fix: merge

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

.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 {
@@ -280,3 +286,25 @@ func IsNonNil[A any](as []A) bool {
 func ConstNil[A any]() []A {
 	return array.ConstNil[[]A]()
 }
+
+func SliceRight[A any](start int) func([]A) []A {
+	return G.SliceRight[[]A](start)
+}
+
+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)
 }
@@ -163,6 +187,14 @@ func IsEmpty[AS ~[]A, A any](as AS) bool {
 	return array.IsEmpty(as)
 }
 
+func IsNil[GA ~[]A, A any](as GA) bool {
+	return array.IsNil(as)
+}
+
+func IsNonNil[GA ~[]A, A any](as GA) bool {
+	return array.IsNonNil(as)
+}
+
 func Match[AS ~[]A, A, B any](onEmpty func() B, onNonEmpty func(AS) B) func(AS) B {
 	return func(as AS) B {
 		if IsEmpty(as) {
@@ -180,3 +212,41 @@ func MatchLeft[AS ~[]A, A, B any](onEmpty func() B, onNonEmpty func(A, AS) B) fu
 		return onNonEmpty(as[0], as[1:])
 	}
 }
+
+func Slice[AS ~[]A, A any](start int, end int) func(AS) AS {
+	return func(a AS) AS {
+		return a[start:end]
+	}
+}
+
+func SliceRight[AS ~[]A, A any](start int) func(AS) AS {
+	return func(a AS) AS {
+		return a[start:]
+	}
+}
+
+func Copy[AS ~[]A, A any](b AS) AS {
+	buf := make(AS, len(b))
+	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

@@ -25,6 +25,40 @@ import (
 	C "github.com/urfave/cli/v2"
 )
 
+func generateUnsliced(f *os.File, i int) {
+	// Create the optionize version
+	fmt.Fprintf(f, "\n// Unsliced%d converts a function taking a slice parameter into a function with %d parameters\n", i, i)
+	fmt.Fprintf(f, "func Unsliced%d[F ~func([]T) R, T, R any](f F) func(", i)
+	for j := 0; j < i; j++ {
+		if j > 0 {
+			fmt.Fprintf(f, ", ")
+		}
+		fmt.Fprintf(f, "T")
+	}
+	fmt.Fprintf(f, ") R {\n")
+	fmt.Fprintf(f, "  return func(")
+	for j := 0; j < i; j++ {
+		if j > 0 {
+			fmt.Fprintf(f, ", ")
+		}
+		fmt.Fprintf(f, "t%d", j+1)
+	}
+	if i > 0 {
+		fmt.Fprintf(f, " T")
+	}
+	fmt.Fprintf(f, ") R {\n")
+	fmt.Fprintf(f, "    return f([]T{")
+	for j := 0; j < i; j++ {
+		if j > 0 {
+			fmt.Fprintf(f, ", ")
+		}
+		fmt.Fprintf(f, "t%d", j+1)
+	}
+	fmt.Fprintln(f, "})")
+	fmt.Fprintln(f, "  }")
+	fmt.Fprintln(f, "}")
+}
+
 func generateVariadic(f *os.File, i int) {
 	// Create the nullary version
 	fmt.Fprintf(f, "\n// Variadic%d converts a function taking %d parameters and a final slice into a function with %d parameters but a final variadic argument\n", i, i, i)
@@ -83,7 +117,7 @@ func generateVariadic(f *os.File, i int) {
 	fmt.Fprintf(f, "v)\n")
 	fmt.Fprintf(f, "  }\n")
 
-	fmt.Fprintf(f, "}")
+	fmt.Fprintf(f, "}\n")
 }
 
 func generateUnvariadic(f *os.File, i int) {
@@ -144,7 +178,7 @@ func generateUnvariadic(f *os.File, i int) {
 	fmt.Fprintf(f, "v...)\n")
 	fmt.Fprintf(f, "  }\n")
 
-	fmt.Fprintf(f, "}")
+	fmt.Fprintf(f, "}\n")
 }
 
 func generateNullary(f *os.File, i int) {
@@ -337,7 +371,7 @@ 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)
 
@@ -347,6 +381,8 @@ func generatePipeHelpers(filename string, count int) error {
 	generateVariadic(f, 0)
 	// unvariadic
 	generateUnvariadic(f, 0)
+	// unsliced
+	generateUnsliced(f, 0)
 
 	for i := 1; i <= count; i++ {
 
@@ -364,6 +400,8 @@ func generatePipeHelpers(filename string, count int) error {
 		generateVariadic(f, i)
 		// unvariadic
 		generateUnvariadic(f, i)
+		// unsliced
+		generateUnsliced(f, i)
 	}
 
 	return nil

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/reader/array.go

@@ -24,6 +24,11 @@ func TraverseArray[A, B any](f func(A) Reader[B]) func([]A) Reader[[]B] {
 	return R.TraverseArray[Reader[B], Reader[[]B], []A](f)
 }
 
+// TraverseArrayWithIndex transforms an array
+func TraverseArrayWithIndex[A, B any](f func(int, A) Reader[B]) func([]A) Reader[[]B] {
+	return R.TraverseArrayWithIndex[Reader[B], Reader[[]B], []A](f)
+}
+
 // SequenceArray converts a homogeneous sequence of either into an either of sequence
 func SequenceArray[A any](ma []Reader[A]) Reader[[]A] {
 	return R.SequenceArray[Reader[A], Reader[[]A]](ma)

context/readereither/array.go

@@ -24,6 +24,11 @@ func TraverseArray[A, B any](f func(A) ReaderEither[B]) func([]A) ReaderEither[[
 	return RE.TraverseArray[ReaderEither[B], ReaderEither[[]B], []A](f)
 }
 
+// TraverseArrayWithIndex transforms an array
+func TraverseArrayWithIndex[A, B any](f func(int, A) ReaderEither[B]) func([]A) ReaderEither[[]B] {
+	return RE.TraverseArrayWithIndex[ReaderEither[B], ReaderEither[[]B], []A](f)
+}
+
 // SequenceArray converts a homogeneous sequence of either into an either of sequence
 func SequenceArray[A any](ma []ReaderEither[A]) ReaderEither[[]A] {
 	return RE.SequenceArray[ReaderEither[A], ReaderEither[[]A]](ma)

context/readerio/array.go

@@ -25,6 +25,11 @@ func TraverseArray[A, B any](f func(A) ReaderIO[B]) func([]A) ReaderIO[[]B] {
 	return R.TraverseArray[ReaderIO[B], ReaderIO[[]B], IO.IO[B], IO.IO[[]B], []A](f)
 }
 
+// TraverseArrayWithIndex transforms an array
+func TraverseArrayWithIndex[A, B any](f func(int, A) ReaderIO[B]) func([]A) ReaderIO[[]B] {
+	return R.TraverseArrayWithIndex[ReaderIO[B], ReaderIO[[]B], IO.IO[B], IO.IO[[]B], []A](f)
+}
+
 // SequenceArray converts a homogeneous sequence of either into an either of sequence
 func SequenceArray[A any](ma []ReaderIO[A]) ReaderIO[[]A] {
 	return R.SequenceArray[ReaderIO[A], ReaderIO[[]A]](ma)

context/readerioeither/gen.go

@@ -1,23 +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.
-
 package readerioeither
 
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 15:42:22.8252325 +0200 CEST m=+0.010212601
+// 2023-09-12 13:44:14.1022311 +0200 CEST m=+0.017763401
+
 
 import (
 	"context"

context/readerioeither/generic/gen.go

@@ -1,23 +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.
-
 package generic
 
