that performs the side effect
+//
+// # Returns
+//
+//   - Operator that chains the side effect while preserving the original value
+//
+// # Example Usage
+//
+//	type Config struct{ LogEnabled bool }
+//
+//	logValue := func(v int) IOEither[error, string] {
+//	    return IOE.Of[error](fmt.Sprintf("Value: %d", v))
+//	}
+//
+//	pipeline := F.Pipe1(
+//	    Of[Config, error](42),
+//	    ChainFirstIOEitherK[Config](logValue),
+//	)
+//	result := pipeline(Config{LogEnabled: true})() // Right(42)
+//
+// # See Also
+//
+//   - TapIOEitherK: Alias for ChainFirstIOEitherK
+//   - ChainIOEitherK: Chains IOEither and uses its result
+//   - ChainFirstEitherK: Similar but for Either computations
+//
+//go:inline
+func ChainFirstIOEitherK[R, E, A, B any](f IOE.Kleisli[E, A, B]) Operator[R, E, A, A] {
+	return fromioeither.ChainFirstIOEitherK(
+		Chain[R, E, A, A],
+		Map[R, E, B, A],
+		FromIOEither[R, E, B],
+		f,
+	)
+}
+
+// TapIOEitherK is an alias for ChainFirstIOEitherK.
+// It executes an IOEither side effect while preserving the original value.
+//
+// The name "Tap" emphasizes the side-effect nature of the operation, similar to
+// tapping into a pipeline to observe or log values without modifying the flow.
+//
+// # Type Parameters
+//
+//   - R: The context/environment type
+//   - E: The error type
+//   - A: The input value type (preserved in output)
+//   - B: The side effect result type (discarded)
+//
+// # Parameters
+//
+//   - f: IOEither.Kleisli function that performs the side effect
+//
+// # Returns
+//
+//   - Operator that executes the side effect while preserving the original value
+//
+// # Example Usage
+//
+//	type Config struct{}
+//
+//	validatePositive := func(v int) IOEither[error, bool] {
+//	    if v > 0 {
+//	        return IOE.Of[error](true)
+//	    }
+//	    return IOE.Left[bool](errors.New("must be positive"))
+//	}
+//
+//	pipeline := F.Pipe1(
+//	    Of[Config, error](42),
+//	    TapIOEitherK[Config](validatePositive),
+//	)
+//	result := pipeline(Config{})() // Right(42) if validation passes
+//
+// # See Also
+//
+//   - ChainFirstIOEitherK: The underlying implementation
+//   - TapEitherK: Similar but for Either computations
+//   - TapIOK: Similar but for IO computations
+//
+//go:inline
+func TapIOEitherK[R, E, A, B any](f IOE.Kleisli[E, A, B]) Operator[R, E, A, A] {
+	return ChainFirstIOEitherK[R](f)
+}
+
 // MonadChainIOK chains an IO-returning computation into a ReaderIOEither.
 // The IO is automatically lifted into the ReaderIOEither context (always succeeds).
 //
@@ -440,6 +939,25 @@ func MonadChainFirstIOK[R, E, A, B any](ma ReaderIOEither[R, E, A], f io.Kleisli
 	)
 }
 
+// MonadTapIOK is an alias for MonadChainFirstIOK.
+// It chains an IO-returning side effect while preserving the original value.
+//
+// # Type Parameters
+//
+//   - R: The context/environment type
+//   - E: The error type
+//   - A: The input value type (preserved in output)
+//   - B: The side effect result type (discarded)
+//
+// # Parameters
+//
+//   - ma: The ReaderIOEither computation
+//   - f: The IO-returning side effect function
+//
+// # Returns
+//
+//   - ReaderIOEither with the original value preserved
+//
 //go:inline
 func MonadTapIOK[R, E, A, B any](ma ReaderIOEither[R, E, A], f io.Kleisli[A, B]) ReaderIOEither[R, E, A] {
 	return MonadChainFirstIOK(ma, f)
@@ -458,6 +976,25 @@ func ChainFirstIOK[R, E, A, B any](f io.Kleisli[A, B]) Operator[R, E, A, A] {
 	)
 }
 
+// TapIOK is an alias for ChainFirstIOK.
+// It returns a function that chains an IO-returning side effect while preserving
+// the original value.
+//
+// # Type Parameters
+//
+//   - R: The context/environment type
+//   - E: The error type
+//   - A: The input value type (preserved in output)
+//   - B: The side effect result type (discarded)
+//
+// # Parameters
+//
+//   - f: The IO-returning side effect function
+//
+// # Returns
+//
+//   - Operator that executes the side effect while preserving the original value
+//
 //go:inline
 func TapIOK[R, E, A, B any](f io.Kleisli[A, B]) Operator[R, E, A, A] {
 	return ChainFirstIOK[R, E](f)
@@ -540,6 +1077,25 @@ func ChainFirst[R, E, A, B any](f Kleisli[R, E, A, B]) Operator[R, E, A, A] {
 		f)
 }
 
+// Tap is an alias for ChainFirst.
+// It returns a function that sequences computations but keeps the first result,
+// emphasizing the side-effect nature of the operation.
+//
+// # Type Parameters
+//
+//   - R: The context/environment type
+//   - E: The error type
+//   - A: The input value type (preserved in output)
+//   - B: The side effect result type (discarded)
+//
+// # Parameters
+//
+//   - f: The Kleisli arrow for the side effect
+//
+// # Returns
+//
+//   - Operator that executes the side effect while preserving the original value
+//
 //go:inline
 func Tap[R, E, A, B any](f Kleisli[R, E, A, B]) Operator[R, E, A, A] {
 	return ChainFirst(f)

