fix: break cyclic dependencies between IOOption and IOEither

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

.github/workflows/build.yml

@@ -29,7 +29,7 @@ jobs:
         go-version: [ '1.20.x', '1.21.x' ]
     steps:
       # full checkout for semantic-release
-      - uses: actions/checkout@8ade135a41bc03ea155e62e844d188df1ea18608 # v4.1.0
+      - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
         with:
           fetch-depth: 0
       - name: Set up go ${{ matrix.go-version }}
@@ -55,12 +55,12 @@ jobs:
     steps:
       # full checkout for semantic-release
       - name: Full checkout
-        uses: actions/checkout@8ade135a41bc03ea155e62e844d188df1ea18608 # v4.1.0
+        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
         with:
           fetch-depth: 0
 
       - name: Set up Node.js ${{ env.NODE_VERSION }}
-        uses: actions/setup-node@e33196f7422957bea03ed53f6fbb155025ffc7b8 # v3.7.0
+        uses: actions/setup-node@8f152de45cc393bb48ce5d89d36b731f54556e65 # v4.0.0
         with:
           node-version: ${{ env.NODE_VERSION }}
 

array/any.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 array
+
+import (
+	G "github.com/IBM/fp-go/array/generic"
+)
+
+// AnyWithIndex tests if any of the elements in the array matches the predicate
+func AnyWithIndex[A any](pred func(int, A) bool) func([]A) bool {
+	return G.AnyWithIndex[[]A](pred)
+}
+
+// Any tests if any of the elements in the array matches the predicate
+func Any[A any](pred func(A) bool) func([]A) bool {
+	return G.Any[[]A](pred)
+}

array/any_test.go

@@ -13,14 +13,18 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// Package reader implements a specialization of the Reader monad assuming a golang context as the context of the monad
+package array
-package reader
 
 import (
-	"context"
+	"testing"
 
-	R "github.com/IBM/fp-go/reader"
+	F "github.com/IBM/fp-go/function"
+	"github.com/stretchr/testify/assert"
 )
 
-// Reader is a specialization of the Reader monad assuming a golang context as the context of the monad
+func TestAny(t *testing.T) {
-type Reader[A any] R.Reader[context.Context, A]
+	anyBool := Any(F.Identity[bool])
+
+	assert.True(t, anyBool(From(false, true, false)))
+	assert.False(t, anyBool(From(false, false, false)))
+}

array/array.go

@@ -52,6 +52,10 @@ func MonadMapRef[A, B any](as []A, f func(a *A) B) []B {
 	return bs
 }
 
+func MapWithIndex[A, B any](f func(int, A) B) func([]A) []B {
+	return G.MapWithIndex[[]A, []B](f)
+}
+
 func Map[A, B any](f func(a A) B) func([]A) []B {
 	return F.Bind2nd(MonadMap[A, B], f)
 }
@@ -60,18 +64,6 @@ func MapRef[A, B any](f func(a *A) B) func([]A) []B {
 	return F.Bind2nd(MonadMapRef[A, B], f)
 }
 
-func filter[A any](fa []A, pred func(A) bool) []A {
-	var result []A
-	count := len(fa)
-	for i := 0; i < count; i++ {
-		a := fa[i]
-		if pred(a) {
-			result = append(result, a)
-		}
-	}
-	return result
-}
-
 func filterRef[A any](fa []A, pred func(a *A) bool) []A {
 	var result []A
 	count := len(fa)
@@ -96,23 +88,38 @@ func filterMapRef[A, B any](fa []A, pred func(a *A) bool, f func(a *A) B) []B {
 	return result
 }
 
+// Filter returns a new array with all elements from the original array that match a predicate
 func Filter[A any](pred func(A) bool) func([]A) []A {
-	return F.Bind2nd(filter[A], pred)
+	return G.Filter[[]A](pred)
+}
+
+// FilterWithIndex returns a new array with all elements from the original array that match a predicate
+func FilterWithIndex[A any](pred func(int, A) bool) func([]A) []A {
+	return G.FilterWithIndex[[]A](pred)
 }
 
 func FilterRef[A any](pred func(*A) bool) func([]A) []A {
 	return F.Bind2nd(filterRef[A], pred)
 }
 
-func MonadFilterMap[A, B any](fa []A, f func(a A) O.Option[B]) []B {
+func MonadFilterMap[A, B any](fa []A, f func(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 MonadFilterMapWithIndex[A, B any](fa []A, f func(int, A) O.Option[B]) []B {
-func FilterMap[A, B any](f func(a A) O.Option[B]) func([]A) []B {
+	return G.MonadFilterMapWithIndex[[]A, []B](fa, f)
+}
+
+// FilterMap 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) O.Option[B]) func([]A) []B {
 	return G.FilterMap[[]A, []B](f)
 }
 