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 15:42:22.8252325 +0200 CEST m=+0.010212601
+// 2023-09-12 13:44:14.1036885 +0200 CEST m=+0.019220801
+
 
 import (
 	"context"

context/readerioeither/generic/traverse.go

@@ -62,6 +62,25 @@ func TraverseArray[
 	)
 }
 
+// TraverseArrayWithIndex transforms an array
+func TraverseArrayWithIndex[
+	AS ~[]A,
+	GRBS ~func(context.Context) GIOBS,
+	GRB ~func(context.Context) GIOB,
+	GIOBS ~func() E.Either[error, BS],
+	GIOB ~func() E.Either[error, B],
+	BS ~[]B,
+	A, B any](f func(int, A) GRB) func(AS) GRBS {
+
+	return RA.TraverseWithIndex[AS](
+		Of[GRBS, GIOBS, BS],
+		Map[GRBS, func(context.Context) func() E.Either[error, func(B) BS], GIOBS, func() E.Either[error, func(B) BS], BS, func(B) BS],
+		Ap[GRBS, func(context.Context) func() E.Either[error, func(B) BS], GRB],
+
+		f,
+	)
+}
+
 // SequenceArray converts a homogeneous sequence of either into an either of sequence
 func SequenceArray[
 	AS ~[]A,
@@ -115,6 +134,26 @@ func TraverseRecord[K comparable,
 	)
 }
 
+// TraverseRecordWithIndex transforms a record
+func TraverseRecordWithIndex[K comparable,
+	AS ~map[K]A,
+	GRBS ~func(context.Context) GIOBS,
+	GRB ~func(context.Context) GIOB,
+	GIOBS ~func() E.Either[error, BS],
+	GIOB ~func() E.Either[error, B],
+	BS ~map[K]B,
+
+	A, B any](f func(K, A) GRB) func(AS) GRBS {
+
+	return RR.TraverseWithIndex[AS](
+		Of[GRBS, GIOBS, BS],
+		Map[GRBS, func(context.Context) func() E.Either[error, func(B) BS], GIOBS, func() E.Either[error, func(B) BS], BS, func(B) BS],
+		Ap[GRBS, func(context.Context) func() E.Either[error, func(B) BS], GRB],
+
+		f,
+	)
+}
+
 // SequenceRecord converts a homogeneous sequence of either into an either of sequence
 func SequenceRecord[K comparable,
 	AS ~map[K]A,

context/readerioeither/http/request_test.go

@@ -21,6 +21,13 @@ import (
 	"testing"
 
 	H "net/http"
+
+	R "github.com/IBM/fp-go/context/readerioeither"
+	E "github.com/IBM/fp-go/either"
+	"github.com/IBM/fp-go/errors"
+	F "github.com/IBM/fp-go/function"
+	IOE "github.com/IBM/fp-go/ioeither"
+	"github.com/stretchr/testify/assert"
 )
 
 type PostItem struct {
@@ -30,6 +37,47 @@ type PostItem struct {
 	Body   string `json:"body"`
 }
 
+func getTitle(item PostItem) string {
+	return item.Title
+}
+
+type simpleRequestBuilder struct {
+	method  string
+	url     string
+	headers H.Header
+}
+
+func requestBuilder() simpleRequestBuilder {
+	return simpleRequestBuilder{method: "GET"}
+}
+
+func (b simpleRequestBuilder) WithURL(url string) simpleRequestBuilder {
+	b.url = url
+	return b
+}
+
+func (b simpleRequestBuilder) WithHeader(key, value string) simpleRequestBuilder {
+	if b.headers == nil {
+		b.headers = make(H.Header)
+	} else {
+		b.headers = b.headers.Clone()
+	}
+	b.headers.Set(key, value)
+	return b
+}
+
+func (b simpleRequestBuilder) Build() R.ReaderIOEither[*H.Request] {
+	return func(ctx context.Context) IOE.IOEither[error, *H.Request] {
+		return IOE.TryCatchError(func() (*H.Request, error) {
+			req, err := H.NewRequestWithContext(ctx, b.method, b.url, nil)
+			if err == nil {
+				req.Header = b.headers
+			}
+			return req, err
+		})
+	}
+}
+
 func TestSendSingleRequest(t *testing.T) {
 
 	client := MakeClient(H.DefaultClient)
@@ -40,7 +88,70 @@ func TestSendSingleRequest(t *testing.T) {
 
 	resp1 := readItem(req1)
 
-	resE := resp1(context.Background())()
+	resE := resp1(context.TODO())()
 
 	fmt.Println(resE)
 }
+
+// setHeaderUnsafe updates a header value in a request object by mutating the request object
+func setHeaderUnsafe(key, value string) func(*H.Request) *H.Request {
+	return func(req *H.Request) *H.Request {
+		req.Header.Set(key, value)
+		return req
+	}
+}
+
+func TestSendSingleRequestWithHeaderUnsafe(t *testing.T) {
+
+	client := MakeClient(H.DefaultClient)
+
+	// this is not safe from a puristic perspective, because the map call mutates the request object
+	req1 := F.Pipe2(
+		"https://jsonplaceholder.typicode.com/posts/1",
+		MakeGetRequest,
+		R.Map(setHeaderUnsafe("Content-Type", "text/html")),
+	)
+
+	readItem := ReadJson[PostItem](client)
+
+	resp1 := F.Pipe2(
+		req1,
+		readItem,
+		R.Map(getTitle),
+	)
+
+	res := F.Pipe1(
+		resp1(context.TODO())(),
+		E.GetOrElse(errors.ToString),
+	)
+
+	assert.Equal(t, "sunt aut facere repellat provident occaecati excepturi optio reprehenderit", res)
+}
+
+func TestSendSingleRequestWithHeaderSafe(t *testing.T) {
+
+	client := MakeClient(H.DefaultClient)
+
+	// the request builder assembles config values to construct
+	// the final http request. Each `With` step creates a copy of the settings
+	// so the flow is pure
+	request := requestBuilder().
+		WithURL("https://jsonplaceholder.typicode.com/posts/1").
+		WithHeader("Content-Type", "text/html").
+		Build()
+
+	readItem := ReadJson[PostItem](client)
+
+	response := F.Pipe2(
+		request,
+		readItem,
+		R.Map(getTitle),
+	)
+
+	res := F.Pipe1(
+		response(context.TODO())(),
+		E.GetOrElse(errors.ToString),
+	)
+
+	assert.Equal(t, "sunt aut facere repellat provident occaecati excepturi optio reprehenderit", res)
+}

context/readerioeither/traverse.go

@@ -24,6 +24,11 @@ func TraverseArray[A, B any](f func(A) ReaderIOEither[B]) func([]A) ReaderIOEith
 	return G.TraverseArray[[]A, ReaderIOEither[[]B]](f)
 }
 
+// TraverseArrayWithIndex uses transforms an array [[]A] into [[]ReaderIOEither[B]] and then resolves that into a [ReaderIOEither[[]B]]
+func TraverseArrayWithIndex[A, B any](f func(int, A) ReaderIOEither[B]) func([]A) ReaderIOEither[[]B] {
+	return G.TraverseArrayWithIndex[[]A, ReaderIOEither[[]B]](f)
+}
+
 // SequenceArray converts a homogeneous sequence of either into an either of sequence
 func SequenceArray[A any](ma []ReaderIOEither[A]) ReaderIOEither[[]A] {
 	return G.SequenceArray[[]A, []ReaderIOEither[A], ReaderIOEither[[]A]](ma)
@@ -34,6 +39,11 @@ func TraverseRecord[K comparable, A, B any](f func(A) ReaderIOEither[B]) func(ma
 	return G.TraverseRecord[K, map[K]A, ReaderIOEither[map[K]B]](f)
 }
 
