Merge pull request #31 from IBM/cleue-add-cache

fix: implement simple cache for pure functions

.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: |

README.md

@@ -73,7 +73,7 @@ This library aims to provide a set of data types and functions that make it easy
 
 The library itself also comprises many small functions, but it's admittedly harder to maintain than code that uses it. However this asymmetry is intended because it offloads complexity from users into a central component.
 
-## Comparation to Idiomatic Go
+## Comparison to Idiomatic Go
 
 In this section we discuss how the functional APIs differ from idiomatic go function signatures and how to convert back and forth.
 
@@ -181,7 +181,7 @@ The `Map` operation for `ReaderIOEither` is defined as:
 func Map[R, E, A, B any](f func(A) B) func(fa ReaderIOEither[R, E, A]) ReaderIOEither[R, E, B]
 ```
 
-and in fact the equivalent operations for all other mondas follow the same pattern, we could try to introduce a new type for `ReaderIOEither` (without a parameter) as a HKT, e.g. like so (made-up syntax, does not work in go):
+and in fact the equivalent operations for all other monads follow the same pattern, we could try to introduce a new type for `ReaderIOEither` (without a parameter) as a HKT, e.g. like so (made-up syntax, does not work in go):
 
 ```go
 func Map[HKT, R, E, A, B any](f func(A) B) func(HKT[R, E, A]) HKT[R, E, B]

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 +294,17 @@ 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)
+}
+
+func Push[A any](a A) func([]A) []A {
+	return G.Push[[]A](a)
+}

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/examples_basic_test.go

@@ -0,0 +1,59 @@
+// 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 array
+
+import (
+	"fmt"
+
+	F "github.com/IBM/fp-go/function"
+	O "github.com/IBM/fp-go/option"
+)
+
+// Example_basic adapts examples from [https://github.com/inato/fp-ts-cheatsheet#basic-manipulation]
+func Example_basic() {
+
+	someArray := From(0, 1, 2, 3, 4, 5, 6, 7, 8, 9) // []int
+
+	isEven := func(num int) bool {
+		return num%2 == 0
+	}
+
+	square := func(num int) int {
+		return num * num
+	}
+
+	// filter and map
+	result := F.Pipe2(
+		someArray,
+		Filter(isEven),
+		Map(square),
+	) // [0 4 16 36 64]
+
+	// or in one go with filterMap
+	resultFilterMap := F.Pipe1(
+		someArray,
+		FilterMap(
+			F.Flow2(O.FromPredicate(isEven), O.Map(square)),
+		),
+	)
+
+	fmt.Println(result)
+	fmt.Println(resultFilterMap)
+
+	// Output:
+	// [0 4 16 36 64]
+	// [0 4 16 36 64]
+}

array/examples_sort_test.go

@@ -0,0 +1,92 @@
+// 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 array
+
+import (
+	"fmt"
+
+	F "github.com/IBM/fp-go/function"
+	I "github.com/IBM/fp-go/number/integer"
+	O "github.com/IBM/fp-go/option"
+	"github.com/IBM/fp-go/ord"
+	S "github.com/IBM/fp-go/string"
+)
+
+type user struct {
+	name string
+	age  O.Option[int]
+}
+
+func (user user) GetName() string {
+	return user.name
+}
+
+func (user user) GetAge() O.Option[int] {
+	return user.age
+}
+
+// Example_sort adapts examples from [https://github.com/inato/fp-ts-cheatsheet#sort-elements-with-ord]
+func Example_sort() {
+
+	strings := From("zyx", "abc", "klm")
+
+	sortedStrings := F.Pipe1(
+		strings,
+		Sort(S.Ord),
+	) // => ['abc', 'klm', 'zyx']
+
+	// reverse sort
+	reverseSortedStrings := F.Pipe1(
+		strings,
+		Sort(ord.Reverse(S.Ord)),
+	) // => ['zyx', 'klm', 'abc']
+
+	// sort Option
+	optionalNumbers := From(O.Some(1337), O.None[int](), O.Some(42))
+
+	sortedNums := F.Pipe1(
+		optionalNumbers,
+		Sort(O.Ord(I.Ord)),
+	)
+
+	// complex object with different rules
+	byName := F.Pipe1(
+		S.Ord,
+		ord.Contramap(user.GetName),
+	) // ord.Ord[user]
+
+	byAge := F.Pipe1(
+		O.Ord(I.Ord),
+		ord.Contramap(user.GetAge),
+	) // ord.Ord[user]
+
+	sortedUsers := F.Pipe1(
+		From(user{name: "a", age: O.Of(30)}, user{name: "d", age: O.Of(10)}, user{name: "c"}, user{name: "b", age: O.Of(10)}),
+		SortBy(From(byAge, byName)),
+	)
+
+	fmt.Println(sortedStrings)
+	fmt.Println(reverseSortedStrings)
+	fmt.Println(sortedNums)
+	fmt.Println(sortedUsers)
+
+	// Output:
+	// [abc klm zyx]
+	// [zyx klm abc]
+	// [None[int] Some[int](42) Some[int](1337)]
+	// [{c {false 0}} {b {true 10}} {d {true 10}} {a {true 30}}]
+
+}

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"
 )
@@ -27,6 +28,14 @@ func Of[GA ~[]A, A any](value A) GA {
 	return GA{value}
 }
 
+func Reduce[GA ~[]A, A, B any](fa GA, f func(B, A) B, initial B) B {
+	return array.Reduce(fa, f, initial)
+}
+
+func ReduceWithIndex[GA ~[]A, A, B any](fa GA, f func(int, B, A) B, initial B) B {
+	return array.ReduceWithIndex(fa, f, initial)
+}
+
 // From constructs an array from a set of variadic arguments
 func From[GA ~[]A, A any](data ...A) GA {
 	return data
@@ -104,6 +113,10 @@ func MonadMap[GA ~[]A, GB ~[]B, A, B any](as GA, f func(a A) B) GB {
 	return array.MonadMap[GA, GB](as, f)
 }
 
+func Map[GA ~[]A, GB ~[]B, A, B any](f func(a A) B) func(GA) GB {
+	return F.Bind2nd(MonadMap[GA, GB, A, B], f)
+}
+
 func Size[GA ~[]A, A any](as GA) int {
 	return len(as)
 }
@@ -118,6 +131,17 @@ 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 +222,23 @@ 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())
+	}
+}
+
+func Push[GA ~[]A, A any](a A) func(GA) GA {
+	return F.Bind2nd(array.Push[GA, A], a)
+}

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
@@ -34,8 +40,17 @@ 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
 	}
 }
+
+// SortBy implements a stable sort on the array given the provided ordering
+func SortBy[GA ~[]T, GO ~[]O.Ord[T], T any](ord GO) func(ma GA) GA {
+	return F.Pipe2(
+		ord,
+		Fold[GO](O.Monoid[T]()),
+		Sort[GA, T],
+	)
+}

array/generic/zip.go

@@ -0,0 +1,52 @@
+// 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"
+	N "github.com/IBM/fp-go/number"
+	T "github.com/IBM/fp-go/tuple"
+)
+
+// ZipWith applies a function to pairs of elements at the same index in two arrays, collecting the results in a new array. If one
+// input array is short, excess elements of the longer array are discarded.
+func ZipWith[AS ~[]A, BS ~[]B, CS ~[]C, FCT ~func(A, B) C, A, B, C any](fa AS, fb BS, f FCT) CS {
+	l := N.Min(len(fa), len(fb))
+	res := make(CS, l)
+	for i := l - 1; i >= 0; i-- {
+		res[i] = f(fa[i], fb[i])
+	}
+	return res
+}
+
+// Zip takes two arrays and returns an array of corresponding pairs. If one input array is short, excess elements of the
+// longer array are discarded
+func Zip[AS ~[]A, BS ~[]B, CS ~[]T.Tuple2[A, B], A, B any](fb BS) func(AS) CS {
+	return F.Bind23of3(ZipWith[AS, BS, CS, func(A, B) T.Tuple2[A, B]])(fb, T.MakeTuple2[A, B])
+}
+
+// Unzip is the function is reverse of [Zip]. Takes an array of pairs and return two corresponding arrays
+func Unzip[AS ~[]A, BS ~[]B, CS ~[]T.Tuple2[A, B], A, B any](cs CS) T.Tuple2[AS, BS] {
+	l := len(cs)
+	as := make(AS, l)
+	bs := make(BS, l)
+	for i := l - 1; i >= 0; i-- {
+		t := cs[i]
+		as[i] = t.F1
+		bs[i] = t.F2
+	}
+	return T.MakeTuple2(as, bs)
+}

array/sort.go

@@ -24,3 +24,13 @@ 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)
+}
+
+// SortBy implements a stable sort on the array given the provided ordering
+func SortBy[T any](ord []O.Ord[T]) func(ma []T) []T {
+	return G.SortBy[[]T, []O.Ord[T]](ord)
+}

array/zip.go

@@ -0,0 +1,38 @@
+// 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 array
+
+import (
+	G "github.com/IBM/fp-go/array/generic"
+	T "github.com/IBM/fp-go/tuple"
+)
+
+// ZipWith applies a function to pairs of elements at the same index in two arrays, collecting the results in a new array. If one
+// input array is short, excess elements of the longer array are discarded.
+func ZipWith[FCT ~func(A, B) C, A, B, C any](fa []A, fb []B, f FCT) []C {
+	return G.ZipWith[[]A, []B, []C, FCT](fa, fb, f)
+}
+
+// Zip takes two arrays and returns an array of corresponding pairs. If one input array is short, excess elements of the
+// longer array are discarded
+func Zip[A, B any](fb []B) func([]A) []T.Tuple2[A, B] {
+	return G.Zip[[]A, []B, []T.Tuple2[A, B]](fb)
+}
+
+// Unzip is the function is reverse of [Zip]. Takes an array of pairs and return two corresponding arrays
+func Unzip[A, B any](cs []T.Tuple2[A, B]) T.Tuple2[[]A, []B] {
+	return G.Unzip[[]A, []B, []T.Tuple2[A, B]](cs)
+}

array/zip_test.go

@@ -0,0 +1,56 @@
+// 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 array
+
+import (
+	"fmt"
+	"testing"
+
+	T "github.com/IBM/fp-go/tuple"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestZipWith(t *testing.T) {
+	left := From(1, 2, 3)
+	right := From("a", "b", "c", "d")
+
+	res := ZipWith(left, right, func(l int, r string) string {
+		return fmt.Sprintf("%s%d", r, l)
+	})
+
+	assert.Equal(t, From("a1", "b2", "c3"), res)
+}
+
+func TestZip(t *testing.T) {
+	left := From(1, 2, 3)
+	right := From("a", "b", "c", "d")
+
+	res := Zip[string](left)(right)
+
+	assert.Equal(t, From(T.MakeTuple2("a", 1), T.MakeTuple2("b", 2), T.MakeTuple2("c", 3)), res)
+}
+
+func TestUnzip(t *testing.T) {
+	left := From(1, 2, 3)
+	right := From("a", "b", "c")
+
+	zipped := Zip[string](left)(right)
+
+	unzipped := Unzip(zipped)
+
+	assert.Equal(t, right, unzipped.F1)
+	assert.Equal(t, left, unzipped.F2)
+}

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

@@ -20,6 +20,7 @@ import (
 	"log"
 	"os"
 	"path/filepath"
+	"strings"
 	"time"
 
 	C "github.com/urfave/cli/v2"
@@ -36,8 +37,51 @@ func writeTupleType(f *os.File, symbol string, i int) {
 	fmt.Fprintf(f, "]")
 }
 
+func makeTupleType(name string) func(i int) string {
+	return func(i int) string {
+		var buf strings.Builder
+		buf.WriteString(fmt.Sprintf("Tuple%d[", i))
+		for j := 0; j < i; j++ {
+			if j > 0 {
+				buf.WriteString(", ")
+			}
+			buf.WriteString(fmt.Sprintf("%s%d", name, j+1))
+		}
+		buf.WriteString("]")
+
+		return buf.String()
+	}
+}
+
+func generatePush(f *os.File, i int) {
+	tuple1 := makeTupleType("T")(i)
+	tuple2 := makeTupleType("T")(i + 1)
+	// Create the replicate version
+	fmt.Fprintf(f, "\n// Push%d creates a [Tuple%d] from a [Tuple%d] by appending a constant value\n", i, i+1, i)
+	fmt.Fprintf(f, "func Push%d[", i)
+	// function prototypes
+	for j := 0; j <= i; j++ {
+		if j > 0 {
+			fmt.Fprintf(f, ", ")
+		}
+		fmt.Fprintf(f, "T%d", j+1)
+	}
+	fmt.Fprintf(f, " any](value T%d) func(%s) %s {\n", i+1, tuple1, tuple2)
+	fmt.Fprintf(f, "  return func(t %s) %s {\n", tuple1, tuple2)
+	fmt.Fprintf(f, "    return MakeTuple%d(", i+1)
+	for j := 0; j < i; j++ {
+		if j > 0 {
+			fmt.Fprintf(f, ", ")
+		}
+		fmt.Fprintf(f, "t.F%d", j+1)
+	}
+	fmt.Fprintf(f, ", value)\n")
+	fmt.Fprintf(f, "  }\n")
+	fmt.Fprintf(f, "}\n")
+}
+
 func generateReplicate(f *os.File, i int) {
-	// Create the optionize version
+	// Create the replicate version
 	fmt.Fprintf(f, "\n// Replicate%d creates a [Tuple%d] with all fields set to the input value `t`\n", i, i)
 	fmt.Fprintf(f, "func Replicate%d[T any](t T) Tuple%d[", i, i)
 	for j := 1; j <= i; j++ {
@@ -355,7 +399,7 @@ 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)
 
@@ -398,6 +442,10 @@ import (
 		generateToArray(f, i)
 		// generate fromArray
 		generateFromArray(f, i)
+		// generate push
+		if i < count {
+			generatePush(f, i)
+		}
 	}
 
 	return nil

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
+// 2023-08-17 22:58:56.457404 +0200 CEST m=+0.024265101
 
 import (
 	"context"

context/readerioeither/generic/gen.go

@@ -1,30 +1,15 @@
-// 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
+// 2023-08-17 22:58:56.457404 +0200 CEST m=+0.024265101
 
 import (
 	"context"
 
 	E "github.com/IBM/fp-go/either"
-	RE "github.com/IBM/fp-go/readerioeither/generic"
 	A "github.com/IBM/fp-go/internal/apply"
+	RE "github.com/IBM/fp-go/readerioeither/generic"
 	T "github.com/IBM/fp-go/tuple"
 )
 

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

@@ -146,8 +146,8 @@ func FromOption[E, A any](onNone func() E) func(O.Option[A]) Either[E, A] {
 	return O.Fold(F.Nullary2(onNone, Left[A, E]), Right[E, A])
 }
 
-func ToOption[E, A any]() func(Either[E, A]) O.Option[A] {
-	return Fold(F.Ignore1of1[E](O.None[A]), O.Some[A])
+func ToOption[E, A any](ma Either[E, A]) O.Option[A] {
+	return MonadFold(ma, F.Ignore1of1[E](O.None[A]), O.Some[A])
 }
 
 func FromError[A any](f func(a A) error) func(A) Either[error, A] {
@@ -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

@@ -1,23 +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.
-
 // 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
-package either
+// 2023-08-17 22:58:57.9925506 +0200 CEST m=+0.033401101
 
+package either
 
 import (
 	A "github.com/IBM/fp-go/internal/apply"
@@ -77,7 +62,7 @@ func SequenceTuple1[E, T1 any](t T.Tuple1[Either[E, T1]]) Either[E, T.Tuple1[T1]
 }
 
 // TraverseTuple1 converts a [Tuple1] of [A] via transformation functions transforming [A] to [Either[E, A]] into a [Either[E, Tuple1]].
-func TraverseTuple1[F1 ~func(A1) Either[E, T1], E, A1, T1 any](f1 F1) func (T.Tuple1[A1]) Either[E, T.Tuple1[T1]] {
+func TraverseTuple1[F1 ~func(A1) Either[E, T1], E, A1, T1 any](f1 F1) func(T.Tuple1[A1]) Either[E, T.Tuple1[T1]] {
 	return func(t T.Tuple1[A1]) Either[E, T.Tuple1[T1]] {
 		return A.TraverseTuple1(
 			Map[E, T1, T.Tuple1[T1]],
@@ -125,7 +110,7 @@ func SequenceTuple2[E, T1, T2 any](t T.Tuple2[Either[E, T1], Either[E, T2]]) Eit
 }
 
 // TraverseTuple2 converts a [Tuple2] of [A] via transformation functions transforming [A] to [Either[E, A]] into a [Either[E, Tuple2]].
-func TraverseTuple2[F1 ~func(A1) Either[E, T1], F2 ~func(A2) Either[E, T2], E, A1, T1, A2, T2 any](f1 F1, f2 F2) func (T.Tuple2[A1, A2]) Either[E, T.Tuple2[T1, T2]] {
+func TraverseTuple2[F1 ~func(A1) Either[E, T1], F2 ~func(A2) Either[E, T2], E, A1, T1, A2, T2 any](f1 F1, f2 F2) func(T.Tuple2[A1, A2]) Either[E, T.Tuple2[T1, T2]] {
 	return func(t T.Tuple2[A1, A2]) Either[E, T.Tuple2[T1, T2]] {
 		return A.TraverseTuple2(
 			Map[E, T1, func(T2) T.Tuple2[T1, T2]],
@@ -178,7 +163,7 @@ func SequenceTuple3[E, T1, T2, T3 any](t T.Tuple3[Either[E, T1], Either[E, T2],
 }
 
