Merge pull request #25 from IBM/cleue-fix-build-break-1

fix: build break

.github/workflows/build.yml

@@ -17,22 +17,25 @@ on:
 env:
   # Currently no way to detect automatically
   DEFAULT_BRANCH: main
-  GO_VERSION: 1.20.5 # renovate: datasource=golang-version depName=golang
+  GO_VERSION: 1.20.6 # renovate: datasource=golang-version depName=golang
   NODE_VERSION: 18
   DRY_RUN: true
 
 jobs:
   build:
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        go-version: [ '1.20.x', '1.21.x' ]
     steps:
       # full checkout for semantic-release
       - uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # v3.5.3
         with:
           fetch-depth: 0
-      - name: Set up go ${{env.GO_VERSION}}
+      - name: Set up go ${{ matrix.go-version }}
         uses: actions/setup-go@v4
         with:
-          go-version: ${{env.GO_VERSION}}
+          go-version: ${{ matrix.go-version }}
       -
         name: Tests
         run: |

array/array.go

@@ -108,10 +108,16 @@ func MonadFilterMap[A, B any](fa []A, f func(a A) O.Option[B]) []B {
 	return G.MonadFilterMap[[]A, []B](fa, f)
 }
 
+// FilterChain maps an array with an iterating function that returns an [O.Option] and it keeps only the Some values discarding the Nones.
 func FilterMap[A, B any](f func(a A) O.Option[B]) func([]A) []B {
 	return G.FilterMap[[]A, []B](f)
 }
 
+// FilterChain maps an array with an iterating function that returns an [O.Option] of an array. It keeps only the Some values discarding the Nones and then flattens the result.
+func FilterChain[A, B any](f func(A) O.Option[[]B]) func([]A) []B {
+	return G.FilterChain[[]A](f)
+}
+
 func FilterMapRef[A, B any](pred func(a *A) bool, f func(a *A) B) func([]A) []B {
 	return func(fa []A) []B {
 		return filterMapRef(fa, pred, f)
@@ -237,7 +243,7 @@ func Intercalate[A any](m M.Monoid[A]) func(A) func([]A) A {
 }
 
 func Flatten[A any](mma [][]A) []A {
-	return MonadChain(mma, F.Identity[[]A])
+	return G.Flatten(mma)
 }
 
 func Slice[A any](low, high int) func(as []A) []A {
@@ -288,3 +294,13 @@ func SliceRight[A any](start int) func([]A) []A {
 func Copy[A any](b []A) []A {
 	return G.Copy(b)
 }
+
+// FoldMap maps and folds an array. Map the Array passing each value to the iterating function. Then fold the results using the provided Monoid.
+func FoldMap[A, B any](m M.Monoid[B]) func(func(A) B) func([]A) B {
+	return G.FoldMap[[]A](m)
+}
+
+// Fold folds the array using the provided Monoid.
+func Fold[A any](m M.Monoid[A]) func([]A) A {
+	return G.Fold[[]A](m)
+}

array/array_test.go

@@ -16,6 +16,7 @@
 package array
 
 import (
+	"fmt"
 	"strings"
 	"testing"
 
@@ -142,3 +143,52 @@ func TestPartition(t *testing.T) {
 	assert.Equal(t, T.MakeTuple2(Empty[int](), Empty[int]()), Partition(pred)(Empty[int]()))
 	assert.Equal(t, T.MakeTuple2(From(1), From(3)), Partition(pred)(From(1, 3)))
 }
+
+func TestFilterChain(t *testing.T) {
+	src := From(1, 2, 3)
+
+	f := func(i int) O.Option[[]string] {
+		if i%2 != 0 {
+			return O.Of(From(fmt.Sprintf("a%d", i), fmt.Sprintf("b%d", i)))
+		}
+		return O.None[[]string]()
+	}
+
+	res := FilterChain(f)(src)
+
+	assert.Equal(t, From("a1", "b1", "a3", "b3"), res)
+}
+
+func TestFilterMap(t *testing.T) {
+	src := From(1, 2, 3)
+
+	f := func(i int) O.Option[string] {
+		if i%2 != 0 {
+			return O.Of(fmt.Sprintf("a%d", i))
+		}
+		return O.None[string]()
+	}
+
+	res := FilterMap(f)(src)
+
+	assert.Equal(t, From("a1", "a3"), res)
+}
+
+func TestFoldMap(t *testing.T) {
+	src := From("a", "b", "c")
+
+	fold := FoldMap[string](S.Monoid)(strings.ToUpper)
+
+	assert.Equal(t, "ABC", fold(src))
+}
+
+func ExampleFoldMap() {
+	src := From("a", "b", "c")
+
+	fold := FoldMap[string](S.Monoid)(strings.ToUpper)
+
+	fmt.Println(fold(src))
+
+	// Output: ABC
+
+}

array/generic/array.go

@@ -18,6 +18,7 @@ package generic
 import (
 	F "github.com/IBM/fp-go/function"
 	"github.com/IBM/fp-go/internal/array"
+	M "github.com/IBM/fp-go/monoid"
 	O "github.com/IBM/fp-go/option"
 	"github.com/IBM/fp-go/tuple"
 )
@@ -118,6 +119,17 @@ func MonadFilterMap[GA ~[]A, GB ~[]B, A, B any](fa GA, f func(a A) O.Option[B])
 	return filterMap[GA, GB](fa, f)
 }
 
+func FilterChain[GA ~[]A, GB ~[]B, A, B any](f func(a A) O.Option[GB]) func(GA) GB {
+	return F.Flow2(
+		FilterMap[GA, []GB](f),
+		Flatten[[]GB],
+	)
+}
+
+func Flatten[GAA ~[]GA, GA ~[]A, A any](mma GAA) GA {
+	return MonadChain(mma, F.Identity[GA])
+}
+
 func FilterMap[GA ~[]A, GB ~[]B, A, B any](f func(a A) O.Option[B]) func(GA) GB {
 	return F.Bind2nd(MonadFilterMap[GA, GB, A, B], f)
 }
@@ -198,3 +210,19 @@ func Copy[AS ~[]A, A any](b AS) AS {
 	copy(buf, b)
 	return buf
 }
+
+func FoldMap[AS ~[]A, A, B any](m M.Monoid[B]) func(func(A) B) func(AS) B {
+	return func(f func(A) B) func(AS) B {
+		return func(as AS) B {
+			return array.Reduce(as, func(cur B, a A) B {
+				return m.Concat(cur, f(a))
+			}, m.Empty())
+		}
+	}
+}
+
+func Fold[AS ~[]A, A any](m M.Monoid[A]) func(AS) A {
+	return func(as AS) A {
+		return array.Reduce(as, m.Concat, m.Empty())
+	}
+}

array/generic/sort.go

@@ -18,11 +18,17 @@ package generic
 import (
 	"sort"
 
+	F "github.com/IBM/fp-go/function"
 	O "github.com/IBM/fp-go/ord"
 )
 
 // Sort implements a stable sort on the array given the provided ordering
 func Sort[GA ~[]T, T any](ord O.Ord[T]) func(ma GA) GA {
+	return SortByKey[GA](ord, F.Identity[T])
+}
+
+// SortByKey implements a stable sort on the array given the provided ordering on an extracted key
+func SortByKey[GA ~[]T, K, T any](ord O.Ord[K], f func(T) K) func(ma GA) GA {
 
 	return func(ma GA) GA {
 		// nothing to sort
@@ -34,7 +40,7 @@ func Sort[GA ~[]T, T any](ord O.Ord[T]) func(ma GA) GA {
 		cpy := make(GA, l)
 		copy(cpy, ma)
 		sort.Slice(cpy, func(i, j int) bool {
-			return ord.Compare(cpy[i], cpy[j]) < 0
+			return ord.Compare(f(cpy[i]), f(cpy[j])) < 0
 		})
 		return cpy
 	}

array/sort.go

@@ -24,3 +24,8 @@ import (
 func Sort[T any](ord O.Ord[T]) func(ma []T) []T {
 	return G.Sort[[]T](ord)
 }
+
+// SortByKey implements a stable sort on the array given the provided ordering on an extracted key
+func SortByKey[K, T any](ord O.Ord[K], f func(T) K) func(ma []T) []T {
+	return G.SortByKey[[]T](ord, f)
+}

cli/apply.go

@@ -388,7 +388,7 @@ func generateApplyHelpers(filename string, count int) error {
 	// some header
 	fmt.Fprintln(f, "// Code generated by go generate; DO NOT EDIT.")
 	fmt.Fprintln(f, "// This file was generated by robots at")
-	fmt.Fprintf(f, "// %s\n", time.Now())
+	fmt.Fprintf(f, "// %s\n\n", time.Now())
 