v2/readerioeither/reader_test.go

@@ -733,3 +733,390 @@ func TestChainLeftIdenticalToOrElse(t *testing.T) {
 		assert.Equal(t, cfg, *chainLeftCfg)
 	})
 }
+
+func TestChainFirstIOEitherK(t *testing.T) {
+	type Config struct {
+		logEnabled bool
+	}
+
+	t.Run("Success - preserves original value", func(t *testing.T) {
+		sideEffectRan := false
+
+		logValue := func(v int) IOE.IOEither[error, string] {
+			return func() E.Either[error, string] {
+				sideEffectRan = true
+				return E.Right[error](fmt.Sprintf("Logged: %d", v))
+			}
+		}
+
+		pipeline := F.Pipe1(
+			Of[Config, error](42),
+			ChainFirstIOEitherK[Config](logValue),
+		)
+
+		result := pipeline(Config{logEnabled: true})()
+		assert.Equal(t, E.Right[error](42), result)
+		assert.True(t, sideEffectRan)
+	})
+
+	t.Run("Success - side effect result is discarded", func(t *testing.T) {
+		sideEffect := func(v int) IOE.IOEither[error, string] {
+			return IOE.Of[error]("side effect result")
+		}
+
+		pipeline := F.Pipe1(
+			Of[Config, error](100),
+			ChainFirstIOEitherK[Config](sideEffect),
+		)
+
+		result := pipeline(Config{})()
+		assert.Equal(t, E.Right[error](100), result)
+	})
+
+	t.Run("Failure - side effect fails", func(t *testing.T) {
+		sideEffectError := errors.New("side effect failed")
+
+		failingSideEffect := func(v int) IOE.IOEither[error, string] {
+			return IOE.Left[string](sideEffectError)
+		}
+
+		pipeline := F.Pipe1(
+			Of[Config, error](42),
+			ChainFirstIOEitherK[Config](failingSideEffect),
+		)
+
+		result := pipeline(Config{})()
+		assert.Equal(t, E.Left[int](sideEffectError), result)
+	})
+
+	t.Run("Failure - original computation fails", func(t *testing.T) {
+		originalError := errors.New("original failed")
+		sideEffectRan := false
+
+		sideEffect := func(v int) IOE.IOEither[error, string] {
+			return func() E.Either[error, string] {
+				sideEffectRan = true
+				return E.Right[error]("logged")
+			}
+		}
+
+		pipeline := F.Pipe1(
+			Left[Config, int](originalError),
+			ChainFirstIOEitherK[Config](sideEffect),
+		)
+
+		result := pipeline(Config{})()
+		assert.Equal(t, E.Left[int](originalError), result)
+		assert.False(t, sideEffectRan, "Side effect should not run when original computation fails")
+	})
+
+	t.Run("Chaining multiple side effects", func(t *testing.T) {
+		log1Ran := false
+		log2Ran := false
+
+		log1 := func(v int) IOE.IOEither[error, string] {
+			return func() E.Either[error, string] {
+				log1Ran = true
+				return E.Right[error]("log1")
+			}
+		}
+
+		log2 := func(v int) IOE.IOEither[error, string] {
+			return func() E.Either[error, string] {
+				log2Ran = true
+				return E.Right[error]("log2")
+			}
+		}
+
+		pipeline := F.Pipe2(
+			Of[Config, error](42),
+			ChainFirstIOEitherK[Config](log1),
+			ChainFirstIOEitherK[Config](log2),
+		)
+
+		result := pipeline(Config{})()
+		assert.Equal(t, E.Right[error](42), result)
+		assert.True(t, log1Ran)
+		assert.True(t, log2Ran)
+	})
+
+	t.Run("Integration with Map", func(t *testing.T) {
+		validate := func(v int) IOE.IOEither[error, bool] {
+			if v > 0 {
+				return IOE.Of[error](true)
+			}
+			return IOE.Left[bool](errors.New("must be positive"))
+		}
+
+		pipeline := F.Pipe2(
+			Of[Config, error](10),
+			ChainFirstIOEitherK[Config](validate),
+			Map[Config, error](func(x int) int { return x * 2 }),
+		)
+
+		result := pipeline(Config{})()
+		assert.Equal(t, E.Right[error](20), result)
+	})
+
+	t.Run("Different types for input and side effect result", func(t *testing.T) {
+		convertToString := func(v int) IOE.IOEither[error, string] {
+			return IOE.Of[error](fmt.Sprintf("Value: %d", v))
+		}
+
+		pipeline := F.Pipe1(
+			Of[Config, error](123),
+			ChainFirstIOEitherK[Config](convertToString),
+		)
+
+		result := pipeline(Config{})()
+		assert.Equal(t, E.Right[error](123), result)
+	})
+
+	t.Run("With context-dependent side effect", func(t *testing.T) {
+		logged := ""
+
+		logIfEnabled := func(v int) IOE.IOEither[error, string] {
+			return func() E.Either[error, string] {
+				logged = fmt.Sprintf("Logged: %d", v)
+				return E.Right[error](logged)
+			}
+		}
+
+		pipeline := F.Pipe1(
+			Of[Config, error](99),
+			ChainFirstIOEitherK[Config](logIfEnabled),
+		)
+
+		result := pipeline(Config{logEnabled: true})()
+		assert.Equal(t, E.Right[error](99), result)
+		assert.Equal(t, "Logged: 99", logged)
+	})
+}
+
+func TestTapIOEitherK(t *testing.T) {
+	type Config struct {
+		debugMode bool
+	}
+
+	t.Run("Success - preserves original value", func(t *testing.T) {
+		tapped := false
+
+		tapFunc := func(v int) IOE.IOEither[error, string] {
+			return func() E.Either[error, string] {
+				tapped = true
+				return E.Right[error](fmt.Sprintf("Tapped: %d", v))
+			}
+		}
+
+		pipeline := F.Pipe1(
+			Of[Config, error](42),
+			TapIOEitherK[Config](tapFunc),
+		)
+
+		result := pipeline(Config{})()
+		assert.Equal(t, E.Right[error](42), result)
+		assert.True(t, tapped)
+	})
+
+	t.Run("Failure - tap fails", func(t *testing.T) {
+		tapError := errors.New("tap failed")
+
+		tapFunc := func(v int) IOE.IOEither[error, string] {
+			return IOE.Left[string](tapError)
+		}
+
+		pipeline := F.Pipe1(
+			Of[Config, error](42),
+			TapIOEitherK[Config](tapFunc),
+		)
+
+		result := pipeline(Config{})()
+		assert.Equal(t, E.Left[int](tapError), result)
+	})
+
+	t.Run("Failure - original computation fails", func(t *testing.T) {
+		originalError := errors.New("original failed")
+		tapped := false
+
+		tapFunc := func(v int) IOE.IOEither[error, string] {
+			return func() E.Either[error, string] {
+				tapped = true
+				return E.Right[error]("tapped")
+			}
+		}
+
+		pipeline := F.Pipe1(
+			Left[Config, int](originalError),
+			TapIOEitherK[Config](tapFunc),
+		)
+
+		result := pipeline(Config{})()
+		assert.Equal(t, E.Left[int](originalError), result)
+		assert.False(t, tapped, "Tap should not run when original computation fails")
+	})
+
+	t.Run("Validation use case", func(t *testing.T) {
+		validatePositive := func(v int) IOE.IOEither[error, bool] {
+			if v > 0 {
+				return IOE.Of[error](true)
+			}
+			return IOE.Left[bool](errors.New("must be positive"))
+		}
+
+		pipeline := F.Pipe1(
+			Of[Config, error](42),
+			TapIOEitherK[Config](validatePositive),
+		)
+
+		result := pipeline(Config{})()
+		assert.Equal(t, E.Right[error](42), result)
+	})
+
+	t.Run("Validation failure", func(t *testing.T) {
+		validatePositive := func(v int) IOE.IOEither[error, bool] {
+			if v > 0 {
+				return IOE.Of[error](true)
+			}
+			return IOE.Left[bool](errors.New("must be positive"))
+		}
+
+		pipeline := F.Pipe1(
+			Of[Config, error](-5),
+			TapIOEitherK[Config](validatePositive),
+		)
+
+		result := pipeline(Config{})()
+		assert.True(t, E.IsLeft(result))
+	})
+
+	t.Run("Multiple taps in sequence", func(t *testing.T) {
+		tap1Ran := false
+		tap2Ran := false
+		tap3Ran := false
+
+		tap1 := func(v int) IOE.IOEither[error, string] {
+			return func() E.Either[error, string] {
+				tap1Ran = true
+				return E.Right[error]("tap1")
+			}
+		}
+
+		tap2 := func(v int) IOE.IOEither[error, string] {
+			return func() E.Either[error, string] {
+				tap2Ran = true
+				return E.Right[error]("tap2")
+			}
+		}
+
+		tap3 := func(v int) IOE.IOEither[error, string] {
+			return func() E.Either[error, string] {
+				tap3Ran = true
+				return E.Right[error]("tap3")
+			}
+		}
+
+		pipeline := F.Pipe3(
+			Of[Config, error](100),
+			TapIOEitherK[Config](tap1),
+			TapIOEitherK[Config](tap2),
+			TapIOEitherK[Config](tap3),
+		)
+
+		result := pipeline(Config{})()
+		assert.Equal(t, E.Right[error](100), result)
+		assert.True(t, tap1Ran)
+		assert.True(t, tap2Ran)
+		assert.True(t, tap3Ran)
+	})
+
+	t.Run("Tap with transformation pipeline", func(t *testing.T) {
+		tappedValue := 0
+
+		tapFunc := func(v int) IOE.IOEither[error, string] {
+			return func() E.Either[error, string] {
+				tappedValue = v
+				return E.Right[error]("tapped")
+			}
+		}
+
+		pipeline := F.Pipe3(
+			Of[Config, error](10),
+			Map[Config, error](func(x int) int { return x * 2 }),
+			TapIOEitherK[Config](tapFunc),
+			Map[Config, error](func(x int) int { return x + 5 }),
+		)
+
+		result := pipeline(Config{})()
+		assert.Equal(t, E.Right[error](25), result)
+		assert.Equal(t, 20, tappedValue)
+	})
+
+	t.Run("Tap is alias for ChainFirstIOEitherK", func(t *testing.T) {
+		// Verify that TapIOEitherK and ChainFirstIOEitherK produce identical results
+		sideEffect := func(v int) IOE.IOEither[error, string] {
+			return IOE.Of[error](fmt.Sprintf("Value: %d", v))
+		}
+
+		pipelineWithTap := F.Pipe1(
+			Of[Config, error](42),
+			TapIOEitherK[Config](sideEffect),
+		)
+
+		pipelineWithChainFirst := F.Pipe1(
+			Of[Config, error](42),
+			ChainFirstIOEitherK[Config](sideEffect),
+		)
+
+		resultTap := pipelineWithTap(Config{})()
+		resultChainFirst := pipelineWithChainFirst(Config{})()
+
+		assert.Equal(t, resultChainFirst, resultTap)
+	})
+
+	t.Run("Logging use case", func(t *testing.T) {
+		logs := []string{}
+
+		logValue := func(v int) IOE.IOEither[error, string] {
+			return func() E.Either[error, string] {
+				logMsg := fmt.Sprintf("Processing value: %d", v)
+				logs = append(logs, logMsg)
+				return E.Right[error](logMsg)
+			}
+		}
+
+		pipeline := F.Pipe2(
+			Of[Config, error](5),
+			TapIOEitherK[Config](logValue),
+			Map[Config, error](func(x int) int { return x * x }),
+		)
+
+		result := pipeline(Config{debugMode: true})()
+		assert.Equal(t, E.Right[error](25), result)
+		assert.Len(t, logs, 1)
+		assert.Equal(t, "Processing value: 5", logs[0])
+	})
+
+	t.Run("Error propagation in tap chain", func(t *testing.T) {
+		tap1 := func(v int) IOE.IOEither[error, string] {
+			return IOE.Of[error]("tap1")
+		}
+
+		tap2 := func(v int) IOE.IOEither[error, string] {
+			return IOE.Left[string](errors.New("tap2 failed"))
+		}
+
+		tap3 := func(v int) IOE.IOEither[error, string] {
+			return IOE.Of[error]("tap3")
+		}
+
+		pipeline := F.Pipe3(
+			Of[Config, error](42),
+			TapIOEitherK[Config](tap1),
+			TapIOEitherK[Config](tap2),
+			TapIOEitherK[Config](tap3),
+		)
+
+		result := pipeline(Config{})()
+		assert.True(t, E.IsLeft(result))
+	})
+}

v2/readerioresult/reader.go

@@ -20,6 +20,7 @@ import (
 
 	"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/reader"
 	RE "github.com/IBM/fp-go/v2/readereither"
 	"github.com/IBM/fp-go/v2/readerio"
@@ -28,6 +29,9 @@ import (
 	"github.com/IBM/fp-go/v2/result"
 )
 
+// FromReaderOption converts a ReaderOption to a ReaderIOResult.
+// If the ReaderOption is None, the provided function is called to produce the error.
+//
 //go:inline
 func FromReaderOption[R, A any](onNone Lazy[error]) Kleisli[R, ReaderOption[R, A], A] {
 	return RIOE.FromReaderOption[R, A](onNone)
@@ -105,6 +109,9 @@ func MonadChainFirst[R, A, B any](fa ReaderIOResult[R, A], f Kleisli[R, A, B]) R
 	return RIOE.MonadChainFirst(fa, f)
 }
 
+// MonadTap is an alias for MonadChainFirst, executing a side effect while preserving the original value.
+// The name "Tap" emphasizes the side-effect nature of the operation.
+//
 //go:inline
 func MonadTap[R, A, B any](fa ReaderIOResult[R, A], f Kleisli[R, A, B]) ReaderIOResult[R, A] {
 	return RIOE.MonadTap(fa, f)
@@ -150,6 +157,8 @@ func MonadChainFirstEitherK[R, A, B any](ma ReaderIOResult[R, A], f result.Kleis
 	return RIOE.MonadChainFirstEitherK(ma, f)
 }
 
+// MonadTapEitherK is an alias for MonadChainFirstEitherK, executing a Result side effect while preserving the original value.
+//
 //go:inline
 func MonadTapEitherK[R, A, B any](ma ReaderIOResult[R, A], f result.Kleisli[A, B]) ReaderIOResult[R, A] {
 	return RIOE.MonadTapEitherK(ma, f)
@@ -163,11 +172,43 @@ func ChainFirstEitherK[R, A, B any](f result.Kleisli[A, B]) Operator[R, A, A] {
 	return RIOE.ChainFirstEitherK[R](f)
 }
 
+// TapEitherK is an alias for ChainFirstEitherK, executing a Result side effect while preserving the original value.
+//
 //go:inline
 func TapEitherK[R, A, B any](f result.Kleisli[A, B]) Operator[R, A, A] {
 	return RIOE.TapEitherK[R](f)
 }
 
+// ChainFirstIOEitherK chains an IOResult computation while preserving the original value.
+// Useful for performing side effects that may fail while keeping the original value.
+//
+//go:inline
+func ChainFirstIOEitherK[R, A, B any](f ioresult.Kleisli[A, B]) Operator[R, A, A] {
+	return RIOE.ChainFirstIOEitherK[R](f)
+}
+
+// TapIOEitherK is an alias for ChainFirstIOEitherK, executing an IOResult side effect while preserving the original value.
+//
+//go:inline
+func TapIOEitherK[R, A, B any](f ioresult.Kleisli[A, B]) Operator[R, A, A] {
+	return RIOE.TapIOEitherK[R](f)
+}
+
+// ChainFirstIOResultK chains an IOResult computation while preserving the original value.
+// This is an alias for ChainFirstIOEitherK with more explicit naming.
+//
+//go:inline
+func ChainFirstIOResultK[R, A, B any](f ioresult.Kleisli[A, B]) Operator[R, A, A] {
+	return RIOE.ChainFirstIOEitherK[R](f)
+}
+
+// TapIOResultK is an alias for ChainFirstIOResultK, executing an IOResult side effect while preserving the original value.
+//
+//go:inline
+func TapIOResultK[R, A, B any](f ioresult.Kleisli[A, B]) Operator[R, A, A] {
+	return RIOE.TapIOEitherK[R](f)
+}
+
 // MonadChainFirstEitherK chains an Either-returning computation but keeps the original value.
 // Useful for validation or side effects that return Either.
 //
@@ -176,19 +217,23 @@ func MonadChainFirstResultK[R, A, B any](ma ReaderIOResult[R, A], f result.Kleis
 	return RIOE.MonadChainFirstEitherK(ma, f)
 }
 