 // TraverseTuple3 converts a [Tuple3] of [A] via transformation functions transforming [A] to [Either[E, A]] into a [Either[E, Tuple3]].
-func TraverseTuple3[F1 ~func(A1) Either[E, T1], F2 ~func(A2) Either[E, T2], F3 ~func(A3) Either[E, T3], E, A1, T1, A2, T2, A3, T3 any](f1 F1, f2 F2, f3 F3) func (T.Tuple3[A1, A2, A3]) Either[E, T.Tuple3[T1, T2, T3]] {
+func TraverseTuple3[F1 ~func(A1) Either[E, T1], F2 ~func(A2) Either[E, T2], F3 ~func(A3) Either[E, T3], E, A1, T1, A2, T2, A3, T3 any](f1 F1, f2 F2, f3 F3) func(T.Tuple3[A1, A2, A3]) Either[E, T.Tuple3[T1, T2, T3]] {
 	return func(t T.Tuple3[A1, A2, A3]) Either[E, T.Tuple3[T1, T2, T3]] {
 		return A.TraverseTuple3(
 			Map[E, T1, func(T2) func(T3) T.Tuple3[T1, T2, T3]],
@@ -236,7 +221,7 @@ func SequenceTuple4[E, T1, T2, T3, T4 any](t T.Tuple4[Either[E, T1], Either[E, T
 }
 
 // TraverseTuple4 converts a [Tuple4] of [A] via transformation functions transforming [A] to [Either[E, A]] into a [Either[E, Tuple4]].
-func TraverseTuple4[F1 ~func(A1) Either[E, T1], F2 ~func(A2) Either[E, T2], F3 ~func(A3) Either[E, T3], F4 ~func(A4) Either[E, T4], E, A1, T1, A2, T2, A3, T3, A4, T4 any](f1 F1, f2 F2, f3 F3, f4 F4) func (T.Tuple4[A1, A2, A3, A4]) Either[E, T.Tuple4[T1, T2, T3, T4]] {
+func TraverseTuple4[F1 ~func(A1) Either[E, T1], F2 ~func(A2) Either[E, T2], F3 ~func(A3) Either[E, T3], F4 ~func(A4) Either[E, T4], E, A1, T1, A2, T2, A3, T3, A4, T4 any](f1 F1, f2 F2, f3 F3, f4 F4) func(T.Tuple4[A1, A2, A3, A4]) Either[E, T.Tuple4[T1, T2, T3, T4]] {
 	return func(t T.Tuple4[A1, A2, A3, A4]) Either[E, T.Tuple4[T1, T2, T3, T4]] {
 		return A.TraverseTuple4(
 			Map[E, T1, func(T2) func(T3) func(T4) T.Tuple4[T1, T2, T3, T4]],
@@ -299,7 +284,7 @@ func SequenceTuple5[E, T1, T2, T3, T4, T5 any](t T.Tuple5[Either[E, T1], Either[
 }
 
 // TraverseTuple5 converts a [Tuple5] of [A] via transformation functions transforming [A] to [Either[E, A]] into a [Either[E, Tuple5]].
-func TraverseTuple5[F1 ~func(A1) Either[E, T1], F2 ~func(A2) Either[E, T2], F3 ~func(A3) Either[E, T3], F4 ~func(A4) Either[E, T4], F5 ~func(A5) Either[E, T5], E, A1, T1, A2, T2, A3, T3, A4, T4, A5, T5 any](f1 F1, f2 F2, f3 F3, f4 F4, f5 F5) func (T.Tuple5[A1, A2, A3, A4, A5]) Either[E, T.Tuple5[T1, T2, T3, T4, T5]] {
+func TraverseTuple5[F1 ~func(A1) Either[E, T1], F2 ~func(A2) Either[E, T2], F3 ~func(A3) Either[E, T3], F4 ~func(A4) Either[E, T4], F5 ~func(A5) Either[E, T5], E, A1, T1, A2, T2, A3, T3, A4, T4, A5, T5 any](f1 F1, f2 F2, f3 F3, f4 F4, f5 F5) func(T.Tuple5[A1, A2, A3, A4, A5]) Either[E, T.Tuple5[T1, T2, T3, T4, T5]] {
 	return func(t T.Tuple5[A1, A2, A3, A4, A5]) Either[E, T.Tuple5[T1, T2, T3, T4, T5]] {
 		return A.TraverseTuple5(
 			Map[E, T1, func(T2) func(T3) func(T4) func(T5) T.Tuple5[T1, T2, T3, T4, T5]],
@@ -367,7 +352,7 @@ func SequenceTuple6[E, T1, T2, T3, T4, T5, T6 any](t T.Tuple6[Either[E, T1], Eit
 }
 
 // TraverseTuple6 converts a [Tuple6] of [A] via transformation functions transforming [A] to [Either[E, A]] into a [Either[E, Tuple6]].
-func TraverseTuple6[F1 ~func(A1) Either[E, T1], F2 ~func(A2) Either[E, T2], F3 ~func(A3) Either[E, T3], F4 ~func(A4) Either[E, T4], F5 ~func(A5) Either[E, T5], F6 ~func(A6) Either[E, T6], E, A1, T1, A2, T2, A3, T3, A4, T4, A5, T5, A6, T6 any](f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6) func (T.Tuple6[A1, A2, A3, A4, A5, A6]) Either[E, T.Tuple6[T1, T2, T3, T4, T5, T6]] {
+func TraverseTuple6[F1 ~func(A1) Either[E, T1], F2 ~func(A2) Either[E, T2], F3 ~func(A3) Either[E, T3], F4 ~func(A4) Either[E, T4], F5 ~func(A5) Either[E, T5], F6 ~func(A6) Either[E, T6], E, A1, T1, A2, T2, A3, T3, A4, T4, A5, T5, A6, T6 any](f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6) func(T.Tuple6[A1, A2, A3, A4, A5, A6]) Either[E, T.Tuple6[T1, T2, T3, T4, T5, T6]] {
 	return func(t T.Tuple6[A1, A2, A3, A4, A5, A6]) Either[E, T.Tuple6[T1, T2, T3, T4, T5, T6]] {
 		return A.TraverseTuple6(
 			Map[E, T1, func(T2) func(T3) func(T4) func(T5) func(T6) T.Tuple6[T1, T2, T3, T4, T5, T6]],
@@ -440,7 +425,7 @@ func SequenceTuple7[E, T1, T2, T3, T4, T5, T6, T7 any](t T.Tuple7[Either[E, T1],
 }
 
 // TraverseTuple7 converts a [Tuple7] of [A] via transformation functions transforming [A] to [Either[E, A]] into a [Either[E, Tuple7]].
-func TraverseTuple7[F1 ~func(A1) Either[E, T1], F2 ~func(A2) Either[E, T2], F3 ~func(A3) Either[E, T3], F4 ~func(A4) Either[E, T4], F5 ~func(A5) Either[E, T5], F6 ~func(A6) Either[E, T6], F7 ~func(A7) Either[E, T7], E, A1, T1, A2, T2, A3, T3, A4, T4, A5, T5, A6, T6, A7, T7 any](f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7) func (T.Tuple7[A1, A2, A3, A4, A5, A6, A7]) Either[E, T.Tuple7[T1, T2, T3, T4, T5, T6, T7]] {
+func TraverseTuple7[F1 ~func(A1) Either[E, T1], F2 ~func(A2) Either[E, T2], F3 ~func(A3) Either[E, T3], F4 ~func(A4) Either[E, T4], F5 ~func(A5) Either[E, T5], F6 ~func(A6) Either[E, T6], F7 ~func(A7) Either[E, T7], E, A1, T1, A2, T2, A3, T3, A4, T4, A5, T5, A6, T6, A7, T7 any](f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7) func(T.Tuple7[A1, A2, A3, A4, A5, A6, A7]) Either[E, T.Tuple7[T1, T2, T3, T4, T5, T6, T7]] {
 	return func(t T.Tuple7[A1, A2, A3, A4, A5, A6, A7]) Either[E, T.Tuple7[T1, T2, T3, T4, T5, T6, T7]] {
 		return A.TraverseTuple7(
 			Map[E, T1, func(T2) func(T3) func(T4) func(T5) func(T6) func(T7) T.Tuple7[T1, T2, T3, T4, T5, T6, T7]],
@@ -518,7 +503,7 @@ func SequenceTuple8[E, T1, T2, T3, T4, T5, T6, T7, T8 any](t T.Tuple8[Either[E,
 }
 
 // TraverseTuple8 converts a [Tuple8] of [A] via transformation functions transforming [A] to [Either[E, A]] into a [Either[E, Tuple8]].
-func TraverseTuple8[F1 ~func(A1) Either[E, T1], F2 ~func(A2) Either[E, T2], F3 ~func(A3) Either[E, T3], F4 ~func(A4) Either[E, T4], F5 ~func(A5) Either[E, T5], F6 ~func(A6) Either[E, T6], F7 ~func(A7) Either[E, T7], F8 ~func(A8) Either[E, T8], E, A1, T1, A2, T2, A3, T3, A4, T4, A5, T5, A6, T6, A7, T7, A8, T8 any](f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7, f8 F8) func (T.Tuple8[A1, A2, A3, A4, A5, A6, A7, A8]) Either[E, T.Tuple8[T1, T2, T3, T4, T5, T6, T7, T8]] {
+func TraverseTuple8[F1 ~func(A1) Either[E, T1], F2 ~func(A2) Either[E, T2], F3 ~func(A3) Either[E, T3], F4 ~func(A4) Either[E, T4], F5 ~func(A5) Either[E, T5], F6 ~func(A6) Either[E, T6], F7 ~func(A7) Either[E, T7], F8 ~func(A8) Either[E, T8], E, A1, T1, A2, T2, A3, T3, A4, T4, A5, T5, A6, T6, A7, T7, A8, T8 any](f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7, f8 F8) func(T.Tuple8[A1, A2, A3, A4, A5, A6, A7, A8]) Either[E, T.Tuple8[T1, T2, T3, T4, T5, T6, T7, T8]] {
 	return func(t T.Tuple8[A1, A2, A3, A4, A5, A6, A7, A8]) Either[E, T.Tuple8[T1, T2, T3, T4, T5, T6, T7, T8]] {
 		return A.TraverseTuple8(
 			Map[E, T1, func(T2) func(T3) func(T4) func(T5) func(T6) func(T7) func(T8) T.Tuple8[T1, T2, T3, T4, T5, T6, T7, T8]],
@@ -601,7 +586,7 @@ func SequenceTuple9[E, T1, T2, T3, T4, T5, T6, T7, T8, T9 any](t T.Tuple9[Either
 }
 
 // TraverseTuple9 converts a [Tuple9] of [A] via transformation functions transforming [A] to [Either[E, A]] into a [Either[E, Tuple9]].
-func TraverseTuple9[F1 ~func(A1) Either[E, T1], F2 ~func(A2) Either[E, T2], F3 ~func(A3) Either[E, T3], F4 ~func(A4) Either[E, T4], F5 ~func(A5) Either[E, T5], F6 ~func(A6) Either[E, T6], F7 ~func(A7) Either[E, T7], F8 ~func(A8) Either[E, T8], F9 ~func(A9) Either[E, T9], E, A1, T1, A2, T2, A3, T3, A4, T4, A5, T5, A6, T6, A7, T7, A8, T8, A9, T9 any](f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7, f8 F8, f9 F9) func (T.Tuple9[A1, A2, A3, A4, A5, A6, A7, A8, A9]) Either[E, T.Tuple9[T1, T2, T3, T4, T5, T6, T7, T8, T9]] {
+func TraverseTuple9[F1 ~func(A1) Either[E, T1], F2 ~func(A2) Either[E, T2], F3 ~func(A3) Either[E, T3], F4 ~func(A4) Either[E, T4], F5 ~func(A5) Either[E, T5], F6 ~func(A6) Either[E, T6], F7 ~func(A7) Either[E, T7], F8 ~func(A8) Either[E, T8], F9 ~func(A9) Either[E, T9], E, A1, T1, A2, T2, A3, T3, A4, T4, A5, T5, A6, T6, A7, T7, A8, T8, A9, T9 any](f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7, f8 F8, f9 F9) func(T.Tuple9[A1, A2, A3, A4, A5, A6, A7, A8, A9]) Either[E, T.Tuple9[T1, T2, T3, T4, T5, T6, T7, T8, T9]] {
 	return func(t T.Tuple9[A1, A2, A3, A4, A5, A6, A7, A8, A9]) Either[E, T.Tuple9[T1, T2, T3, T4, T5, T6, T7, T8, T9]] {
 		return A.TraverseTuple9(
 			Map[E, T1, func(T2) func(T3) func(T4) func(T5) func(T6) func(T7) func(T8) func(T9) T.Tuple9[T1, T2, T3, T4, T5, T6, T7, T8, T9]],
@@ -689,7 +674,7 @@ func SequenceTuple10[E, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10 any](t T.Tuple10
 }
 
 // TraverseTuple10 converts a [Tuple10] of [A] via transformation functions transforming [A] to [Either[E, A]] into a [Either[E, Tuple10]].
-func TraverseTuple10[F1 ~func(A1) Either[E, T1], F2 ~func(A2) Either[E, T2], F3 ~func(A3) Either[E, T3], F4 ~func(A4) Either[E, T4], F5 ~func(A5) Either[E, T5], F6 ~func(A6) Either[E, T6], F7 ~func(A7) Either[E, T7], F8 ~func(A8) Either[E, T8], F9 ~func(A9) Either[E, T9], F10 ~func(A10) Either[E, T10], E, A1, T1, A2, T2, A3, T3, A4, T4, A5, T5, A6, T6, A7, T7, A8, T8, A9, T9, A10, T10 any](f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7, f8 F8, f9 F9, f10 F10) func (T.Tuple10[A1, A2, A3, A4, A5, A6, A7, A8, A9, A10]) Either[E, T.Tuple10[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10]] {
+func TraverseTuple10[F1 ~func(A1) Either[E, T1], F2 ~func(A2) Either[E, T2], F3 ~func(A3) Either[E, T3], F4 ~func(A4) Either[E, T4], F5 ~func(A5) Either[E, T5], F6 ~func(A6) Either[E, T6], F7 ~func(A7) Either[E, T7], F8 ~func(A8) Either[E, T8], F9 ~func(A9) Either[E, T9], F10 ~func(A10) Either[E, T10], E, A1, T1, A2, T2, A3, T3, A4, T4, A5, T5, A6, T6, A7, T7, A8, T8, A9, T9, A10, T10 any](f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7, f8 F8, f9 F9, f10 F10) func(T.Tuple10[A1, A2, A3, A4, A5, A6, A7, A8, A9, A10]) Either[E, T.Tuple10[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10]] {
 	return func(t T.Tuple10[A1, A2, A3, A4, A5, A6, A7, A8, A9, A10]) Either[E, T.Tuple10[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10]] {
 		return A.TraverseTuple10(
 			Map[E, T1, func(T2) func(T3) func(T4) func(T5) func(T6) func(T7) func(T8) func(T9) func(T10) T.Tuple10[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10]],

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

@@ -1,22 +1,9 @@
-// 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
+// 2023-08-17 22:59:01.9404821 +0200 CEST m=+0.161366801
+
 package function
+
 // Combinations for a total of 1 arguments
 
 // Bind1of1 takes a function with 1 parameters and returns a new function with 1 parameters that will bind these parameters to the positions [1] of the original function.
@@ -35,6 +22,7 @@ func Ignore1of1[T1 any, F ~func() R, R any](f F) func(T1) R {
 		return f()
 	}
 }
+
 // Combinations for a total of 2 arguments
 
 // Bind1of2 takes a function with 2 parameters and returns a new function with 1 parameters that will bind these parameters to the positions [1] of the original function.
@@ -87,6 +75,7 @@ func Ignore12of2[T1, T2 any, F ~func() R, R any](f F) func(T1, T2) R {
 		return f()
 	}
 }
+
 // Combinations for a total of 3 arguments
 
 // Bind1of3 takes a function with 3 parameters and returns a new function with 1 parameters that will bind these parameters to the positions [1] of the original function.
@@ -207,6 +196,7 @@ func Ignore123of3[T1, T2, T3 any, F ~func() R, R any](f F) func(T1, T2, T3) R {
 		return f()
 	}
 }
+
 // Combinations for a total of 4 arguments
 
 // Bind1of4 takes a function with 4 parameters and returns a new function with 1 parameters that will bind these parameters to the positions [1] of the original function.