 	fmt.Fprintf(f, "package %s\n\n", pkg)
 

cli/bind.go

@@ -266,7 +266,7 @@ func generateBindHelpers(filename string, count int) error {
 	// some header
 	fmt.Fprintln(f, "// Code generated by go generate; DO NOT EDIT.")
 	fmt.Fprintln(f, "// This file was generated by robots at")
-	fmt.Fprintf(f, "// %s\n", time.Now())
+	fmt.Fprintf(f, "// %s\n\n", time.Now())
 
 	fmt.Fprintf(f, "package %s\n", pkg)
 

cli/either.go

@@ -150,7 +150,7 @@ func generateEitherHelpers(filename string, count int) error {
 	// some header
 	fmt.Fprintln(f, "// Code generated by go generate; DO NOT EDIT.")
 	fmt.Fprintln(f, "// This file was generated by robots at")
-	fmt.Fprintf(f, "// %s\n", time.Now())
+	fmt.Fprintf(f, "// %s\n\n", time.Now())
 
 	fmt.Fprintf(f, "package %s\n\n", pkg)
 

cli/header.go

@@ -27,5 +27,5 @@ func writePackage(f *os.File, pkg string) {
 	// some header
 	fmt.Fprintln(f, "// Code generated by go generate; DO NOT EDIT.")
 	fmt.Fprintln(f, "// This file was generated by robots at")
-	fmt.Fprintf(f, "// %s\n", time.Now())
+	fmt.Fprintf(f, "// %s\n\n", time.Now())
 }

cli/identity.go

@@ -62,7 +62,7 @@ func generateIdentityHelpers(filename string, count int) error {
 	// some header
 	fmt.Fprintln(f, "// Code generated by go generate; DO NOT EDIT.")
 	fmt.Fprintln(f, "// This file was generated by robots at")
-	fmt.Fprintf(f, "// %s\n", time.Now())
+	fmt.Fprintf(f, "// %s\n\n", time.Now())
 
 	fmt.Fprintf(f, "package %s\n\n", pkg)
 

cli/io.go

@@ -81,7 +81,7 @@ func generateIOHelpers(filename string, count int) error {
 	// some header
 	fmt.Fprintln(f, "// Code generated by go generate; DO NOT EDIT.")
 	fmt.Fprintln(f, "// This file was generated by robots at")
-	fmt.Fprintf(f, "// %s\n", time.Now())
+	fmt.Fprintf(f, "// %s\n\n", time.Now())
 
 	fmt.Fprintf(f, "package %s\n\n", pkg)
 

cli/ioeither.go

@@ -217,7 +217,7 @@ func generateIOEitherHelpers(filename string, count int) error {
 	// some header
 	fmt.Fprintln(f, "// Code generated by go generate; DO NOT EDIT.")
 	fmt.Fprintln(f, "// This file was generated by robots at")
-	fmt.Fprintf(f, "// %s\n", time.Now())
+	fmt.Fprintf(f, "// %s\n\n", time.Now())
 
 	fmt.Fprintf(f, "package %s\n\n", pkg)
 

cli/iooption.go

@@ -81,7 +81,7 @@ func generateIOOptionHelpers(filename string, count int) error {
 	// some header
 	fmt.Fprintln(f, "// Code generated by go generate; DO NOT EDIT.")
 	fmt.Fprintln(f, "// This file was generated by robots at")
-	fmt.Fprintf(f, "// %s\n", time.Now())
+	fmt.Fprintf(f, "// %s\n\n", time.Now())
 
 	fmt.Fprintf(f, "package %s\n\n", pkg)
 

cli/option.go

@@ -148,7 +148,7 @@ func generateOptionHelpers(filename string, count int) error {
 	// some header
 	fmt.Fprintln(f, "// Code generated by go generate; DO NOT EDIT.")
 	fmt.Fprintln(f, "// This file was generated by robots at")
-	fmt.Fprintf(f, "// %s\n", time.Now())
+	fmt.Fprintf(f, "// %s\n\n", time.Now())
 
 	fmt.Fprintf(f, "package %s\n\n", pkg)
 

cli/pipe.go

@@ -337,7 +337,7 @@ func generatePipeHelpers(filename string, count int) error {
 	// some header
 	fmt.Fprintln(f, "// Code generated by go generate; DO NOT EDIT.")
 	fmt.Fprintln(f, "// This file was generated by robots at")
-	fmt.Fprintf(f, "// %s\n", time.Now())
+	fmt.Fprintf(f, "// %s\n\n", time.Now())
 
 	fmt.Fprintf(f, "package %s\n", pkg)
 

cli/reader.go

@@ -12,6 +12,7 @@
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
+
 package cli
 
 import (
@@ -117,7 +118,7 @@ func generateReaderHelpers(filename string, count int) error {
 	// some header
 	fmt.Fprintln(f, "// Code generated by go generate; DO NOT EDIT.")
 	fmt.Fprintln(f, "// This file was generated by robots at")
-	fmt.Fprintf(f, "// %s\n", time.Now())
+	fmt.Fprintf(f, "// %s\n\n", time.Now())
 
 	fmt.Fprintf(f, "package %s\n\n", pkg)
 

cli/readerioeither.go

@@ -169,7 +169,7 @@ func generateReaderIOEitherHelpers(filename string, count int) error {
 	// some header
 	fmt.Fprintln(f, "// Code generated by go generate; DO NOT EDIT.")
 	fmt.Fprintln(f, "// This file was generated by robots at")
-	fmt.Fprintf(f, "// %s\n", time.Now())
+	fmt.Fprintf(f, "// %s\n\n", time.Now())
 
 	fmt.Fprintf(f, "package %s\n\n", pkg)
 

cli/tuple.go

@@ -355,7 +355,7 @@ func generateTupleHelpers(filename string, count int) error {
 	// some header
 	fmt.Fprintln(f, "// Code generated by go generate; DO NOT EDIT.")
 	fmt.Fprintln(f, "// This file was generated by robots at")
-	fmt.Fprintf(f, "// %s\n", time.Now())
+	fmt.Fprintf(f, "// %s\n\n", time.Now())
 
 	fmt.Fprintf(f, "package %s\n\n", pkg)
 

context/readerioeither/gen.go

@@ -1,23 +1,8 @@
-// Copyright (c) 2023 IBM Corp.
-// All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
 package readerioeither
 
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 22:48:20.012425 +0200 CEST m=+0.019517901
+// 2023-08-11 11:37:34.0836986 +0200 CEST m=+0.009764601
 
 import (
 	"context"

context/readerioeither/generic/gen.go

@@ -1,23 +1,8 @@
-// Copyright (c) 2023 IBM Corp.
-// All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
 package generic
 
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 22:48:20.012425 +0200 CEST m=+0.019517901
+// 2023-08-11 11:37:34.0838811 +0200 CEST m=+0.009947101
 
 import (
 	"context"

either/doc.go

@@ -13,6 +13,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// Package option defines the [Either] datastructure and its monadic operations
 package either
 
 //go:generate go run .. either --count 10 --filename gen.go

either/either.go

@@ -182,7 +182,7 @@ func FromPredicate[E, A any](pred func(A) bool, onFalse func(A) E) func(A) Eithe
 	}
 }
 