+// MonadTapResultK is an alias for MonadChainFirstResultK, executing a Result side effect while preserving the original value.
+//
 //go:inline
 func MonadTapResultK[R, A, B any](ma ReaderIOResult[R, A], f result.Kleisli[A, B]) ReaderIOResult[R, A] {
 	return RIOE.MonadTapEitherK(ma, f)
 }
 
-// ChainFirstEitherK returns a function that chains an Either computation while preserving the original value.
-// This is the curried version of MonadChainFirstEitherK.
+// ChainFirstResultK returns a function that chains a Result computation while preserving the original value.
+// This is an alias for ChainFirstEitherK with more explicit naming.
 //
 //go:inline
 func ChainFirstResultK[R, A, B any](f result.Kleisli[A, B]) Operator[R, A, A] {
 	return RIOE.ChainFirstEitherK[R](f)
 }
 
+// TapResultK is an alias for ChainFirstResultK, executing a Result side effect while preserving the original value.
+//
 //go:inline
 func TapResultK[R, A, B any](f result.Kleisli[A, B]) Operator[R, A, A] {
 	return RIOE.TapEitherK[R](f)
@@ -210,36 +255,54 @@ func ChainReaderK[R, A, B any](f reader.Kleisli[R, A, B]) Operator[R, A, B] {
 	return RIOE.ChainReaderK[error](f)
 }
 
+// MonadChainFirstReaderK chains a Reader computation but keeps the original value.
+// Useful for performing Reader-based side effects while preserving the original value.
+//
 //go:inline
 func MonadChainFirstReaderK[R, A, B any](ma ReaderIOResult[R, A], f reader.Kleisli[R, A, B]) ReaderIOResult[R, A] {
 	return RIOE.MonadChainFirstReaderK(ma, f)
 }
 
+// MonadTapReaderK is an alias for MonadChainFirstReaderK, executing a Reader side effect while preserving the original value.
+//
 //go:inline
 func MonadTapReaderK[R, A, B any](ma ReaderIOResult[R, A], f reader.Kleisli[R, A, B]) ReaderIOResult[R, A] {
 	return RIOE.MonadTapReaderK(ma, f)
 }
 
+// ChainFirstReaderK returns a function that chains a Reader computation while preserving the original value.
+// This is the curried version of MonadChainFirstReaderK.
+//
 //go:inline
 func ChainFirstReaderK[R, A, B any](f reader.Kleisli[R, A, B]) Operator[R, A, A] {
 	return RIOE.ChainFirstReaderK[error](f)
 }
 
+// TapReaderK is an alias for ChainFirstReaderK, executing a Reader side effect while preserving the original value.
+//
 //go:inline
 func TapReaderK[R, A, B any](f reader.Kleisli[R, A, B]) Operator[R, A, A] {
 	return RIOE.TapReaderK[error](f)
 }
 
+// ChainReaderOptionK returns a function that chains a ReaderOption-returning function into ReaderIOResult.
+// If the ReaderOption is None, the provided error function is called.
+//
 //go:inline
 func ChainReaderOptionK[R, A, B any](onNone Lazy[error]) func(readeroption.Kleisli[R, A, B]) Operator[R, A, B] {
 	return RIOE.ChainReaderOptionK[R, A, B](onNone)
 }
 
+// ChainFirstReaderOptionK chains a ReaderOption computation while preserving the original value.
+// If the ReaderOption is None, the provided error function is called.
+//
 //go:inline
 func ChainFirstReaderOptionK[R, A, B any](onNone Lazy[error]) func(readeroption.Kleisli[R, A, B]) Operator[R, A, A] {
 	return RIOE.ChainFirstReaderOptionK[R, A, B](onNone)
 }
 
+// TapReaderOptionK is an alias for ChainFirstReaderOptionK, executing a ReaderOption side effect while preserving the original value.
+//
 //go:inline
 func TapReaderOptionK[R, A, B any](onNone Lazy[error]) func(readeroption.Kleisli[R, A, B]) Operator[R, A, A] {
 	return RIOE.TapReaderOptionK[R, A, B](onNone)
@@ -261,84 +324,123 @@ func ChainReaderEitherK[R, A, B any](f RE.Kleisli[R, error, A, B]) Operator[R, A
 	return RIOE.ChainReaderEitherK(f)
 }
 
+// MonadChainFirstReaderEitherK chains a ReaderEither computation but keeps the original value.
+// Useful for performing ReaderEither-based side effects while preserving the original value.
+//
 //go:inline
 func MonadChainFirstReaderEitherK[R, A, B any](ma ReaderIOResult[R, A], f RE.Kleisli[R, error, A, B]) ReaderIOResult[R, A] {
 	return RIOE.MonadChainFirstReaderEitherK(ma, f)
 }
 
+// MonadTapReaderEitherK is an alias for MonadChainFirstReaderEitherK, executing a ReaderEither side effect while preserving the original value.
+//
 //go:inline
 func MonadTapReaderEitherK[R, A, B any](ma ReaderIOResult[R, A], f RE.Kleisli[R, error, A, B]) ReaderIOResult[R, A] {
 	return RIOE.MonadTapReaderEitherK(ma, f)
 }
 
+// ChainFirstReaderEitherK returns a function that chains a ReaderEither computation while preserving the original value.
+// This is the curried version of MonadChainFirstReaderEitherK.
+//
 //go:inline
 func ChainFirstReaderEitherK[R, A, B any](f RE.Kleisli[R, error, A, B]) Operator[R, A, A] {
 	return RIOE.ChainFirstReaderEitherK(f)
 }
 
+// TapReaderEitherK is an alias for ChainFirstReaderEitherK, executing a ReaderEither side effect while preserving the original value.
+//
 //go:inline
 func TapReaderEitherK[R, A, B any](f RE.Kleisli[R, error, A, B]) Operator[R, A, A] {
 	return RIOE.TapReaderEitherK(f)
 }
 
+// MonadChainReaderResultK chains a ReaderResult-returning computation into a ReaderIOResult.
+// This is an alias for MonadChainReaderEitherK with more explicit naming.
+//
 //go:inline
 func MonadChainReaderResultK[R, A, B any](ma ReaderIOResult[R, A], f RE.Kleisli[R, error, A, B]) ReaderIOResult[R, B] {
 	return RIOE.MonadChainReaderEitherK(ma, f)
 }
 
-// ChainReaderK returns a function that chains a Reader-returning function into ReaderIOResult.
-// This is the curried version of MonadChainReaderK.
+// ChainReaderResultK returns a function that chains a ReaderResult-returning function into ReaderIOResult.
+// This is an alias for ChainReaderEitherK with more explicit naming.
 //
 //go:inline
 func ChainReaderResultK[R, A, B any](f RE.Kleisli[R, error, A, B]) Operator[R, A, B] {
 	return RIOE.ChainReaderEitherK(f)
 }
 
+// MonadChainFirstReaderResultK chains a ReaderResult computation but keeps the original value.
+// This is an alias for MonadChainFirstReaderEitherK with more explicit naming.
+//
 //go:inline
 func MonadChainFirstReaderResultK[R, A, B any](ma ReaderIOResult[R, A], f RE.Kleisli[R, error, A, B]) ReaderIOResult[R, A] {
 	return RIOE.MonadChainFirstReaderEitherK(ma, f)
 }
 
+// MonadTapReaderResultK is an alias for MonadChainFirstReaderResultK, executing a ReaderResult side effect while preserving the original value.
+//
 //go:inline
 func MonadTapReaderResultK[R, A, B any](ma ReaderIOResult[R, A], f RE.Kleisli[R, error, A, B]) ReaderIOResult[R, A] {
 	return RIOE.MonadTapReaderEitherK(ma, f)
 }
 
+// ChainFirstReaderResultK returns a function that chains a ReaderResult computation while preserving the original value.
+// This is an alias for ChainFirstReaderEitherK with more explicit naming.
+//
 //go:inline
 func ChainFirstReaderResultK[R, A, B any](f RE.Kleisli[R, error, A, B]) Operator[R, A, A] {
 	return RIOE.ChainFirstReaderEitherK(f)
 }
 
+// TapReaderResultK is an alias for ChainFirstReaderResultK, executing a ReaderResult side effect while preserving the original value.
+//
 //go:inline
 func TapReaderResultK[R, A, B any](f RE.Kleisli[R, error, A, B]) Operator[R, A, A] {
 	return RIOE.TapReaderEitherK(f)
 }
 
+// MonadChainReaderIOK chains a ReaderIO-returning computation into a ReaderIOResult.
+// The ReaderIO is automatically lifted into the ReaderIOResult context (always succeeds).
+//
 //go:inline
 func MonadChainReaderIOK[R, A, B any](ma ReaderIOResult[R, A], f readerio.Kleisli[R, A, B]) ReaderIOResult[R, B] {
 	return RIOE.MonadChainReaderIOK(ma, f)
 }
 
+// ChainReaderIOK returns a function that chains a ReaderIO-returning function into ReaderIOResult.
+// This is the curried version of MonadChainReaderIOK.
+//
 //go:inline
 func ChainReaderIOK[R, A, B any](f readerio.Kleisli[R, A, B]) Operator[R, A, B] {
 	return RIOE.ChainReaderIOK[error](f)
 }
 
+// MonadChainFirstReaderIOK chains a ReaderIO computation but keeps the original value.
+// Useful for performing ReaderIO-based side effects while preserving the original value.
+//
 //go:inline
 func MonadChainFirstReaderIOK[R, A, B any](ma ReaderIOResult[R, A], f readerio.Kleisli[R, A, B]) ReaderIOResult[R, A] {
 	return RIOE.MonadChainFirstReaderIOK(ma, f)
 }
 
+// MonadTapReaderIOK is an alias for MonadChainFirstReaderIOK, executing a ReaderIO side effect while preserving the original value.
+//
 //go:inline
 func MonadTapReaderIOK[R, A, B any](ma ReaderIOResult[R, A], f readerio.Kleisli[R, A, B]) ReaderIOResult[R, A] {
 	return RIOE.MonadTapReaderIOK(ma, f)
 }
 
+// ChainFirstReaderIOK returns a function that chains a ReaderIO computation while preserving the original value.
+// This is the curried version of MonadChainFirstReaderIOK.
+//
 //go:inline
 func ChainFirstReaderIOK[R, A, B any](f readerio.Kleisli[R, A, B]) Operator[R, A, A] {
 	return RIOE.ChainFirstReaderIOK[error](f)
 }
 
+// TapReaderIOK is an alias for ChainFirstReaderIOK, executing a ReaderIO side effect while preserving the original value.
+//
 //go:inline
 func TapReaderIOK[R, A, B any](f readerio.Kleisli[R, A, B]) Operator[R, A, A] {
 	return RIOE.TapReaderIOK[error](f)
@@ -400,6 +502,8 @@ func MonadChainFirstIOK[R, A, B any](ma ReaderIOResult[R, A], f func(A) IO[B]) R
 	return RIOE.MonadChainFirstIOK(ma, f)
 }
 