+// TraverseRecordWithIndex uses transforms a record [map[K]A] into [map[K]ReaderIOEither[B]] and then resolves that into a [ReaderIOEither[map[K]B]]
+func TraverseRecordWithIndex[K comparable, A, B any](f func(K, A) ReaderIOEither[B]) func(map[K]A) ReaderIOEither[map[K]B] {
+	return G.TraverseRecordWithIndex[K, map[K]A, ReaderIOEither[map[K]B]](f)
+}
+
 // SequenceRecord converts a homogeneous sequence of either into an either of sequence
 func SequenceRecord[K comparable, A any](ma map[K]ReaderIOEither[A]) ReaderIOEither[map[K]A] {
 	return G.SequenceRecord[K, map[K]A, map[K]ReaderIOEither[A], ReaderIOEither[map[K]A]](ma)

either/array.go

@@ -0,0 +1,74 @@
+// 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 (
+	F "github.com/IBM/fp-go/function"
+	RA "github.com/IBM/fp-go/internal/array"
+)
+
+// TraverseArrayG transforms an array
+func TraverseArrayG[GA ~[]A, GB ~[]B, E, A, B any](f func(A) Either[E, B]) func(GA) Either[E, GB] {
+	return RA.Traverse[GA](
+		Of[E, GB],
+		Map[E, GB, func(B) GB],
+		Ap[GB, E, B],
+
+		f,
+	)
+}
+
+// TraverseArray transforms an array
+func TraverseArray[E, A, B any](f func(A) Either[E, B]) func([]A) Either[E, []B] {
+	return TraverseArrayG[[]A, []B](f)
+}
+
+// TraverseArrayWithIndexG transforms an array
+func TraverseArrayWithIndexG[GA ~[]A, GB ~[]B, E, A, B any](f func(int, A) Either[E, B]) func(GA) Either[E, GB] {
+	return RA.TraverseWithIndex[GA](
+		Of[E, GB],
+		Map[E, GB, func(B) GB],
+		Ap[GB, E, B],
+
+		f,
+	)
+}
+
+// TraverseArrayWithIndex transforms an array
+func TraverseArrayWithIndex[E, A, B any](f func(int, A) Either[E, B]) func([]A) Either[E, []B] {
+	return TraverseArrayWithIndexG[[]A, []B](f)
+}
+
+func SequenceArrayG[GA ~[]A, GOA ~[]Either[E, A], E, A any](ma GOA) Either[E, GA] {
+	return TraverseArrayG[GOA, GA](F.Identity[Either[E, A]])(ma)
+}
+
+// SequenceArray converts a homogeneous sequence of either into an either of sequence
+func SequenceArray[E, A any](ma []Either[E, A]) Either[E, []A] {
+	return SequenceArrayG[[]A](ma)
+}
+
+// CompactArrayG discards the none values and keeps the some values
+func CompactArrayG[A1 ~[]Either[E, A], A2 ~[]A, E, A any](fa A1) A2 {
+	return RA.Reduce(fa, func(out A2, value Either[E, A]) A2 {
+		return MonadFold(value, F.Constant1[E](out), F.Bind1st(RA.Append[A2, A], out))
+	}, make(A2, len(fa)))
+}
+
+// CompactArray discards the none values and keeps the some values
+func CompactArray[E, A any](fa []Either[E, A]) []A {
+	return CompactArrayG[[]Either[E, A], []A](fa)
+}

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

@@ -91,11 +91,11 @@ func MonadChainTo[E, A, B any](ma Either[E, A], mb Either[E, B]) Either[E, B] {
 	return mb
 }
 
-func MonadChainOptionK[E, A, B any](onNone func() E, ma Either[E, A], f func(A) O.Option[B]) Either[E, B] {
+func MonadChainOptionK[A, B, E any](onNone func() E, ma Either[E, A], f func(A) O.Option[B]) Either[E, B] {
 	return MonadChain(ma, F.Flow2(f, FromOption[E, B](onNone)))
 }
 
-func ChainOptionK[E, A, B any](onNone func() E) func(func(A) O.Option[B]) func(Either[E, A]) Either[E, B] {
+func ChainOptionK[A, B, E any](onNone func() E) func(func(A) O.Option[B]) func(Either[E, A]) Either[E, B] {
 	from := FromOption[E, B](onNone)
 	return func(f func(A) O.Option[B]) func(Either[E, A]) Either[E, B] {
 		return Chain(F.Flow2(f, from))
@@ -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))
 }
 
@@ -209,7 +209,7 @@ func OrElse[E, A any](onLeft func(e E) Either[E, A]) func(Either[E, A]) Either[E
 	return Fold(onLeft, Of[E, A])
 }
 
-func ToType[E, A any](onError func(any) E) func(any) Either[E, A] {
+func ToType[A, E any](onError func(any) E) func(any) Either[E, A] {
 	return func(value any) Either[E, A] {
 		return F.Pipe2(
 			value,

either/either_test.go

@@ -100,7 +100,7 @@ func TestChainFirst(t *testing.T) {
 }
 
 func TestChainOptionK(t *testing.T) {
-	f := ChainOptionK[string, int, int](F.Constant("a"))(func(n int) O.Option[int] {
+	f := ChainOptionK[int, int](F.Constant("a"))(func(n int) O.Option[int] {
 		if n > 0 {
 			return O.Some(n)
 		}

either/examples_create_test.go

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

either/examples_extract_test.go

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

either/gen.go

@@ -1,21 +1,7 @@
-// Copyright (c) 2023 IBM Corp.
-// All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 15:42:24.2984201 +0200 CEST m=+0.008649601
+// 2023-09-12 13:44:15.6356542 +0200 CEST m=+0.009418901
+
 package either
 
 

either/record.go

@@ -20,7 +20,7 @@ import (
 	RR "github.com/IBM/fp-go/internal/record"
 )
 
-// TraverseRecord transforms a record of options into an option of a record
+// TraverseRecordG transforms a record of options into an option of a record
 func TraverseRecordG[GA ~map[K]A, GB ~map[K]B, K comparable, E, A, B any](f func(A) Either[E, B]) func(GA) Either[E, GB] {
 	return RR.Traverse[GA](
 		Of[E, GB],
@@ -35,6 +35,21 @@ func TraverseRecord[K comparable, E, A, B any](f func(A) Either[E, B]) func(map[
 	return TraverseRecordG[map[K]A, map[K]B](f)
 }
 
+// TraverseRecordWithIndexG transforms a record of options into an option of a record
+func TraverseRecordWithIndexG[GA ~map[K]A, GB ~map[K]B, K comparable, E, A, B any](f func(K, A) Either[E, B]) func(GA) Either[E, GB] {
+	return RR.TraverseWithIndex[GA](
+		Of[E, GB],
+		Map[E, GB, func(B) GB],
+		Ap[GB, E, B],
+		f,
+	)
+}
+
+// TraverseRecordWithIndex transforms a record of eithers into an either of a record
+func TraverseRecordWithIndex[K comparable, E, A, B any](f func(K, A) Either[E, B]) func(map[K]A) Either[E, map[K]B] {
+	return TraverseRecordWithIndexG[map[K]A, map[K]B](f)
+}
+
 func SequenceRecordG[GA ~map[K]A, GOA ~map[K]Either[E, A], K comparable, E, A any](ma GOA) Either[E, GA] {
 	return TraverseRecordG[GOA, GA](F.Identity[Either[E, A]])(ma)
 }
@@ -43,3 +58,24 @@ func SequenceRecordG[GA ~map[K]A, GOA ~map[K]Either[E, A], K comparable, E, A an
 func SequenceRecord[K comparable, E, A any](ma map[K]Either[E, A]) Either[E, map[K]A] {
 	return SequenceRecordG[map[K]A](ma)
 }
+
+func upsertAtReadWrite[M ~map[K]V, K comparable, V any](r M, k K, v V) M {
+	r[k] = v
+	return r
+}
+
+// CompactRecordG discards the noe values and keeps the some values
+func CompactRecordG[M1 ~map[K]Either[E, A], M2 ~map[K]A, K comparable, E, A any](m M1) M2 {
+	out := make(M2)
+	onLeft := F.Constant1[E](out)
+	return RR.ReduceWithIndex(m, func(key K, _ M2, value Either[E, A]) M2 {
+		return MonadFold(value, onLeft, func(v A) M2 {
+			return upsertAtReadWrite(out, key, v)
+		})
+	}, out)
+}
+
+// CompactRecord discards all none values and keeps the somes
+func CompactRecord[K comparable, E, A any](m map[K]Either[E, A]) map[K]A {
+	return CompactRecordG[map[K]Either[E, A], map[K]A](m)
+}