function/cache.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 function
+
+import (
+	G "github.com/IBM/fp-go/function/generic"
+)
+
+// Cache converts a unary function into a unary function that caches the value depending on the parameter
+func Cache[K comparable, T any](f func(K) T) func(K) T {
+	return G.Cache(f)
+}
+
+// ContramapCache converts a unary function into a unary function that caches the value depending on the parameter
+func ContramapCache[A any, K comparable, T any](kf func(A) K) func(func(A) T) func(A) T {
+	return G.ContramapCache[func(A) T](kf)
+}

function/cache_test.go

@@ -0,0 +1,50 @@
+// 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 (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestCache(t *testing.T) {
+	var count int
+
+	withSideEffect := func(n int) int {
+		count++
+		return n
+	}
+
+	cached := Cache(withSideEffect)
+
+	assert.Equal(t, 0, count)
+
+	assert.Equal(t, 10, cached(10))
+	assert.Equal(t, 1, count)
+
+	assert.Equal(t, 10, cached(10))
+	assert.Equal(t, 1, count)
+
+	assert.Equal(t, 20, cached(20))
+	assert.Equal(t, 2, count)
+
+	assert.Equal(t, 20, cached(20))
+	assert.Equal(t, 2, count)
+
+	assert.Equal(t, 10, cached(10))
+	assert.Equal(t, 2, count)
+}

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
+// 2023-08-17 22:58:59.8663985 +0200 CEST m=+0.103744101
+
 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
@@ -30,12 +16,14 @@ func Variadic0[V, R any](f func([]V) R) func(...V) R {
 		return f(v)
 	}
 }
+
 // Unvariadic0 converts a function taking 0 parameters and a final variadic argument into a function with 0 parameters but a final slice argument
 func Unvariadic0[V, R any](f func(...V) R) func([]V) R {
 	return func(v []V) R {
 		return f(v...)
 	}
 }
+
 // Pipe1 takes an initial value t0 and successively applies 1 functions where the input of a function is the return value of the previous function
 // The final return value is the result of the last function application
 func Pipe1[F1 ~func(T0) T1, T0, T1 any](t0 T0, f1 F1) T1 {
@@ -80,12 +68,14 @@ func Variadic1[T1, V, R any](f func(T1, []V) R) func(T1, ...V) R {
 		return f(t1, v)
 	}
 }
+
 // Unvariadic1 converts a function taking 1 parameters and a final variadic argument into a function with 1 parameters but a final slice argument
 func Unvariadic1[T1, V, R any](f func(T1, ...V) R) func(T1, []V) R {
 	return func(t1 T1, v []V) R {
 		return f(t1, v...)
 	}
 }
+
 // Pipe2 takes an initial value t0 and successively applies 2 functions where the input of a function is the return value of the previous function
 // The final return value is the result of the last function application
 func Pipe2[F1 ~func(T0) T1, F2 ~func(T1) T2, T0, T1, T2 any](t0 T0, f1 F1, f2 F2) T2 {
@@ -133,12 +123,14 @@ func Variadic2[T1, T2, V, R any](f func(T1, T2, []V) R) func(T1, T2, ...V) R {
 		return f(t1, t2, v)
 	}
 }
+
 // Unvariadic2 converts a function taking 2 parameters and a final variadic argument into a function with 2 parameters but a final slice argument
 func Unvariadic2[T1, T2, V, R any](f func(T1, T2, ...V) R) func(T1, T2, []V) R {
 	return func(t1 T1, t2 T2, v []V) R {
 		return f(t1, t2, v...)
 	}
 }
+
 // Pipe3 takes an initial value t0 and successively applies 3 functions where the input of a function is the return value of the previous function
 // The final return value is the result of the last function application
 func Pipe3[F1 ~func(T0) T1, F2 ~func(T1) T2, F3 ~func(T2) T3, T0, T1, T2, T3 any](t0 T0, f1 F1, f2 F2, f3 F3) T3 {
@@ -189,12 +181,14 @@ func Variadic3[T1, T2, T3, V, R any](f func(T1, T2, T3, []V) R) func(T1, T2, T3,
 		return f(t1, t2, t3, v)
 	}
 }
+
 // Unvariadic3 converts a function taking 3 parameters and a final variadic argument into a function with 3 parameters but a final slice argument
 func Unvariadic3[T1, T2, T3, V, R any](f func(T1, T2, T3, ...V) R) func(T1, T2, T3, []V) R {
 	return func(t1 T1, t2 T2, t3 T3, v []V) R {
 		return f(t1, t2, t3, v...)
 	}
 }
+
 // Pipe4 takes an initial value t0 and successively applies 4 functions where the input of a function is the return value of the previous function
 // The final return value is the result of the last function application
 func Pipe4[F1 ~func(T0) T1, F2 ~func(T1) T2, F3 ~func(T2) T3, F4 ~func(T3) T4, T0, T1, T2, T3, T4 any](t0 T0, f1 F1, f2 F2, f3 F3, f4 F4) T4 {
@@ -248,12 +242,14 @@ func Variadic4[T1, T2, T3, T4, V, R any](f func(T1, T2, T3, T4, []V) R) func(T1,
 		return f(t1, t2, t3, t4, v)
 	}
 }
+
 // Unvariadic4 converts a function taking 4 parameters and a final variadic argument into a function with 4 parameters but a final slice argument
 func Unvariadic4[T1, T2, T3, T4, V, R any](f func(T1, T2, T3, T4, ...V) R) func(T1, T2, T3, T4, []V) R {
 	return func(t1 T1, t2 T2, t3 T3, t4 T4, v []V) R {
 		return f(t1, t2, t3, t4, v...)
 	}
 }
+
 // Pipe5 takes an initial value t0 and successively applies 5 functions where the input of a function is the return value of the previous function
 // The final return value is the result of the last function application
 func Pipe5[F1 ~func(T0) T1, F2 ~func(T1) T2, F3 ~func(T2) T3, F4 ~func(T3) T4, F5 ~func(T4) T5, T0, T1, T2, T3, T4, T5 any](t0 T0, f1 F1, f2 F2, f3 F3, f4 F4, f5 F5) T5 {
@@ -310,12 +306,14 @@ func Variadic5[T1, T2, T3, T4, T5, V, R any](f func(T1, T2, T3, T4, T5, []V) R)
 		return f(t1, t2, t3, t4, t5, v)
 	}
 }
+
 // Unvariadic5 converts a function taking 5 parameters and a final variadic argument into a function with 5 parameters but a final slice argument
 func Unvariadic5[T1, T2, T3, T4, T5, V, R any](f func(T1, T2, T3, T4, T5, ...V) R) func(T1, T2, T3, T4, T5, []V) R {
 	return func(t1 T1, t2 T2, t3 T3, t4 T4, t5 T5, v []V) R {
 		return f(t1, t2, t3, t4, t5, v...)
 	}
 }
+
 // Pipe6 takes an initial value t0 and successively applies 6 functions where the input of a function is the return value of the previous function
 // The final return value is the result of the last function application
 func Pipe6[F1 ~func(T0) T1, F2 ~func(T1) T2, F3 ~func(T2) T3, F4 ~func(T3) T4, F5 ~func(T4) T5, F6 ~func(T5) T6, T0, T1, T2, T3, T4, T5, T6 any](t0 T0, f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6) T6 {
@@ -375,12 +373,14 @@ func Variadic6[T1, T2, T3, T4, T5, T6, V, R any](f func(T1, T2, T3, T4, T5, T6,
 		return f(t1, t2, t3, t4, t5, t6, v)
 	}
 }
+
 // Unvariadic6 converts a function taking 6 parameters and a final variadic argument into a function with 6 parameters but a final slice argument
 func Unvariadic6[T1, T2, T3, T4, T5, T6, V, R any](f func(T1, T2, T3, T4, T5, T6, ...V) R) func(T1, T2, T3, T4, T5, T6, []V) R {
 	return func(t1 T1, t2 T2, t3 T3, t4 T4, t5 T5, t6 T6, v []V) R {
 		return f(t1, t2, t3, t4, t5, t6, v...)
 	}
 }
+
 // Pipe7 takes an initial value t0 and successively applies 7 functions where the input of a function is the return value of the previous function
 // The final return value is the result of the last function application
 func Pipe7[F1 ~func(T0) T1, F2 ~func(T1) T2, F3 ~func(T2) T3, F4 ~func(T3) T4, F5 ~func(T4) T5, F6 ~func(T5) T6, F7 ~func(T6) T7, T0, T1, T2, T3, T4, T5, T6, T7 any](t0 T0, f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7) T7 {
@@ -443,12 +443,14 @@ func Variadic7[T1, T2, T3, T4, T5, T6, T7, V, R any](f func(T1, T2, T3, T4, T5,
 		return f(t1, t2, t3, t4, t5, t6, t7, v)
 	}
 }
+
 // Unvariadic7 converts a function taking 7 parameters and a final variadic argument into a function with 7 parameters but a final slice argument
 func Unvariadic7[T1, T2, T3, T4, T5, T6, T7, V, R any](f func(T1, T2, T3, T4, T5, T6, T7, ...V) R) func(T1, T2, T3, T4, T5, T6, T7, []V) R {
 	return func(t1 T1, t2 T2, t3 T3, t4 T4, t5 T5, t6 T6, t7 T7, v []V) R {
 		return f(t1, t2, t3, t4, t5, t6, t7, v...)
 	}
 }
+
 // Pipe8 takes an initial value t0 and successively applies 8 functions where the input of a function is the return value of the previous function
 // The final return value is the result of the last function application
 func Pipe8[F1 ~func(T0) T1, F2 ~func(T1) T2, F3 ~func(T2) T3, F4 ~func(T3) T4, F5 ~func(T4) T5, F6 ~func(T5) T6, F7 ~func(T6) T7, F8 ~func(T7) T8, T0, T1, T2, T3, T4, T5, T6, T7, T8 any](t0 T0, f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7, f8 F8) T8 {
@@ -514,12 +516,14 @@ func Variadic8[T1, T2, T3, T4, T5, T6, T7, T8, V, R any](f func(T1, T2, T3, T4,
 		return f(t1, t2, t3, t4, t5, t6, t7, t8, v)
 	}
 }
+
 // Unvariadic8 converts a function taking 8 parameters and a final variadic argument into a function with 8 parameters but a final slice argument
 func Unvariadic8[T1, T2, T3, T4, T5, T6, T7, T8, V, R any](f func(T1, T2, T3, T4, T5, T6, T7, T8, ...V) R) func(T1, T2, T3, T4, T5, T6, T7, T8, []V) R {
 	return func(t1 T1, t2 T2, t3 T3, t4 T4, t5 T5, t6 T6, t7 T7, t8 T8, v []V) R {
 		return f(t1, t2, t3, t4, t5, t6, t7, t8, v...)
 	}
 }
+
 // Pipe9 takes an initial value t0 and successively applies 9 functions where the input of a function is the return value of the previous function
 // The final return value is the result of the last function application
 func Pipe9[F1 ~func(T0) T1, F2 ~func(T1) T2, F3 ~func(T2) T3, F4 ~func(T3) T4, F5 ~func(T4) T5, F6 ~func(T5) T6, F7 ~func(T6) T7, F8 ~func(T7) T8, F9 ~func(T8) T9, T0, T1, T2, T3, T4, T5, T6, T7, T8, T9 any](t0 T0, f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7, f8 F8, f9 F9) T9 {
@@ -588,12 +592,14 @@ func Variadic9[T1, T2, T3, T4, T5, T6, T7, T8, T9, V, R any](f func(T1, T2, T3,
 		return f(t1, t2, t3, t4, t5, t6, t7, t8, t9, v)
 	}
 }
+
 // Unvariadic9 converts a function taking 9 parameters and a final variadic argument into a function with 9 parameters but a final slice argument
 func Unvariadic9[T1, T2, T3, T4, T5, T6, T7, T8, T9, V, R any](f func(T1, T2, T3, T4, T5, T6, T7, T8, T9, ...V) R) func(T1, T2, T3, T4, T5, T6, T7, T8, T9, []V) R {
 	return func(t1 T1, t2 T2, t3 T3, t4 T4, t5 T5, t6 T6, t7 T7, t8 T8, t9 T9, v []V) R {
 		return f(t1, t2, t3, t4, t5, t6, t7, t8, t9, v...)
 	}
 }
+
 // Pipe10 takes an initial value t0 and successively applies 10 functions where the input of a function is the return value of the previous function
 // The final return value is the result of the last function application
 func Pipe10[F1 ~func(T0) T1, F2 ~func(T1) T2, F3 ~func(T2) T3, F4 ~func(T3) T4, F5 ~func(T4) T5, F6 ~func(T5) T6, F7 ~func(T6) T7, F8 ~func(T7) T8, F9 ~func(T8) T9, F10 ~func(T9) T10, T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10 any](t0 T0, f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7, f8 F8, f9 F9, f10 F10) T10 {
@@ -665,12 +671,14 @@ func Variadic10[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, V, R any](f func(T1, T2
 		return f(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, v)
 	}
 }
+
 // Unvariadic10 converts a function taking 10 parameters and a final variadic argument into a function with 10 parameters but a final slice argument
 func Unvariadic10[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, V, R any](f func(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, ...V) R) func(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, []V) R {
 	return func(t1 T1, t2 T2, t3 T3, t4 T4, t5 T5, t6 T6, t7 T7, t8 T8, t9 T9, t10 T10, v []V) R {
 		return f(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, v...)
 	}
 }
+
 // Pipe11 takes an initial value t0 and successively applies 11 functions where the input of a function is the return value of the previous function
 // The final return value is the result of the last function application
 func Pipe11[F1 ~func(T0) T1, F2 ~func(T1) T2, F3 ~func(T2) T3, F4 ~func(T3) T4, F5 ~func(T4) T5, F6 ~func(T5) T6, F7 ~func(T6) T7, F8 ~func(T7) T8, F9 ~func(T8) T9, F10 ~func(T9) T10, F11 ~func(T10) T11, T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11 any](t0 T0, f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7, f8 F8, f9 F9, f10 F10, f11 F11) T11 {
@@ -745,12 +753,14 @@ func Variadic11[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, V, R any](f func(T
 		return f(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, v)
 	}
 }
+
 // Unvariadic11 converts a function taking 11 parameters and a final variadic argument into a function with 11 parameters but a final slice argument
 func Unvariadic11[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, V, R any](f func(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, ...V) R) func(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, []V) R {
 	return func(t1 T1, t2 T2, t3 T3, t4 T4, t5 T5, t6 T6, t7 T7, t8 T8, t9 T9, t10 T10, t11 T11, v []V) R {
 		return f(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, v...)
 	}
 }
+
 // Pipe12 takes an initial value t0 and successively applies 12 functions where the input of a function is the return value of the previous function
 // The final return value is the result of the last function application
 func Pipe12[F1 ~func(T0) T1, F2 ~func(T1) T2, F3 ~func(T2) T3, F4 ~func(T3) T4, F5 ~func(T4) T5, F6 ~func(T5) T6, F7 ~func(T6) T7, F8 ~func(T7) T8, F9 ~func(T8) T9, F10 ~func(T9) T10, F11 ~func(T10) T11, F12 ~func(T11) T12, T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12 any](t0 T0, f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7, f8 F8, f9 F9, f10 F10, f11 F11, f12 F12) T12 {
@@ -828,12 +838,14 @@ func Variadic12[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, V, R any](f f
 		return f(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, v)
 	}
 }
+
 // Unvariadic12 converts a function taking 12 parameters and a final variadic argument into a function with 12 parameters but a final slice argument
 func Unvariadic12[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, V, R any](f func(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, ...V) R) func(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, []V) R {
 	return func(t1 T1, t2 T2, t3 T3, t4 T4, t5 T5, t6 T6, t7 T7, t8 T8, t9 T9, t10 T10, t11 T11, t12 T12, v []V) R {
 		return f(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, v...)
 	}
 }
+
 // Pipe13 takes an initial value t0 and successively applies 13 functions where the input of a function is the return value of the previous function
 // The final return value is the result of the last function application
 func Pipe13[F1 ~func(T0) T1, F2 ~func(T1) T2, F3 ~func(T2) T3, F4 ~func(T3) T4, F5 ~func(T4) T5, F6 ~func(T5) T6, F7 ~func(T6) T7, F8 ~func(T7) T8, F9 ~func(T8) T9, F10 ~func(T9) T10, F11 ~func(T10) T11, F12 ~func(T11) T12, F13 ~func(T12) T13, T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13 any](t0 T0, f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7, f8 F8, f9 F9, f10 F10, f11 F11, f12 F12, f13 F13) T13 {
@@ -914,12 +926,14 @@ func Variadic13[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, V, R any
 		return f(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, v)
 	}
 }
+
 // Unvariadic13 converts a function taking 13 parameters and a final variadic argument into a function with 13 parameters but a final slice argument
 func Unvariadic13[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, V, R any](f func(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, ...V) R) func(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, []V) R {
 	return func(t1 T1, t2 T2, t3 T3, t4 T4, t5 T5, t6 T6, t7 T7, t8 T8, t9 T9, t10 T10, t11 T11, t12 T12, t13 T13, v []V) R {
 		return f(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, v...)
 	}
 }
+
 // Pipe14 takes an initial value t0 and successively applies 14 functions where the input of a function is the return value of the previous function
 // The final return value is the result of the last function application
 func Pipe14[F1 ~func(T0) T1, F2 ~func(T1) T2, F3 ~func(T2) T3, F4 ~func(T3) T4, F5 ~func(T4) T5, F6 ~func(T5) T6, F7 ~func(T6) T7, F8 ~func(T7) T8, F9 ~func(T8) T9, F10 ~func(T9) T10, F11 ~func(T10) T11, F12 ~func(T11) T12, F13 ~func(T12) T13, F14 ~func(T13) T14, T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14 any](t0 T0, f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7, f8 F8, f9 F9, f10 F10, f11 F11, f12 F12, f13 F13, f14 F14) T14 {
@@ -1003,12 +1017,14 @@ func Variadic14[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, V,
 		return f(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, v)
 	}
 }
+
 // Unvariadic14 converts a function taking 14 parameters and a final variadic argument into a function with 14 parameters but a final slice argument
 func Unvariadic14[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, V, R any](f func(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, ...V) R) func(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, []V) R {
 	return func(t1 T1, t2 T2, t3 T3, t4 T4, t5 T5, t6 T6, t7 T7, t8 T8, t9 T9, t10 T10, t11 T11, t12 T12, t13 T13, t14 T14, v []V) R {
 		return f(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, v...)
 	}
 }
+
 // Pipe15 takes an initial value t0 and successively applies 15 functions where the input of a function is the return value of the previous function
 // The final return value is the result of the last function application
 func Pipe15[F1 ~func(T0) T1, F2 ~func(T1) T2, F3 ~func(T2) T3, F4 ~func(T3) T4, F5 ~func(T4) T5, F6 ~func(T5) T6, F7 ~func(T6) T7, F8 ~func(T7) T8, F9 ~func(T8) T9, F10 ~func(T9) T10, F11 ~func(T10) T11, F12 ~func(T11) T12, F13 ~func(T12) T13, F14 ~func(T13) T14, F15 ~func(T14) T15, T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15 any](t0 T0, f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7, f8 F8, f9 F9, f10 F10, f11 F11, f12 F12, f13 F13, f14 F14, f15 F15) T15 {
@@ -1095,12 +1111,14 @@ func Variadic15[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15
 		return f(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, v)
 	}
 }
+
 // Unvariadic15 converts a function taking 15 parameters and a final variadic argument into a function with 15 parameters but a final slice argument
 func Unvariadic15[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, V, R any](f func(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, ...V) R) func(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, []V) R {
 	return func(t1 T1, t2 T2, t3 T3, t4 T4, t5 T5, t6 T6, t7 T7, t8 T8, t9 T9, t10 T10, t11 T11, t12 T12, t13 T13, t14 T14, t15 T15, v []V) R {
 		return f(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, v...)
 	}
 }
+
 // Pipe16 takes an initial value t0 and successively applies 16 functions where the input of a function is the return value of the previous function
 // The final return value is the result of the last function application
 func Pipe16[F1 ~func(T0) T1, F2 ~func(T1) T2, F3 ~func(T2) T3, F4 ~func(T3) T4, F5 ~func(T4) T5, F6 ~func(T5) T6, F7 ~func(T6) T7, F8 ~func(T7) T8, F9 ~func(T8) T9, F10 ~func(T9) T10, F11 ~func(T10) T11, F12 ~func(T11) T12, F13 ~func(T12) T13, F14 ~func(T13) T14, F15 ~func(T14) T15, F16 ~func(T15) T16, T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16 any](t0 T0, f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7, f8 F8, f9 F9, f10 F10, f11 F11, f12 F12, f13 F13, f14 F14, f15 F15, f16 F16) T16 {
@@ -1190,12 +1208,14 @@ func Variadic16[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15
 		return f(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16, v)
 	}
 }
+
 // Unvariadic16 converts a function taking 16 parameters and a final variadic argument into a function with 16 parameters but a final slice argument
 func Unvariadic16[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, V, R any](f func(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, ...V) R) func(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, []V) R {
 	return func(t1 T1, t2 T2, t3 T3, t4 T4, t5 T5, t6 T6, t7 T7, t8 T8, t9 T9, t10 T10, t11 T11, t12 T12, t13 T13, t14 T14, t15 T15, t16 T16, v []V) R {
 		return f(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16, v...)
 	}
 }
+
 // Pipe17 takes an initial value t0 and successively applies 17 functions where the input of a function is the return value of the previous function
 // The final return value is the result of the last function application
 func Pipe17[F1 ~func(T0) T1, F2 ~func(T1) T2, F3 ~func(T2) T3, F4 ~func(T3) T4, F5 ~func(T4) T5, F6 ~func(T5) T6, F7 ~func(T6) T7, F8 ~func(T7) T8, F9 ~func(T8) T9, F10 ~func(T9) T10, F11 ~func(T10) T11, F12 ~func(T11) T12, F13 ~func(T12) T13, F14 ~func(T13) T14, F15 ~func(T14) T15, F16 ~func(T15) T16, F17 ~func(T16) T17, T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17 any](t0 T0, f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7, f8 F8, f9 F9, f10 F10, f11 F11, f12 F12, f13 F13, f14 F14, f15 F15, f16 F16, f17 F17) T17 {
@@ -1288,12 +1308,14 @@ func Variadic17[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15
 		return f(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16, t17, v)
 	}
 }
+
 // Unvariadic17 converts a function taking 17 parameters and a final variadic argument into a function with 17 parameters but a final slice argument
 func Unvariadic17[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, V, R any](f func(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, ...V) R) func(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, []V) R {
 	return func(t1 T1, t2 T2, t3 T3, t4 T4, t5 T5, t6 T6, t7 T7, t8 T8, t9 T9, t10 T10, t11 T11, t12 T12, t13 T13, t14 T14, t15 T15, t16 T16, t17 T17, v []V) R {
 		return f(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16, t17, v...)
 	}
 }
+
 // Pipe18 takes an initial value t0 and successively applies 18 functions where the input of a function is the return value of the previous function
 // The final return value is the result of the last function application
 func Pipe18[F1 ~func(T0) T1, F2 ~func(T1) T2, F3 ~func(T2) T3, F4 ~func(T3) T4, F5 ~func(T4) T5, F6 ~func(T5) T6, F7 ~func(T6) T7, F8 ~func(T7) T8, F9 ~func(T8) T9, F10 ~func(T9) T10, F11 ~func(T10) T11, F12 ~func(T11) T12, F13 ~func(T12) T13, F14 ~func(T13) T14, F15 ~func(T14) T15, F16 ~func(T15) T16, F17 ~func(T16) T17, F18 ~func(T17) T18, T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18 any](t0 T0, f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7, f8 F8, f9 F9, f10 F10, f11 F11, f12 F12, f13 F13, f14 F14, f15 F15, f16 F16, f17 F17, f18 F18) T18 {
@@ -1389,12 +1411,14 @@ func Variadic18[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15
 		return f(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16, t17, t18, v)
 	}
 }
+
 // Unvariadic18 converts a function taking 18 parameters and a final variadic argument into a function with 18 parameters but a final slice argument
 func Unvariadic18[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, V, R any](f func(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, ...V) R) func(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, []V) R {
 	return func(t1 T1, t2 T2, t3 T3, t4 T4, t5 T5, t6 T6, t7 T7, t8 T8, t9 T9, t10 T10, t11 T11, t12 T12, t13 T13, t14 T14, t15 T15, t16 T16, t17 T17, t18 T18, v []V) R {
 		return f(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16, t17, t18, v...)
 	}
 }
+
 // Pipe19 takes an initial value t0 and successively applies 19 functions where the input of a function is the return value of the previous function
 // The final return value is the result of the last function application
 func Pipe19[F1 ~func(T0) T1, F2 ~func(T1) T2, F3 ~func(T2) T3, F4 ~func(T3) T4, F5 ~func(T4) T5, F6 ~func(T5) T6, F7 ~func(T6) T7, F8 ~func(T7) T8, F9 ~func(T8) T9, F10 ~func(T9) T10, F11 ~func(T10) T11, F12 ~func(T11) T12, F13 ~func(T12) T13, F14 ~func(T13) T14, F15 ~func(T14) T15, F16 ~func(T15) T16, F17 ~func(T16) T17, F18 ~func(T17) T18, F19 ~func(T18) T19, T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19 any](t0 T0, f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7, f8 F8, f9 F9, f10 F10, f11 F11, f12 F12, f13 F13, f14 F14, f15 F15, f16 F16, f17 F17, f18 F18, f19 F19) T19 {
@@ -1493,12 +1517,14 @@ func Variadic19[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15
 		return f(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16, t17, t18, t19, v)
 	}
 }
+
 // Unvariadic19 converts a function taking 19 parameters and a final variadic argument into a function with 19 parameters but a final slice argument
 func Unvariadic19[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, V, R any](f func(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, ...V) R) func(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, []V) R {
 	return func(t1 T1, t2 T2, t3 T3, t4 T4, t5 T5, t6 T6, t7 T7, t8 T8, t9 T9, t10 T10, t11 T11, t12 T12, t13 T13, t14 T14, t15 T15, t16 T16, t17 T17, t18 T18, t19 T19, v []V) R {
 		return f(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16, t17, t18, t19, v...)
 	}
 }
+
 // Pipe20 takes an initial value t0 and successively applies 20 functions where the input of a function is the return value of the previous function
 // The final return value is the result of the last function application
 func Pipe20[F1 ~func(T0) T1, F2 ~func(T1) T2, F3 ~func(T2) T3, F4 ~func(T3) T4, F5 ~func(T4) T5, F6 ~func(T5) T6, F7 ~func(T6) T7, F8 ~func(T7) T8, F9 ~func(T8) T9, F10 ~func(T9) T10, F11 ~func(T10) T11, F12 ~func(T11) T12, F13 ~func(T12) T13, F14 ~func(T13) T14, F15 ~func(T14) T15, F16 ~func(T15) T16, F17 ~func(T16) T17, F18 ~func(T17) T18, F19 ~func(T18) T19, F20 ~func(T19) T20, T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20 any](t0 T0, f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7, f8 F8, f9 F9, f10 F10, f11 F11, f12 F12, f13 F13, f14 F14, f15 F15, f16 F16, f17 F17, f18 F18, f19 F19, f20 F20) T20 {
@@ -1600,6 +1626,7 @@ func Variadic20[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15
 		return f(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16, t17, t18, t19, t20, v)
 	}
 }
+
 // Unvariadic20 converts a function taking 20 parameters and a final variadic argument into a function with 20 parameters but a final slice argument
 func Unvariadic20[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, V, R any](f func(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, ...V) R) func(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, []V) R {
 	return func(t1 T1, t2 T2, t3 T3, t4 T4, t5 T5, t6 T6, t7 T7, t8 T8, t9 T9, t10 T10, t11 T11, t12 T12, t13 T13, t14 T14, t15 T15, t16 T16, t17 T17, t18 T18, t19 T19, t20 T20, v []V) R {