+// MonadTapIOK is an alias for MonadChainFirstIOK, executing an IO side effect while preserving the original value.
+//
 //go:inline
 func MonadTapIOK[R, A, B any](ma ReaderIOResult[R, A], f func(A) IO[B]) ReaderIOResult[R, A] {
 	return RIOE.MonadTapIOK(ma, f)
@@ -413,6 +517,8 @@ func ChainFirstIOK[R, A, B any](f func(A) IO[B]) Operator[R, A, A] {
 	return RIOE.ChainFirstIOK[R, error](f)
 }
 
+// TapIOK is an alias for ChainFirstIOK, executing an IO side effect while preserving the original value.
+//
 //go:inline
 func TapIOK[R, A, B any](f func(A) IO[B]) Operator[R, A, A] {
 	return RIOE.TapIOK[R, error](f)
@@ -473,6 +579,9 @@ func ChainFirst[R, A, B any](f Kleisli[R, A, B]) Operator[R, A, A] {
 	return RIOE.ChainFirst(f)
 }
 
+// Tap is an alias for ChainFirst, executing a side effect while preserving the original value.
+// The name "Tap" emphasizes the side-effect nature of the operation.
+//
 //go:inline
 func Tap[R, A, B any](f Kleisli[R, A, B]) Operator[R, A, A] {
 	return RIOE.Tap(f)
@@ -767,46 +876,70 @@ func Local[A, R1, R2 any](f func(R2) R1) func(ReaderIOResult[R1, A]) ReaderIORes
 	return RIOE.Local[error, A](f)
 }
 
+// Read executes a ReaderIOResult by providing a concrete environment value.
+// This converts a ReaderIOResult[R, A] into an IOResult[A] by supplying the R value.
+//
 //go:inline
 func Read[A, R any](r R) func(ReaderIOResult[R, A]) IOResult[A] {
 	return RIOE.Read[error, A](r)
 }
 
+// MonadChainLeft chains a computation on the error channel, allowing error recovery or transformation.
+// If the computation is successful (Right), it passes through unchanged.
+//
 //go:inline
 func MonadChainLeft[R, A any](fa ReaderIOResult[R, A], f Kleisli[R, error, A]) ReaderIOResult[R, A] {
 	return RIOE.MonadChainLeft(fa, f)
 }
 
+// ChainLeft returns a function that chains a computation on the error channel.
+// This is the curried version of MonadChainLeft.
+//
 //go:inline
 func ChainLeft[R, A any](f Kleisli[R, error, A]) func(ReaderIOResult[R, A]) ReaderIOResult[R, A] {
 	return RIOE.ChainLeft(f)
 }
 
+// MonadChainFirstLeft chains an error-handling computation but preserves the original error.
+// Useful for logging or side effects on errors without changing the error value.
+//
 //go:inline
 func MonadChainFirstLeft[A, R, B any](ma ReaderIOResult[R, A], f Kleisli[R, error, B]) ReaderIOResult[R, A] {
 	return RIOE.MonadChainFirstLeft(ma, f)
 }
 
+// MonadTapLeft is an alias for MonadChainFirstLeft, executing a side effect on errors while preserving the original error.
+//
 //go:inline
 func MonadTapLeft[A, R, B any](ma ReaderIOResult[R, A], f Kleisli[R, error, B]) ReaderIOResult[R, A] {
 	return RIOE.MonadTapLeft(ma, f)
 }
 
+// ChainFirstLeft returns a function that chains an error-handling computation while preserving the original error.
+// This is the curried version of MonadChainFirstLeft.
+//
 //go:inline
 func ChainFirstLeft[A, R, B any](f Kleisli[R, error, B]) Operator[R, A, A] {
 	return RIOE.ChainFirstLeft[A](f)
 }
 
+// ChainFirstLeftIOK chains an IO computation on errors while preserving the original error.
+// Useful for IO-based error logging or side effects.
+//
 //go:inline
 func ChainFirstLeftIOK[A, R, B any](f io.Kleisli[error, B]) Operator[R, A, A] {
 	return RIOE.ChainFirstLeftIOK[A, R](f)
 }
 
+// TapLeft is an alias for ChainFirstLeft, executing a side effect on errors while preserving the original error.
+//
 //go:inline
 func TapLeft[A, R, B any](f Kleisli[R, error, B]) Operator[R, A, A] {
 	return RIOE.TapLeft[A](f)
 }
 
+// TapLeftIOK is an alias for ChainFirstLeftIOK, executing an IO side effect on errors while preserving the original error.
+//
 //go:inline
 func TapLeftIOK[A, R, B any](f io.Kleisli[error, B]) Operator[R, A, A] {
 	return RIOE.TapLeftIOK[A, R](f)