either/record_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 either
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestCompactRecord(t *testing.T) {
+	// make the map
+	m := make(map[string]Either[string, int])
+	m["foo"] = Left[int]("error")
+	m["bar"] = Right[string](1)
+	// compact it
+	m1 := CompactRecord(m)
+	// check expected
+	exp := map[string]int{
+		"bar": 1,
+	}
+
+	assert.Equal(t, exp, m1)
+}

either/traverse.go

@@ -27,13 +27,13 @@ HKTRB = HKT<Either[B]>
 HKTA = HKT<A>
 HKTB = HKT<B>
 */
-func traverse[E, A, B, HKTA, HKTB, HKTRB any](
-	_of func(Either[E, B]) HKTRB,
-	_map func(HKTB, func(B) Either[E, B]) HKTRB,
+func traverse[E, A, B, HKTB, HKTRB any](
+	mof func(Either[E, B]) HKTRB,
+	mmap func(func(B) Either[E, B]) func(HKTB) HKTRB,
 ) func(Either[E, A], func(A) HKTB) HKTRB {
 
-	left := F.Flow2(Left[B, E], _of)
-	right := F.Bind2nd(_map, Right[E, B])
+	left := F.Flow2(Left[B, E], mof)
+	right := mmap(Right[E, B])
 
 	return func(ta Either[E, A], f func(A) HKTB) HKTRB {
 		return MonadFold(ta,
@@ -43,27 +43,21 @@ func traverse[E, A, B, HKTA, HKTB, HKTRB any](
 	}
 }
 
-func Traverse[E, A, B, HKTA, HKTB, HKTRB any](
-	_of func(Either[E, B]) HKTRB,
-	_map func(HKTB, func(B) Either[E, B]) HKTRB,
+// Traverse converts an [Either] of some higher kinded type into the higher kinded type of an [Either]
+func Traverse[A, E, B, HKTB, HKTRB any](
+	mof func(Either[E, B]) HKTRB,
+	mmap func(func(B) Either[E, B]) func(HKTB) HKTRB,
 ) func(func(A) HKTB) func(Either[E, A]) HKTRB {
-	delegate := traverse[E, A, B, HKTA](_of, _map)
+	delegate := traverse[E, A, B](mof, mmap)
 	return func(f func(A) HKTB) func(Either[E, A]) HKTRB {
 		return F.Bind2nd(delegate, f)
 	}
 }
 
-/*
-*
-We need to pass the members of the applicative explicitly, because golang does neither support higher kinded types nor template methods on structs or interfaces
-
-HKTRA = HKT<Either[A]>
-HKTA = HKT<A>
-HKTB = HKT<B>
-*/
+// Sequence converts an [Either] of some higher kinded type into the higher kinded type of an [Either]
 func Sequence[E, A, HKTA, HKTRA any](
-	_of func(Either[E, A]) HKTRA,
-	_map func(HKTA, func(A) Either[E, A]) HKTRA,
+	mof func(Either[E, A]) HKTRA,
+	mmap func(func(A) Either[E, A]) func(HKTA) HKTRA,
 ) func(Either[E, HKTA]) HKTRA {
-	return Fold(F.Flow2(Left[A, E], _of), F.Bind2nd(_map, Right[E, A]))
+	return Fold(F.Flow2(Left[A, E], mof), mmap(Right[E, A]))
 }

either/traverse_test.go

@@ -30,9 +30,9 @@ func TestTraverse(t *testing.T) {
 		}
 		return O.None[int]()
 	}
-	trav := Traverse[string, int, int, O.Option[Either[string, int]]](
+	trav := Traverse[int](
 		O.Of[Either[string, int]],
-		O.MonadMap[int, Either[string, int]],
+		O.Map[int, Either[string, int]],
 	)(f)
 
 	assert.Equal(t, O.Of(Left[int]("a")), F.Pipe1(Left[int]("a"), trav))
@@ -44,7 +44,7 @@ func TestSequence(t *testing.T) {
 
 	seq := Sequence(
 		O.Of[Either[string, int]],
-		O.MonadMap[int, Either[string, int]],
+		O.Map[int, Either[string, int]],
 	)
 
 	assert.Equal(t, O.Of(Right[string](1)), seq(Right[string](O.Of(1))))

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

file/getters.go

@@ -0,0 +1,23 @@
+// 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 file
+
+import "os"
+
+// GetName is the getter for the `Name` property of [os.File]
+func GetName(f *os.File) string {
+	return f.Name()
+}

function/binds.go

@@ -1,21 +1,7 @@
-// Copyright (c) 2023 IBM Corp.
-// All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 15:42:51.4021911 +0200 CEST m=+0.009058101
+// 2023-09-12 13:44:23.4226437 +0200 CEST m=+0.011841001
+
 package function
 // Combinations for a total of 1 arguments
 