-func FromNillable[E, A any](e E) func(*A) Either[E, *A] {
+func FromNillable[A, E any](e E) func(*A) Either[E, *A] {
 	return FromPredicate(F.IsNonNil[A], F.Constant1[*A](e))
 }
 

either/examples_create_test.go

@@ -0,0 +1,58 @@
+// Copyright (c) 2023 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package either
+
+import (
+	"fmt"
+
+	"github.com/IBM/fp-go/errors"
+)
+
+func ExampleEither_creation() {
+	// Build an Either
+	leftValue := Left[string](fmt.Errorf("some error"))
+	rightValue := Right[error]("value")
+
+	// Build from a value
+	fromNillable := FromNillable[string](fmt.Errorf("value was nil"))
+	leftFromNil := fromNillable(nil)
+	value := "value"
+	rightFromPointer := fromNillable(&value)
+
+	// some predicate
+	isEven := func(num int) bool {
+		return num%2 == 0
+	}
+	fromEven := FromPredicate(isEven, errors.OnSome[int]("%d is an odd number"))
+	leftFromPred := fromEven(3)
+	rightFromPred := fromEven(4)
+
+	fmt.Println(leftValue)
+	fmt.Println(rightValue)
+	fmt.Println(leftFromNil)
+	fmt.Println(IsRight(rightFromPointer))
+	fmt.Println(leftFromPred)
+	fmt.Println(rightFromPred)
+
+	// Output:
+	// Left[*errors.errorString, string](some error)
+	// Right[<nil>, string](value)
+	// Left[*errors.errorString, *string](value was nil)
+	// true
+	// Left[*errors.errorString, int](3 is an odd number)
+	// Right[<nil>, int](4)
+
+}

either/examples_extract_test.go

@@ -0,0 +1,64 @@
+// Copyright (c) 2023 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package either
+
+import (
+	"fmt"
+
+	F "github.com/IBM/fp-go/function"
+	N "github.com/IBM/fp-go/number"
+)
+
+func ExampleEither_extraction() {
+	leftValue := Left[int](fmt.Errorf("Division by Zero!"))
+	rightValue := Right[error](10)
+
+	// Convert Either[E, A] to A with a default value
+	leftWithDefault := GetOrElse(F.Constant1[error](0))(leftValue)   // 0
+	rightWithDefault := GetOrElse(F.Constant1[error](0))(rightValue) // 10
+
+	// Apply a different function on Left(...)/Right(...)
+	doubleOrZero := Fold(F.Constant1[error](0), N.Mul(2)) // func(Either[error, int]) int
+	doubleFromLeft := doubleOrZero(leftValue)             // 0
+	doubleFromRight := doubleOrZero(rightValue)           // 20
+
+	// Pro-tip: Fold is short for the following:
+	doubleOrZeroBis := F.Flow2(
+		Map[error](N.Mul(2)),
+		GetOrElse(F.Constant1[error](0)),
+	)
+	doubleFromLeftBis := doubleOrZeroBis(leftValue)   // 0
+	doubleFromRightBis := doubleOrZeroBis(rightValue) // 20
+
+	fmt.Println(leftValue)
+	fmt.Println(rightValue)
+	fmt.Println(leftWithDefault)
+	fmt.Println(rightWithDefault)
+	fmt.Println(doubleFromLeft)
+	fmt.Println(doubleFromRight)
+	fmt.Println(doubleFromLeftBis)
+	fmt.Println(doubleFromRightBis)
+
+	// Output:
+	// Left[*errors.errorString, int](Division by Zero!)
+	// Right[<nil>, int](10)
+	// 0
+	// 10
+	// 0
+	// 20
+	// 0
+	// 20
+}

either/gen.go

@@ -1,21 +1,7 @@
-// Copyright (c) 2023 IBM Corp.
-// All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 22:48:23.165015 +0200 CEST m=+0.038998801
+// 2023-08-11 11:37:35.9608486 +0200 CEST m=+0.009664501
+
 package either
 
 import (

endomorphism/monoid.go

@@ -21,16 +21,12 @@ import (
 	S "github.com/IBM/fp-go/semigroup"
 )
 
-func concat[A any](first, second func(A) A) func(A) A {
-	return F.Flow2(first, second)
-}
-
 // Semigroup for the Endomorphism where the `concat` operation is the usual function composition.
 func Semigroup[A any]() S.Semigroup[func(A) A] {
-	return S.MakeSemigroup(concat[A])
+	return S.MakeSemigroup(F.Flow2[func(A) A, func(A) A])
 }
 
 // Monoid for the Endomorphism where the `concat` operation is the usual function composition.
 func Monoid[A any]() M.Monoid[func(A) A] {
-	return M.MakeMonoid(concat[A], F.Identity[A])
+	return M.MakeMonoid(F.Flow2[func(A) A, func(A) A], F.Identity[A])
 }

errors/messages.go

@@ -28,6 +28,22 @@ func OnNone(msg string, args ...any) func() error {
 	}
 }
 
+// OnSome generates a unary function that produces a formatted error
+func OnSome[T any](msg string, args ...any) func(T) error {
+	l := len(args)
+	if l == 0 {
+		return func(value T) error {
+			return fmt.Errorf(msg, value)
+		}
+	}
+	return func(value T) error {
+		data := make([]any, l)
+		copy(data[1:], args)
+		data[0] = value
+		return fmt.Errorf(msg, data...)
+	}
+}
+
 // OnError generates a unary function that produces a formatted error. The argument
 // to that function is the root cause of the error and the message will be augmented with
 // a format string containing %w

function/binds.go

@@ -1,21 +1,7 @@
-// Copyright (c) 2023 IBM Corp.
-// All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 22:48:40.161663 +0200 CEST m=+0.009458101
+// 2023-08-11 11:37:50.171038 +0200 CEST m=+0.031513801
+
 package function
 
 // Combinations for a total of 1 arguments

function/doc.go

@@ -13,6 +13,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// Package function implements function composition primitives, most prominently [Pipe2] and [Flow2]
 package function
 
 //go:generate go run .. pipe --count 20 --filename gen.go

function/gen.go

@@ -1,21 +1,7 @@
-// Copyright (c) 2023 IBM Corp.
-// All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 22:48:27.8029852 +0200 CEST m=+0.051432001
+// 2023-08-11 11:37:38.4916948 +0200 CEST m=+0.060448601
+
 package function
 
 // Pipe0 takes an initial value t0 and successively applies 0 functions where the input of a function is the return value of the previous function

function/pipe_test.go

@@ -0,0 +1,62 @@
+// Copyright (c) 2023 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package function
+
+import (
+	"fmt"
+)
+
+func addSthg(value int) int {
+	return value + 1
+}
+
+func doSthgElse(value int) int {
+	return value * 2
+}
+
+func doFinalSthg(value int) string {
+	return fmt.Sprintf("final value: %d", value)
+}
+
+func Example() {
+	// start point
+	value := 1
+	// imperative style
+	value1 := addSthg(value)                    // 2
+	value2 := doSthgElse(value1)                // 4
+	finalValueImperative := doFinalSthg(value2) // "final value: 4"
+
+	// the same but inline
+	finalValueInline := doFinalSthg(doSthgElse(addSthg(value)))
+
+	// with pipe
+	finalValuePipe := Pipe3(value, addSthg, doSthgElse, doFinalSthg)
+
+	// with flow
+	transform := Flow3(addSthg, doSthgElse, doFinalSthg)
+	finalValueFlow := transform(value)
+
+	fmt.Println(finalValueImperative)
+	fmt.Println(finalValueInline)
+	fmt.Println(finalValuePipe)
+	fmt.Println(finalValueFlow)
+
+	// Output:
+	// final value: 4
+	// final value: 4
+	// final value: 4
+	// final value: 4
+}

identity/gen.go

@@ -1,21 +1,7 @@
-// Copyright (c) 2023 IBM Corp.
-// All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 22:48:46.7920356 +0200 CEST m=+0.045177201
+// 2023-08-11 11:38:00.2678592 +0200 CEST m=+0.008890401
+
 package identity
 
 import (

internal/apply/gen.go

@@ -1,21 +1,7 @@
-// Copyright (c) 2023 IBM Corp.
-// All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 22:48:49.4210571 +0200 CEST m=+0.040316501
+// 2023-08-11 11:38:01.6948567 +0200 CEST m=+0.013530301
+
 package apply
 
 import (

io/gen.go

@@ -1,21 +1,7 @@
-// Copyright (c) 2023 IBM Corp.
-// All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 22:48:57.7378739 +0200 CEST m=+0.063371401
+// 2023-08-11 11:38:07.3305497 +0200 CEST m=+0.014821301
+
 package io
 
 import (

io/generic/gen.go

@@ -1,21 +1,6 @@
-// Copyright (c) 2023 IBM Corp.
-// All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 22:48:57.7499229 +0200 CEST m=+0.075420401
+// 2023-08-11 11:38:07.3305497 +0200 CEST m=+0.014821301
 package generic
 
 import (

ioeither/gen.go

@@ -1,21 +1,7 @@
-// Copyright (c) 2023 IBM Corp.
-// All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 22:49:00.7618943 +0200 CEST m=+0.065441701
+// 2023-08-11 11:38:09.4187123 +0200 CEST m=+0.099620101
+
 package ioeither
 
 import (

ioeither/generic/gen.go

@@ -1,21 +1,6 @@
-// Copyright (c) 2023 IBM Corp.
-// All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 22:49:00.7765028 +0200 CEST m=+0.080050201
+// 2023-08-11 11:38:09.4489926 +0200 CEST m=+0.129900401
 package generic
 