v2/readerioresult/reader_test.go

@@ -619,3 +619,453 @@ func TestLocalIOResultK(t *testing.T) {
 		assert.True(t, result.IsLeft(resErr))
 	})
 }
+
+func TestChainFirstIOResultK(t *testing.T) {
+	type Config struct {
+		logEnabled bool
+	}
+
+	t.Run("Success - preserves original value", func(t *testing.T) {
+		sideEffectRan := false
+
+		logValue := func(v int) IOResult[string] {
+			return func() Result[string] {
+				sideEffectRan = true
+				return result.Of(fmt.Sprintf("Logged: %d", v))
+			}
+		}
+
+		pipeline := F.Pipe1(
+			Of[Config](42),
+			ChainFirstIOResultK[Config](logValue),
+		)
+
+		res := pipeline(Config{logEnabled: true})()
+		assert.Equal(t, result.Of(42), res)
+		assert.True(t, sideEffectRan)
+	})
+
+	t.Run("Failure - side effect fails", func(t *testing.T) {
+		sideEffectError := errors.New("side effect failed")
+
+		failingSideEffect := func(v int) IOResult[string] {
+			return func() Result[string] {
+				return result.Left[string](sideEffectError)
+			}
+		}
+
+		pipeline := F.Pipe1(
+			Of[Config](42),
+			ChainFirstIOResultK[Config](failingSideEffect),
+		)
+
+		res := pipeline(Config{})()
+		assert.True(t, E.IsLeft(res))
+	})
+
+	t.Run("Failure - original computation fails", func(t *testing.T) {
+		originalError := errors.New("original failed")
+		sideEffectRan := false
+
+		sideEffect := func(v int) IOResult[string] {
+			return func() Result[string] {
+				sideEffectRan = true
+				return result.Of("logged")
+			}
+		}
+
+		pipeline := F.Pipe1(
+			Left[Config, int](originalError),
+			ChainFirstIOResultK[Config](sideEffect),
+		)
+
+		res := pipeline(Config{})()
+		assert.Equal(t, result.Left[int](originalError), res)
+		assert.False(t, sideEffectRan)
+	})
+}
+
+func TestTapIOResultK(t *testing.T) {
+	type Config struct{}
+
+	t.Run("Success - preserves original value", func(t *testing.T) {
+		tapped := false
+
+		tapFunc := func(v int) IOResult[string] {
+			return func() Result[string] {
+				tapped = true
+				return result.Of(fmt.Sprintf("Tapped: %d", v))
+			}
+		}
+
+		pipeline := F.Pipe1(
+			Of[Config](42),
+			TapIOResultK[Config](tapFunc),
+		)
+
+		res := pipeline(Config{})()
+		assert.Equal(t, result.Of(42), res)
+		assert.True(t, tapped)
+	})
+
+	t.Run("Validation use case", func(t *testing.T) {
+		validatePositive := func(v int) IOResult[bool] {
+			return func() Result[bool] {
+				if v > 0 {
+					return result.Of(true)
+				}
+				return result.Left[bool](errors.New("must be positive"))
+			}
+		}
+
+		pipeline := F.Pipe1(
+			Of[Config](42),
+			TapIOResultK[Config](validatePositive),
+		)
+
+		res := pipeline(Config{})()
+		assert.Equal(t, result.Of(42), res)
+	})
+
+	t.Run("Validation failure", func(t *testing.T) {
+		validatePositive := func(v int) IOResult[bool] {
+			return func() Result[bool] {
+				if v > 0 {
+					return result.Of(true)
+				}
+				return result.Left[bool](errors.New("must be positive"))
+			}
+		}
+
+		pipeline := F.Pipe1(
+			Of[Config](-5),
+			TapIOResultK[Config](validatePositive),
+		)
+
+		res := pipeline(Config{})()
+		assert.True(t, E.IsLeft(res))
+	})
+}
+
+func TestTap(t *testing.T) {
+	type Config struct{}
+
+	t.Run("Success - preserves original value", func(t *testing.T) {
+		tapped := false
+
+		tapFunc := func(v int) ReaderIOResult[Config, string] {
+			return func(cfg Config) IOResult[string] {
+				return func() Result[string] {
+					tapped = true
+					return result.Of(fmt.Sprintf("Tapped: %d", v))
+				}
+			}
+		}
+
+		pipeline := F.Pipe1(
+			Of[Config](42),
+			Tap[Config](tapFunc),
+		)
+
+		res := pipeline(Config{})()
+		assert.Equal(t, result.Of(42), res)
+		assert.True(t, tapped)
+	})
+
+	t.Run("Tap is alias for ChainFirst", func(t *testing.T) {
+		sideEffect := func(v int) ReaderIOResult[Config, string] {
+			return func(cfg Config) IOResult[string] {
+				return func() Result[string] {
+					return result.Of(fmt.Sprintf("Value: %d", v))
+				}
+			}
+		}
+
+		pipelineWithTap := F.Pipe1(
+			Of[Config](42),
+			Tap[Config](sideEffect),
+		)
+
+		pipelineWithChainFirst := F.Pipe1(
+			Of[Config](42),
+			ChainFirst[Config](sideEffect),
+		)
+
+		resultTap := pipelineWithTap(Config{})()
+		resultChainFirst := pipelineWithChainFirst(Config{})()
+
+		assert.Equal(t, resultChainFirst, resultTap)
+	})
+}
+
+func TestMonadTap(t *testing.T) {
+	type Config struct{}
+
+	t.Run("Success - preserves original value", func(t *testing.T) {
+		tapped := false
+
+		tapFunc := func(v int) ReaderIOResult[Config, string] {
+			return func(cfg Config) IOResult[string] {
+				return func() Result[string] {
+					tapped = true
+					return result.Of("tapped")
+				}
+			}
+		}
+
+		res := MonadTap(Of[Config](42), tapFunc)(Config{})()
+		assert.Equal(t, result.Of(42), res)
+		assert.True(t, tapped)
+	})
+}
+
+func TestTapEitherK(t *testing.T) {
+	type Config struct{}
+
+	t.Run("Success - preserves original value", func(t *testing.T) {
+		tapped := false
+
+		tapFunc := func(v int) Result[string] {
+			tapped = true
+			return result.Of(fmt.Sprintf("Tapped: %d", v))
+		}
+
+		pipeline := F.Pipe1(
+			Of[Config](42),
+			TapEitherK[Config](tapFunc),
+		)
+
+		res := pipeline(Config{})()
+		assert.Equal(t, result.Of(42), res)
+		assert.True(t, tapped)
+	})
+
+	t.Run("Failure - tap fails", func(t *testing.T) {
+		tapError := errors.New("tap failed")
+
+		tapFunc := func(v int) Result[string] {
+			return result.Left[string](tapError)
+		}
+
+		pipeline := F.Pipe1(
+			Of[Config](42),
+			TapEitherK[Config](tapFunc),
+		)
+
+		res := pipeline(Config{})()
+		assert.True(t, E.IsLeft(res))
+	})
+}
+
+func TestTapResultK(t *testing.T) {
+	type Config struct{}
+
+	t.Run("Success - preserves original value", func(t *testing.T) {
+		tapped := false
+
+		tapFunc := func(v int) Result[string] {
+			tapped = true
+			return result.Of("tapped")
+		}
+
+		pipeline := F.Pipe1(
+			Of[Config](42),
+			TapResultK[Config](tapFunc),
+		)
+
+		res := pipeline(Config{})()
+		assert.Equal(t, result.Of(42), res)
+		assert.True(t, tapped)
+	})
+}
+
+func TestTapReaderK(t *testing.T) {
+	type Config struct {
+		multiplier int
+	}
+
+	t.Run("Success - preserves original value with context", func(t *testing.T) {
+		tapped := false
+
+		tapFunc := func(v int) R.Reader[Config, string] {
+			return func(cfg Config) string {
+				tapped = true
+				return fmt.Sprintf("Value: %d, Multiplier: %d", v, cfg.multiplier)
+			}
+		}
+
+		pipeline := F.Pipe1(
+			Of[Config](42),
+			TapReaderK[Config](tapFunc),
+		)
+
+		res := pipeline(Config{multiplier: 2})()
+		assert.Equal(t, result.Of(42), res)
+		assert.True(t, tapped)
+	})
+}
+
+func TestTapIOK(t *testing.T) {
+	type Config struct{}
+
+	t.Run("Success - preserves original value", func(t *testing.T) {
+		tapped := false
+
+		tapFunc := func(v int) IO[string] {
+			return func() string {
+				tapped = true
+				return fmt.Sprintf("Tapped: %d", v)
+			}
+		}
+
+		pipeline := F.Pipe1(
+			Of[Config](42),
+			TapIOK[Config](tapFunc),
+		)
+
+		res := pipeline(Config{})()
+		assert.Equal(t, result.Of(42), res)
+		assert.True(t, tapped)
+	})
+}
+
+func TestRead(t *testing.T) {
+	type Config struct {
+		value int
+	}
+
+	t.Run("Success - provides environment", func(t *testing.T) {
+		computation := func(cfg Config) IOResult[int] {
+			return func() Result[int] {
+				return result.Of(cfg.value * 2)
+			}
+		}
+
+		res := Read[int](Config{value: 21})(computation)()
+		assert.Equal(t, result.Of(42), res)
+	})
+
+	t.Run("Failure - computation fails", func(t *testing.T) {
+		compError := errors.New("computation failed")
+
+		computation := func(cfg Config) IOResult[int] {
+			return func() Result[int] {
+				return result.Left[int](compError)
+			}
+		}
+
+		res := Read[int](Config{value: 21})(computation)()
+		assert.Equal(t, result.Left[int](compError), res)
+	})
+}
+
+func TestChainLeft(t *testing.T) {
+	type Config struct{}
+
+	t.Run("Right passes through unchanged", func(t *testing.T) {
+		pipeline := F.Pipe1(
+			Right[Config](42),
+			ChainLeft[Config](func(err error) ReaderIOResult[Config, int] {
+				return Left[Config, int](errors.New("should not run"))
+			}),
+		)
+
+		res := pipeline(Config{})()
+		assert.Equal(t, result.Of(42), res)
+	})
+
+	t.Run("Left transforms error", func(t *testing.T) {
+		originalError := errors.New("original")
+		newError := errors.New("transformed")
+
+		pipeline := F.Pipe1(
+			Left[Config, int](originalError),
+			ChainLeft[Config](func(err error) ReaderIOResult[Config, int] {
+				return Left[Config, int](newError)
+			}),
+		)
+
+		res := pipeline(Config{})()
+		assert.Equal(t, result.Left[int](newError), res)
+	})
+
+	t.Run("Left recovers to Right", func(t *testing.T) {
+		pipeline := F.Pipe1(
+			Left[Config, int](errors.New("error")),
+			ChainLeft[Config](func(err error) ReaderIOResult[Config, int] {
+				return Right[Config](99)
+			}),
+		)
+
+		res := pipeline(Config{})()
+		assert.Equal(t, result.Of(99), res)
+	})
+}
+
+func TestTapLeft(t *testing.T) {
+	type Config struct{}
+
+	t.Run("Right does not call function", func(t *testing.T) {
+		tapped := false
+
+		pipeline := F.Pipe1(
+			Right[Config](42),
+			TapLeft[int, Config](func(err error) ReaderIOResult[Config, string] {
+				return func(cfg Config) IOResult[string] {
+					return func() Result[string] {
+						tapped = true
+						return result.Of("logged")
+					}
+				}
+			}),
+		)
+
+		res := pipeline(Config{})()
+		assert.Equal(t, result.Of(42), res)
+		assert.False(t, tapped)
+	})
+
+	t.Run("Left calls function but preserves error", func(t *testing.T) {
+		tapped := false
+		originalError := errors.New("original error")
+
+		pipeline := F.Pipe1(
+			Left[Config, int](originalError),
+			TapLeft[int, Config](func(err error) ReaderIOResult[Config, string] {
+				return func(cfg Config) IOResult[string] {
+					return func() Result[string] {
+						tapped = true
+						return result.Of("side effect done")
+					}
+				}
+			}),
+		)
+
+		res := pipeline(Config{})()
+		assert.Equal(t, result.Left[int](originalError), res)
+		assert.True(t, tapped)
+	})
+}
+
+func TestTapLeftIOK(t *testing.T) {
+	type Config struct{}
+
+	t.Run("Left calls IO function but preserves error", func(t *testing.T) {
+		tapped := false
+		originalError := errors.New("original error")
+
+		pipeline := F.Pipe1(
+			Left[Config, int](originalError),
+			TapLeftIOK[int, Config](func(err error) IO[string] {
+				return func() string {
+					tapped = true
+					return "logged error"
+				}
+			}),
+		)
+
+		res := pipeline(Config{})()
+		assert.Equal(t, result.Left[int](originalError), res)
+		assert.True(t, tapped)
+	})
+}

v2/readerreaderioeither/reader.go

@@ -38,51 +38,75 @@ import (
 	"github.com/IBM/fp-go/v2/readeroption"
 )
 
+// FromReaderOption converts a ReaderOption to a ReaderReaderIOEither.
+// If the ReaderOption is None, the provided function is called to produce the error.
+//
 //go:inline
 func FromReaderOption[R, C, A, E any](onNone Lazy[E]) Kleisli[R, C, E, ReaderOption[R, A], A] {
 	return reader.Map[R](RIOE.FromOption[C, A](onNone))
 }
 
+// FromReaderIOEither lifts a ReaderIOEither into a ReaderReaderIOEither context.
+//
 //go:inline
 func FromReaderIOEither[C, E, R, A any](ma ReaderIOEither[R, E, A]) ReaderReaderIOEither[R, C, E, A] {
 	return reader.MonadMap(ma, RIOE.FromIOEither[C])
 }
 
+// FromReaderIO lifts a ReaderIO into a ReaderReaderIOEither, placing the result in the Right side.
+//
 //go:inline
 func FromReaderIO[C, E, R, A any](ma ReaderIO[R, A]) ReaderReaderIOEither[R, C, E, A] {
 	return RightReaderIO[C, E](ma)
 }
 
+// RightReaderIO lifts a ReaderIO into a ReaderReaderIOEither, placing the result in the Right side.
+//
 //go:inline
 func RightReaderIO[C, E, R, A any](ma ReaderIO[R, A]) ReaderReaderIOEither[R, C, E, A] {
 	return reader.MonadMap(ma, RIOE.RightIO[C, E, A])
 }
 
+// LeftReaderIO lifts a ReaderIO into a ReaderReaderIOEither, placing the result in the Left (error) side.
+//
 //go:inline
 func LeftReaderIO[C, A, R, E any](me ReaderIO[R, E]) ReaderReaderIOEither[R, C, E, A] {
 	return reader.MonadMap(me, RIOE.LeftIO[C, A, E])
 }
 
+// MonadMap applies a function to the value inside a ReaderReaderIOEither context.
+// If the computation is successful (Right), the function is applied to the value.
+//
 //go:inline
 func MonadMap[R, C, E, A, B any](fa ReaderReaderIOEither[R, C, E, A], f func(A) B) ReaderReaderIOEither[R, C, E, B] {
 	return reader.MonadMap(fa, RIOE.Map[C, E](f))
 }
 
+// Map returns a function that applies a transformation to the success value.
+// This is the curried version of MonadMap.
+//
 //go:inline
 func Map[R, C, E, A, B any](f func(A) B) Operator[R, C, E, A, B] {
 	return reader.Map[R](RIOE.Map[C, E](f))
 }
 
+// MonadMapTo replaces the success value with a constant value.
+//
 //go:inline
 func MonadMapTo[R, C, E, A, B any](fa ReaderReaderIOEither[R, C, E, A], b B) ReaderReaderIOEither[R, C, E, B] {
 	return reader.MonadMap(fa, RIOE.MapTo[C, E, A](b))
 }
 
+// MapTo returns a function that replaces the success value with a constant.
+// This is the curried version of MonadMapTo.
+//
 //go:inline
 func MapTo[R, C, E, A, B any](b B) Operator[R, C, E, A, B] {
 	return reader.Map[R](RIOE.MapTo[C, E, A](b))
 }
 
+// MonadChain sequences two computations where the second depends on the result of the first.
+//
 //go:inline
 func MonadChain[R, C, E, A, B any](fa ReaderReaderIOEither[R, C, E, A], f Kleisli[R, C, E, A, B]) ReaderReaderIOEither[R, C, E, B] {
 	return readert.MonadChain(
@@ -92,6 +116,9 @@ func MonadChain[R, C, E, A, B any](fa ReaderReaderIOEither[R, C, E, A], f Kleisl
 	)
 }
 
+// MonadChainFirst sequences two computations but keeps the result of the first.
+// Useful for performing side effects while preserving the original value.
+//
 //go:inline
 func MonadChainFirst[R, C, E, A, B any](fa ReaderReaderIOEither[R, C, E, A], f Kleisli[R, C, E, A, B]) ReaderReaderIOEither[R, C, E, A] {
 	return chain.MonadChainFirst(
@@ -101,11 +128,15 @@ func MonadChainFirst[R, C, E, A, B any](fa ReaderReaderIOEither[R, C, E, A], f K
 		f)
 }
 
+// MonadTap is an alias for MonadChainFirst, executing a side effect while preserving the original value.
+//
 //go:inline
 func MonadTap[R, C, E, A, B any](fa ReaderReaderIOEither[R, C, E, A], f Kleisli[R, C, E, A, B]) ReaderReaderIOEither[R, C, E, A] {
 	return MonadChainFirst(fa, f)
 }
 