function/generic/cache.go

@@ -0,0 +1,65 @@
+// 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 (
+	"sync"
+
+	L "github.com/IBM/fp-go/internal/lazy"
+)
+
+// Cache converts a unary function into a unary function that caches the value depending on the parameter
+func Cache[F ~func(K) T, K comparable, T any](f F) F {
+	return ContramapCache[F](func(k K) K { return k })(f)
+}
+
+// ContramapCache converts a unary function into a unary function that caches the value depending on the parameter
+func ContramapCache[F ~func(A) T, KF func(A) K, A any, K comparable, T any](kf KF) func(F) F {
+	return CacheCallback[F](kf, getOrCreate[K, T]())
+}
+
+// getOrCreate is a naive implementation of a cache, without bounds
+func getOrCreate[K comparable, T any]() func(K, func() func() T) func() T {
+	cache := make(map[K]func() T)
+	var l sync.Mutex
+
+	return func(k K, cb func() func() T) func() T {
+		// only lock to access a lazy accessor to the value
+		l.Lock()
+		existing, ok := cache[k]
+		if !ok {
+			existing = cb()
+			cache[k] = existing
+		}
+		l.Unlock()
+		// compute the value outside of the lock
+		return existing
+	}
+}
+
+// CacheCallback converts a unary function into a unary function that caches the value depending on the parameter
+func CacheCallback[F ~func(A) T, KF func(A) K, C ~func(K, func() func() T) func() T, A any, K comparable, T any](kf KF, getOrCreate C) func(F) F {
+	return func(f F) F {
+		return func(a A) T {
+			// cache entry
+			return getOrCreate(kf(a), func() func() T {
+				return L.Memoize[func() T](func() T {
+					return f(a)
+				})
+			})()
+		}
+	}
+}

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

@@ -1,23 +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.
-
 // 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
-package identity
+// 2023-08-17 22:59:06.2987136 +0200 CEST m=+0.049156901
 
+package identity
 
 import (
 	A "github.com/IBM/fp-go/internal/apply"
@@ -41,7 +26,7 @@ func SequenceTuple1[T1 any](t T.Tuple1[T1]) T.Tuple1[T1] {
 }
 
 // TraverseTuple1 converts a [Tuple1] of [A] via transformation functions transforming [A] to [A] into a [Tuple1].
-func TraverseTuple1[F1 ~func(A1) T1, A1, T1 any](f1 F1) func (T.Tuple1[A1]) T.Tuple1[T1] {
+func TraverseTuple1[F1 ~func(A1) T1, A1, T1 any](f1 F1) func(T.Tuple1[A1]) T.Tuple1[T1] {
 	return func(t T.Tuple1[A1]) T.Tuple1[T1] {
 		return A.TraverseTuple1(
 			Map[T1, T.Tuple1[T1]],
@@ -71,7 +56,7 @@ func SequenceTuple2[T1, T2 any](t T.Tuple2[T1, T2]) T.Tuple2[T1, T2] {
 }
 
 // TraverseTuple2 converts a [Tuple2] of [A] via transformation functions transforming [A] to [A] into a [Tuple2].
-func TraverseTuple2[F1 ~func(A1) T1, F2 ~func(A2) T2, A1, T1, A2, T2 any](f1 F1, f2 F2) func (T.Tuple2[A1, A2]) T.Tuple2[T1, T2] {
+func TraverseTuple2[F1 ~func(A1) T1, F2 ~func(A2) T2, A1, T1, A2, T2 any](f1 F1, f2 F2) func(T.Tuple2[A1, A2]) T.Tuple2[T1, T2] {
 	return func(t T.Tuple2[A1, A2]) T.Tuple2[T1, T2] {
 		return A.TraverseTuple2(
 			Map[T1, func(T2) T.Tuple2[T1, T2]],
@@ -106,7 +91,7 @@ func SequenceTuple3[T1, T2, T3 any](t T.Tuple3[T1, T2, T3]) T.Tuple3[T1, T2, T3]
 }
 
 // TraverseTuple3 converts a [Tuple3] of [A] via transformation functions transforming [A] to [A] into a [Tuple3].
-func TraverseTuple3[F1 ~func(A1) T1, F2 ~func(A2) T2, F3 ~func(A3) T3, A1, T1, A2, T2, A3, T3 any](f1 F1, f2 F2, f3 F3) func (T.Tuple3[A1, A2, A3]) T.Tuple3[T1, T2, T3] {
+func TraverseTuple3[F1 ~func(A1) T1, F2 ~func(A2) T2, F3 ~func(A3) T3, A1, T1, A2, T2, A3, T3 any](f1 F1, f2 F2, f3 F3) func(T.Tuple3[A1, A2, A3]) T.Tuple3[T1, T2, T3] {
 	return func(t T.Tuple3[A1, A2, A3]) T.Tuple3[T1, T2, T3] {
 		return A.TraverseTuple3(
 			Map[T1, func(T2) func(T3) T.Tuple3[T1, T2, T3]],
@@ -146,7 +131,7 @@ func SequenceTuple4[T1, T2, T3, T4 any](t T.Tuple4[T1, T2, T3, T4]) T.Tuple4[T1,
 }
 
 // TraverseTuple4 converts a [Tuple4] of [A] via transformation functions transforming [A] to [A] into a [Tuple4].
-func TraverseTuple4[F1 ~func(A1) T1, F2 ~func(A2) T2, F3 ~func(A3) T3, F4 ~func(A4) T4, A1, T1, A2, T2, A3, T3, A4, T4 any](f1 F1, f2 F2, f3 F3, f4 F4) func (T.Tuple4[A1, A2, A3, A4]) T.Tuple4[T1, T2, T3, T4] {
+func TraverseTuple4[F1 ~func(A1) T1, F2 ~func(A2) T2, F3 ~func(A3) T3, F4 ~func(A4) T4, A1, T1, A2, T2, A3, T3, A4, T4 any](f1 F1, f2 F2, f3 F3, f4 F4) func(T.Tuple4[A1, A2, A3, A4]) T.Tuple4[T1, T2, T3, T4] {
 	return func(t T.Tuple4[A1, A2, A3, A4]) T.Tuple4[T1, T2, T3, T4] {
 		return A.TraverseTuple4(
 			Map[T1, func(T2) func(T3) func(T4) T.Tuple4[T1, T2, T3, T4]],
@@ -191,7 +176,7 @@ func SequenceTuple5[T1, T2, T3, T4, T5 any](t T.Tuple5[T1, T2, T3, T4, T5]) T.Tu
 }
 