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"
+)
+
+// Memoize converts a unary function into a unary function that caches the value depending on the parameter
+func Memoize[K comparable, T any](f func(K) T) func(K) T {
+	return G.Memoize(f)
+}
+
+// ContramapMemoize converts a unary function into a unary function that caches the value depending on the parameter
+func ContramapMemoize[A any, K comparable, T any](kf func(A) K) func(func(A) T) func(A) T {
+	return G.ContramapMemoize[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 := Memoize(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 15:42:43.1490717 +0200 CEST m=+0.010222401
+// 2023-09-12 13:44:17.0002767 +0200 CEST m=+0.008233101
+
 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 +16,21 @@ 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...)
   }
 }
+
+// Unsliced0 converts a function taking a slice parameter into a function with 0 parameters
+func Unsliced0[F ~func([]T) R, T, R any](f F) func() R {
+  return func() R {
+    return f([]T{})
+  }
+}
+
 // 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 +75,21 @@ 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...)
   }
 }
+
+// Unsliced1 converts a function taking a slice parameter into a function with 1 parameters
+func Unsliced1[F ~func([]T) R, T, R any](f F) func(T) R {
+  return func(t1 T) R {
+    return f([]T{t1})
+  }
+}
+
 // 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 +137,21 @@ 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...)
   }
 }
+
+// Unsliced2 converts a function taking a slice parameter into a function with 2 parameters
+func Unsliced2[F ~func([]T) R, T, R any](f F) func(T, T) R {
+  return func(t1, t2 T) R {
+    return f([]T{t1, t2})
+  }
+}
+
 // 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 +202,21 @@ 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...)
   }
 }
+
+// Unsliced3 converts a function taking a slice parameter into a function with 3 parameters
+func Unsliced3[F ~func([]T) R, T, R any](f F) func(T, T, T) R {
+  return func(t1, t2, t3 T) R {
+    return f([]T{t1, t2, t3})
+  }
+}
+
 // 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 +270,21 @@ 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...)
   }
 }
+
+// Unsliced4 converts a function taking a slice parameter into a function with 4 parameters
+func Unsliced4[F ~func([]T) R, T, R any](f F) func(T, T, T, T) R {
+  return func(t1, t2, t3, t4 T) R {
+    return f([]T{t1, t2, t3, t4})
+  }
+}
+
 // 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 +341,21 @@ 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...)
   }
 }
+
+// Unsliced5 converts a function taking a slice parameter into a function with 5 parameters
+func Unsliced5[F ~func([]T) R, T, R any](f F) func(T, T, T, T, T) R {
+  return func(t1, t2, t3, t4, t5 T) R {
+    return f([]T{t1, t2, t3, t4, t5})
+  }
+}
+
 // 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 +415,21 @@ 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...)
   }
 }
+
+// Unsliced6 converts a function taking a slice parameter into a function with 6 parameters
+func Unsliced6[F ~func([]T) R, T, R any](f F) func(T, T, T, T, T, T) R {
+  return func(t1, t2, t3, t4, t5, t6 T) R {
+    return f([]T{t1, t2, t3, t4, t5, t6})
+  }
+}
+
 // 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 +492,21 @@ 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...)
   }
 }
+
+// Unsliced7 converts a function taking a slice parameter into a function with 7 parameters
+func Unsliced7[F ~func([]T) R, T, R any](f F) func(T, T, T, T, T, T, T) R {
+  return func(t1, t2, t3, t4, t5, t6, t7 T) R {
+    return f([]T{t1, t2, t3, t4, t5, t6, t7})
+  }
+}
+
 // 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 +572,21 @@ 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...)
   }
 }
+
+// Unsliced8 converts a function taking a slice parameter into a function with 8 parameters
+func Unsliced8[F ~func([]T) R, T, R any](f F) func(T, T, T, T, T, T, T, T) R {
+  return func(t1, t2, t3, t4, t5, t6, t7, t8 T) R {
+    return f([]T{t1, t2, t3, t4, t5, t6, t7, t8})
+  }
+}
+
 // 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 +655,21 @@ 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...)
   }
 }
+
+// Unsliced9 converts a function taking a slice parameter into a function with 9 parameters
+func Unsliced9[F ~func([]T) R, T, R any](f F) func(T, T, T, T, T, T, T, T, T) R {
+  return func(t1, t2, t3, t4, t5, t6, t7, t8, t9 T) R {
+    return f([]T{t1, t2, t3, t4, t5, t6, t7, t8, t9})
+  }
+}
+
 // 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 +741,21 @@ 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...)
   }
 }
+
+// Unsliced10 converts a function taking a slice parameter into a function with 10 parameters
+func Unsliced10[F ~func([]T) R, T, R any](f F) func(T, T, T, T, T, T, T, T, T, T) R {
+  return func(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10 T) R {
+    return f([]T{t1, t2, t3, t4, t5, t6, t7, t8, t9, t10})
+  }
+}
+
 // 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 +830,21 @@ 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...)
   }
 }
+
+// Unsliced11 converts a function taking a slice parameter into a function with 11 parameters
+func Unsliced11[F ~func([]T) R, T, R any](f F) func(T, T, T, T, T, T, T, T, T, T, T) R {
+  return func(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11 T) R {
+    return f([]T{t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11})
+  }
+}
+
 // 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 +922,21 @@ 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...)
   }
 }
+
+// Unsliced12 converts a function taking a slice parameter into a function with 12 parameters
+func Unsliced12[F ~func([]T) R, T, R any](f F) func(T, T, T, T, T, T, T, T, T, T, T, T) R {
+  return func(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12 T) R {
+    return f([]T{t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12})
+  }
+}
+
 // 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 +1017,21 @@ 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...)
   }
 }
+
+// Unsliced13 converts a function taking a slice parameter into a function with 13 parameters
+func Unsliced13[F ~func([]T) R, T, R any](f F) func(T, T, T, T, T, T, T, T, T, T, T, T, T) R {
+  return func(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13 T) R {
+    return f([]T{t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13})
+  }
+}
+
 // 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 +1115,21 @@ 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...)
   }
 }
+
+// Unsliced14 converts a function taking a slice parameter into a function with 14 parameters
+func Unsliced14[F ~func([]T) R, T, R any](f F) func(T, T, T, T, T, T, T, T, T, T, T, T, T, T) R {
+  return func(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14 T) R {
+    return f([]T{t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14})
+  }
+}
+
 // 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 +1216,21 @@ 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...)
   }
 }
+
+// Unsliced15 converts a function taking a slice parameter into a function with 15 parameters
+func Unsliced15[F ~func([]T) R, T, R any](f F) func(T, T, T, T, T, T, T, T, T, T, T, T, T, T, T) R {
+  return func(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15 T) R {
+    return f([]T{t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15})
+  }
+}
+
 // 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 +1320,21 @@ 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...)
   }
 }
+
+// Unsliced16 converts a function taking a slice parameter into a function with 16 parameters
+func Unsliced16[F ~func([]T) R, T, R any](f F) func(T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T) R {
+  return func(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16 T) R {
+    return f([]T{t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16})
+  }
+}
+
 // 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 +1427,21 @@ 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...)
   }
 }
+
+// Unsliced17 converts a function taking a slice parameter into a function with 17 parameters
+func Unsliced17[F ~func([]T) R, T, R any](f F) func(T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T) R {
+  return func(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16, t17 T) R {
+    return f([]T{t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16, t17})
+  }
+}
+
 // 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 +1537,21 @@ 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...)
   }
 }
+
+// Unsliced18 converts a function taking a slice parameter into a function with 18 parameters
+func Unsliced18[F ~func([]T) R, T, R any](f F) func(T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T) R {
+  return func(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16, t17, t18 T) R {
+    return f([]T{t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16, t17, t18})
+  }
+}
+
 // 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 +1650,21 @@ 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...)
   }
 }
+
+// Unsliced19 converts a function taking a slice parameter into a function with 19 parameters
+func Unsliced19[F ~func([]T) R, T, R any](f F) func(T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T) R {
+  return func(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16, t17, t18, t19 T) R {
+    return f([]T{t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16, t17, t18, t19})
+  }
+}
+
 // 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 {
@@ -1600,9 +1766,17 @@ 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 {
     return f(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16, t17, t18, t19, t20, v...)
   }
-}
+}
+
+// Unsliced20 converts a function taking a slice parameter into a function with 20 parameters
+func Unsliced20[F ~func([]T) R, T, R any](f F) func(T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T) R {
+  return func(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16, t17, t18, t19, t20 T) R {
+    return f([]T{t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16, t17, t18, t19, t20})
+  }
+}

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"
+)
+
+// Memoize converts a unary function into a unary function that caches the value depending on the parameter
+func Memoize[F ~func(K) T, K comparable, T any](f F) F {
+	return ContramapMemoize[F](func(k K) K { return k })(f)
+}
+
+// ContramapMemoize converts a unary function into a unary function that caches the value depending on the parameter
+func ContramapMemoize[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
+}

function/unvariadic_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 function
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func fromLibrary(data ...string) string {
+	return strings.Join(data, "-")
+}
+
+func TestUnvariadic(t *testing.T) {
+
+	res := Pipe1(
+		[]string{"A", "B"},
+		Unvariadic0(fromLibrary),
+	)
+
+	assert.Equal(t, "A-B", res)
+}
+
+func TestVariadicArity(t *testing.T) {
+
+	f := Unsliced2(Unvariadic0(fromLibrary))
+
+	res := f("A", "B")
+	assert.Equal(t, "A-B", res)
+}

identity/gen.go

@@ -1,21 +1,7 @@
-// Copyright (c) 2023 IBM Corp.
-// All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 15:42:58.8116745 +0200 CEST m=+0.008252901
+// 2023-09-12 13:44:24.9409324 +0200 CEST m=+0.008573601
+
 package identity
 
 

internal/apply/gen.go

@@ -1,21 +1,7 @@
-// Copyright (c) 2023 IBM Corp.
-// All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 15:43:00.6284756 +0200 CEST m=+0.013494201
+// 2023-09-12 13:44:26.2499883 +0200 CEST m=+0.007601301
+
 package apply
 
 

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/array/traverse.go

@@ -37,6 +37,24 @@ func MonadTraverse[GA ~[]A, GB ~[]B, A, B, HKTB, HKTAB, HKTRB any](
 	return MonadTraverseReduce(fof, fmap, fap, ta, f, Append[GB, B], Empty[GB]())
 }
 