+// MonadChainEitherK chains a computation that returns an Either into a ReaderReaderIOEither.
+//
 //go:inline
 func MonadChainEitherK[R, C, E, A, B any](ma ReaderReaderIOEither[R, C, E, A], f either.Kleisli[E, A, B]) ReaderReaderIOEither[R, C, E, B] {
 	return fromeither.MonadChainEitherK(
@@ -116,6 +147,9 @@ func MonadChainEitherK[R, C, E, A, B any](ma ReaderReaderIOEither[R, C, E, A], f
 	)
 }
 
+// ChainEitherK returns a function that chains an Either-returning function into ReaderReaderIOEither.
+// This is the curried version of MonadChainEitherK.
+//
 //go:inline
 func ChainEitherK[R, C, E, A, B any](f either.Kleisli[E, A, B]) Operator[R, C, E, A, B] {
 	return fromeither.ChainEitherK(
@@ -125,6 +159,8 @@ func ChainEitherK[R, C, E, A, B any](f either.Kleisli[E, A, B]) Operator[R, C, E
 	)
 }
 
+// MonadChainFirstEitherK chains an Either-returning computation but keeps the original value.
+//
 //go:inline
 func MonadChainFirstEitherK[R, C, E, A, B any](ma ReaderReaderIOEither[R, C, E, A], f either.Kleisli[E, A, B]) ReaderReaderIOEither[R, C, E, A] {
 	return fromeither.MonadChainFirstEitherK(
@@ -136,11 +172,16 @@ func MonadChainFirstEitherK[R, C, E, A, B any](ma ReaderReaderIOEither[R, C, E,
 	)
 }
 
+// MonadTapEitherK is an alias for MonadChainFirstEitherK, executing an Either side effect while preserving the original value.
+//
 //go:inline
 func MonadTapEitherK[R, C, E, A, B any](ma ReaderReaderIOEither[R, C, E, A], f either.Kleisli[E, A, B]) ReaderReaderIOEither[R, C, E, A] {
 	return MonadChainFirstEitherK(ma, f)
 }
 
+// ChainFirstEitherK returns a function that chains an Either computation while preserving the original value.
+// This is the curried version of MonadChainFirstEitherK.
+//
 //go:inline
 func ChainFirstEitherK[R, C, E, A, B any](f either.Kleisli[E, A, B]) Operator[R, C, E, A, A] {
 	return fromeither.ChainFirstEitherK(
@@ -151,11 +192,15 @@ func ChainFirstEitherK[R, C, E, A, B any](f either.Kleisli[E, A, B]) Operator[R,
 	)
 }
 
+// TapEitherK is an alias for ChainFirstEitherK, executing an Either side effect while preserving the original value.
+//
 //go:inline
 func TapEitherK[R, C, E, A, B any](f either.Kleisli[E, A, B]) Operator[R, C, E, A, A] {
 	return ChainFirstEitherK[R, C](f)
 }
 
+// MonadChainReaderK chains a Reader-returning computation into a ReaderReaderIOEither.
+//
 //go:inline
 func MonadChainReaderK[C, E, R, A, B any](ma ReaderReaderIOEither[R, C, E, A], f reader.Kleisli[R, A, B]) ReaderReaderIOEither[R, C, E, B] {
 	return fromreader.MonadChainReaderK(
@@ -166,6 +211,9 @@ func MonadChainReaderK[C, E, R, A, B any](ma ReaderReaderIOEither[R, C, E, A], f
 	)
 }
 
+// ChainReaderK returns a function that chains a Reader-returning function into ReaderReaderIOEither.
+// This is the curried version of MonadChainReaderK.
+//
 //go:inline
 func ChainReaderK[C, E, R, A, B any](f reader.Kleisli[R, A, B]) Operator[R, C, E, A, B] {
 	return fromreader.ChainReaderK(
@@ -175,6 +223,8 @@ func ChainReaderK[C, E, R, A, B any](f reader.Kleisli[R, A, B]) Operator[R, C, E
 	)
 }
 
+// MonadChainFirstReaderK chains a Reader computation but keeps the original value.
+//
 //go:inline
 func MonadChainFirstReaderK[C, E, R, A, B any](ma ReaderReaderIOEither[R, C, E, A], f reader.Kleisli[R, A, B]) ReaderReaderIOEither[R, C, E, A] {
 	return fromreader.MonadChainFirstReaderK(
@@ -185,11 +235,16 @@ func MonadChainFirstReaderK[C, E, R, A, B any](ma ReaderReaderIOEither[R, C, E,
 	)
 }
 
+// MonadTapReaderK is an alias for MonadChainFirstReaderK, executing a Reader side effect while preserving the original value.
+//
 //go:inline
 func MonadTapReaderK[C, E, R, A, B any](ma ReaderReaderIOEither[R, C, E, A], f reader.Kleisli[R, A, B]) ReaderReaderIOEither[R, C, E, A] {
 	return MonadChainFirstReaderK(ma, f)
 }
 
+// ChainFirstReaderK returns a function that chains a Reader computation while preserving the original value.
+// This is the curried version of MonadChainFirstReaderK.
+//
 //go:inline
 func ChainFirstReaderK[C, E, R, A, B any](f reader.Kleisli[R, A, B]) Operator[R, C, E, A, A] {
 	return fromreader.ChainFirstReaderK(
@@ -199,11 +254,15 @@ func ChainFirstReaderK[C, E, R, A, B any](f reader.Kleisli[R, A, B]) Operator[R,
 	)
 }
 
+// TapReaderK is an alias for ChainFirstReaderK, executing a Reader side effect while preserving the original value.
+//
 //go:inline
 func TapReaderK[C, E, R, A, B any](f reader.Kleisli[R, A, B]) Operator[R, C, E, A, A] {
 	return ChainFirstReaderK[C, E](f)
 }
 
+// MonadChainReaderIOK chains a ReaderIO-returning computation into a ReaderReaderIOEither.
+//
 //go:inline
 func MonadChainReaderIOK[C, E, R, A, B any](ma ReaderReaderIOEither[R, C, E, A], f readerio.Kleisli[R, A, B]) ReaderReaderIOEither[R, C, E, B] {
 	return fromreader.MonadChainReaderK(
@@ -214,6 +273,9 @@ func MonadChainReaderIOK[C, E, R, A, B any](ma ReaderReaderIOEither[R, C, E, A],
 	)
 }
 
+// ChainReaderIOK returns a function that chains a ReaderIO-returning function into ReaderReaderIOEither.
+// This is the curried version of MonadChainReaderIOK.
+//
 //go:inline
 func ChainReaderIOK[C, E, R, A, B any](f readerio.Kleisli[R, A, B]) Operator[R, C, E, A, B] {
 	return fromreader.ChainReaderK(
@@ -223,6 +285,8 @@ func ChainReaderIOK[C, E, R, A, B any](f readerio.Kleisli[R, A, B]) Operator[R,
 	)
 }
 
+// MonadChainFirstReaderIOK chains a ReaderIO computation but keeps the original value.
+//
 //go:inline
 func MonadChainFirstReaderIOK[C, E, R, A, B any](ma ReaderReaderIOEither[R, C, E, A], f readerio.Kleisli[R, A, B]) ReaderReaderIOEither[R, C, E, A] {
 	return fromreader.MonadChainFirstReaderK(
@@ -233,11 +297,16 @@ func MonadChainFirstReaderIOK[C, E, R, A, B any](ma ReaderReaderIOEither[R, C, E
 	)
 }
 
+// MonadTapReaderIOK is an alias for MonadChainFirstReaderIOK, executing a ReaderIO side effect while preserving the original value.
+//
 //go:inline
 func MonadTapReaderIOK[C, E, R, A, B any](ma ReaderReaderIOEither[R, C, E, A], f readerio.Kleisli[R, A, B]) ReaderReaderIOEither[R, C, E, A] {
 	return MonadChainFirstReaderIOK(ma, f)
 }
 
+// ChainFirstReaderIOK returns a function that chains a ReaderIO computation while preserving the original value.
+// This is the curried version of MonadChainFirstReaderIOK.
+//
 //go:inline
 func ChainFirstReaderIOK[C, E, R, A, B any](f readerio.Kleisli[R, A, B]) Operator[R, C, E, A, A] {
 	return fromreader.ChainFirstReaderK(
@@ -247,11 +316,15 @@ func ChainFirstReaderIOK[C, E, R, A, B any](f readerio.Kleisli[R, A, B]) Operato
 	)
 }
 
+// TapReaderIOK is an alias for ChainFirstReaderIOK, executing a ReaderIO side effect while preserving the original value.
+//
 //go:inline
 func TapReaderIOK[C, E, R, A, B any](f readerio.Kleisli[R, A, B]) Operator[R, C, E, A, A] {
 	return ChainFirstReaderIOK[C, E](f)
 }
 
+// MonadChainReaderEitherK chains a ReaderEither-returning computation into a ReaderReaderIOEither.
+//
 //go:inline
 func MonadChainReaderEitherK[R, C, E, A, B any](ma ReaderReaderIOEither[R, C, E, A], f RE.Kleisli[R, E, A, B]) ReaderReaderIOEither[R, C, E, B] {
 	return fromreader.MonadChainReaderK(
@@ -262,6 +335,9 @@ func MonadChainReaderEitherK[R, C, E, A, B any](ma ReaderReaderIOEither[R, C, E,
 	)
 }
 
+// ChainReaderEitherK returns a function that chains a ReaderEither-returning function into ReaderReaderIOEither.
+// This is the curried version of MonadChainReaderEitherK.
+//
 //go:inline
 func ChainReaderEitherK[C, E, R, A, B any](f RE.Kleisli[R, E, A, B]) Operator[R, C, E, A, B] {
 	return fromreader.ChainReaderK(
@@ -271,6 +347,8 @@ func ChainReaderEitherK[C, E, R, A, B any](f RE.Kleisli[R, E, A, B]) Operator[R,
 	)
 }
 
+// ChainReaderIOEitherK returns a function that chains a ReaderIOEither-returning function into ReaderReaderIOEither.
+//
 //go:inline
 func ChainReaderIOEitherK[C, R, E, A, B any](f RIOE.Kleisli[R, E, A, B]) Operator[R, C, E, A, B] {
 	return fromreader.ChainReaderK(
@@ -280,6 +358,8 @@ func ChainReaderIOEitherK[C, R, E, A, B any](f RIOE.Kleisli[R, E, A, B]) Operato
 	)
 }
 
+// MonadChainFirstReaderEitherK chains a ReaderEither computation but keeps the original value.
+//
 //go:inline
 func MonadChainFirstReaderEitherK[R, C, E, A, B any](ma ReaderReaderIOEither[R, C, E, A], f RE.Kleisli[R, E, A, B]) ReaderReaderIOEither[R, C, E, A] {
 	return fromreader.MonadChainFirstReaderK(
@@ -290,11 +370,16 @@ func MonadChainFirstReaderEitherK[R, C, E, A, B any](ma ReaderReaderIOEither[R,
 	)
 }
 