 // TraverseTuple5 converts a [Tuple5] of [A] via transformation functions transforming [A] to [A] into a [Tuple5].
-func TraverseTuple5[F1 ~func(A1) T1, F2 ~func(A2) T2, F3 ~func(A3) T3, F4 ~func(A4) T4, F5 ~func(A5) T5, A1, T1, A2, T2, A3, T3, A4, T4, A5, T5 any](f1 F1, f2 F2, f3 F3, f4 F4, f5 F5) func (T.Tuple5[A1, A2, A3, A4, A5]) T.Tuple5[T1, T2, T3, T4, T5] {
+func TraverseTuple5[F1 ~func(A1) T1, F2 ~func(A2) T2, F3 ~func(A3) T3, F4 ~func(A4) T4, F5 ~func(A5) T5, A1, T1, A2, T2, A3, T3, A4, T4, A5, T5 any](f1 F1, f2 F2, f3 F3, f4 F4, f5 F5) func(T.Tuple5[A1, A2, A3, A4, A5]) T.Tuple5[T1, T2, T3, T4, T5] {
 	return func(t T.Tuple5[A1, A2, A3, A4, A5]) T.Tuple5[T1, T2, T3, T4, T5] {
 		return A.TraverseTuple5(
 			Map[T1, func(T2) func(T3) func(T4) func(T5) T.Tuple5[T1, T2, T3, T4, T5]],
@@ -241,7 +226,7 @@ func SequenceTuple6[T1, T2, T3, T4, T5, T6 any](t T.Tuple6[T1, T2, T3, T4, T5, T
 }
 
 // TraverseTuple6 converts a [Tuple6] of [A] via transformation functions transforming [A] to [A] into a [Tuple6].
-func TraverseTuple6[F1 ~func(A1) T1, F2 ~func(A2) T2, F3 ~func(A3) T3, F4 ~func(A4) T4, F5 ~func(A5) T5, F6 ~func(A6) T6, A1, T1, A2, T2, A3, T3, A4, T4, A5, T5, A6, T6 any](f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6) func (T.Tuple6[A1, A2, A3, A4, A5, A6]) T.Tuple6[T1, T2, T3, T4, T5, T6] {
+func TraverseTuple6[F1 ~func(A1) T1, F2 ~func(A2) T2, F3 ~func(A3) T3, F4 ~func(A4) T4, F5 ~func(A5) T5, F6 ~func(A6) T6, A1, T1, A2, T2, A3, T3, A4, T4, A5, T5, A6, T6 any](f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6) func(T.Tuple6[A1, A2, A3, A4, A5, A6]) T.Tuple6[T1, T2, T3, T4, T5, T6] {
 	return func(t T.Tuple6[A1, A2, A3, A4, A5, A6]) T.Tuple6[T1, T2, T3, T4, T5, T6] {
 		return A.TraverseTuple6(
 			Map[T1, func(T2) func(T3) func(T4) func(T5) func(T6) T.Tuple6[T1, T2, T3, T4, T5, T6]],
@@ -296,7 +281,7 @@ func SequenceTuple7[T1, T2, T3, T4, T5, T6, T7 any](t T.Tuple7[T1, T2, T3, T4, T
 }
 
 // TraverseTuple7 converts a [Tuple7] of [A] via transformation functions transforming [A] to [A] into a [Tuple7].
-func TraverseTuple7[F1 ~func(A1) T1, F2 ~func(A2) T2, F3 ~func(A3) T3, F4 ~func(A4) T4, F5 ~func(A5) T5, F6 ~func(A6) T6, F7 ~func(A7) T7, A1, T1, A2, T2, A3, T3, A4, T4, A5, T5, A6, T6, A7, T7 any](f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7) func (T.Tuple7[A1, A2, A3, A4, A5, A6, A7]) T.Tuple7[T1, T2, T3, T4, T5, T6, T7] {
+func TraverseTuple7[F1 ~func(A1) T1, F2 ~func(A2) T2, F3 ~func(A3) T3, F4 ~func(A4) T4, F5 ~func(A5) T5, F6 ~func(A6) T6, F7 ~func(A7) T7, A1, T1, A2, T2, A3, T3, A4, T4, A5, T5, A6, T6, A7, T7 any](f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7) func(T.Tuple7[A1, A2, A3, A4, A5, A6, A7]) T.Tuple7[T1, T2, T3, T4, T5, T6, T7] {
 	return func(t T.Tuple7[A1, A2, A3, A4, A5, A6, A7]) T.Tuple7[T1, T2, T3, T4, T5, T6, T7] {
 		return A.TraverseTuple7(
 			Map[T1, func(T2) func(T3) func(T4) func(T5) func(T6) func(T7) T.Tuple7[T1, T2, T3, T4, T5, T6, T7]],
@@ -356,7 +341,7 @@ func SequenceTuple8[T1, T2, T3, T4, T5, T6, T7, T8 any](t T.Tuple8[T1, T2, T3, T
 }
 
 // TraverseTuple8 converts a [Tuple8] of [A] via transformation functions transforming [A] to [A] into a [Tuple8].
-func TraverseTuple8[F1 ~func(A1) T1, F2 ~func(A2) T2, F3 ~func(A3) T3, F4 ~func(A4) T4, F5 ~func(A5) T5, F6 ~func(A6) T6, F7 ~func(A7) T7, F8 ~func(A8) T8, A1, T1, A2, T2, A3, T3, A4, T4, A5, T5, A6, T6, A7, T7, A8, T8 any](f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7, f8 F8) func (T.Tuple8[A1, A2, A3, A4, A5, A6, A7, A8]) T.Tuple8[T1, T2, T3, T4, T5, T6, T7, T8] {
+func TraverseTuple8[F1 ~func(A1) T1, F2 ~func(A2) T2, F3 ~func(A3) T3, F4 ~func(A4) T4, F5 ~func(A5) T5, F6 ~func(A6) T6, F7 ~func(A7) T7, F8 ~func(A8) T8, A1, T1, A2, T2, A3, T3, A4, T4, A5, T5, A6, T6, A7, T7, A8, T8 any](f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7, f8 F8) func(T.Tuple8[A1, A2, A3, A4, A5, A6, A7, A8]) T.Tuple8[T1, T2, T3, T4, T5, T6, T7, T8] {
 	return func(t T.Tuple8[A1, A2, A3, A4, A5, A6, A7, A8]) T.Tuple8[T1, T2, T3, T4, T5, T6, T7, T8] {
 		return A.TraverseTuple8(
 			Map[T1, func(T2) func(T3) func(T4) func(T5) func(T6) func(T7) func(T8) T.Tuple8[T1, T2, T3, T4, T5, T6, T7, T8]],
@@ -421,7 +406,7 @@ func SequenceTuple9[T1, T2, T3, T4, T5, T6, T7, T8, T9 any](t T.Tuple9[T1, T2, T
 }
 
 // TraverseTuple9 converts a [Tuple9] of [A] via transformation functions transforming [A] to [A] into a [Tuple9].
-func TraverseTuple9[F1 ~func(A1) T1, F2 ~func(A2) T2, F3 ~func(A3) T3, F4 ~func(A4) T4, F5 ~func(A5) T5, F6 ~func(A6) T6, F7 ~func(A7) T7, F8 ~func(A8) T8, F9 ~func(A9) T9, A1, T1, A2, T2, A3, T3, A4, T4, A5, T5, A6, T6, A7, T7, A8, T8, A9, T9 any](f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7, f8 F8, f9 F9) func (T.Tuple9[A1, A2, A3, A4, A5, A6, A7, A8, A9]) T.Tuple9[T1, T2, T3, T4, T5, T6, T7, T8, T9] {
+func TraverseTuple9[F1 ~func(A1) T1, F2 ~func(A2) T2, F3 ~func(A3) T3, F4 ~func(A4) T4, F5 ~func(A5) T5, F6 ~func(A6) T6, F7 ~func(A7) T7, F8 ~func(A8) T8, F9 ~func(A9) T9, A1, T1, A2, T2, A3, T3, A4, T4, A5, T5, A6, T6, A7, T7, A8, T8, A9, T9 any](f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7, f8 F8, f9 F9) func(T.Tuple9[A1, A2, A3, A4, A5, A6, A7, A8, A9]) T.Tuple9[T1, T2, T3, T4, T5, T6, T7, T8, T9] {
 	return func(t T.Tuple9[A1, A2, A3, A4, A5, A6, A7, A8, A9]) T.Tuple9[T1, T2, T3, T4, T5, T6, T7, T8, T9] {
 		return A.TraverseTuple9(
 			Map[T1, func(T2) func(T3) func(T4) func(T5) func(T6) func(T7) func(T8) func(T9) T.Tuple9[T1, T2, T3, T4, T5, T6, T7, T8, T9]],
@@ -491,7 +476,7 @@ func SequenceTuple10[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10 any](t T.Tuple10[T1
 }
 
 // TraverseTuple10 converts a [Tuple10] of [A] via transformation functions transforming [A] to [A] into a [Tuple10].
-func TraverseTuple10[F1 ~func(A1) T1, F2 ~func(A2) T2, F3 ~func(A3) T3, F4 ~func(A4) T4, F5 ~func(A5) T5, F6 ~func(A6) T6, F7 ~func(A7) T7, F8 ~func(A8) T8, F9 ~func(A9) T9, F10 ~func(A10) T10, A1, T1, A2, T2, A3, T3, A4, T4, A5, T5, A6, T6, A7, T7, A8, T8, A9, T9, A10, T10 any](f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7, f8 F8, f9 F9, f10 F10) func (T.Tuple10[A1, A2, A3, A4, A5, A6, A7, A8, A9, A10]) T.Tuple10[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10] {
+func TraverseTuple10[F1 ~func(A1) T1, F2 ~func(A2) T2, F3 ~func(A3) T3, F4 ~func(A4) T4, F5 ~func(A5) T5, F6 ~func(A6) T6, F7 ~func(A7) T7, F8 ~func(A8) T8, F9 ~func(A9) T9, F10 ~func(A10) T10, A1, T1, A2, T2, A3, T3, A4, T4, A5, T5, A6, T6, A7, T7, A8, T8, A9, T9, A10, T10 any](f1 F1, f2 F2, f3 F3, f4 F4, f5 F5, f6 F6, f7 F7, f8 F8, f9 F9, f10 F10) func(T.Tuple10[A1, A2, A3, A4, A5, A6, A7, A8, A9, A10]) T.Tuple10[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10] {
 	return func(t T.Tuple10[A1, A2, A3, A4, A5, A6, A7, A8, A9, A10]) T.Tuple10[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10] {
 		return A.TraverseTuple10(
 			Map[T1, func(T2) func(T3) func(T4) func(T5) func(T6) func(T7) func(T8) func(T9) func(T10) T.Tuple10[T1, T2, T3, T4, T5, T6, T7, T8, T9, T10]],

internal/apply/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.
-
 // 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
-package apply
+// 2023-08-17 22:59:08.1313362 +0200 CEST m=+0.111171801
 
+package apply
 
 import (
 	F "github.com/IBM/fp-go/function"
@@ -43,7 +28,7 @@ func SequenceT1[
 	return F.Pipe1(
 		t1,
 		fmap(tupleConstructor1[T1]()),
-)
+	)
 }
 
 // SequenceTuple1 is a utility function used to implement the sequence operation for higher kinded types based only on map and ap.
@@ -60,7 +45,7 @@ func SequenceTuple1[
 	return F.Pipe1(
 		t.F1,
 		fmap(tupleConstructor1[T1]()),
-)
+	)
 }
 
 // TraverseTuple1 is a utility function used to implement the sequence operation for higher kinded types based only on map and ap.
@@ -79,7 +64,7 @@ func TraverseTuple1[
 	return F.Pipe1(
 		f1(t.F1),
 		fmap(tupleConstructor1[T1]()),
-)
+	)
 }
 
 // tupleConstructor2 returns a curried version of [T.MakeTuple2]
@@ -108,7 +93,7 @@ func SequenceT2[
 		t1,
 		fmap(tupleConstructor2[T1, T2]()),
 		fap1(t2),
-)
+	)
 }
 
 // SequenceTuple2 is a utility function used to implement the sequence operation for higher kinded types based only on map and ap.
@@ -131,7 +116,7 @@ func SequenceTuple2[
 		t.F1,
 		fmap(tupleConstructor2[T1, T2]()),
 		fap1(t.F2),
-)
+	)
 }
 
 // TraverseTuple2 is a utility function used to implement the sequence operation for higher kinded types based only on map and ap.
@@ -158,7 +143,7 @@ func TraverseTuple2[
 		f1(t.F1),
 		fmap(tupleConstructor2[T1, T2]()),
 		fap1(f2(t.F2)),
-)
+	)
 }
 
 // tupleConstructor3 returns a curried version of [T.MakeTuple3]
@@ -194,7 +179,7 @@ func SequenceT3[
 		fmap(tupleConstructor3[T1, T2, T3]()),
 		fap1(t2),
 		fap2(t3),
-)
+	)
 }
 
 // SequenceTuple3 is a utility function used to implement the sequence operation for higher kinded types based only on map and ap.
@@ -223,7 +208,7 @@ func SequenceTuple3[
 		fmap(tupleConstructor3[T1, T2, T3]()),
 		fap1(t.F2),
 		fap2(t.F3),
-)
+	)
 }
 
 // TraverseTuple3 is a utility function used to implement the sequence operation for higher kinded types based only on map and ap.
@@ -258,7 +243,7 @@ func TraverseTuple3[
 		fmap(tupleConstructor3[T1, T2, T3]()),
 		fap1(f2(t.F2)),
 		fap2(f3(t.F3)),
-)
+	)
 }
 
 // tupleConstructor4 returns a curried version of [T.MakeTuple4]
@@ -301,7 +286,7 @@ func SequenceT4[
 		fap1(t2),
 		fap2(t3),
 		fap3(t4),
-)
+	)
 }
 
 // SequenceTuple4 is a utility function used to implement the sequence operation for higher kinded types based only on map and ap.
@@ -336,7 +321,7 @@ func SequenceTuple4[
 		fap1(t.F2),
 		fap2(t.F3),
 		fap3(t.F4),
-)
+	)
 }
 
 // TraverseTuple4 is a utility function used to implement the sequence operation for higher kinded types based only on map and ap.
@@ -379,7 +364,7 @@ func TraverseTuple4[
 		fap1(f2(t.F2)),
 		fap2(f3(t.F3)),
 		fap3(f4(t.F4)),
-)
+	)
 }
 
 // tupleConstructor5 returns a curried version of [T.MakeTuple5]
@@ -429,7 +414,7 @@ func SequenceT5[
 		fap2(t3),
 		fap3(t4),
 		fap4(t5),
-)
+	)
 }
 
 // SequenceTuple5 is a utility function used to implement the sequence operation for higher kinded types based only on map and ap.
@@ -470,7 +455,7 @@ func SequenceTuple5[
 		fap2(t.F3),
 		fap3(t.F4),
 		fap4(t.F5),
-)
+	)
 }
 
 // TraverseTuple5 is a utility function used to implement the sequence operation for higher kinded types based only on map and ap.
@@ -521,7 +506,7 @@ func TraverseTuple5[
 		fap2(f3(t.F3)),
 		fap3(f4(t.F4)),
 		fap4(f5(t.F5)),
-)
+	)
 }
 
 // tupleConstructor6 returns a curried version of [T.MakeTuple6]
@@ -578,7 +563,7 @@ func SequenceT6[
 		fap3(t4),
 		fap4(t5),
 		fap5(t6),
-)
+	)
 }
 
 // SequenceTuple6 is a utility function used to implement the sequence operation for higher kinded types based only on map and ap.
@@ -625,7 +610,7 @@ func SequenceTuple6[
 		fap3(t.F4),
 		fap4(t.F5),
 		fap5(t.F6),
-)
+	)
 }
 
 // TraverseTuple6 is a utility function used to implement the sequence operation for higher kinded types based only on map and ap.
@@ -684,7 +669,7 @@ func TraverseTuple6[
 		fap3(f4(t.F4)),
 		fap4(f5(t.F5)),
 		fap5(f6(t.F6)),
-)
+	)
 }
 
 // tupleConstructor7 returns a curried version of [T.MakeTuple7]
@@ -748,7 +733,7 @@ func SequenceT7[
 		fap4(t5),
 		fap5(t6),
 		fap6(t7),
-)
+	)
 }
 
 // SequenceTuple7 is a utility function used to implement the sequence operation for higher kinded types based only on map and ap.
@@ -801,7 +786,7 @@ func SequenceTuple7[
 		fap4(t.F5),
 		fap5(t.F6),
 		fap6(t.F7),
-)
+	)
 }
 
 // TraverseTuple7 is a utility function used to implement the sequence operation for higher kinded types based only on map and ap.
@@ -868,7 +853,7 @@ func TraverseTuple7[
 		fap4(f5(t.F5)),
 		fap5(f6(t.F6)),
 		fap6(f7(t.F7)),
-)
+	)
 }
 
 // tupleConstructor8 returns a curried version of [T.MakeTuple8]
@@ -939,7 +924,7 @@ func SequenceT8[
 		fap5(t6),
 		fap6(t7),
 		fap7(t8),
-)
+	)
 }
 
 // SequenceTuple8 is a utility function used to implement the sequence operation for higher kinded types based only on map and ap.
@@ -998,7 +983,7 @@ func SequenceTuple8[
 		fap5(t.F6),
 		fap6(t.F7),
 		fap7(t.F8),
-)
+	)
 }
 