 import (

iooption/gen.go

@@ -1,21 +1,7 @@
-// Copyright (c) 2023 IBM Corp.
-// All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 22:49:03.8471425 +0200 CEST m=+0.087124201
+// 2023-08-11 11:38:12.1021634 +0200 CEST m=+0.041956701
+
 package iooption
 
 import (

iooption/generic/gen.go

@@ -1,21 +1,6 @@
-// Copyright (c) 2023 IBM Corp.
-// All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 22:49:03.8541587 +0200 CEST m=+0.094140401
+// 2023-08-11 11:38:12.1210201 +0200 CEST m=+0.060813401
 package generic
 
 import (

iterator/stateless/first.go

@@ -0,0 +1,26 @@
+// Copyright (c) 2023 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package stateless
+
+import (
+	G "github.com/IBM/fp-go/iterator/stateless/generic"
+	O "github.com/IBM/fp-go/option"
+)
+
+// First returns the first item in an iterator if such an item exists
+func First[U any](mu Iterator[U]) O.Option[U] {
+	return G.First[Iterator[U]](mu)
+}

iterator/stateless/first_test.go

@@ -0,0 +1,41 @@
+// Copyright (c) 2023 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package stateless
+
+import (
+	"testing"
+
+	O "github.com/IBM/fp-go/option"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestFirst(t *testing.T) {
+
+	seq := From(1, 2, 3)
+
+	fst := First(seq)
+
+	assert.Equal(t, O.Of(1), fst)
+}
+
+func TestNoFirst(t *testing.T) {
+
+	seq := Empty[int]()
+
+	fst := First(seq)
+
+	assert.Equal(t, O.None[int](), fst)
+}

iterator/stateless/generic/first.go

@@ -0,0 +1,30 @@
+// Copyright (c) 2023 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package generic
+
+import (
+	F "github.com/IBM/fp-go/function"
+	O "github.com/IBM/fp-go/option"
+	T "github.com/IBM/fp-go/tuple"
+)
+
+// First returns the first item in an iterator if such an item exists
+func First[GU ~func() O.Option[T.Tuple2[GU, U]], U any](mu GU) O.Option[U] {
+	return F.Pipe1(
+		mu(),
+		O.Map(T.Second[GU, U]),
+	)
+}

iterator/stateless/generic/iterator.go

@@ -20,6 +20,7 @@ import (
 	F "github.com/IBM/fp-go/function"
 	"github.com/IBM/fp-go/internal/utils"
 	IO "github.com/IBM/fp-go/iooption/generic"
+	M "github.com/IBM/fp-go/monoid"
 	N "github.com/IBM/fp-go/number"
 	O "github.com/IBM/fp-go/option"
 	T "github.com/IBM/fp-go/tuple"
@@ -49,18 +50,21 @@ func FromArray[GU ~func() O.Option[T.Tuple2[GU, U]], US ~[]U, U any](as US) GU {
 	})(as)
 }
 
+// reduce applies a function for each value of the iterator with a floating result
+func reduce[GU ~func() O.Option[T.Tuple2[GU, U]], U, V any](as GU, f func(V, U) V, initial V) V {
+	next, ok := O.Unwrap(as())
+	current := initial
+	for ok {
+		// next (with bad side effect)
+		current = f(current, next.F2)
+		next, ok = O.Unwrap(next.F1())
+	}
+	return current
+}
+
 // Reduce applies a function for each value of the iterator with a floating result
 func Reduce[GU ~func() O.Option[T.Tuple2[GU, U]], U, V any](f func(V, U) V, initial V) func(GU) V {
-	return func(as GU) V {
-		next, ok := O.Unwrap(as())
-		current := initial
-		for ok {
-			// next (with bad side effect)
-			current = f(current, next.F2)
-			next, ok = O.Unwrap(next.F1())
-		}
-		return current
-	}
+	return F.Bind23of3(reduce[GU, U, V])(f, initial)
 }
 
 // ToArray converts the iterator to an array
@@ -216,3 +220,22 @@ func Ap[GUV ~func() O.Option[T.Tuple2[GUV, func(U) V]], GV ~func() O.Option[T.Tu
 func MonadAp[GUV ~func() O.Option[T.Tuple2[GUV, func(U) V]], GV ~func() O.Option[T.Tuple2[GV, V]], GU ~func() O.Option[T.Tuple2[GU, U]], U, V any](fab GUV, ma GU) GV {
 	return Ap[GUV, GV, GU](ma)(fab)
 }
+
+func FilterChain[GVV ~func() O.Option[T.Tuple2[GVV, GV]], GV ~func() O.Option[T.Tuple2[GV, V]], GU ~func() O.Option[T.Tuple2[GU, U]], FCT ~func(U) O.Option[GV], U, V any](f FCT) func(ma GU) GV {
+	return F.Flow2(
+		FilterMap[GVV, GU](f),
+		Flatten[GVV],
+	)
+}
+
+func FoldMap[GU ~func() O.Option[T.Tuple2[GU, U]], FCT ~func(U) V, U, V any](m M.Monoid[V]) func(FCT) func(ma GU) V {
+	return func(f FCT) func(ma GU) V {
+		return Reduce[GU](func(cur V, a U) V {
+			return m.Concat(cur, f(a))
+		}, m.Empty())
+	}
+}
+
+func Fold[GU ~func() O.Option[T.Tuple2[GU, U]], U any](m M.Monoid[U]) func(ma GU) U {
+	return Reduce[GU](m.Concat, m.Empty())
+}

iterator/stateless/generic/last.go

@@ -0,0 +1,27 @@
+// Copyright (c) 2023 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package generic
+
+import (
+	F "github.com/IBM/fp-go/function"
+	O "github.com/IBM/fp-go/option"
+	T "github.com/IBM/fp-go/tuple"
+)
+
+// Last returns the last item in an iterator if such an item exists
+func Last[GU ~func() O.Option[T.Tuple2[GU, U]], U any](mu GU) O.Option[U] {
+	return reduce(mu, F.Ignore1of2[O.Option[U]](O.Of[U]), O.None[U]())
+}

iterator/stateless/iterator.go

@@ -18,6 +18,7 @@ package stateless
 import (
 	G "github.com/IBM/fp-go/iterator/stateless/generic"
 	L "github.com/IBM/fp-go/lazy"
+	M "github.com/IBM/fp-go/monoid"
 	O "github.com/IBM/fp-go/option"
 	T "github.com/IBM/fp-go/tuple"
 )
@@ -118,3 +119,18 @@ func Repeat[U any](n int, a U) Iterator[U] {
 func Count(start int) Iterator[int] {
 	return G.Count[Iterator[int]](start)
 }
+
+// FilterChain filters and transforms the content of an iterator
+func FilterChain[U, V any](f func(U) O.Option[Iterator[V]]) func(ma Iterator[U]) Iterator[V] {
+	return G.FilterChain[Iterator[Iterator[V]], Iterator[V], Iterator[U]](f)
+}
+
+// FoldMap maps and folds an iterator. Map the iterator passing each value to the iterating function. Then fold the results using the provided Monoid.
+func FoldMap[U, V any](m M.Monoid[V]) func(func(U) V) func(ma Iterator[U]) V {
+	return G.FoldMap[Iterator[U], func(U) V, U, V](m)
+}
+
+// Fold folds the iterator using the provided Monoid.
+func Fold[U any](m M.Monoid[U]) func(Iterator[U]) U {
+	return G.Fold[Iterator[U]](m)
+}

iterator/stateless/iterator_test.go

@@ -18,12 +18,14 @@ package stateless
 import (
 	"fmt"
 	"math"
+	"strings"
 	"testing"
 