+/*
+*
+We need to pass the members of the applicative explicitly, because golang does neither support higher kinded types nor template methods on structs or interfaces
+
+HKTRB = HKT<GB>
+HKTB = HKT<B>
+HKTAB = HKT<func(A)B>
+*/
+func MonadTraverseWithIndex[GA ~[]A, GB ~[]B, A, B, HKTB, HKTAB, HKTRB any](
+	fof func(GB) HKTRB,
+	fmap func(func(GB) func(B) GB) func(HKTRB) HKTAB,
+	fap func(HKTB) func(HKTAB) HKTRB,
+
+	ta GA,
+	f func(int, A) HKTB) HKTRB {
+	return MonadTraverseReduceWithIndex(fof, fmap, fap, ta, f, Append[GB, B], Empty[GB]())
+}
+
 func Traverse[GA ~[]A, GB ~[]B, A, B, HKTB, HKTAB, HKTRB any](
 	fof func(GB) HKTRB,
 	fmap func(func(GB) func(B) GB) func(HKTRB) HKTAB,
@@ -49,6 +67,18 @@ func Traverse[GA ~[]A, GB ~[]B, A, B, HKTB, HKTAB, HKTRB any](
 	}
 }
 
+func TraverseWithIndex[GA ~[]A, GB ~[]B, A, B, HKTB, HKTAB, HKTRB any](
+	fof func(GB) HKTRB,
+	fmap func(func(GB) func(B) GB) func(HKTRB) HKTAB,
+	fap func(HKTB) func(HKTAB) HKTRB,
+
+	f func(int, A) HKTB) func(GA) HKTRB {
+
+	return func(ma GA) HKTRB {
+		return MonadTraverseWithIndex(fof, fmap, fap, ma, f)
+	}
+}
+
 func MonadTraverseReduce[GA ~[]A, GB, A, B, HKTB, HKTAB, HKTRB any](
 	fof func(GB) HKTRB,
 	fmap func(func(GB) func(B) GB) func(HKTRB) HKTAB,
@@ -71,6 +101,28 @@ func MonadTraverseReduce[GA ~[]A, GB, A, B, HKTB, HKTAB, HKTRB any](
 	}, fof(initial))
 }
 
+func MonadTraverseReduceWithIndex[GA ~[]A, GB, A, B, HKTB, HKTAB, HKTRB any](
+	fof func(GB) HKTRB,
+	fmap func(func(GB) func(B) GB) func(HKTRB) HKTAB,
+	fap func(HKTB) func(HKTAB) HKTRB,
+
+	ta GA,
+
+	transform func(int, A) HKTB,
+	reduce func(GB, B) GB,
+	initial GB,
+) HKTRB {
+	mmap := fmap(F.Curry2(reduce))
+
+	return ReduceWithIndex(ta, func(idx int, r HKTRB, a A) HKTRB {
+		return F.Pipe2(
+			r,
+			mmap,
+			fap(transform(idx, a)),
+		)
+	}, fof(initial))
+}
+
 func TraverseReduce[GA ~[]A, GB, A, B, HKTB, HKTAB, HKTRB any](
 	fof func(GB) HKTRB,
 	fmap func(func(GB) func(B) GB) func(HKTRB) HKTAB,
@@ -84,3 +136,17 @@ func TraverseReduce[GA ~[]A, GB, A, B, HKTB, HKTAB, HKTRB any](
 		return MonadTraverseReduce(fof, fmap, fap, ta, transform, reduce, initial)
 	}
 }
+
+func TraverseReduceWithIndex[GA ~[]A, GB, A, B, HKTB, HKTAB, HKTRB any](
+	fof func(GB) HKTRB,
+	fmap func(func(GB) func(B) GB) func(HKTRB) HKTAB,
+	fap func(HKTB) func(HKTAB) HKTRB,
+
+	transform func(int, A) HKTB,
+	reduce func(GB, B) GB,
+	initial GB,
+) func(GA) HKTRB {
+	return func(ta GA) HKTRB {
+		return MonadTraverseReduceWithIndex(fof, fmap, fap, ta, transform, reduce, initial)
+	}
+}

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/file/file.go

@@ -0,0 +1,39 @@
+// 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 file
+
+import (
+	"io"
+	"os"
+
+	IO "github.com/IBM/fp-go/io"
+)
+
+// Close closes a closeable resource and ignores a potential error
+func Close[R io.Closer](r R) IO.IO[R] {
+	return IO.MakeIO[R](func() R {
+		r.Close() // #nosec: G104
+		return r
+	})
+}
+
+// Remove removes a resource and ignores a potential error
+func Remove(name string) IO.IO[string] {
+	return IO.MakeIO[string](func() string {
+		os.Remove(name) // #nosec: G104
+		return name
+	})
+}

io/gen.go

@@ -1,21 +1,7 @@
-// Copyright (c) 2023 IBM Corp.
-// All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 15:43:07.1016885 +0200 CEST m=+0.039744901
+// 2023-09-12 13:44:27.9813739 +0200 CEST m=+0.011088001
+
 package io
 
 

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

@@ -1,21 +1,6 @@
-// Copyright (c) 2023 IBM Corp.
-// All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 15:43:07.1026882 +0200 CEST m=+0.040744601
+// 2023-09-12 13:44:27.9813739 +0200 CEST m=+0.011088001
 package generic
 
 

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

io/generic/traverse.go

@@ -42,6 +42,16 @@ func TraverseArray[GB ~func() B, GBS ~func() BBS, AAS ~[]A, BBS ~[]B, A, B any](
 	)
 }
 
+func TraverseArrayWithIndex[GB ~func() B, GBS ~func() BBS, AAS ~[]A, BBS ~[]B, A, B any](f func(int, A) GB) func(AAS) GBS {
+	return RA.TraverseWithIndex[AAS](
+		Of[GBS, BBS],
+		Map[GBS, func() func(B) BBS, BBS, func(B) BBS],
+		Ap[GBS, func() func(B) BBS, GB],
+
+		f,
+	)
+}
+
 func SequenceArray[GA ~func() A, GAS ~func() AAS, AAS ~[]A, GAAS ~[]GA, A any](tas GAAS) GAS {
 	return MonadTraverseArray[GA, GAS](tas, F.Identity[GA])
 }
@@ -66,6 +76,16 @@ func TraverseRecord[GB ~func() B, GBS ~func() MB, MA ~map[K]A, MB ~map[K]B, K co
 	)
 }
 
+// TraverseRecordWithIndex transforms a record using an IO transform an IO of a record
+func TraverseRecordWithIndex[GB ~func() B, GBS ~func() MB, MA ~map[K]A, MB ~map[K]B, K comparable, A, B any](f func(K, A) GB) func(MA) GBS {
+	return RR.TraverseWithIndex[MA](
+		Of[GBS, MB],
+		Map[GBS, func() func(B) MB, MB, func(B) MB],
+		Ap[GBS, func() func(B) MB, GB],
+		f,
+	)
+}
+
 func SequenceRecord[GA ~func() A, GAS ~func() AAS, AAS ~map[K]A, GAAS ~map[K]GA, K comparable, A any](tas GAAS) GAS {
 	return MonadTraverseRecord[GA, GAS](tas, F.Identity[GA])
 }

io/traverse.go

@@ -29,6 +29,12 @@ func TraverseArray[A, B any](f func(A) IO[B]) func([]A) IO[[]B] {
 	return G.TraverseArray[IO[B], IO[[]B], []A](f)
 }
 
+// TraverseArrayWithIndex applies a function returning an [IO] to all elements in an array and the
+// transforms this into an [IO] of that array
+func TraverseArrayWithIndex[A, B any](f func(int, A) IO[B]) func([]A) IO[[]B] {
+	return G.TraverseArrayWithIndex[IO[B], IO[[]B], []A](f)
+}
+
 // SequenceArray converts an array of [IO] to an [IO] of an array
 func SequenceArray[A any](tas []IO[A]) IO[[]A] {
 	return G.SequenceArray[IO[A], IO[[]A]](tas)
@@ -38,12 +44,18 @@ func MonadTraverseRecord[K comparable, A, B any](tas map[K]A, f func(A) IO[B]) I
 	return G.MonadTraverseRecord[IO[B], IO[map[K]B]](tas, f)
 }
 