 // TraverseTuple8 is a utility function used to implement the sequence operation for higher kinded types based only on map and ap.
@@ -1073,7 +1058,7 @@ func TraverseTuple8[
 		fap5(f6(t.F6)),
 		fap6(f7(t.F7)),
 		fap7(f8(t.F8)),
-)
+	)
 }
 
 // tupleConstructor9 returns a curried version of [T.MakeTuple9]
@@ -1151,7 +1136,7 @@ func SequenceT9[
 		fap6(t7),
 		fap7(t8),
 		fap8(t9),
-)
+	)
 }
 
 // SequenceTuple9 is a utility function used to implement the sequence operation for higher kinded types based only on map and ap.
@@ -1216,7 +1201,7 @@ func SequenceTuple9[
 		fap6(t.F7),
 		fap7(t.F8),
 		fap8(t.F9),
-)
+	)
 }
 
 // TraverseTuple9 is a utility function used to implement the sequence operation for higher kinded types based only on map and ap.
@@ -1299,7 +1284,7 @@ func TraverseTuple9[
 		fap6(f7(t.F7)),
 		fap7(f8(t.F8)),
 		fap8(f9(t.F9)),
-)
+	)
 }
 
 // tupleConstructor10 returns a curried version of [T.MakeTuple10]
@@ -1384,7 +1369,7 @@ func SequenceT10[
 		fap7(t8),
 		fap8(t9),
 		fap9(t10),
-)
+	)
 }
 
 // SequenceTuple10 is a utility function used to implement the sequence operation for higher kinded types based only on map and ap.
@@ -1455,7 +1440,7 @@ func SequenceTuple10[
 		fap7(t.F8),
 		fap8(t.F9),
 		fap9(t.F10),
-)
+	)
 }
 
 // TraverseTuple10 is a utility function used to implement the sequence operation for higher kinded types based only on map and ap.
@@ -1546,5 +1531,5 @@ func TraverseTuple10[
 		fap7(f8(t.F8)),
 		fap8(f9(t.F9)),
 		fap9(f10(t.F10)),
-)
+	)
 }

internal/array/array.go

@@ -42,10 +42,27 @@ func Reduce[GA ~[]A, A, B any](fa GA, f func(B, A) B, initial B) B {
 	return current
 }
 
+func ReduceWithIndex[GA ~[]A, A, B any](fa GA, f func(int, B, A) B, initial B) B {
+	current := initial
+	count := len(fa)
+	for i := 0; i < count; i++ {
+		current = f(i, current, fa[i])
+	}
+	return current
+}
+
 func Append[GA ~[]A, A any](as GA, a A) GA {
 	return append(as, a)
 }
 
+func Push[GA ~[]A, A any](as GA, a A) GA {
+	l := len(as)
+	cpy := make(GA, l+1)
+	copy(cpy, as)
+	cpy[l] = a
+	return cpy
+}
+
 func Empty[GA ~[]A, A any]() GA {
 	return make(GA, 0)
 }

internal/bindt/bind.go

@@ -0,0 +1,75 @@
+// 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 bindt
+
+import (
+	F "github.com/IBM/fp-go/function"
+	I "github.com/IBM/fp-go/identity"
+	T "github.com/IBM/fp-go/tuple"
+)
+
+func Bind[SET ~func(B) func(S1) S2, FCT ~func(S1) HKTB, S1, S2, B, HKTS1, HKTS2, HKTB any](
+	mchain func(func(S1) HKTS2) func(HKTS1) HKTS2,
+	mmap func(func(B) S2) func(HKTB) HKTS2,
+	s SET,
+	f FCT,
+) func(HKTS1) HKTS2 {
+	return mchain(F.Flow3(
+		T.Replicate2[S1],
+		T.Map2(F.Flow2(
+			I.Ap[S2, S1],
+			F.Flow2(
+				F.Bind1st(F.Flow2[SET, func(func(S1) S2) S2], s),
+				mmap,
+			)), f),
+		T.Tupled2(I.MonadAp[HKTS2, HKTB]),
+	))
+}
+
+func BindTo[SET ~func(B) S2, S2, B, HKTS2, HKTB any](
+	mmap func(func(B) S2) func(HKTB) HKTS2,
+	s SET,
+) func(HKTB) HKTS2 {
+	return mmap(s)
+}
+
+func ApS[
+	SET ~func(B) func(S1) S2,
+	S1, S2, B, HKTS1S2, HKTS1, HKTS2, HKTB any,
+](
+	ap func(HKTS1) func(HKTS1S2) HKTS2,
+	mmap func(func(B) func(S1) S2) func(HKTB) HKTS1S2,
+	s SET, fb HKTB) func(HKTS1) HKTS2 {
+
+	return F.Flow2(
+		ap,
+		I.Ap[HKTS2, HKTS1S2](mmap(s)(fb)),
+	)
+}
+
+func Let[SET ~func(B) func(S1) S2, FCT ~func(S1) B, S1, S2, B, HKTS1, HKTS2 any](
+	mmap func(func(S1) S2) func(HKTS1) HKTS2,
+	s SET,
+	f FCT,
+) func(HKTS1) HKTS2 {
+	return mmap(F.Flow3(
+		T.Replicate2[S1],
+		T.Map2(F.Flow2(
+			I.Ap[S2, S1],
+			F.Bind1st(F.Flow2[SET, func(func(S1) S2) S2], s)), f),
+		T.Tupled2(I.MonadAp[S2, B]),
+	))
+}

internal/lazy/memoize.go

@@ -0,0 +1,34 @@
+// 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 lazy
+
+import "sync"
+
+// Memoize computes the value of the provided IO monad lazily but exactly once
+func Memoize[GA ~func() A, A any](ma GA) GA {
+	// synchronization primitives
+	var once sync.Once
+	var result A
+	// callback
+	gen := func() {
+		result = ma()
+	}
+	// returns our memoized wrapper
+	return func() A {
+		once.Do(gen)
+		return result
+	}
+}

io/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.
-
 // 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
-package io
+// 2023-08-17 22:59:10.1040409 +0200 CEST m=+0.089470201
 
+package io
 
 import (
 	G "github.com/IBM/fp-go/io/generic"

io/generic/ap.go

@@ -64,6 +64,28 @@ func MonadApFirst[GA ~func() A, GB ~func() B, GBA ~func() func(B) A, A, B any](f
 	)
 }
 
+// MonadApFirstPar combines two effectful actions, keeping only the result of the first.
+func MonadApFirstPar[GA ~func() A, GB ~func() B, GBA ~func() func(B) A, A, B any](first GA, second GB) GA {
+	return G.MonadApFirst(
+		MonadApPar[GB, GA, GBA, B, A],
+		MonadMap[GA, GBA, A, func(B) A],
+
+		first,
+		second,
+	)
+}
+
+// MonadApFirstSeq combines two effectful actions, keeping only the result of the first.
+func MonadApFirstSeq[GA ~func() A, GB ~func() B, GBA ~func() func(B) A, A, B any](first GA, second GB) GA {
+	return G.MonadApFirst(
+		MonadApSeq[GB, GA, GBA, B, A],
+		MonadMap[GA, GBA, A, func(B) A],
+
+		first,
+		second,
+	)
+}
+
 // ApFirst combines two effectful actions, keeping only the result of the first.
 func ApFirst[GA ~func() A, GB ~func() B, GBA ~func() func(B) A, A, B any](second GB) func(GA) GA {
 	return G.ApFirst(
@@ -74,6 +96,26 @@ func ApFirst[GA ~func() A, GB ~func() B, GBA ~func() func(B) A, A, B any](second
 	)
 }
 
+// ApFirstPar combines two effectful actions, keeping only the result of the first.
+func ApFirstPar[GA ~func() A, GB ~func() B, GBA ~func() func(B) A, A, B any](second GB) func(GA) GA {
+	return G.ApFirst(
+		MonadApPar[GB, GA, GBA, B, A],
+		MonadMap[GA, GBA, A, func(B) A],
+
+		second,
+	)
+}
+
+// ApFirstSeq combines two effectful actions, keeping only the result of the first.
+func ApFirstSeq[GA ~func() A, GB ~func() B, GBA ~func() func(B) A, A, B any](second GB) func(GA) GA {
+	return G.ApFirst(
+		MonadApSeq[GB, GA, GBA, B, A],
+		MonadMap[GA, GBA, A, func(B) A],
+
+		second,
+	)
+}
+
 // MonadApSecond combines two effectful actions, keeping only the result of the second.
 func MonadApSecond[GA ~func() A, GB ~func() B, GBB ~func() func(B) B, A, B any](first GA, second GB) GB {
 	return G.MonadApSecond(

io/generic/gen.go

@@ -1,27 +1,11 @@
-// 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
+// 2023-08-17 22:59:10.1132645 +0200 CEST m=+0.098693801
 package generic
 
-
 import (
-	T "github.com/IBM/fp-go/tuple"
 	A "github.com/IBM/fp-go/internal/apply"
+	T "github.com/IBM/fp-go/tuple"
 )
 
 // SequenceT1 converts 1 [func() T] into a [func() T.Tuple1[T1]]

io/generic/io.go

@@ -16,11 +16,11 @@
 package generic
 
 import (
-	"sync"
 	"time"
 
 	F "github.com/IBM/fp-go/function"
 	C "github.com/IBM/fp-go/internal/chain"
+	L "github.com/IBM/fp-go/internal/lazy"
 )
 
 // type IO[A any] = func() A
@@ -119,18 +119,7 @@ func Flatten[GA ~func() A, GAA ~func() GA, A any](mma GAA) GA {
 
 // Memoize computes the value of the provided IO monad lazily but exactly once
 func Memoize[GA ~func() A, A any](ma GA) GA {
-	// synchronization primitives
-	var once sync.Once
-	var result A
-	// callback
-	gen := func() {
-		result = ma()
-	}
-	// returns our memoized wrapper
-	return func() A {
-		once.Do(gen)
-		return result
-	}
+	return L.Memoize[GA, A](ma)
 }
 
 // Delay creates an operation that passes in the value after some delay

ioeither/bind.go

@@ -0,0 +1,44 @@
+// 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 ioeither
+
+import (
+	G "github.com/IBM/fp-go/ioeither/generic"
+)
+
+// Bind applies a function to an input state and merges the result into that state
+func Bind[E, A, S1, S2 any](s func(A) func(S1) S2, f func(S1) IOEither[E, A]) func(IOEither[E, S1]) IOEither[E, S2] {
+	return G.Bind[IOEither[E, S1], IOEither[E, S2], IOEither[E, A], func(S1) IOEither[E, A]](s, f)
+}
+
+// BindTo initializes some state based on a value
+func BindTo[
+	E, A, S2 any](s func(A) S2) func(IOEither[E, A]) IOEither[E, S2] {
+	return G.BindTo[IOEither[E, S2], IOEither[E, A]](s)
+}
+
+func ApS[
+	E, A, S1, S2 any,
+](s func(A) func(S1) S2, fa IOEither[E, A]) func(IOEither[E, S1]) IOEither[E, S2] {
+	return G.ApS[IOEither[E, S1], IOEither[E, S2], IOEither[E, A], IOEither[E, func(S1) S2]](s, fa)
+}
+
+func Let[E, A, S1, S2 any](
+	s func(A) func(S1) S2,
+	f func(S1) A,
+) func(IOEither[E, S1]) IOEither[E, S2] {
+	return G.Let[IOEither[E, S1], IOEither[E, S2]](s, f)
+}

ioeither/examples_create_test.go

@@ -0,0 +1,57 @@
+// 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 ioeither
+
+import (
+	"fmt"
+
+	E "github.com/IBM/fp-go/either"
+)
+
+func ExampleIOEither_creation() {
+	// Build an IOEither
+	leftValue := Left[string](fmt.Errorf("some error"))
+	rightValue := Right[error]("value")
+
+	// Convert from Either
+	eitherValue := E.Of[error](42)
+	ioFromEither := FromEither(eitherValue)
+
+	// some predicate
+	isEven := func(num int) (int, error) {
+		if num%2 == 0 {
+			return num, nil
+		}
+		return 0, fmt.Errorf("%d is an odd number", num)
+	}
+	fromEven := Eitherize1(isEven)
+	leftFromPred := fromEven(3)
+	rightFromPred := fromEven(4)
+
+	fmt.Println(leftValue())
+	fmt.Println(rightValue())
+	fmt.Println(ioFromEither())
+	fmt.Println(leftFromPred())
+	fmt.Println(rightFromPred())
+
+	// Output:
+	// Left[*errors.errorString, string](some error)
+	// Right[<nil>, string](value)
+	// Right[<nil>, int](42)
+	// Left[*errors.errorString, int](3 is an odd number)
+	// Right[<nil>, int](4)
+
+}

ioeither/examples_do_test.go

@@ -0,0 +1,57 @@
+// 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 ioeither
+
+import (
+	"fmt"
+	"log"
+
+	F "github.com/IBM/fp-go/function"
+	IO "github.com/IBM/fp-go/io"
+	T "github.com/IBM/fp-go/tuple"
+)
+
+func ExampleIOEither_do() {
+	foo := Of[error]("foo")
+	bar := Of[error](1)
+
+	// quux consumes the state of three bindings and returns an [IO] instead of an [IOEither]
+	quux := func(t T.Tuple3[string, int, string]) IO.IO[any] {
+		return IO.FromImpure(func() {
+			log.Printf("t1: %s, t2: %d, t3: %s", t.F1, t.F2, t.F3)
+		})
+	}
+
+	transform := func(t T.Tuple3[string, int, string]) int {
+		return len(t.F1) + t.F2 + len(t.F3)
+	}
+
+	b := F.Pipe5(
+		foo,
+		BindTo[error](T.Of[string]),
+		ApS(T.Push1[string, int], bar),
+		Bind(T.Push2[string, int, string], func(t T.Tuple2[string, int]) IOEither[error, string] {
+			return Of[error](fmt.Sprintf("%s%d", t.F1, t.F2))
+		}),
+		ChainFirstIOK[error](quux),
+		Map[error](transform),
+	)
+
+	fmt.Println(b())
+
+	// Output:
+	// Right[<nil>, int](8)
+}

ioeither/examples_extract_test.go

@@ -0,0 +1,45 @@
+// 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 ioeither
+
+import (
+	"fmt"
+
+	E "github.com/IBM/fp-go/either"
+	F "github.com/IBM/fp-go/function"
+	IO "github.com/IBM/fp-go/io"
+)
+
+func ExampleIOEither_extraction() {
+	// IOEither
+	someIOEither := Right[error](42)
+	eitherValue := someIOEither()                            // E.Right(42)
+	value := E.GetOrElse(F.Constant1[error](0))(eitherValue) // 42
+
+	// Or more directly
+	infaillibleIO := GetOrElse(F.Constant1[error](IO.Of(0)))(someIOEither) // => IO.Right(42)
+	valueFromIO := infaillibleIO()                                         // => 42
+
+	fmt.Println(eitherValue)
+	fmt.Println(value)
+	fmt.Println(valueFromIO)
+
+	// Output:
+	// Right[<nil>, int](42)
+	// 42
+	// 42
+
+}

ioeither/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.
-
 // 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
-package ioeither
+// 2023-08-17 22:59:12.0033119 +0200 CEST m=+0.096740401
 
+package ioeither
 
 import (
 	G "github.com/IBM/fp-go/ioeither/generic"

ioeither/generic/bind.go

@@ -0,0 +1,79 @@
+// 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 (
+	ET "github.com/IBM/fp-go/either"
+	G "github.com/IBM/fp-go/internal/bindt"
+)
+
+// Bind applies a function to an input state and merges the result into that state
+func Bind[
+	GS1 ~func() ET.Either[E, S1],
+	GS2 ~func() ET.Either[E, S2],
+	GA ~func() ET.Either[E, A],
+	FCT ~func(S1) GA,
+	E any,
+	SET ~func(A) func(S1) S2,
+	A, S1, S2 any](s SET, f FCT) func(GS1) GS2 {
+	return G.Bind(
+		Chain[GS1, GS2, E, S1, S2],
+		Map[GA, GS2, E, A, S2],
+		s,
+		f,
+	)
+}
+
+// BindTo initializes some state based on a value
+func BindTo[
+	GS2 ~func() ET.Either[E, S2],
+	GA ~func() ET.Either[E, A],
+	E any,
+	SET ~func(A) S2,
+	A, S2 any](s SET) func(GA) GS2 {
+	return G.BindTo(
+		Map[GA, GS2, E, A, S2],
+		s,
+	)
+}
+
+func ApS[
+	GS1 ~func() ET.Either[E, S1],
+	GS2 ~func() ET.Either[E, S2],
+	GB ~func() ET.Either[E, B],
+	GS1S2 ~func() ET.Either[E, func(S1) S2],
+	SET ~func(B) func(S1) S2,
+	E, S1, S2, B any,
+](s SET, fb GB) func(GS1) GS2 {
+	return G.ApS[SET, S1, S2, B, GS1S2, GS1, GS2, GB](
+		Ap[GS2, GS1S2, GS1, E, S1, S2],
+		Map[GB, GS1S2, E, B, func(S1) S2],
+		s,
+		fb,
+	)
+}
+
+func Let[
+	GS1 ~func() ET.Either[E, S1],
+	GS2 ~func() ET.Either[E, S2],
+	SET ~func(B) func(S1) S2,
+	FCT ~func(S1) B,
+	E, S1, S2, B any](
+	s SET,
+	f FCT,
+) func(GS1) GS2 {
+	return G.Let[SET, FCT, S1, S2, B, GS1, GS2](Map[GS1, GS2, E, S1, S2], s, f)
+}

ioeither/generic/gen.go

@@ -1,28 +1,12 @@
-// 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
+// 2023-08-17 22:59:12.0246635 +0200 CEST m=+0.118092001
 package generic
 