 	A "github.com/IBM/fp-go/array"
 	F "github.com/IBM/fp-go/function"
 	"github.com/IBM/fp-go/internal/utils"
 	O "github.com/IBM/fp-go/option"
+	S "github.com/IBM/fp-go/string"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -102,3 +104,14 @@ func TestAp(t *testing.T) {
 
 	assert.Equal(t, A.From("a-1-c", "a-1-d", "a-2-c", "a-2-d", "b-1-c", "b-1-d", "b-2-c", "b-2-d"), it)
 }
+
+func ExampleFoldMap() {
+	src := From("a", "b", "c")
+
+	fold := FoldMap[string](S.Monoid)(strings.ToUpper)
+
+	fmt.Println(fold(src))
+
+	// Output: ABC
+
+}

iterator/stateless/last.go

@@ -0,0 +1,27 @@
+// Copyright (c) 2023 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package stateless
+
+import (
+	G "github.com/IBM/fp-go/iterator/stateless/generic"
+	O "github.com/IBM/fp-go/option"
+)
+
+// Last returns the last item in an iterator if such an item exists
+// Note that the function will consume the [Iterator] in this call completely, to identify the last element. Do not use this for infinite iterators
+func Last[U any](mu Iterator[U]) O.Option[U] {
+	return G.Last[Iterator[U]](mu)
+}

iterator/stateless/last_test.go

@@ -0,0 +1,41 @@
+// Copyright (c) 2023 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package stateless
+
+import (
+	"testing"
+
+	O "github.com/IBM/fp-go/option"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestLast(t *testing.T) {
+
+	seq := From(1, 2, 3)
+
+	fst := Last(seq)
+
+	assert.Equal(t, O.Of(3), fst)
+}
+
+func TestNoLast(t *testing.T) {
+
+	seq := Empty[int]()
+
+	fst := Last(seq)
+
+	assert.Equal(t, O.None[int](), fst)
+}

number/utils.go

@@ -30,6 +30,13 @@ func Add[T Number](left T) func(T) T {
 	}
 }
 
+// Mul is a curried function used to add two numbers
+func Mul[T Number](coeff T) func(T) T {
+	return func(value T) T {
+		return coeff * value
+	}
+}
+
 // Inc is a function that increments a number
 func Inc[T Number](value T) T {
 	return value + 1

option/doc.go

@@ -13,6 +13,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// Package option defines the [Option] datastructure and its monadic operations
 package option
 
 //go:generate go run .. option --count 10 --filename gen.go

option/examples_create_test.go

@@ -0,0 +1,55 @@
+// Copyright (c) 2023 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package option
+
+import "fmt"
+
+func ExampleOption_creation() {
+
+	// Build an Option
+	none1 := None[int]()
+	some1 := Some("value")
+
+	// Build from a value
+	fromNillable := FromNillable[string]
+	nonFromNil := fromNillable(nil) // None[*string]
+	value := "value"
+	someFromPointer := fromNillable(&value) // Some[*string](xxx)
+
+	// some predicate
+	isEven := func(num int) bool {
+		return num%2 == 0
+	}
+
+	fromEven := FromPredicate(isEven)
+	noneFromPred := fromEven(3) // None[int]
+	someFromPred := fromEven(4) // Some[int](4)
+
+	fmt.Println(none1)
+	fmt.Println(some1)
+	fmt.Println(nonFromNil)
+	fmt.Println(IsSome(someFromPointer))
+	fmt.Println(noneFromPred)
+	fmt.Println(someFromPred)
+
+	// Output:
+	// None[int]
+	// Some[string](value)
+	// None[*string]
+	// true
+	// None[int]
+	// Some[int](4)
+}

option/examples_extract_test.go

@@ -0,0 +1,73 @@
+// Copyright (c) 2023 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package option
+
+import (
+	"fmt"
+
+	F "github.com/IBM/fp-go/function"
+	N "github.com/IBM/fp-go/number"
+)
+
+func ExampleOption_extraction() {
+
+	noneValue := None[int]()
+	someValue := Of(42)
+
+	// Convert Option[T] to T
+	fromNone, okFromNone := Unwrap(noneValue) // 0, false
+	fromSome, okFromSome := Unwrap(someValue) // 42, true
+
+	// Convert Option[T] with a default value
+	noneWithDefault := GetOrElse(F.Constant(0))(noneValue) // 0
+	someWithDefault := GetOrElse(F.Constant(0))(someValue) // 42
+
+	// Apply a different function on None/Some(...)
+	doubleOrZero := Fold(
+		F.Constant(0), // none case
+		N.Mul(2),      // some case
+	) // func(ma Option[int]) int
+
+	doubleFromNone := doubleOrZero(noneValue) // 0
+	doubleFromSome := doubleOrZero(someValue) // 84
+
+	// Pro-tip: Fold is short for the following:
+	doubleOfZeroBis := F.Flow2(
+		Map(N.Mul(2)),            // some case
+		GetOrElse(F.Constant(0)), // none case
+	)
+	doubleFromNoneBis := doubleOfZeroBis(noneValue) // 0
+	doubleFromSomeBis := doubleOfZeroBis(someValue) // 84
+
+	fmt.Printf("%d, %t\n", fromNone, okFromNone)
+	fmt.Printf("%d, %t\n", fromSome, okFromSome)
+	fmt.Println(noneWithDefault)
+	fmt.Println(someWithDefault)
+	fmt.Println(doubleFromNone)
+	fmt.Println(doubleFromSome)
+	fmt.Println(doubleFromNoneBis)
+	fmt.Println(doubleFromSomeBis)
+
+	// Output:
+	// 0, false
+	// 42, true
+	// 0
+	// 42
+	// 0
+	// 84
+	// 0
+	// 84
+}

option/gen.go

@@ -1,21 +1,7 @@
-// Copyright (c) 2023 IBM Corp.
-// All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 22:49:06.6236747 +0200 CEST m=+0.039283301
+// 2023-08-11 11:38:14.9503867 +0200 CEST m=+0.020206701
+
 package option
 
 import (

reader/gen.go

@@ -1,21 +1,7 @@
-// Copyright (c) 2023 IBM Corp.
-// All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 22:49:14.4173227 +0200 CEST m=+0.013163201
+// 2023-08-11 11:38:23.1396887 +0200 CEST m=+0.020805301
+
 package reader
 
 import (

reader/generic/gen.go

@@ -1,21 +1,6 @@
-// Copyright (c) 2023 IBM Corp.
-// All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 22:49:14.4173227 +0200 CEST m=+0.013163201
+// 2023-08-11 11:38:23.1402159 +0200 CEST m=+0.021332501
 package generic
 
 // From0 converts a function with 1 parameters returning a [R] into a function with 0 parameters returning a [GRA]

readerioeither/gen.go

@@ -1,21 +1,7 @@
-// Copyright (c) 2023 IBM Corp.
-// All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 22:49:16.5272334 +0200 CEST m=+0.043108701
+// 2023-08-11 11:38:26.9546728 +0200 CEST m=+0.032178301
+
 package readerioeither
 
 import (

readerioeither/generic/gen.go

@@ -1,21 +1,6 @@
-// Copyright (c) 2023 IBM Corp.
-// All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 22:49:16.5292332 +0200 CEST m=+0.045108501
+// 2023-08-11 11:38:26.9556725 +0200 CEST m=+0.033178001
 package generic
 
 import (

record/doc.go

@@ -0,0 +1,17 @@
+// Copyright (c) 2023 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package record contains monadic operations for maps as well as a rich set of utility functions
+package record

record/generic/monoid.go

@@ -16,6 +16,7 @@
 package generic
 
 import (
+	F "github.com/IBM/fp-go/function"
 	M "github.com/IBM/fp-go/monoid"
 	S "github.com/IBM/fp-go/semigroup"
 )
@@ -26,3 +27,17 @@ func UnionMonoid[N ~map[K]V, K comparable, V any](s S.Semigroup[V]) M.Monoid[N]
 		Empty[N](),
 	)
 }
+
+func UnionLastMonoid[N ~map[K]V, K comparable, V any]() M.Monoid[N] {
+	return M.MakeMonoid(
+		unionLast[N],
+		Empty[N](),
+	)
+}
+
+func UnionFirstMonoid[N ~map[K]V, K comparable, V any]() M.Monoid[N] {
+	return M.MakeMonoid(
+		F.Swap(unionLast[N]),
+		Empty[N](),
+	)
+}

record/generic/record.go

@@ -16,10 +16,14 @@
 package generic
 
 import (
+	"sort"
+
 	F "github.com/IBM/fp-go/function"
 	G "github.com/IBM/fp-go/internal/record"
 	Mg "github.com/IBM/fp-go/magma"
+	Mo "github.com/IBM/fp-go/monoid"
 	O "github.com/IBM/fp-go/option"
+	"github.com/IBM/fp-go/ord"
 	T "github.com/IBM/fp-go/tuple"
 )
 
@@ -39,6 +43,46 @@ func Values[M ~map[K]V, GV ~[]V, K comparable, V any](r M) GV {
 	return collect[M, GV](r, F.Second[K, V])
 }
 