+// MonadTapReaderEitherK is an alias for MonadChainFirstReaderEitherK, executing a ReaderEither side effect while preserving the original value.
+//
 //go:inline
 func MonadTapReaderEitherK[R, C, E, A, B any](ma ReaderReaderIOEither[R, C, E, A], f RE.Kleisli[R, E, A, B]) ReaderReaderIOEither[R, C, E, A] {
 	return MonadChainFirstReaderEitherK(ma, f)
 }
 
+// ChainFirstReaderEitherK returns a function that chains a ReaderEither computation while preserving the original value.
+// This is the curried version of MonadChainFirstReaderEitherK.
+//
 //go:inline
 func ChainFirstReaderEitherK[C, E, R, A, B any](f RE.Kleisli[R, E, A, B]) Operator[R, C, E, A, A] {
 	return fromreader.ChainFirstReaderK(
@@ -304,11 +389,15 @@ func ChainFirstReaderEitherK[C, E, R, A, B any](f RE.Kleisli[R, E, A, B]) Operat
 	)
 }
 
+// TapReaderEitherK is an alias for ChainFirstReaderEitherK, executing a ReaderEither side effect while preserving the original value.
+//
 //go:inline
 func TapReaderEitherK[C, E, R, A, B any](f RE.Kleisli[R, E, A, B]) Operator[R, C, E, A, A] {
 	return ChainFirstReaderEitherK[C](f)
 }
 
+// ChainReaderOptionK returns a function that chains a ReaderOption-returning function into ReaderReaderIOEither.
+// If the ReaderOption is None, the provided error function is called.
 func ChainReaderOptionK[R, C, A, B, E any](onNone Lazy[E]) func(readeroption.Kleisli[R, A, B]) Operator[R, C, E, A, B] {
 
 	fro := FromReaderOption[R, C, B](onNone)
@@ -323,6 +412,8 @@ func ChainReaderOptionK[R, C, A, B, E any](onNone Lazy[E]) func(readeroption.Kle
 	}
 }
 
+// ChainFirstReaderOptionK chains a ReaderOption computation while preserving the original value.
+// If the ReaderOption is None, the provided error function is called.
 func ChainFirstReaderOptionK[R, C, A, B, E any](onNone Lazy[E]) func(readeroption.Kleisli[R, A, B]) Operator[R, C, E, A, A] {
 	fro := FromReaderOption[R, C, B](onNone)
 	return func(f readeroption.Kleisli[R, A, B]) Operator[R, C, E, A, A] {
@@ -334,11 +425,15 @@ func ChainFirstReaderOptionK[R, C, A, B, E any](onNone Lazy[E]) func(readeroptio
 	}
 }
 
+// TapReaderOptionK is an alias for ChainFirstReaderOptionK, executing a ReaderOption side effect while preserving the original value.
+//
 //go:inline
 func TapReaderOptionK[R, C, A, B, E any](onNone Lazy[E]) func(readeroption.Kleisli[R, A, B]) Operator[R, C, E, A, A] {
 	return ChainFirstReaderOptionK[R, C, A, B](onNone)
 }
 
+// MonadChainIOEitherK chains an IOEither-returning computation into a ReaderReaderIOEither.
+//
 //go:inline
 func MonadChainIOEitherK[R, C, E, A, B any](ma ReaderReaderIOEither[R, C, E, A], f IOE.Kleisli[E, A, B]) ReaderReaderIOEither[R, C, E, B] {
 	return fromioeither.MonadChainIOEitherK(
@@ -349,6 +444,9 @@ func MonadChainIOEitherK[R, C, E, A, B any](ma ReaderReaderIOEither[R, C, E, A],
 	)
 }
 
+// ChainIOEitherK returns a function that chains an IOEither-returning function into ReaderReaderIOEither.
+// This is the curried version of MonadChainIOEitherK.
+//
 //go:inline
 func ChainIOEitherK[R, C, E, A, B any](f IOE.Kleisli[E, A, B]) Operator[R, C, E, A, B] {
 	return fromioeither.ChainIOEitherK(
@@ -358,6 +456,8 @@ func ChainIOEitherK[R, C, E, A, B any](f IOE.Kleisli[E, A, B]) Operator[R, C, E,
 	)
 }
 
+// MonadChainIOK chains an IO-returning computation into a ReaderReaderIOEither.
+//
 //go:inline
 func MonadChainIOK[R, C, E, A, B any](ma ReaderReaderIOEither[R, C, E, A], f io.Kleisli[A, B]) ReaderReaderIOEither[R, C, E, B] {
 	return fromio.MonadChainIOK(
@@ -368,6 +468,9 @@ func MonadChainIOK[R, C, E, A, B any](ma ReaderReaderIOEither[R, C, E, A], f io.
 	)
 }
 
+// ChainIOK returns a function that chains an IO-returning function into ReaderReaderIOEither.
+// This is the curried version of MonadChainIOK.
+//
 //go:inline
 func ChainIOK[R, C, E, A, B any](f io.Kleisli[A, B]) Operator[R, C, E, A, B] {
 	return fromio.ChainIOK(
@@ -377,6 +480,8 @@ func ChainIOK[R, C, E, A, B any](f io.Kleisli[A, B]) Operator[R, C, E, A, B] {
 	)
 }
 
+// MonadChainFirstIOK chains an IO computation but keeps the original value.
+//
 //go:inline
 func MonadChainFirstIOK[R, C, E, A, B any](ma ReaderReaderIOEither[R, C, E, A], f io.Kleisli[A, B]) ReaderReaderIOEither[R, C, E, A] {
 	return fromio.MonadChainFirstIOK(
@@ -388,11 +493,16 @@ func MonadChainFirstIOK[R, C, E, A, B any](ma ReaderReaderIOEither[R, C, E, A],
 	)
 }
 
+// MonadTapIOK is an alias for MonadChainFirstIOK, executing an IO side effect while preserving the original value.
+//
 //go:inline
 func MonadTapIOK[R, C, E, A, B any](ma ReaderReaderIOEither[R, C, E, A], f io.Kleisli[A, B]) ReaderReaderIOEither[R, C, E, A] {
 	return MonadChainFirstIOK(ma, f)
 }
 
+// ChainFirstIOK returns a function that chains an IO computation while preserving the original value.
+// This is the curried version of MonadChainFirstIOK.
+//
 //go:inline
 func ChainFirstIOK[R, C, E, A, B any](f io.Kleisli[A, B]) Operator[R, C, E, A, A] {
 	return fromio.ChainFirstIOK(
@@ -403,11 +513,16 @@ func ChainFirstIOK[R, C, E, A, B any](f io.Kleisli[A, B]) Operator[R, C, E, A, A
 	)
 }
 
+// TapIOK is an alias for ChainFirstIOK, executing an IO side effect while preserving the original value.
+//
 //go:inline
 func TapIOK[R, C, E, A, B any](f io.Kleisli[A, B]) Operator[R, C, E, A, A] {
 	return ChainFirstIOK[R, C, E](f)
 }
 
+// ChainOptionK returns a function that chains an Option-returning function into ReaderReaderIOEither.
+// If the Option is None, the provided error function is called.
+//
 //go:inline
 func ChainOptionK[R, C, A, B, E any](onNone Lazy[E]) func(option.Kleisli[A, B]) Operator[R, C, E, A, B] {
 	return fromeither.ChainOptionK(
@@ -417,6 +532,8 @@ func ChainOptionK[R, C, A, B, E any](onNone Lazy[E]) func(option.Kleisli[A, B])
 	)
 }
 
+// MonadAp applies a function wrapped in a context to a value wrapped in a context.
+//
 //go:inline
 func MonadAp[R, C, E, A, B any](fab ReaderReaderIOEither[R, C, E, func(A) B], fa ReaderReaderIOEither[R, C, E, A]) ReaderReaderIOEither[R, C, E, B] {
 	return readert.MonadAp[
@@ -429,6 +546,8 @@ func MonadAp[R, C, E, A, B any](fab ReaderReaderIOEither[R, C, E, func(A) B], fa
 	)
 }
 
+// MonadApSeq applies a function in a context to a value in a context, executing them sequentially.
+//
 //go:inline
 func MonadApSeq[R, C, E, A, B any](fab ReaderReaderIOEither[R, C, E, func(A) B], fa ReaderReaderIOEither[R, C, E, A]) ReaderReaderIOEither[R, C, E, B] {
 	return readert.MonadAp[
@@ -441,6 +560,8 @@ func MonadApSeq[R, C, E, A, B any](fab ReaderReaderIOEither[R, C, E, func(A) B],
 	)
 }
 
+// MonadApPar applies a function in a context to a value in a context, executing them in parallel.
+//
 //go:inline
 func MonadApPar[R, C, E, A, B any](fab ReaderReaderIOEither[R, C, E, func(A) B], fa ReaderReaderIOEither[R, C, E, A]) ReaderReaderIOEither[R, C, E, B] {
 	return readert.MonadAp[
@@ -453,6 +574,9 @@ func MonadApPar[R, C, E, A, B any](fab ReaderReaderIOEither[R, C, E, func(A) B],
 	)
 }
 
+// Ap returns a function that applies a function in a context to a value in a context.
+// This is the curried version of MonadAp.
+//
 //go:inline
 func Ap[B, R, C, E, A any](fa ReaderReaderIOEither[R, C, E, A]) Operator[R, C, E, func(A) B, B] {
 	return readert.Ap[
@@ -464,6 +588,9 @@ func Ap[B, R, C, E, A any](fa ReaderReaderIOEither[R, C, E, A]) Operator[R, C, E
 	)
 }
 
+// Chain returns a function that sequences computations where the second depends on the first.
+// This is the curried version of MonadChain.
+//
 //go:inline
 func Chain[R, C, E, A, B any](f Kleisli[R, C, E, A, B]) Operator[R, C, E, A, B] {
 	return readert.Chain[ReaderReaderIOEither[R, C, E, A]](
@@ -472,6 +599,9 @@ func Chain[R, C, E, A, B any](f Kleisli[R, C, E, A, B]) Operator[R, C, E, A, B]
 	)
 }
 
+// ChainFirst returns a function that sequences computations but keeps the first result.
+// This is the curried version of MonadChainFirst.
+//
 //go:inline
 func ChainFirst[R, C, E, A, B any](f Kleisli[R, C, E, A, B]) Operator[R, C, E, A, A] {
 	return chain.ChainFirst(
@@ -480,96 +610,137 @@ func ChainFirst[R, C, E, A, B any](f Kleisli[R, C, E, A, B]) Operator[R, C, E, A
 		f)
 }
 
+// Tap is an alias for ChainFirst, executing a side effect while preserving the original value.
+//
 //go:inline
 func Tap[R, C, E, A, B any](f Kleisli[R, C, E, A, B]) Operator[R, C, E, A, A] {
 	return ChainFirst(f)
 }
 
+// Right creates a successful ReaderReaderIOEither with the given value.
+//
 //go:inline
 func Right[R, C, E, A any](a A) ReaderReaderIOEither[R, C, E, A] {
 	return reader.Of[R](RIOE.Right[C, E](a))
 }
 