-
 import (
 	ET "github.com/IBM/fp-go/either"
-	T "github.com/IBM/fp-go/tuple"
 	A "github.com/IBM/fp-go/internal/apply"
+	T "github.com/IBM/fp-go/tuple"
 )
 
 // Eitherize0 converts a function with 0 parameters returning a tuple into a function with 0 parameters returning a [GIOA]
@@ -31,7 +15,8 @@ func Eitherize0[GIOA ~func() ET.Either[error, R], F ~func() (R, error), R any](f
 	return func() GIOA {
 		return func() ET.Either[error, R] {
 			return e()
-    }}
+		}
+	}
 }
 
 // Uneitherize0 converts a function with 0 parameters returning a tuple into a function with 0 parameters returning a [GIOA]
@@ -47,7 +32,8 @@ func Eitherize1[GIOA ~func() ET.Either[error, R], F ~func(T1) (R, error), T1, R
 	return func(t1 T1) GIOA {
 		return func() ET.Either[error, R] {
 			return e(t1)
-    }}
+		}
+	}
 }
 
 // Uneitherize1 converts a function with 1 parameters returning a tuple into a function with 1 parameters returning a [GIOA]
@@ -100,7 +86,8 @@ func Eitherize2[GIOA ~func() ET.Either[error, R], F ~func(T1, T2) (R, error), T1
 	return func(t1 T1, t2 T2) GIOA {
 		return func() ET.Either[error, R] {
 			return e(t1, t2)
-    }}
+		}
+	}
 }
 
 // Uneitherize2 converts a function with 2 parameters returning a tuple into a function with 2 parameters returning a [GIOA]
@@ -163,7 +150,8 @@ func Eitherize3[GIOA ~func() ET.Either[error, R], F ~func(T1, T2, T3) (R, error)
 	return func(t1 T1, t2 T2, t3 T3) GIOA {
 		return func() ET.Either[error, R] {
 			return e(t1, t2, t3)
-    }}
+		}
+	}
 }
 
 // Uneitherize3 converts a function with 3 parameters returning a tuple into a function with 3 parameters returning a [GIOA]
@@ -236,7 +224,8 @@ func Eitherize4[GIOA ~func() ET.Either[error, R], F ~func(T1, T2, T3, T4) (R, er
 	return func(t1 T1, t2 T2, t3 T3, t4 T4) GIOA {
 		return func() ET.Either[error, R] {
 			return e(t1, t2, t3, t4)
-    }}
+		}
+	}
 }
 
 // Uneitherize4 converts a function with 4 parameters returning a tuple into a function with 4 parameters returning a [GIOA]
@@ -319,7 +308,8 @@ func Eitherize5[GIOA ~func() ET.Either[error, R], F ~func(T1, T2, T3, T4, T5) (R
 	return func(t1 T1, t2 T2, t3 T3, t4 T4, t5 T5) GIOA {
 		return func() ET.Either[error, R] {
 			return e(t1, t2, t3, t4, t5)
-    }}
+		}
+	}
 }
 
 // Uneitherize5 converts a function with 5 parameters returning a tuple into a function with 5 parameters returning a [GIOA]
@@ -412,7 +402,8 @@ func Eitherize6[GIOA ~func() ET.Either[error, R], F ~func(T1, T2, T3, T4, T5, T6
 	return func(t1 T1, t2 T2, t3 T3, t4 T4, t5 T5, t6 T6) GIOA {
 		return func() ET.Either[error, R] {
 			return e(t1, t2, t3, t4, t5, t6)
-    }}
+		}
+	}
 }
 
 // Uneitherize6 converts a function with 6 parameters returning a tuple into a function with 6 parameters returning a [GIOA]
@@ -515,7 +506,8 @@ func Eitherize7[GIOA ~func() ET.Either[error, R], F ~func(T1, T2, T3, T4, T5, T6
 	return func(t1 T1, t2 T2, t3 T3, t4 T4, t5 T5, t6 T6, t7 T7) GIOA {
 		return func() ET.Either[error, R] {
 			return e(t1, t2, t3, t4, t5, t6, t7)
-    }}
+		}
+	}
 }
 
 // Uneitherize7 converts a function with 7 parameters returning a tuple into a function with 7 parameters returning a [GIOA]
@@ -628,7 +620,8 @@ func Eitherize8[GIOA ~func() ET.Either[error, R], F ~func(T1, T2, T3, T4, T5, T6
 	return func(t1 T1, t2 T2, t3 T3, t4 T4, t5 T5, t6 T6, t7 T7, t8 T8) GIOA {
 		return func() ET.Either[error, R] {
 			return e(t1, t2, t3, t4, t5, t6, t7, t8)
-    }}
+		}
+	}
 }
 
 // Uneitherize8 converts a function with 8 parameters returning a tuple into a function with 8 parameters returning a [GIOA]
@@ -751,7 +744,8 @@ func Eitherize9[GIOA ~func() ET.Either[error, R], F ~func(T1, T2, T3, T4, T5, T6
 	return func(t1 T1, t2 T2, t3 T3, t4 T4, t5 T5, t6 T6, t7 T7, t8 T8, t9 T9) GIOA {
 		return func() ET.Either[error, R] {
 			return e(t1, t2, t3, t4, t5, t6, t7, t8, t9)
-    }}
+		}
+	}
 }
 
 // Uneitherize9 converts a function with 9 parameters returning a tuple into a function with 9 parameters returning a [GIOA]
@@ -884,7 +878,8 @@ func Eitherize10[GIOA ~func() ET.Either[error, R], F ~func(T1, T2, T3, T4, T5, T
 	return func(t1 T1, t2 T2, t3 T3, t4 T4, t5 T5, t6 T6, t7 T7, t8 T8, t9 T9, t10 T10) GIOA {
 		return func() ET.Either[error, R] {
 			return e(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10)
-    }}
+		}
+	}
 }
 
 // Uneitherize10 converts a function with 10 parameters returning a tuple into a function with 10 parameters returning a [GIOA]

iooption/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.
-
 // 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
-package iooption
+// 2023-08-17 22:59:14.0582736 +0200 CEST m=+0.248503201
 
+package iooption
 
 import (
 	G "github.com/IBM/fp-go/iooption/generic"

iooption/generic/gen.go

@@ -1,28 +1,12 @@
-// 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
+// 2023-08-17 22:59:14.0642289 +0200 CEST m=+0.254458501
 package generic
 
-
 import (
-	T "github.com/IBM/fp-go/tuple"
-	O "github.com/IBM/fp-go/option"
 	A "github.com/IBM/fp-go/internal/apply"
+	O "github.com/IBM/fp-go/option"
+	T "github.com/IBM/fp-go/tuple"
 )
 
 // SequenceT1 converts 1 [func() O.Option[T]] into a [func() O.Option[T.Tuple1[T1]]]

iterator/stateless/compress.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"
+	T "github.com/IBM/fp-go/tuple"
+)
+
+// Compress returns an [Iterator] that filters elements from a data [Iterator] returning only those that have a corresponding element in selector [Iterator] that evaluates to `true`.
+// Stops when either the data or selectors iterator has been exhausted.
+func Compress[U any](sel Iterator[bool]) func(Iterator[U]) Iterator[U] {
+	return G.Compress[Iterator[U], Iterator[bool], Iterator[T.Tuple2[U, bool]]](sel)
+}

iterator/stateless/compress_test.go

@@ -0,0 +1,35 @@
+// 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"
+
+	A "github.com/IBM/fp-go/array"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestCompress(t *testing.T) {
+	// sequence of 5 items
+	data := From(0, 1, 2, 3)
+	// select some of these items
+	selector := From(true, false, false, true)
+	// compressed result
+	compressed := Compress[int](selector)(data)
+
+	assert.Equal(t, A.From(0, 3), ToArray(compressed))
+
+}

iterator/stateless/cycle.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"
+)
+
+// DropWhile creates an [Iterator] that drops elements from the [Iterator] as long as the predicate is true; afterwards, returns every element.
+// Note, the [Iterator] does not produce any output until the predicate first becomes false
+func Cycle[U any](ma Iterator[U]) Iterator[U] {
+	return G.Cycle[Iterator[U]](ma)
+}

iterator/stateless/cycle_test.go

@@ -0,0 +1,33 @@
+// 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"
+
+	A "github.com/IBM/fp-go/array"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestCycle(t *testing.T) {
+	// sequence of 5 items
+	items := Take[int](5)(Count(0))
+	// repeat
+	repeated := Take[int](17)(Cycle(items))
+
+	assert.Equal(t, A.From(0, 1, 2, 3, 4, 0, 1, 2, 3, 4, 0, 1, 2, 3, 4, 0, 1), ToArray(repeated))
+
+}

iterator/stateless/dropwhile.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"
+)
+
+// DropWhile creates an [Iterator] that drops elements from the [Iterator] as long as the predicate is true; afterwards, returns every element.
+// Note, the [Iterator] does not produce any output until the predicate first becomes false
+func DropWhile[U any](pred func(U) bool) func(Iterator[U]) Iterator[U] {
+	return G.DropWhile[Iterator[U]](pred)
+}

iterator/stateless/dropwhile_test.go

@@ -0,0 +1,35 @@
+// 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"
+
+	A "github.com/IBM/fp-go/array"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestDropWhile(t *testing.T) {
+	// sequence of 5 items
+	data := Take[int](10)(Cycle(From(0, 1, 2, 3)))
+
+	total := DropWhile(func(data int) bool {
+		return data <= 2
+	})(data)
+
+	assert.Equal(t, A.From(3, 0, 1, 2, 3, 0, 1), ToArray(total))
+
+}

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/compress.go

@@ -0,0 +1,34 @@
+// 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"
+)
+
+// Compress returns an [Iterator] that filters elements from a data [Iterator] returning only those that have a corresponding element in selector [Iterator] that evaluates to `true`.
+// Stops when either the data or selectors iterator has been exhausted.
+func Compress[GU ~func() O.Option[T.Tuple2[GU, U]], GB ~func() O.Option[T.Tuple2[GB, bool]], CS ~func() O.Option[T.Tuple2[CS, T.Tuple2[U, bool]]], U any](sel GB) func(GU) GU {
+	return F.Flow2(
+		Zip[GU, GB, CS](sel),
+		FilterMap[GU, CS](F.Flow2(
+			O.FromPredicate(T.Second[U, bool]),
+			O.Map(T.First[U, bool]),
+		)),
+	)
+}

iterator/stateless/generic/cycle.go

@@ -0,0 +1,43 @@
+// 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"
+)
+
+func Cycle[GU ~func() O.Option[T.Tuple2[GU, U]], U any](ma GU) GU {
+	// avoid cyclic references
+	var m func(O.Option[T.Tuple2[GU, U]]) O.Option[T.Tuple2[GU, U]]
+
+	recurse := func(mu GU) GU {
+		return F.Nullary2(
+			mu,
+			m,
+		)
+	}
+
+	m = O.Fold(func() O.Option[T.Tuple2[GU, U]] {
+		return recurse(ma)()
+	}, F.Flow2(
+		T.Map2(recurse, F.Identity[U]),
+		O.Of[T.Tuple2[GU, U]],
+	))
+
+	return recurse(ma)
+}

iterator/stateless/generic/dropwhile.go

@@ -0,0 +1,49 @@
+// 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"
+	P "github.com/IBM/fp-go/predicate"
+	T "github.com/IBM/fp-go/tuple"
+)
+
+// DropWhile creates an [Iterator] that drops elements from the [Iterator] as long as the predicate is true; afterwards, returns every element.
+// Note, the [Iterator] does not produce any output until the predicate first becomes false
+func DropWhile[GU ~func() O.Option[T.Tuple2[GU, U]], U any](pred func(U) bool) func(GU) GU {
+	// avoid cyclic references
+	var m func(O.Option[T.Tuple2[GU, U]]) O.Option[T.Tuple2[GU, U]]
+
+	fromPred := O.FromPredicate(P.Not(P.ContraMap(T.Second[GU, U])(pred)))
+
+	recurse := func(mu GU) GU {
+		return F.Nullary2(
+			mu,
+			m,
+		)
+	}
+
+	m = O.Chain(func(t T.Tuple2[GU, U]) O.Option[T.Tuple2[GU, U]] {
+		return F.Pipe2(
+			t,
+			fromPred,
+			O.Fold(recurse(t.F1), O.Of[T.Tuple2[GU, U]]),
+		)
+	})
+
+	return recurse
+}

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

@@ -20,7 +20,8 @@ import (
 	F "github.com/IBM/fp-go/function"
 	"github.com/IBM/fp-go/internal/utils"
 	IO "github.com/IBM/fp-go/iooption/generic"
-	N "github.com/IBM/fp-go/number/integer"
+	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"
 )
@@ -49,9 +50,8 @@ 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](f func(V, U) V, initial V) func(GU) V {
-	return func(as GU) V {
+// 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 {
@@ -60,7 +60,11 @@ func Reduce[GU ~func() O.Option[T.Tuple2[GU, U]], U, V any](f func(V, U) V, init
 		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 F.Bind23of3(reduce[GU, U, V])(f, initial)
 }
 
 // ToArray converts the iterator to an array
@@ -135,38 +139,49 @@ func Flatten[GV ~func() O.Option[T.Tuple2[GV, GU]], GU ~func() O.Option[T.Tuple2
 	return MonadChain(ma, F.Identity[GU])
 }
 
-// MakeBy returns an [Iterator] with `n` elements initialized with `f(i)`
-func MakeBy[GU ~func() O.Option[T.Tuple2[GU, U]], FCT ~func(int) U, U any](n int, f FCT) GU {
+// MakeBy returns an [Iterator] with an infinite number of elements initialized with `f(i)`
+func MakeBy[GU ~func() O.Option[T.Tuple2[GU, U]], FCT ~func(int) U, U any](f FCT) GU {
 
 	var m func(int) O.Option[T.Tuple2[GU, U]]
 
 	recurse := func(i int) GU {
-		return func() O.Option[T.Tuple2[GU, U]] {
-			return F.Pipe1(
-				i,
+		return F.Nullary2(
+			F.Constant(i),
 			m,
 		)
 	}
-	}
 
-	m = F.Flow2(
-		O.FromPredicate(N.Between(0, n)),
-		O.Map(F.Flow2(
+	m = F.Flow3(
 		T.Replicate2[int],
 		T.Map2(F.Flow2(
 			utils.Inc,
 			recurse),
 			f),
-		)),
+		O.Of[T.Tuple2[GU, U]],
 	)
 
 	// bootstrap
 	return recurse(0)
 }
 
-// Replicate creates an [Iterator] containing a value repeated the specified number of times.
-func Replicate[GU ~func() O.Option[T.Tuple2[GU, U]], U any](n int, a U) GU {
-	return MakeBy[GU](n, F.Constant1[int](a))
+// Replicate creates an infinite [Iterator] containing a value.
+func Replicate[GU ~func() O.Option[T.Tuple2[GU, U]], U any](a U) GU {
+	return MakeBy[GU](F.Constant1[int](a))
+}
+
+// Repeat creates an [Iterator] containing a value repeated the specified number of times.
+// Alias of [Replicate] combined with [Take]
+func Repeat[GU ~func() O.Option[T.Tuple2[GU, U]], U any](n int, a U) GU {
+	return F.Pipe2(
+		a,
+		Replicate[GU],
+		Take[GU](n),
+	)
+}
+
+// Count creates an [Iterator] containing a consecutive sequence of integers starting with the provided start value
+func Count[GU ~func() O.Option[T.Tuple2[GU, int]]](start int) GU {
+	return MakeBy[GU](N.Add(start))
 }
 
 func FilterMap[GV ~func() O.Option[T.Tuple2[GV, V]], GU ~func() O.Option[T.Tuple2[GU, U]], FCT ~func(U) O.Option[V], U, V any](f FCT) func(ma GU) GV {
@@ -205,3 +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/generic/reflect.go