+// FilterMapWithIndex maps an array with an iterating function that returns an [O.Option] and it keeps only the Some values discarding the Nones.
+func FilterMapWithIndex[A, B any](f func(int, A) O.Option[B]) func([]A) []B {
+	return G.FilterMapWithIndex[[]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)
@@ -134,9 +141,19 @@ func reduceRef[A, B any](fa []A, f func(B, *A) B, initial B) B {
 }
 
 func Reduce[A, B any](f func(B, A) B, initial B) func([]A) B {
-	return func(as []A) B {
+	return G.Reduce[[]A](f, initial)
-		return array.Reduce(as, f, initial)
+}
-	}
+
+func ReduceWithIndex[A, B any](f func(int, B, A) B, initial B) func([]A) B {
+	return G.ReduceWithIndex[[]A](f, initial)
+}
+
+func ReduceRight[A, B any](f func(A, B) B, initial B) func([]A) B {
+	return G.ReduceRight[[]A](f, initial)
+}
+
+func ReduceRightWithIndex[A, B any](f func(int, A, B) B, initial B) func([]A) B {
+	return G.ReduceRightWithIndex[[]A](f, initial)
 }
 
 func ReduceRef[A, B any](f func(B, *A) B, initial B) func([]A) B {
@@ -300,6 +317,11 @@ func FoldMap[A, B any](m M.Monoid[B]) func(func(A) B) func([]A) B {
 	return G.FoldMap[[]A](m)
 }
 
+// FoldMapWithIndex maps and folds an array. Map the Array passing each value to the iterating function. Then fold the results using the provided Monoid.
+func FoldMapWithIndex[A, B any](m M.Monoid[B]) func(func(int, A) B) func([]A) B {
+	return G.FoldMapWithIndex[[]A](m)
+}
+
 // Fold folds the array using the provided Monoid.
 func Fold[A any](m M.Monoid[A]) func([]A) A {
 	return G.Fold[[]A](m)

array/array_test.go

@@ -59,6 +59,17 @@ func TestMap(t *testing.T) {
 	assert.Equal(t, dst, []string{"A", "B", "C"})
 }
 
+func TestReduceRight(t *testing.T) {
+	values := From("a", "b", "c")
+	f := func(a, acc string) string {
+		return fmt.Sprintf("%s%s", acc, a)
+	}
+	b := ""
+
+	assert.Equal(t, "cba", ReduceRight(f, b)(values))
+	assert.Equal(t, "", ReduceRight(f, b)(Empty[string]()))
+}
+
 func TestReduce(t *testing.T) {
 
 	values := MakeBy(101, F.Identity[int])

array/example_any_test.go

@@ -0,0 +1,77 @@
+// 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"
+)
+
+func Example_any() {
+
+	pred := func(val int) bool {
+		return val&2 == 0
+	}
+
+	data1 := From(1, 2, 3)
+
+	fmt.Println(Any(pred)(data1))
+
+	// Output:
+	// true
+}
+
+func Example_any_filter() {
+
+	pred := func(val int) bool {
+		return val&2 == 0
+	}
+
+	data1 := From(1, 2, 3)
+
+	// Any tests if any of the entries in the array matches the condition
+	Any := F.Flow2(
+		Filter(pred),
+		IsNonEmpty[int],
+	)
+
+	fmt.Println(Any(data1))
+
+	// Output:
+	// true
+}
+
+func Example_any_find() {
+
+	pred := func(val int) bool {
+		return val&2 == 0
+	}
+
+	data1 := From(1, 2, 3)
+
+	// Any tests if any of the entries in the array matches the condition
+	Any := F.Flow2(
+		FindFirst(pred),
+		O.IsSome[int],
+	)
+
+	fmt.Println(Any(data1))
+
+	// Output:
+	// true
+}

array/example_find_test.go

@@ -0,0 +1,55 @@
+// Copyright (c) 2023 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package array
+
+import (
+	"fmt"
+
+	F "github.com/IBM/fp-go/function"
+)
+
+func Example_find() {
+
+	pred := func(val int) bool {
+		return val&2 == 0
+	}
+
+	data1 := From(1, 2, 3)
+
+	fmt.Println(FindFirst(pred)(data1))
+
+	// Output:
+	// Some[int](1)
+}
+
+func Example_find_filter() {
+
+	pred := func(val int) bool {
+		return val&2 == 0
+	}
+
+	data1 := From(1, 2, 3)
+
+	Find := F.Flow2(
+		Filter(pred),
+		Head[int],
+	)
+
+	fmt.Println(Find(data1))
+
+	// Output:
+	// Some[int](1)
+}