+// Left creates a failed ReaderReaderIOEither with the given error.
+//
 //go:inline
 func Left[R, C, A, E any](e E) ReaderReaderIOEither[R, C, E, A] {
 	return reader.Of[R](RIOE.Left[C, A](e))
 }
 
+// Of creates a successful ReaderReaderIOEither with the given value.
+// This is the pointed functor operation.
+//
 //go:inline
 func Of[R, C, E, A any](a A) ReaderReaderIOEither[R, C, E, A] {
 	return Right[R, C, E](a)
 }
 
+// Flatten removes one level of nesting from a nested ReaderReaderIOEither.
+//
 //go:inline
 func Flatten[R, C, E, A any](mma ReaderReaderIOEither[R, C, E, ReaderReaderIOEither[R, C, E, A]]) ReaderReaderIOEither[R, C, E, A] {
 	return MonadChain(mma, function.Identity[ReaderReaderIOEither[R, C, E, A]])
 }
 
+// FromEither lifts an Either into a ReaderReaderIOEither context.
+//
 //go:inline
 func FromEither[R, C, E, A any](t Either[E, A]) ReaderReaderIOEither[R, C, E, A] {
 	return reader.Of[R](RIOE.FromEither[C](t))
 }
 
+// RightReader lifts a Reader into a ReaderReaderIOEither, placing the result in the Right side.
+//
 //go:inline
 func RightReader[C, E, R, A any](ma Reader[R, A]) ReaderReaderIOEither[R, C, E, A] {
 	return reader.MonadMap(ma, RIOE.Right[C, E])
 }
 
+// LeftReader lifts a Reader into a ReaderReaderIOEither, placing the result in the Left (error) side.
+//
 //go:inline
 func LeftReader[C, A, R, E any](ma Reader[R, E]) ReaderReaderIOEither[R, C, E, A] {
 	return reader.MonadMap(ma, RIOE.Left[C, A])
 }
 
+// FromReader lifts a Reader into a ReaderReaderIOEither context.
+//
 //go:inline
 func FromReader[C, E, R, A any](ma Reader[R, A]) ReaderReaderIOEither[R, C, E, A] {
 	return RightReader[C, E](ma)
 }
 
+// RightIO lifts an IO into a ReaderReaderIOEither, placing the result in the Right side.
+//
 //go:inline
 func RightIO[R, C, E, A any](ma IO[A]) ReaderReaderIOEither[R, C, E, A] {
 	return reader.Of[R](RIOE.RightIO[C, E](ma))
 }
 
+// LeftIO lifts an IO into a ReaderReaderIOEither, placing the result in the Left (error) side.
+//
 //go:inline
 func LeftIO[R, C, A, E any](ma IO[E]) ReaderReaderIOEither[R, C, E, A] {
 	return reader.Of[R](RIOE.LeftIO[C, A](ma))
 }
 
+// FromIO lifts an IO into a ReaderReaderIOEither context.
+//
 //go:inline
 func FromIO[R, C, E, A any](ma IO[A]) ReaderReaderIOEither[R, C, E, A] {
 	return RightIO[R, C, E](ma)
 }
 
+// FromIOEither lifts an IOEither into a ReaderReaderIOEither context.
+//
 //go:inline
 func FromIOEither[R, C, E, A any](ma IOEither[E, A]) ReaderReaderIOEither[R, C, E, A] {
 	return reader.Of[R](RIOE.FromIOEither[C](ma))
 }
 
+// FromReaderEither lifts a ReaderEither into a ReaderReaderIOEither context.
+//
 //go:inline
 func FromReaderEither[R, C, E, A any](ma RE.ReaderEither[R, E, A]) ReaderReaderIOEither[R, C, E, A] {
 	return reader.MonadMap(ma, RIOE.FromEither[C])
 }
 
+// Ask returns a ReaderReaderIOEither that retrieves the outer context.
+//
 //go:inline
 func Ask[R, C, E any]() ReaderReaderIOEither[R, C, E, R] {
 	return fromreader.Ask(FromReader[C, E, R, R])()
 }
 
+// Asks returns a ReaderReaderIOEither that retrieves a value derived from the outer context.
+//
 //go:inline
 func Asks[C, E, R, A any](r Reader[R, A]) ReaderReaderIOEither[R, C, E, A] {
 	return fromreader.Asks(FromReader[C, E, R, A])(r)
 }
 
+// FromOption converts an Option to a ReaderReaderIOEither.
+// If the Option is None, the provided function is called to produce the error.
+//
 //go:inline
 func FromOption[R, C, A, E any](onNone Lazy[E]) func(Option[A]) ReaderReaderIOEither[R, C, E, A] {
 	return fromeither.FromOption(FromEither[R, C, E, A], onNone)
 }
 
+// FromPredicate creates a ReaderReaderIOEither from a predicate.
+// If the predicate returns false, the onFalse function is called to produce the error.
+//
 //go:inline
 func FromPredicate[R, C, E, A any](pred func(A) bool, onFalse func(A) E) func(A) ReaderReaderIOEither[R, C, E, A] {
 	return fromeither.FromPredicate(FromEither[R, C, E, A], pred, onFalse)
 }
 
+// MonadAlt tries the first computation, and if it fails, tries the second.
+//
 //go:inline
 func MonadAlt[R, C, E, A any](first ReaderReaderIOEither[R, C, E, A], second Lazy[ReaderReaderIOEither[R, C, E, A]]) ReaderReaderIOEither[R, C, E, A] {
 	return func(r R) ReaderIOEither[C, E, A] {
@@ -579,36 +750,53 @@ func MonadAlt[R, C, E, A any](first ReaderReaderIOEither[R, C, E, A], second Laz
 	}
 }
 
+// Alt returns a function that tries an alternative computation if the first fails.
+// This is the curried version of MonadAlt.
+//
 //go:inline
 func Alt[R, C, E, A any](second Lazy[ReaderReaderIOEither[R, C, E, A]]) Operator[R, C, E, A, A] {
 	return function.Bind2nd(MonadAlt, second)
 }
 
+// MonadFlap applies a value to a function wrapped in a context.
+//
 //go:inline
 func MonadFlap[R, C, E, B, A any](fab ReaderReaderIOEither[R, C, E, func(A) B], a A) ReaderReaderIOEither[R, C, E, B] {
 	return functor.MonadFlap(MonadMap[R, C, E, func(A) B, B], fab, a)
 }
 
+// Flap returns a function that applies a fixed value to a function in a context.
+// This is the curried version of MonadFlap.
+//
 //go:inline
 func Flap[R, C, E, B, A any](a A) Operator[R, C, E, func(A) B, B] {
 	return functor.Flap(Map[R, C, E, func(A) B, B], a)
 }
 
+// MonadMapLeft applies a function to the error value, leaving success unchanged.
+//
 //go:inline
 func MonadMapLeft[R, C, E1, E2, A any](fa ReaderReaderIOEither[R, C, E1, A], f func(E1) E2) ReaderReaderIOEither[R, C, E2, A] {
 	return reader.MonadMap(fa, RIOE.MapLeft[C, A](f))
 }
 
+// MapLeft returns a function that transforms the error channel.
+// This is the curried version of MonadMapLeft.
+//
 //go:inline
 func MapLeft[R, C, A, E1, E2 any](f func(E1) E2) func(ReaderReaderIOEither[R, C, E1, A]) ReaderReaderIOEither[R, C, E2, A] {
 	return reader.Map[R](RIOE.MapLeft[C, A](f))
 }
 
+// Read executes a ReaderReaderIOEither by providing a concrete outer environment value.
+//
 //go:inline
 func Read[C, E, A, R any](r R) func(ReaderReaderIOEither[R, C, E, A]) ReaderIOEither[C, E, A] {
 	return reader.Read[ReaderIOEither[C, E, A]](r)
 }
 
+// ReadIOEither executes a ReaderReaderIOEither by providing an outer environment obtained from an IOEither.
+//
 //go:inline
 func ReadIOEither[A, R, C, E any](rio IOEither[E, R]) func(ReaderReaderIOEither[R, C, E, A]) ReaderIOEither[C, E, A] {
 	return func(rri ReaderReaderIOEither[R, C, E, A]) ReaderIOEither[C, E, A] {
@@ -623,6 +811,8 @@ func ReadIOEither[A, R, C, E any](rio IOEither[E, R]) func(ReaderReaderIOEither[
 	}
 }
 
+// ReadIO executes a ReaderReaderIOEither by providing an outer environment obtained from an IO.
+//
 //go:inline
 func ReadIO[C, E, A, R any](rio IO[R]) func(ReaderReaderIOEither[R, C, E, A]) ReaderIOEither[C, E, A] {
 	return func(rri ReaderReaderIOEither[R, C, E, A]) ReaderIOEither[C, E, A] {
@@ -637,6 +827,8 @@ func ReadIO[C, E, A, R any](rio IO[R]) func(ReaderReaderIOEither[R, C, E, A]) Re
 	}
 }
 
+// MonadChainLeft chains a computation on the error channel, allowing error recovery or transformation.
+//
 //go:inline
 func MonadChainLeft[R, C, EA, EB, A any](fa ReaderReaderIOEither[R, C, EA, A], f Kleisli[R, C, EB, EA, A]) ReaderReaderIOEither[R, C, EB, A] {
 	return readert.MonadChain(
@@ -646,6 +838,9 @@ func MonadChainLeft[R, C, EA, EB, A any](fa ReaderReaderIOEither[R, C, EA, A], f
 	)
 }
 
+// ChainLeft returns a function that chains a computation on the error channel.
+// This is the curried version of MonadChainLeft.
+//
 //go:inline
 func ChainLeft[R, C, EA, EB, A any](f Kleisli[R, C, EB, EA, A]) func(ReaderReaderIOEither[R, C, EA, A]) ReaderReaderIOEither[R, C, EB, A] {
 	return readert.Chain[ReaderReaderIOEither[R, C, EA, A]](
@@ -654,16 +849,22 @@ func ChainLeft[R, C, EA, EB, A any](f Kleisli[R, C, EB, EA, A]) func(ReaderReade
 	)
 }
 
+// Delay creates an operation that passes in the value after some delay.
+//
 //go:inline
 func Delay[R, C, E, A any](delay time.Duration) Operator[R, C, E, A, A] {
 	return reader.Map[R](RIOE.Delay[C, E, A](delay))
 }
 
+// After creates an operation that passes after the given time.Time.
+//
 //go:inline
 func After[R, C, E, A any](timestamp time.Time) Operator[R, C, E, A, A] {
 	return reader.Map[R](RIOE.After[C, E, A](timestamp))
 }
 
+// Defer creates a ReaderReaderIOEither lazily via a generator function.
+// The generator is called each time the ReaderReaderIOEither is executed.
 func Defer[R, C, E, A any](fa Lazy[ReaderReaderIOEither[R, C, E, A]]) ReaderReaderIOEither[R, C, E, A] {
 	return func(r R) ReaderIOEither[C, E, A] {
 		return func(c C) RIOE.IOEither[E, A] {