@@ -0,0 +1,53 @@
+// 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 (
+	R "reflect"
+
+	F "github.com/IBM/fp-go/function"
+	LG "github.com/IBM/fp-go/io/generic"
+	L "github.com/IBM/fp-go/lazy"
+	N "github.com/IBM/fp-go/number"
+	I "github.com/IBM/fp-go/number/integer"
+	O "github.com/IBM/fp-go/option"
+	T "github.com/IBM/fp-go/tuple"
+)
+
+func FromReflect[GR ~func() O.Option[T.Tuple2[GR, R.Value]]](val R.Value) GR {
+	// recursive callback
+	var recurse func(idx int) GR
+
+	// limits the index
+	fromPred := O.FromPredicate(I.Between(0, val.Len()))
+
+	recurse = func(idx int) GR {
+		return F.Pipe3(
+			idx,
+			L.Of[int],
+			L.Map(fromPred),
+			LG.Map[L.Lazy[O.Option[int]], GR](O.Map(
+				F.Flow2(
+					T.Replicate2[int],
+					T.Map2(F.Flow2(N.Add(1), recurse), val.Index),
+				),
+			)),
+		)
+	}
+
+	// start the recursion
+	return recurse(0)
+}

iterator/stateless/generic/scan.go

@@ -0,0 +1,45 @@
+// 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"
+)
+
+func apTuple[A, B any](t T.Tuple2[func(A) B, A]) T.Tuple2[B, A] {
+	return T.MakeTuple2(t.F1(t.F2), t.F2)
+}
+
+func Scan[GV ~func() O.Option[T.Tuple2[GV, V]], GU ~func() O.Option[T.Tuple2[GU, U]], FCT ~func(V, U) V, U, V any](f FCT, initial V) func(ma GU) GV {
+	// pre-declare to avoid cyclic reference
+	var m func(GU) func(V) GV
+
+	recurse := func(ma GU, current V) GV {
+		return F.Nullary2(
+			ma,
+			O.Map(F.Flow2(
+				T.Map2(m, F.Bind1st(f, current)),
+				apTuple[V, GV],
+			)),
+		)
+	}
+
+	m = F.Curry2(recurse)
+
+	return F.Bind2nd(recurse, initial)
+}

iterator/stateless/generic/take.go

@@ -0,0 +1,43 @@
+// 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"
+	N "github.com/IBM/fp-go/number/integer"
+	O "github.com/IBM/fp-go/option"
+	T "github.com/IBM/fp-go/tuple"
+)
+
+func Take[GU ~func() O.Option[T.Tuple2[GU, U]], U any](n int) func(ma GU) GU {
+	// pre-declare to avoid cyclic reference
+	var recurse func(ma GU, idx int) GU
+
+	fromPred := O.FromPredicate(N.Between(0, n))
+
+	recurse = func(ma GU, idx int) GU {
+		return F.Nullary3(
+			F.Constant(idx),
+			fromPred,
+			O.Chain(F.Ignore1of1[int](F.Nullary2(
+				ma,
+				O.Map(T.Map2(F.Bind2nd(recurse, idx+1), F.Identity[U])),
+			))),
+		)
+	}
+
+	return F.Bind2nd(recurse, 0)
+}

iterator/stateless/generic/uniq.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 generic
+
+import (
+	F "github.com/IBM/fp-go/function"
+	O "github.com/IBM/fp-go/option"
+	T "github.com/IBM/fp-go/tuple"
+)
+
+// addToMap makes a deep copy of a map and adds a value
+func addToMap[A comparable](a A, m map[A]bool) map[A]bool {
+	cpy := make(map[A]bool, len(m)+1)
+	for k, v := range m {
+		cpy[k] = v
+	}
+	cpy[a] = true
+	return cpy
+}
+
+func Uniq[AS ~func() O.Option[T.Tuple2[AS, A]], K comparable, A any](f func(A) K) func(as AS) AS {
+
+	var recurse func(as AS, mp map[K]bool) AS
+
+	recurse = func(as AS, mp map[K]bool) AS {
+		return F.Nullary2(
+			as,
+			O.Chain(func(a T.Tuple2[AS, A]) O.Option[T.Tuple2[AS, A]] {
+				return F.Pipe3(
+					a.F2,
+					f,
+					O.FromPredicate(func(k K) bool {
+						_, ok := mp[k]
+						return !ok
+					}),
+					O.Fold(recurse(a.F1, mp), func(k K) O.Option[T.Tuple2[AS, A]] {
+						return O.Of(T.MakeTuple2(recurse(a.F1, addToMap(k, mp)), a.F2))
+					}),
+				)
+			}),
+		)
+	}
+
+	return F.Bind2nd(recurse, make(map[K]bool, 0))
+}
+
+func StrictUniq[AS ~func() O.Option[T.Tuple2[AS, A]], A comparable](as AS) AS {
+	return Uniq[AS](F.Identity[A])(as)
+}

iterator/stateless/generic/zip.go

@@ -0,0 +1,54 @@
+// 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"
+)
+
+// ZipWith applies a function to pairs of elements at the same index in two iterators, collecting the results in a new iterator. If one
+// input iterator is short, excess elements of the longer iterator are discarded.
+func ZipWith[AS ~func() O.Option[T.Tuple2[AS, A]], BS ~func() O.Option[T.Tuple2[BS, B]], CS ~func() O.Option[T.Tuple2[CS, C]], FCT ~func(A, B) C, A, B, C any](fa AS, fb BS, f FCT) CS {
+	// pre-declare to avoid cyclic reference
+	var m func(T.Tuple2[O.Option[T.Tuple2[AS, A]], O.Option[T.Tuple2[BS, B]]]) O.Option[T.Tuple2[CS, C]]
+
+	recurse := func(as AS, bs BS) CS {
+		return func() O.Option[T.Tuple2[CS, C]] {
+			// combine
+			return F.Pipe1(
+				T.MakeTuple2(as(), bs()),
+				m,
+			)
+		}
+	}
+
+	m = F.Flow2(
+		O.SequenceTuple2[T.Tuple2[AS, A], T.Tuple2[BS, B]],
+		O.Map(func(t T.Tuple2[T.Tuple2[AS, A], T.Tuple2[BS, B]]) T.Tuple2[CS, C] {
+			return T.MakeTuple2(recurse(t.F1.F1, t.F2.F1), f(t.F1.F2, t.F2.F2))
+		}))
+
+	// trigger the recursion
+	return recurse(fa, fb)
+}
+
+// Zip takes two iterators and returns an iterators of corresponding pairs. If one input iterators is short, excess elements of the
+// longer iterator are discarded
+func Zip[AS ~func() O.Option[T.Tuple2[AS, A]], BS ~func() O.Option[T.Tuple2[BS, B]], CS ~func() O.Option[T.Tuple2[CS, T.Tuple2[A, B]]], A, B any](fb BS) func(AS) CS {
+	return F.Bind23of3(ZipWith[AS, BS, CS, func(A, B) T.Tuple2[A, B]])(fb, T.MakeTuple2[A, B])
+}

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"
 )
@@ -78,14 +79,14 @@ func From[U any](data ...U) Iterator[U] {
 	return G.From[Iterator[U]](data...)
 }
 
-// MakeBy returns an [Iterator] with `n` elements initialized with `f(i)`
-func MakeBy[FCT ~func(int) U, U any](n int, f FCT) Iterator[U] {
-	return G.MakeBy[Iterator[U]](n, f)
+// MakeBy returns an [Iterator] with an infinite number of elements initialized with `f(i)`
+func MakeBy[FCT ~func(int) U, U any](f FCT) Iterator[U] {
+	return G.MakeBy[Iterator[U]](f)
 }
 
-// Replicate creates an [Iterator] containing a value repeated the specified number of times.
-func Replicate[U any](n int, a U) Iterator[U] {
-	return G.Replicate[Iterator[U]](n, a)
+// Replicate creates an [Iterator] containing a value repeated an infinite number of times.
+func Replicate[U any](a U) Iterator[U] {
+	return G.Replicate[Iterator[U]](a)
 }
 
 // FilterMap filters and transforms the content of an iterator
@@ -107,3 +108,29 @@ func Ap[V, U any](ma Iterator[U]) func(Iterator[func(U) V]) Iterator[V] {
 func MonadAp[V, U any](fab Iterator[func(U) V], ma Iterator[U]) Iterator[V] {
 	return G.MonadAp[Iterator[func(U) V], Iterator[V]](fab, ma)
 }
+
+// Repeat creates an [Iterator] containing a value repeated the specified number of times.
+// Alias of [Replicate]
+func Repeat[U any](n int, a U) Iterator[U] {
+	return G.Repeat[Iterator[U]](n, a)
+}
+
+// Count creates an [Iterator] containing a consecutive sequence of integers starting with the provided start value
+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"
 )
 
@@ -76,8 +78,9 @@ func isPrimeNumber(num int) bool {
 
 func TestFilterMap(t *testing.T) {
 
-	it := F.Pipe2(
-		MakeBy(100, utils.Inc),
+	it := F.Pipe3(
+		MakeBy(utils.Inc),
+		Take[int](100),
 		FilterMap(O.FromPredicate(isPrimeNumber)),
 		ToArray[int],
 	)
@@ -101,3 +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)
+}

iterator/stateless/reflect.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 (
+	R "reflect"
+
+	G "github.com/IBM/fp-go/iterator/stateless/generic"
+)
+
+// FromReflect creates an iterator that can iterate over types that define [R.Index] and [R.Len]
+func FromReflect(val R.Value) Iterator[R.Value] {
+	return G.FromReflect[Iterator[R.Value]](val)
+}

iterator/stateless/reflect_test.go

@@ -0,0 +1,38 @@
+// 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 (
+	"reflect"
+	"testing"
+
+	A "github.com/IBM/fp-go/array"
+	F "github.com/IBM/fp-go/function"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestReflect(t *testing.T) {
+	ar := A.From("a", "b", "c")
+
+	res := F.Pipe3(
+		reflect.ValueOf(ar),
+		FromReflect,
+		ToArray[reflect.Value],
+		A.Map(reflect.Value.String),
+	)
+
+	assert.Equal(t, ar, res)
+}

iterator/stateless/scan.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"
+)
+
+// Scan takes an [Iterator] and returns a new [Iterator] of the same length, where the values
+// of the new [Iterator] are the result of the application of `f` to the value of the
+// source iterator with the previously accumulated value
+func Scan[FCT ~func(V, U) V, U, V any](f FCT, initial V) func(ma Iterator[U]) Iterator[V] {
+	return G.Scan[Iterator[V], Iterator[U], FCT](f, initial)
+}

iterator/stateless/scan_test.go

@@ -0,0 +1,42 @@
+// 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"
+
+	F "github.com/IBM/fp-go/function"
+	T "github.com/IBM/fp-go/tuple"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestScan(t *testing.T) {
+
+	src := From("a", "b", "c")
+
+	dst := F.Pipe1(
+		src,
+		Scan(func(cur T.Tuple2[int, string], val string) T.Tuple2[int, string] {
+			return T.MakeTuple2(cur.F1+1, val)
+		}, T.MakeTuple2(0, "")),
+	)
+
+	assert.Equal(t, ToArray(From(
+		T.MakeTuple2(1, "a"),
+		T.MakeTuple2(2, "b"),
+		T.MakeTuple2(3, "c"),
+	)), ToArray(dst))
+}

iterator/stateless/take.go

@@ -0,0 +1,25 @@
+// 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"
+)
+
+// Take limits the number of values in the [Iterator] to a maximum number
+func Take[U any](n int) func(ma Iterator[U]) Iterator[U] {
+	return G.Take[Iterator[U]](n)
+}

iterator/stateless/take_test.go

@@ -0,0 +1,37 @@
+// 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"
+
+	A "github.com/IBM/fp-go/array"
+	F "github.com/IBM/fp-go/function"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestTake(t *testing.T) {
+
+	total := MakeBy(F.Identity[int])
+
+	trimmed := F.Pipe1(
+		total,
+		Take[int](10),
+	)
+
+	assert.Equal(t, A.MakeBy(10, F.Identity[int]), ToArray(trimmed))
+
+}

iterator/stateless/uniq.go

@@ -0,0 +1,32 @@
+// 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"
+)
+
+// StrictUniq converts an [Iterator] or arbitrary items into an [Iterator] or unique items
+// where uniqueness is determined by the built-in uniqueness constraint
+func StrictUniq[A comparable](as Iterator[A]) Iterator[A] {
+	return G.StrictUniq[Iterator[A]](as)
+}
+
+// Uniq converts an [Iterator] or arbitrary items into an [Iterator] or unique items
+// where uniqueness is determined based on a key extractor function
+func Uniq[A any, K comparable](f func(A) K) func(as Iterator[A]) Iterator[A] {
+	return G.Uniq[Iterator[A], K](f)
+}

iterator/stateless/uniq_test.go

@@ -0,0 +1,31 @@
+// 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"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestUniq(t *testing.T) {
+	// iterator with duplicate items
+	dups := From(1, 2, 3, 1, 4, 5, 2)
+
+	u := StrictUniq(dups)
+
+	assert.Equal(t, ToArray(From(1, 2, 3, 4, 5)), ToArray(u))
+}

iterator/stateless/zip.go

@@ -0,0 +1,33 @@
+// 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"
+	T "github.com/IBM/fp-go/tuple"
+)
+
+// ZipWith applies a function to pairs of elements at the same index in two iterators, collecting the results in a new iterator. If one
+// input iterator is short, excess elements of the longer iterator are discarded.
+func ZipWith[FCT ~func(A, B) C, A, B, C any](fa Iterator[A], fb Iterator[B], f FCT) Iterator[C] {
+	return G.ZipWith[Iterator[A], Iterator[B], Iterator[C]](fa, fb, f)
+}
+
+// Zip takes two iterators and returns an iterators of corresponding pairs. If one input iterators is short, excess elements of the
+// longer iterator are discarded
+func Zip[A, B any](fb Iterator[B]) func(Iterator[A]) Iterator[T.Tuple2[A, B]] {
+	return G.Zip[Iterator[A], Iterator[B], Iterator[T.Tuple2[A, B]]](fb)
+}

iterator/stateless/zip_test.go

@@ -0,0 +1,44 @@
+// 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 (
+	"fmt"
+	"testing"
+
+	T "github.com/IBM/fp-go/tuple"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestZipWith(t *testing.T) {
+	left := From(1, 2, 3)
+	right := From("a", "b", "c", "d")
+
+	res := ZipWith(left, right, func(l int, r string) string {
+		return fmt.Sprintf("%s%d", r, l)
+	})
+
+	assert.Equal(t, ToArray(From("a1", "b2", "c3")), ToArray(res))
+}
+
+func TestZip(t *testing.T) {
+	left := From(1, 2, 3)
+	right := From("a", "b", "c", "d")
+
+	res := Zip[string](left)(right)
+
+	assert.Equal(t, ToArray(From(T.MakeTuple2("a", 1), T.MakeTuple2("b", 2), T.MakeTuple2("c", 3))), ToArray(res))
+}

json/type.go

@@ -32,6 +32,6 @@ func ToTypeE[A any](src any) E.Either[error, A] {
 func ToTypeO[A any](src any) O.Option[A] {
 	return F.Pipe1(
 		ToTypeE[A](src),
-		E.ToOption[error, A](),
+		E.ToOption[error, A],
 	)
 }

lambda/y.go

@@ -19,14 +19,11 @@ type (
 	// RecFct is the function called recursively
 	RecFct[T, R any] func(T) R
 
-	// transformer
-	Transformer[T, R any] func(RecFct[T, R]) RecFct[T, R]
-
 	internalCombinator[T, R any] func(internalCombinator[T, R]) RecFct[T, R]
 )
 
 // Y is the Y-combinator based on https://dreamsongs.com/Files/WhyOfY.pdf
-func Y[T, R any](f Transformer[T, R]) RecFct[T, R] {
+func Y[TRFRM ~func(RecFct[T, R]) RecFct[T, R], T, R any](f TRFRM) RecFct[T, R] {
 	g := func(h internalCombinator[T, R]) RecFct[T, R] {
 		return func(t T) R {
 			return f(h(h))(t)

lazy/example_lazy_test.go

@@ -0,0 +1,38 @@
+// 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 lazy
+
+import (
+	"fmt"
+	"strconv"
+
+	F "github.com/IBM/fp-go/function"
+)
+
+func ExampleLazy_creation() {
+	// lazy function of a constant value
+	val := Of(42)
+	// create another function to transform this
+	valS := F.Pipe1(
+		val,
+		Map(strconv.Itoa),
+	)
+
+	fmt.Println(valS())
+
+	// Output:
+	// 42
+}

lazy/lazy.go

@@ -72,18 +72,18 @@ func Chain[A, B any](f func(A) Lazy[B]) func(Lazy[A]) Lazy[B] {
 }
 
 func MonadAp[B, A any](mab Lazy[func(A) B], ma Lazy[A]) Lazy[B] {
-	return G.MonadAp[Lazy[A], Lazy[B]](mab, ma)
+	return G.MonadApSeq[Lazy[A], Lazy[B]](mab, ma)
 }
 
 func Ap[B, A any](ma Lazy[A]) func(Lazy[func(A) B]) Lazy[B] {
-	return G.Ap[Lazy[B], Lazy[func(A) B], Lazy[A]](ma)
+	return G.ApSeq[Lazy[B], Lazy[func(A) B], Lazy[A]](ma)
 }
 
 func Flatten[A any](mma Lazy[Lazy[A]]) Lazy[A] {
 	return G.Flatten(mma)
 }
 
-// Memoize computes the value of the provided IO monad lazily but exactly once
+// Memoize computes the value of the provided [Lazy] monad lazily but exactly once
 func Memoize[A any](ma Lazy[A]) Lazy[A] {
 	return G.Memoize(ma)
 }

number/utils.go

@@ -30,7 +30,30 @@ 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
 }
+
+// Min takes the minimum of two values. If they are considered equal, the first argument is chosen
+func Min[A C.Ordered](a, b A) A {
+	if a < b {
+		return a
+	}
+	return b
+}
+
+// Max takes the maximum of two values. If they are considered equal, the first argument is chosen
+func Max[A C.Ordered](a, b A) A {
+	if a > b {
+		return a
+	}
+	return b
+}

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
+}