+func KeysOrd[M ~map[K]V, GK ~[]K, K comparable, V any](o ord.Ord[K]) func(r M) GK {
+	return func(r M) GK {
+		return collectOrd[M, GK](o, r, F.First[K, V])
+	}
+}
+
+func ValuesOrd[M ~map[K]V, GV ~[]V, K comparable, V any](o ord.Ord[K]) func(r M) GV {
+	return func(r M) GV {
+		return collectOrd[M, GV](o, r, F.Second[K, V])
+	}
+}
+
+func collectOrd[M ~map[K]V, GR ~[]R, K comparable, V, R any](o ord.Ord[K], r M, f func(K, V) R) GR {
+	// create the entries
+	entries := toEntriesOrd[M, []T.Tuple2[K, V]](o, r)
+	// collect this array
+	ft := T.Tupled2(f)
+	count := len(entries)
+	result := make(GR, count)
+	for i := count - 1; i >= 0; i-- {
+		result[i] = ft(entries[i])
+	}
+	// done
+	return result
+}
+
+func reduceOrd[M ~map[K]V, K comparable, V, R any](o ord.Ord[K], r M, f func(K, R, V) R, initial R) R {
+	// create the entries
+	entries := toEntriesOrd[M, []T.Tuple2[K, V]](o, r)
+	// collect this array
+	current := initial
+	count := len(entries)
+	for i := 0; i < count; i++ {
+		t := entries[i]
+		current = f(T.First(t), current, T.Second(t))
+	}
+	// done
+	return current
+}
+
 func collect[M ~map[K]V, GR ~[]R, K comparable, V, R any](r M, f func(K, V) R) GR {
 	count := len(r)
 	result := make(GR, count)
@@ -82,6 +126,34 @@ func MonadMap[M ~map[K]V, N ~map[K]R, K comparable, V, R any](r M, f func(V) R)
 	return MonadMapWithIndex[M, N](r, F.Ignore1of2[K](f))
 }
 
+func MonadChainWithIndex[M ~map[K]V1, N ~map[K]V2, K comparable, V1, V2 any](m Mo.Monoid[N], r M, f func(K, V1) N) N {
+	return G.ReduceWithIndex(r, func(k K, dst N, b V1) N {
+		return m.Concat(dst, f(k, b))
+	}, m.Empty())
+}
+
+func MonadChain[M ~map[K]V1, N ~map[K]V2, K comparable, V1, V2 any](m Mo.Monoid[N], r M, f func(V1) N) N {
+	return G.Reduce(r, func(dst N, b V1) N {
+		return m.Concat(dst, f(b))
+	}, m.Empty())
+}
+
+func ChainWithIndex[M ~map[K]V1, N ~map[K]V2, K comparable, V1, V2 any](m Mo.Monoid[N]) func(func(K, V1) N) func(M) N {
+	return func(f func(K, V1) N) func(M) N {
+		return func(ma M) N {
+			return MonadChainWithIndex(m, ma, f)
+		}
+	}
+}
+
+func Chain[M ~map[K]V1, N ~map[K]V2, K comparable, V1, V2 any](m Mo.Monoid[N]) func(func(V1) N) func(M) N {
+	return func(f func(V1) N) func(M) N {
+		return func(ma M) N {
+			return MonadChain(m, ma, f)
+		}
+	}
+}
+
 func MonadMapWithIndex[M ~map[K]V, N ~map[K]R, K comparable, V, R any](r M, f func(K, V) R) N {
 	return G.ReduceWithIndex(r, func(k K, dst N, v V) N {
 		return upsertAtReadWrite(dst, k, f(k, v))
@@ -114,15 +186,14 @@ func MapRefWithIndex[M ~map[K]V, N ~map[K]R, K comparable, V, R any](f func(K, *
 	return F.Bind2nd(MonadMapRefWithIndex[M, N, K, V, R], f)
 }
 
-func lookup[M ~map[K]V, K comparable, V any](r M, k K) O.Option[V] {
-	if val, ok := r[k]; ok {
-		return O.Some(val)
-	}
-	return O.None[V]()
-}
-
 func Lookup[M ~map[K]V, K comparable, V any](k K) func(M) O.Option[V] {
-	return F.Bind2nd(lookup[M, K, V], k)
+	n := O.None[V]()
+	return func(m M) O.Option[V] {
+		if val, ok := m[k]; ok {
+			return O.Some(val)
+		}
+		return n
+	}
 }
 
 func Has[M ~map[K]V, K comparable, V any](k K, r M) bool {
@@ -161,6 +232,31 @@ func union[M ~map[K]V, K comparable, V any](m Mg.Magma[V], left M, right M) M {
 	return result
 }
 
+func unionLast[M ~map[K]V, K comparable, V any](left M, right M) M {
+	lenLeft := len(left)
+
+	if lenLeft == 0 {
+		return right
+	}
+
+	lenRight := len(right)
+	if lenRight == 0 {
+		return left
+	}
+
+	result := make(M, lenLeft+lenRight)
+
+	for k, v := range left {
+		result[k] = v
+	}
+
+	for k, v := range right {
+		result[k] = v
+	}
+
+	return result
+}
+
 func Union[M ~map[K]V, K comparable, V any](m Mg.Magma[V]) func(M) func(M) M {
 	return func(right M) func(M) M {
 		return func(left M) M {
@@ -169,6 +265,22 @@ func Union[M ~map[K]V, K comparable, V any](m Mg.Magma[V]) func(M) func(M) M {
 	}
 }
 
+func UnionLast[M ~map[K]V, K comparable, V any](right M) func(M) M {
+	return func(left M) M {
+		return unionLast(left, right)
+	}
+}
+
+func Merge[M ~map[K]V, K comparable, V any](right M) func(M) M {
+	return UnionLast(right)
+}
+
+func UnionFirst[M ~map[K]V, K comparable, V any](right M) func(M) M {
+	return func(left M) M {
+		return unionLast(right, left)
+	}
+}
+
 func Empty[M ~map[K]V, K comparable, V any]() M {
 	return make(M)
 }
@@ -181,6 +293,27 @@ func ToArray[M ~map[K]V, GT ~[]T.Tuple2[K, V], K comparable, V any](r M) GT {
 	return collect[M, GT](r, T.MakeTuple2[K, V])
 }
 
+func toEntriesOrd[M ~map[K]V, GT ~[]T.Tuple2[K, V], K comparable, V any](o ord.Ord[K], r M) GT {
+	// total number of elements
+	count := len(r)
+	// produce an array that we can sort by key
+	entries := make(GT, count)
+	idx := 0
+	for k, v := range r {
+		entries[idx] = T.MakeTuple2(k, v)
+		idx++
+	}
+	sort.Slice(entries, func(i, j int) bool {
+		return o.Compare(T.First(entries[i]), T.First(entries[j])) < 0
+	})
+	// final entries
+	return entries
+}
+
+func ToEntriesOrd[M ~map[K]V, GT ~[]T.Tuple2[K, V], K comparable, V any](o ord.Ord[K]) func(r M) GT {
+	return F.Bind1st(toEntriesOrd[M, GT, K, V], o)
+}
+
 func ToEntries[M ~map[K]V, GT ~[]T.Tuple2[K, V], K comparable, V any](r M) GT {
 	return ToArray[M, GT](r)
 }
@@ -269,6 +402,33 @@ func FilterMap[M ~map[K]V1, N ~map[K]V2, K comparable, V1, V2 any](f func(V1) O.
 	return F.Bind2nd(filterMapWithIndex[M, N, K, V1, V2], F.Ignore1of2[K](f))
 }
 