-// TraverseArray applies a function returning an [IO] to all elements in a record and the
+// TraverseRecord applies a function returning an [IO] to all elements in a record and the
 // transforms this into an [IO] of that record
 func TraverseRecord[K comparable, A, B any](f func(A) IO[B]) func(map[K]A) IO[map[K]B] {
 	return G.TraverseRecord[IO[B], IO[map[K]B], map[K]A](f)
 }
 
+// TraverseRecordWithIndex applies a function returning an [IO] to all elements in a record and the
+// transforms this into an [IO] of that record
+func TraverseRecordWithIndex[K comparable, A, B any](f func(K, A) IO[B]) func(map[K]A) IO[map[K]B] {
+	return G.TraverseRecordWithIndex[IO[B], IO[map[K]B], map[K]A](f)
+}
+
 // SequenceRecord converts a record of [IO] to an [IO] of a record
 func SequenceRecord[K comparable, A any](tas map[K]IO[A]) IO[map[K]A] {
 	return G.SequenceRecord[IO[A], IO[map[K]A]](tas)

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/file/close.go

@@ -21,6 +21,7 @@ import (
 	IOE "github.com/IBM/fp-go/ioeither"
 )
 
+// onClose closes a closeable resource
 func onClose[R io.Closer](r R) IOE.IOEither[error, R] {
 	return IOE.TryCatchError(func() (R, error) {
 		return r, r.Close()

ioeither/file/file.go

@@ -24,14 +24,24 @@ import (
 var (
 	// Open opens a file for reading
 	Open = IOE.Eitherize1(os.Open)
+	// Create opens a file for writing
+	Create = IOE.Eitherize1(os.Create)
 	// ReadFile reads the context of a file
 	ReadFile = IOE.Eitherize1(os.ReadFile)
-	// WriteFile writes a data blob to a file
-	WriteFile = func(dstName string, perm os.FileMode) func([]byte) IOE.IOEither[error, []byte] {
-		return func(data []byte) IOE.IOEither[error, []byte] {
-			return IOE.TryCatchError(func() ([]byte, error) {
-				return data, os.WriteFile(dstName, data, perm)
-			})
-		}
-	}
 )
+
+// WriteFile writes a data blob to a file
+func WriteFile(dstName string, perm os.FileMode) func([]byte) IOE.IOEither[error, []byte] {
+	return func(data []byte) IOE.IOEither[error, []byte] {
+		return IOE.TryCatchError(func() ([]byte, error) {
+			return data, os.WriteFile(dstName, data, perm)
+		})
+	}
+}
+
+// Remove removes a file by name
+func Remove(name string) IOE.IOEither[error, string] {
+	return IOE.TryCatchError(func() (string, error) {
+		return name, os.Remove(name)
+	})
+}

ioeither/file/readall.go

@@ -29,7 +29,7 @@ func onReadAll[R io.Reader](r R) IOE.IOEither[error, []byte] {
 
 // ReadAll uses a generator function to create a stream, reads it and closes it
 func ReadAll[R io.ReadCloser](acquire IOE.IOEither[error, R]) IOE.IOEither[error, []byte] {
-	return IOE.WithResource[error, R, []byte](
+	return IOE.WithResource[[]byte](
 		acquire,
 		onClose[R])(
 		onReadAll[R],

ioeither/file/tempfile.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 file
+
+import (
+	"os"
+
+	FL "github.com/IBM/fp-go/file"
+	F "github.com/IBM/fp-go/function"
+	IO "github.com/IBM/fp-go/io"
+	IOF "github.com/IBM/fp-go/io/file"
+	IOE "github.com/IBM/fp-go/ioeither"
+)
+
+var (
+	// CreateTemp created a temp file with proper parametrization
+	CreateTemp = IOE.Eitherize2(os.CreateTemp)
+	// onCreateTempFile creates a temp file with sensible defaults
+	onCreateTempFile = CreateTemp("", "*")
+	// destroy handler
+	onReleaseTempFile = F.Flow4(
+		IOF.Close[*os.File],
+		IO.Map(FL.GetName),
+		IOE.FromIO[error, string],
+		IOE.Chain(Remove),
+	)
+)
+
+// WithTempFile creates a temporary file, then invokes a callback to create a resource based on the file, then close and remove the temp file
+func WithTempFile[A any](f func(*os.File) IOE.IOEither[error, A]) IOE.IOEither[error, A] {
+	return IOE.WithResource[A](onCreateTempFile, onReleaseTempFile)(f)
+}

ioeither/file/tempfile_test.go

@@ -0,0 +1,46 @@
+// 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 file
+
+import (
+	"os"
+	"testing"
+
+	E "github.com/IBM/fp-go/either"
+	F "github.com/IBM/fp-go/function"
+	IOE "github.com/IBM/fp-go/ioeither"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestWithTempFile(t *testing.T) {
+
+	res := WithTempFile(onWriteAll[*os.File]([]byte("Carsten")))
+
+	assert.Equal(t, E.Of[error]([]byte("Carsten")), res())
+}
+
+func TestWithTempFileOnClosedFile(t *testing.T) {
+
+	res := WithTempFile(func(f *os.File) IOE.IOEither[error, []byte] {
+		return F.Pipe2(
+			f,
+			onWriteAll[*os.File]([]byte("Carsten")),
+			IOE.ChainFirst(F.Constant1[[]byte](onClose(f))),
+		)
+	})
+
+	assert.Equal(t, E.Of[error]([]byte("Carsten")), res())
+}

ioeither/file/write.go

@@ -34,7 +34,7 @@ func onWriteAll[W io.Writer](data []byte) func(w W) IOE.IOEither[error, []byte]
 func WriteAll[W io.WriteCloser](data []byte) func(acquire IOE.IOEither[error, W]) IOE.IOEither[error, []byte] {
 	onWrite := onWriteAll[W](data)
 	return func(onCreate IOE.IOEither[error, W]) IOE.IOEither[error, []byte] {
-		return IOE.WithResource[error, W, []byte](
+		return IOE.WithResource[[]byte](
 			onCreate,
 			onClose[W])(
 			onWrite,
@@ -43,8 +43,8 @@ func WriteAll[W io.WriteCloser](data []byte) func(acquire IOE.IOEither[error, W]
 }
 
 // Write uses a generator function to create a stream, writes data to it and closes it
-func Write[W io.WriteCloser, R any](acquire IOE.IOEither[error, W]) func(use func(W) IOE.IOEither[error, R]) IOE.IOEither[error, R] {
-	return IOE.WithResource[error, W, R](
+func Write[R any, W io.WriteCloser](acquire IOE.IOEither[error, W]) func(use func(W) IOE.IOEither[error, R]) IOE.IOEither[error, R] {
+	return IOE.WithResource[R](
 		acquire,
 		onClose[W])
 }

ioeither/gen.go

@@ -1,21 +1,7 @@
-// Copyright (c) 2023 IBM Corp.
-// All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 15:43:09.9125541 +0200 CEST m=+0.083065801
+// 2023-09-12 13:44:29.4935658 +0200 CEST m=+0.015377401
+
 package ioeither
 
 

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

@@ -1,21 +1,6 @@
-// Copyright (c) 2023 IBM Corp.
-// All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 15:43:09.9180997 +0200 CEST m=+0.088611401
+// 2023-09-12 13:44:29.4935658 +0200 CEST m=+0.015377401
 package generic
 
 

ioeither/generic/traverse.go

@@ -45,6 +45,29 @@ func TraverseArray[GB ~func() ET.Either[E, B], GBS ~func() ET.Either[E, BBS], AA
 	)
 }
 