array/find.go

@@ -0,0 +1,61 @@
+// 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"
+	O "github.com/IBM/fp-go/option"
+)
+
+// FindFirst finds the first element which satisfies a predicate (or a refinement) function
+func FindFirst[A any](pred func(A) bool) func([]A) O.Option[A] {
+	return G.FindFirst[[]A](pred)
+}
+
+// FindFirstWithIndex finds the first element which satisfies a predicate (or a refinement) function
+func FindFirstWithIndex[A any](pred func(int, A) bool) func([]A) O.Option[A] {
+	return G.FindFirstWithIndex[[]A](pred)
+}
+
+// FindFirstMap finds the first element returned by an [O.Option] based selector function
+func FindFirstMap[A, B any](sel func(A) O.Option[B]) func([]A) O.Option[B] {
+	return G.FindFirstMap[[]A](sel)
+}
+
+// FindFirstMapWithIndex finds the first element returned by an [O.Option] based selector function
+func FindFirstMapWithIndex[A, B any](sel func(int, A) O.Option[B]) func([]A) O.Option[B] {
+	return G.FindFirstMapWithIndex[[]A](sel)
+}
+
+// FindLast finds the Last element which satisfies a predicate (or a refinement) function
+func FindLast[A any](pred func(A) bool) func([]A) O.Option[A] {
+	return G.FindLast[[]A](pred)
+}
+
+// FindLastWithIndex finds the Last element which satisfies a predicate (or a refinement) function
+func FindLastWithIndex[A any](pred func(int, A) bool) func([]A) O.Option[A] {
+	return G.FindLastWithIndex[[]A](pred)
+}
+
+// FindLastMap finds the Last element returned by an [O.Option] based selector function
+func FindLastMap[A, B any](sel func(A) O.Option[B]) func([]A) O.Option[B] {
+	return G.FindLastMap[[]A](sel)
+}
+
+// FindLastMapWithIndex finds the Last element returned by an [O.Option] based selector function
+func FindLastMapWithIndex[A, B any](sel func(int, A) O.Option[B]) func([]A) O.Option[B] {
+	return G.FindLastMapWithIndex[[]A](sel)
+}

array/generic/any.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"
+)
+
+// AnyWithIndex tests if any of the elements in the array matches the predicate
+func AnyWithIndex[AS ~[]A, PRED ~func(int, A) bool, A any](pred PRED) func(AS) bool {
+	return F.Flow2(
+		FindFirstWithIndex[AS](pred),
+		O.IsSome[A],
+	)
+}
+
+// Any tests if any of the elements in the array matches the predicate
+func Any[AS ~[]A, PRED ~func(A) bool, A any](pred PRED) func(AS) bool {
+	return AnyWithIndex[AS](F.Ignore1of2[int](pred))
+}

array/generic/array.go

@@ -29,14 +29,46 @@ 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 {
+func Reduce[GA ~[]A, A, B any](f func(B, A) B, initial B) func(GA) B {
+	return func(as GA) B {
+		return MonadReduce[GA](as, f, initial)
+	}
+}
+
+func ReduceWithIndex[GA ~[]A, A, B any](f func(int, B, A) B, initial B) func(GA) B {
+	return func(as GA) B {
+		return MonadReduceWithIndex[GA](as, f, initial)
+	}
+}
+
+func ReduceRight[GA ~[]A, A, B any](f func(A, B) B, initial B) func(GA) B {
+	return func(as GA) B {
+		return MonadReduceRight[GA](as, f, initial)
+	}
+}
+
+func ReduceRightWithIndex[GA ~[]A, A, B any](f func(int, A, B) B, initial B) func(GA) B {
+	return func(as GA) B {
+		return MonadReduceRightWithIndex[GA](as, f, initial)
+	}
+}
+
+func MonadReduce[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 {
+func MonadReduceWithIndex[GA ~[]A, A, B any](fa GA, f func(int, B, A) B, initial B) B {
 	return array.ReduceWithIndex(fa, f, initial)
 }
 
+func MonadReduceRight[GA ~[]A, A, B any](fa GA, f func(A, B) B, initial B) B {
+	return array.ReduceRight(fa, f, initial)
+}
+
+func MonadReduceRightWithIndex[GA ~[]A, A, B any](fa GA, f func(int, A, B) B, initial B) B {
+	return array.ReduceRightWithIndex(fa, f, initial)
+}
+
 // From constructs an array from a set of variadic arguments
 func From[GA ~[]A, A any](data ...A) GA {
 	return data
@@ -118,20 +150,56 @@ 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 MonadMapWithIndex[GA ~[]A, GB ~[]B, A, B any](as GA, f func(int, A) B) GB {
+	return array.MonadMapWithIndex[GA, GB](as, f)
+}
+
+func MapWithIndex[GA ~[]A, GB ~[]B, A, B any](f func(int, A) B) func(GA) GB {
+	return F.Bind2nd(MonadMapWithIndex[GA, GB, A, B], f)
+}
+
 func Size[GA ~[]A, A any](as GA) int {
 	return len(as)
 }
 