+// Flatten converts a nested map into a regular map
+func Flatten[M ~map[K]N, N ~map[K]V, K comparable, V any](m Mo.Monoid[N]) func(M) N {
+	return Chain[M, N](m)(F.Identity[N])
+}
+
+// FilterChainWithIndex creates a new map with only the elements for which the transformation function creates a Some
+func FilterChainWithIndex[M ~map[K]V1, N ~map[K]V2, K comparable, V1, V2 any](m Mo.Monoid[N]) func(func(K, V1) O.Option[N]) func(M) N {
+	flatten := Flatten[map[K]N, N](m)
+	return func(f func(K, V1) O.Option[N]) func(M) N {
+		return F.Flow2(
+			FilterMapWithIndex[M, map[K]N](f),
+			flatten,
+		)
+	}
+}
+
+// FilterChain creates a new map with only the elements for which the transformation function creates a Some
+func FilterChain[M ~map[K]V1, N ~map[K]V2, K comparable, V1, V2 any](m Mo.Monoid[N]) func(func(V1) O.Option[N]) func(M) N {
+	flatten := Flatten[map[K]N, N](m)
+	return func(f func(V1) O.Option[N]) func(M) N {
+		return F.Flow2(
+			FilterMap[M, map[K]N](f),
+			flatten,
+		)
+	}
+}
+
 // IsNil checks if the map is set to nil
 func IsNil[M ~map[K]V, K comparable, V any](m M) bool {
 	return m == nil
@@ -283,3 +443,67 @@ func IsNonNil[M ~map[K]V, K comparable, V any](m M) bool {
 func ConstNil[M ~map[K]V, K comparable, V any]() M {
 	return (M)(nil)
 }
+
+func FoldMap[AS ~map[K]A, K comparable, A, B any](m Mo.Monoid[B]) func(func(A) B) func(AS) B {
+	return func(f func(A) B) func(AS) B {
+		return Reduce[AS](func(cur B, a A) B {
+			return m.Concat(cur, f(a))
+		}, m.Empty())
+	}
+}
+
+func Fold[AS ~map[K]A, K comparable, A any](m Mo.Monoid[A]) func(AS) A {
+	return Reduce[AS](m.Concat, m.Empty())
+}
+
+func FoldMapWithIndex[AS ~map[K]A, K comparable, A, B any](m Mo.Monoid[B]) func(func(K, A) B) func(AS) B {
+	return func(f func(K, A) B) func(AS) B {
+		return ReduceWithIndex[AS](func(k K, cur B, a A) B {
+			return m.Concat(cur, f(k, a))
+		}, m.Empty())
+	}
+}
+
+func ReduceOrdWithIndex[M ~map[K]V, K comparable, V, R any](o ord.Ord[K]) func(func(K, R, V) R, R) func(M) R {
+	return func(f func(K, R, V) R, initial R) func(M) R {
+		return func(m M) R {
+			return reduceOrd(o, m, f, initial)
+		}
+	}
+}
+
+func ReduceOrd[M ~map[K]V, K comparable, V, R any](o ord.Ord[K]) func(func(R, V) R, R) func(M) R {
+	ro := ReduceOrdWithIndex[M, K, V, R](o)
+	return func(f func(R, V) R, initial R) func(M) R {
+		return ro(F.Ignore1of3[K](f), initial)
+	}
+}
+
+func FoldMapOrd[AS ~map[K]A, K comparable, A, B any](o ord.Ord[K]) func(m Mo.Monoid[B]) func(func(A) B) func(AS) B {
+	red := ReduceOrd[AS, K, A, B](o)
+	return func(m Mo.Monoid[B]) func(func(A) B) func(AS) B {
+		return func(f func(A) B) func(AS) B {
+			return red(func(cur B, a A) B {
+				return m.Concat(cur, f(a))
+			}, m.Empty())
+		}
+	}
+}
+
+func FoldOrd[AS ~map[K]A, K comparable, A any](o ord.Ord[K]) func(m Mo.Monoid[A]) func(AS) A {
+	red := ReduceOrd[AS, K, A, A](o)
+	return func(m Mo.Monoid[A]) func(AS) A {
+		return red(m.Concat, m.Empty())
+	}
+}
+
+func FoldMapOrdWithIndex[AS ~map[K]A, K comparable, A, B any](o ord.Ord[K]) func(m Mo.Monoid[B]) func(func(K, A) B) func(AS) B {
+	red := ReduceOrdWithIndex[AS, K, A, B](o)
+	return func(m Mo.Monoid[B]) func(func(K, A) B) func(AS) B {
+		return func(f func(K, A) B) func(AS) B {
+			return red(func(k K, cur B, a A) B {
+				return m.Concat(cur, f(k, a))
+			}, m.Empty())
+		}
+	}
+}

record/generic/semigroup.go

@@ -20,8 +20,19 @@ import (
 )
 
 func UnionSemigroup[N ~map[K]V, K comparable, V any](s S.Semigroup[V]) S.Semigroup[N] {
-	union := Union[N, K, V](s)
 	return S.MakeSemigroup(func(first N, second N) N {
-		return union(second)(first)
+		return union[N, K, V](S.ToMagma(s), first, second)
+	})
+}
+
+func UnionLastSemigroup[N ~map[K]V, K comparable, V any]() S.Semigroup[N] {
+	return S.MakeSemigroup(func(first N, second N) N {
+		return unionLast[N, K, V](first, second)
+	})
+}
+
+func UnionFirstSemigroup[N ~map[K]V, K comparable, V any]() S.Semigroup[N] {
+	return S.MakeSemigroup(func(first N, second N) N {
+		return unionLast[N, K, V](second, first)
 	})
 }

record/monoid.go

@@ -21,6 +21,22 @@ import (
 	S "github.com/IBM/fp-go/semigroup"
 )
 
+// UnionMonoid computes the union of two maps of the same type
 func UnionMonoid[K comparable, V any](s S.Semigroup[V]) M.Monoid[map[K]V] {
 	return G.UnionMonoid[map[K]V](s)
 }
+
+// UnionLastMonoid computes the union of two maps of the same type giving the last map precedence
+func UnionLastMonoid[K comparable, V any]() M.Monoid[map[K]V] {
+	return G.UnionLastMonoid[map[K]V]()
+}
+
+// UnionFirstMonoid computes the union of two maps of the same type giving the first map precedence
+func UnionFirstMonoid[K comparable, V any]() M.Monoid[map[K]V] {
+	return G.UnionFirstMonoid[map[K]V]()
+}
+
+// MergeMonoid computes the union of two maps of the same type giving the last map precedence
+func MergeMonoid[K comparable, V any]() M.Monoid[map[K]V] {
+	return G.UnionLastMonoid[map[K]V]()
+}

record/record.go

@@ -17,27 +17,34 @@ package record
 
 import (
 	Mg "github.com/IBM/fp-go/magma"
+	Mo "github.com/IBM/fp-go/monoid"
 	O "github.com/IBM/fp-go/option"
+	"github.com/IBM/fp-go/ord"
 	G "github.com/IBM/fp-go/record/generic"
 	T "github.com/IBM/fp-go/tuple"
 )
 
+// IsEmpty tests if a map is empty
 func IsEmpty[K comparable, V any](r map[K]V) bool {
 	return G.IsEmpty(r)
 }
 
+// IsNonEmpty tests if a map is not empty
 func IsNonEmpty[K comparable, V any](r map[K]V) bool {
 	return G.IsNonEmpty(r)
 }
 
+// Keys returns the key in a map
 func Keys[K comparable, V any](r map[K]V) []K {
 	return G.Keys[map[K]V, []K](r)
 }
 
+// Values returns the values in a map
 func Values[K comparable, V any](r map[K]V) []V {
 	return G.Values[map[K]V, []V](r)
 }
 
+// Collect applies a collector function to the key value pairs in a map and returns the result as an array
 func Collect[K comparable, V, R any](f func(K, V) R) func(map[K]V) []R {
 	return G.Collect[map[K]V, []R](f)
 }
@@ -90,10 +97,12 @@ func MapRefWithIndex[K comparable, V, R any](f func(K, *V) R) func(map[K]V) map[
 	return G.MapRefWithIndex[map[K]V, map[K]R](f)
 }
 
+// Lookup returns the entry for a key in a map if it exists
 func Lookup[K comparable, V any](k K) func(map[K]V) O.Option[V] {
 	return G.Lookup[map[K]V](k)
 }
 
+// Has tests if a key is contained in a map
 func Has[K comparable, V any](k K, r map[K]V) bool {
 	return G.Has(k, r)
 }
@@ -102,10 +111,17 @@ func Union[K comparable, V any](m Mg.Magma[V]) func(map[K]V) func(map[K]V) map[K
 	return G.Union[map[K]V](m)
 }
 
+// Merge combines two maps giving the values in the right one precedence. Also refer to [MergeMonoid]
+func Merge[K comparable, V any](right map[K]V) func(map[K]V) map[K]V {
+	return G.Merge[map[K]V](right)
+}
+
+// Empty creates an empty map
 func Empty[K comparable, V any]() map[K]V {
 	return G.Empty[map[K]V]()
 }
 
+// Size returns the number of elements in a map
 func Size[K comparable, V any](r map[K]V) int {
 	return G.Size(r)
 }
@@ -130,6 +146,7 @@ func DeleteAt[K comparable, V any](k K) func(map[K]V) map[K]V {
 	return G.DeleteAt[map[K]V](k)
 }
 