+// MonadTraverseArrayWithIndex transforms an array
+func MonadTraverseArrayWithIndex[GB ~func() ET.Either[E, B], GBS ~func() ET.Either[E, BBS], AAS ~[]A, BBS ~[]B, E, A, B any](tas AAS, f func(int, A) GB) GBS {
+	return RA.MonadTraverseWithIndex[AAS](
+		Of[GBS, E, BBS],
+		Map[GBS, func() ET.Either[E, func(B) BBS], E, BBS, func(B) BBS],
+		Ap[GBS, func() ET.Either[E, func(B) BBS], GB],
+
+		tas,
+		f,
+	)
+}
+
+// TraverseArrayWithIndex transforms an array
+func TraverseArrayWithIndex[GB ~func() ET.Either[E, B], GBS ~func() ET.Either[E, BBS], AAS ~[]A, BBS ~[]B, E, A, B any](f func(int, A) GB) func(AAS) GBS {
+	return RA.TraverseWithIndex[AAS](
+		Of[GBS, E, BBS],
+		Map[GBS, func() ET.Either[E, func(B) BBS], E, BBS, func(B) BBS],
+		Ap[GBS, func() ET.Either[E, func(B) BBS], GB],
+
+		f,
+	)
+}
+
 // SequenceArray converts a homogeneous sequence of either into an either of sequence
 func SequenceArray[GA ~func() ET.Either[E, A], GAS ~func() ET.Either[E, AAS], AAS ~[]A, GAAS ~[]GA, E, A any](tas GAAS) GAS {
 	return MonadTraverseArray[GA, GAS](tas, F.Identity[GA])
@@ -73,6 +96,17 @@ func TraverseRecord[GB ~func() ET.Either[E, B], GBS ~func() ET.Either[E, BBS], A
 	)
 }
 
+// TraverseRecordWithIndex transforms an array
+func TraverseRecordWithIndex[GB ~func() ET.Either[E, B], GBS ~func() ET.Either[E, BBS], AAS ~map[K]A, BBS ~map[K]B, K comparable, E, A, B any](f func(K, A) GB) func(AAS) GBS {
+	return RR.TraverseWithIndex[AAS](
+		Of[GBS, E, BBS],
+		Map[GBS, func() ET.Either[E, func(B) BBS], E, BBS, func(B) BBS],
+		Ap[GBS, func() ET.Either[E, func(B) BBS], GB],
+
+		f,
+	)
+}
+
 // SequenceRecord converts a homogeneous sequence of either into an either of sequence
 func SequenceRecord[GA ~func() ET.Either[E, A], GAS ~func() ET.Either[E, AAS], AAS ~map[K]A, GAAS ~map[K]GA, K comparable, E, A any](tas GAAS) GAS {
 	return MonadTraverseRecord[GA, GAS](tas, F.Identity[GA])

ioeither/ioeither.go

@@ -192,7 +192,7 @@ func ChainFirstIOK[E, A, B any](f func(A) I.IO[B]) func(IOEither[E, A]) IOEither
 }
 
 // WithResource constructs a function that creates a resource, then operates on it and then releases the resource
-func WithResource[E, R, A, ANY any](onCreate IOEither[E, R], onRelease func(R) IOEither[E, ANY]) func(func(R) IOEither[E, A]) IOEither[E, A] {
+func WithResource[A, E, R, ANY any](onCreate IOEither[E, R], onRelease func(R) IOEither[E, ANY]) func(func(R) IOEither[E, A]) IOEither[E, A] {
 	return G.WithResource[IOEither[E, A]](onCreate, onRelease)
 }
 

ioeither/traverse.go

@@ -24,6 +24,11 @@ func TraverseArray[E, A, B any](f func(A) IOEither[E, B]) func([]A) IOEither[E,
 	return G.TraverseArray[IOEither[E, B], IOEither[E, []B], []A](f)
 }
 
+// TraverseArrayWithIndex transforms an array
+func TraverseArrayWithIndex[E, A, B any](f func(int, A) IOEither[E, B]) func([]A) IOEither[E, []B] {
+	return G.TraverseArrayWithIndex[IOEither[E, B], IOEither[E, []B], []A](f)
+}
+
 // SequenceArray converts a homogeneous sequence of either into an either of sequence
 func SequenceArray[E, A any](ma []IOEither[E, A]) IOEither[E, []A] {
 	return G.SequenceArray[IOEither[E, A], IOEither[E, []A]](ma)
@@ -34,6 +39,11 @@ func TraverseRecord[K comparable, E, A, B any](f func(A) IOEither[E, B]) func(ma
 	return G.TraverseRecord[IOEither[E, B], IOEither[E, map[K]B], map[K]A](f)
 }
 
+// TraverseRecordWithIndex transforms a record
+func TraverseRecordWithIndex[K comparable, E, A, B any](f func(K, A) IOEither[E, B]) func(map[K]A) IOEither[E, map[K]B] {
+	return G.TraverseRecordWithIndex[IOEither[E, B], IOEither[E, map[K]B], map[K]A](f)
+}
+
 // SequenceRecord converts a homogeneous sequence of either into an either of sequence
 func SequenceRecord[K comparable, E, A any](ma map[K]IOEither[E, A]) IOEither[E, map[K]A] {
 	return G.SequenceRecord[IOEither[E, A], IOEither[E, map[K]A]](ma)

ioeither/traverse_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 ioeither
+
+import (
+	"fmt"
+	"testing"
+
+	A "github.com/IBM/fp-go/array"
+	E "github.com/IBM/fp-go/either"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestTraverseArray(t *testing.T) {
+
+	src := A.From("A", "B")
+
+	trfrm := TraverseArrayWithIndex(func(idx int, data string) IOEither[error, string] {
+		return Of[error](fmt.Sprintf("idx: %d, data: %s", idx, data))
+	})
+
+	assert.Equal(t, E.Of[error](A.From("idx: 0, data: A", "idx: 1, data: B")), trfrm(src)())
+
+}

iooption/array.go

@@ -24,6 +24,11 @@ func TraverseArray[A, B any](f func(A) IOOption[B]) func([]A) IOOption[[]B] {
 	return G.TraverseArray[IOOption[B], IOOption[[]B], []A](f)
 }
 
+// TraverseArrayWithIndex transforms an array
+func TraverseArrayWithIndex[A, B any](f func(int, A) IOOption[B]) func([]A) IOOption[[]B] {
+	return G.TraverseArrayWithIndex[IOOption[B], IOOption[[]B], []A](f)
+}
+
 // SequenceArray converts a homogeneous sequence of either into an either of sequence
 func SequenceArray[A any](ma []IOOption[A]) IOOption[[]A] {
 	return G.SequenceArray[IOOption[A], IOOption[[]A], []IOOption[A], []A, A](ma)

iooption/gen.go

@@ -1,21 +1,7 @@
-// Copyright (c) 2023 IBM Corp.
-// All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 15:43:14.520059 +0200 CEST m=+0.012057201
+// 2023-09-12 13:44:32.1514823 +0200 CEST m=+0.098931001
+
 package iooption
 
 

iooption/generic/gen.go

@@ -1,21 +1,6 @@
-// Copyright (c) 2023 IBM Corp.
-// All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-07-28 15:43:14.5210603 +0200 CEST m=+0.013058501
+// 2023-09-12 13:44:32.1546277 +0200 CEST m=+0.102076401
 package generic
 
 

iooption/generic/traverse.go

@@ -28,6 +28,13 @@ func TraverseArray[TB ~func() O.Option[B], TBS ~func() O.Option[GB], GA ~[]A, GB
 	)
 }
 
+func TraverseArrayWithIndex[TB ~func() O.Option[B], TBS ~func() O.Option[GB], GA ~[]A, GB ~[]B, A, B any](f func(int, A) TB) func(GA) TBS {
+	return F.Flow2(
+		I.TraverseArrayWithIndex[TB, func() []O.Option[B], GA](f),
+		I.Map[func() []O.Option[B], TBS](O.SequenceArrayG[GB, []O.Option[B], B]),
+	)
+}
+
 func SequenceArray[TB ~func() O.Option[B], TBS ~func() O.Option[GB], GA ~[]TB, GB ~[]B, A, B any](ma GA) TBS {
 	return TraverseArray[TB, TBS, GA](F.Identity[TB])(ma)
 }

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
+}