+// Singleton creates a new map with a single entry
 func Singleton[K comparable, V any](k K, v V) map[K]V {
 	return G.Singleton[map[K]V](k, v)
 }
@@ -168,3 +185,84 @@ func IsNonNil[K comparable, V any](m map[K]V) bool {
 func ConstNil[K comparable, V any]() map[K]V {
 	return (map[K]V)(nil)
 }
+
+func MonadChainWithIndex[V1 any, K comparable, V2 any](m Mo.Monoid[map[K]V2], r map[K]V1, f func(K, V1) map[K]V2) map[K]V2 {
+	return G.MonadChainWithIndex(m, r, f)
+}
+
+func MonadChain[V1 any, K comparable, V2 any](m Mo.Monoid[map[K]V2], r map[K]V1, f func(V1) map[K]V2) map[K]V2 {
+	return G.MonadChain(m, r, f)
+}
+
+func ChainWithIndex[V1 any, K comparable, V2 any](m Mo.Monoid[map[K]V2]) func(func(K, V1) map[K]V2) func(map[K]V1) map[K]V2 {
+	return G.ChainWithIndex[map[K]V1](m)
+}
+
+func Chain[V1 any, K comparable, V2 any](m Mo.Monoid[map[K]V2]) func(func(V1) map[K]V2) func(map[K]V1) map[K]V2 {
+	return G.Chain[map[K]V1](m)
+}
+
+// Flatten converts a nested map into a regular map
+func Flatten[K comparable, V any](m Mo.Monoid[map[K]V]) func(map[K]map[K]V) map[K]V {
+	return G.Flatten[map[K]map[K]V](m)
+}
+
+// FilterChainWithIndex creates a new map with only the elements for which the transformation function creates a Some
+func FilterChainWithIndex[V1 any, K comparable, V2 any](m Mo.Monoid[map[K]V2]) func(func(K, V1) O.Option[map[K]V2]) func(map[K]V1) map[K]V2 {
+	return G.FilterChainWithIndex[map[K]V1](m)
+}
+
+// FilterChain creates a new map with only the elements for which the transformation function creates a Some
+func FilterChain[V1 any, K comparable, V2 any](m Mo.Monoid[map[K]V2]) func(func(V1) O.Option[map[K]V2]) func(map[K]V1) map[K]V2 {
+	return G.FilterChain[map[K]V1](m)
+}
+
+// FoldMap maps and folds a record. Map the record passing each value to the iterating function. Then fold the results using the provided Monoid.
+func FoldMap[K comparable, A, B any](m Mo.Monoid[B]) func(func(A) B) func(map[K]A) B {
+	return G.FoldMap[map[K]A](m)
+}
+
+// FoldMapWithIndex maps and folds a record. Map the record passing each value to the iterating function. Then fold the results using the provided Monoid.
+func FoldMapWithIndex[K comparable, A, B any](m Mo.Monoid[B]) func(func(K, A) B) func(map[K]A) B {
+	return G.FoldMapWithIndex[map[K]A](m)
+}
+
+// Fold folds the record using the provided Monoid.
+func Fold[K comparable, A any](m Mo.Monoid[A]) func(map[K]A) A {
+	return G.Fold[map[K]A](m)
+}
+
+// ReduceOrdWithIndex reduces a map into a single value via a reducer function making sure that the keys are passed to the reducer in the specified order
+func ReduceOrdWithIndex[V, R any, K comparable](o ord.Ord[K]) func(func(K, R, V) R, R) func(map[K]V) R {
+	return G.ReduceOrdWithIndex[map[K]V, K, V, R](o)
+}
+
+// ReduceOrd reduces a map into a single value via a reducer function making sure that the keys are passed to the reducer in the specified order
+func ReduceOrd[V, R any, K comparable](o ord.Ord[K]) func(func(R, V) R, R) func(map[K]V) R {
+	return G.ReduceOrd[map[K]V, K, V, R](o)
+}
+
+// FoldMap maps and folds a record. Map the record passing each value to the iterating function. Then fold the results using the provided Monoid and the items in the provided order
+func FoldMapOrd[A, B any, K comparable](o ord.Ord[K]) func(m Mo.Monoid[B]) func(func(A) B) func(map[K]A) B {
+	return G.FoldMapOrd[map[K]A, K, A, B](o)
+}
+
+// Fold folds the record using the provided Monoid with the items passed in the given order
+func FoldOrd[A any, K comparable](o ord.Ord[K]) func(m Mo.Monoid[A]) func(map[K]A) A {
+	return G.FoldOrd[map[K]A, K, A](o)
+}
+
+// FoldMapWithIndex maps and folds a record. Map the record passing each value to the iterating function. Then fold the results using the provided Monoid and the items in the provided order
+func FoldMapOrdWithIndex[K comparable, A, B any](o ord.Ord[K]) func(m Mo.Monoid[B]) func(func(K, A) B) func(map[K]A) B {
+	return G.FoldMapOrdWithIndex[map[K]A, K, A, B](o)
+}
+
+// KeysOrd returns the keys in the map in their given order
+func KeysOrd[V any, K comparable](o ord.Ord[K]) func(r map[K]V) []K {
+	return G.KeysOrd[map[K]V, []K, K, V](o)
+}
+
+// ValuesOrd returns the values in the map ordered by their keys in the given order
+func ValuesOrd[V any, K comparable](o ord.Ord[K]) func(r map[K]V) []V {
+	return G.ValuesOrd[map[K]V, []V, K, V](o)
+}

record/record_test.go

@@ -16,11 +16,14 @@
 package record
 
 import (
+	"fmt"
 	"sort"
+	"strings"
 	"testing"
 
 	"github.com/IBM/fp-go/internal/utils"
 	O "github.com/IBM/fp-go/option"
+	S "github.com/IBM/fp-go/string"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -71,3 +74,60 @@ func TestLookup(t *testing.T) {
 	assert.Equal(t, O.Some("a"), Lookup[string, string]("a")(data))
 	assert.Equal(t, O.None[string](), Lookup[string, string]("a1")(data))
 }
+
+func TestFilterChain(t *testing.T) {
+	src := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+	}
+
+	f := func(k string, value int) O.Option[map[string]string] {
+		if value%2 != 0 {
+			return O.Of(map[string]string{
+				k: fmt.Sprintf("%s%d", k, value),
+			})
+		}
+		return O.None[map[string]string]()
+	}
+
+	// monoid
+	monoid := MergeMonoid[string, string]()
+
+	res := FilterChainWithIndex[int](monoid)(f)(src)
+
+	assert.Equal(t, map[string]string{
+		"a": "a1",
+		"c": "c3",
+	}, res)
+}
+
+func ExampleFoldMap() {
+	src := map[string]string{
+		"a": "a",
+		"b": "b",
+		"c": "c",
+	}
+
+	fold := FoldMapOrd[string, string](S.Ord)(S.Monoid)(strings.ToUpper)
+
+	fmt.Println(fold(src))
+
+	// Output: ABC
+
+}
+
+func ExampleValuesOrd() {
+	src := map[string]string{
+		"c": "a",
+		"b": "b",
+		"a": "c",
+	}
+
+	getValues := ValuesOrd[string](S.Ord)
+
+	fmt.Println(getValues(src))
+
+	// Output: [c b a]
+
+}

record/semigroup.go

@@ -12,6 +12,7 @@
 // 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 record
 
 import (
@@ -22,3 +23,11 @@ import (
 func UnionSemigroup[K comparable, V any](s S.Semigroup[V]) S.Semigroup[map[K]V] {
 	return G.UnionSemigroup[map[K]V](s)
 }
+
+func UnionLastSemigroup[K comparable, V any]() S.Semigroup[map[K]V] {
+	return G.UnionLastSemigroup[map[K]V]()
+}
+
+func UnionFirstSemigroup[K comparable, V any]() S.Semigroup[map[K]V] {
+	return G.UnionFirstSemigroup[map[K]V]()
+}

semigroup/semigroup.go

@@ -59,3 +59,8 @@ func First[A any]() Semigroup[A] {
 func Last[A any]() Semigroup[A] {
 	return MakeSemigroup(F.Second[A, A])
 }
+
+// ToMagma converts a semigroup to a magma
+func ToMagma[A any](s Semigroup[A]) M.Magma[A] {
+	return s
+}

tuple/gen.go

@@ -1,21 +1,7 @@
-// Copyright (c) 2023 IBM Corp.
-// All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 22:49:18.7141124 +0200 CEST m=+0.109464201
+// 2023-08-11 11:38:30.5947727 +0200 CEST m=+0.033600301
+
 package tuple
 
 import (

writer/writer_test.go

@@ -31,7 +31,7 @@ func doubleAndLog(data int) Writer[[]string, int] {
 	}
 }
 
-func ExampleLoggingWriter() {
+func ExampleWriter_logging() {
 
 	m := A.Monoid[string]()
 	s := M.ToSemigroup(m)