-func filterMap[GA ~[]A, GB ~[]B, A, B any](fa GA, f func(a A) O.Option[B]) GB {
+func filterMap[GA ~[]A, GB ~[]B, A, B any](fa GA, f func(A) O.Option[B]) GB {
 	return array.Reduce(fa, func(bs GB, a A) GB {
 		return O.MonadFold(f(a), F.Constant(bs), F.Bind1st(Append[GB, B], bs))
 	}, Empty[GB]())
 }
 
-func MonadFilterMap[GA ~[]A, GB ~[]B, A, B any](fa GA, f func(a A) O.Option[B]) GB {
+func filterMapWithIndex[GA ~[]A, GB ~[]B, A, B any](fa GA, f func(int, A) O.Option[B]) GB {
+	return array.ReduceWithIndex(fa, func(idx int, bs GB, a A) GB {
+		return O.MonadFold(f(idx, a), F.Constant(bs), F.Bind1st(Append[GB, B], bs))
+	}, Empty[GB]())
+}
+
+func MonadFilterMap[GA ~[]A, GB ~[]B, A, B any](fa GA, f func(A) O.Option[B]) GB {
 	return filterMap[GA, GB](fa, f)
 }
 
+func MonadFilterMapWithIndex[GA ~[]A, GB ~[]B, A, B any](fa GA, f func(int, A) O.Option[B]) GB {
+	return filterMapWithIndex[GA, GB](fa, f)
+}
+
+func filterWithIndex[AS ~[]A, PRED ~func(int, A) bool, A any](fa AS, pred PRED) AS {
+	result := make(AS, 0, len(fa))
+	for i, a := range fa {
+		if pred(i, a) {
+			result = append(result, a)
+		}
+	}
+	return result
+}
+
+func FilterWithIndex[AS ~[]A, PRED ~func(int, A) bool, A any](pred PRED) func(AS) AS {
+	return F.Bind2nd(filterWithIndex[AS, PRED, A], pred)
+}
+
+func Filter[AS ~[]A, PRED ~func(A) bool, A any](pred PRED) func(AS) AS {
+	return FilterWithIndex[AS](F.Ignore1of2[int](pred))
+}
+
 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),
@@ -143,10 +211,14 @@ 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 {
+func FilterMap[GA ~[]A, GB ~[]B, A, B any](f func(A) O.Option[B]) func(GA) GB {
 	return F.Bind2nd(MonadFilterMap[GA, GB, A, B], f)
 }
 
+func FilterMapWithIndex[GA ~[]A, GB ~[]B, A, B any](f func(int, A) O.Option[B]) func(GA) GB {
+	return F.Bind2nd(MonadFilterMapWithIndex[GA, GB, A, B], f)
+}
+
 func MonadPartition[GA ~[]A, A any](as GA, pred func(A) bool) tuple.Tuple2[GA, GA] {
 	left := Empty[GA]()
 	right := Empty[GA]()
@@ -242,6 +314,16 @@ func FoldMap[AS ~[]A, A, B any](m M.Monoid[B]) func(func(A) B) func(AS) B {
 	}
 }
 
+func FoldMapWithIndex[AS ~[]A, A, B any](m M.Monoid[B]) func(func(int, A) B) func(AS) B {
+	return func(f func(int, A) B) func(AS) B {
+		return func(as AS) B {
+			return array.ReduceWithIndex(as, func(idx int, cur B, a A) B {
+				return m.Concat(cur, f(idx, a))
+			}, m.Empty())
+		}
+	}
+}
+
 func Fold[AS ~[]A, A any](m M.Monoid[A]) func(AS) A {
 	return func(as AS) A {
 		return array.Reduce(as, m.Concat, m.Empty())

array/generic/find.go

@@ -0,0 +1,97 @@
+// 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"
+)
+
+// FindFirstWithIndex finds the first element which satisfies a predicate (or a refinement) function
+func FindFirstWithIndex[AS ~[]A, PRED ~func(int, A) bool, A any](pred PRED) func(AS) O.Option[A] {
+	none := O.None[A]()
+	return func(as AS) O.Option[A] {
+		for i, a := range as {
+			if pred(i, a) {
+				return O.Some(a)
+			}
+		}
+		return none
+	}
+}
+
+// FindFirst finds the first element which satisfies a predicate (or a refinement) function
+func FindFirst[AS ~[]A, PRED ~func(A) bool, A any](pred PRED) func(AS) O.Option[A] {
+	return FindFirstWithIndex[AS](F.Ignore1of2[int](pred))
+}
+
+// FindFirstMapWithIndex finds the first element returned by an [O.Option] based selector function
+func FindFirstMapWithIndex[AS ~[]A, PRED ~func(int, A) O.Option[B], A, B any](pred PRED) func(AS) O.Option[B] {
+	none := O.None[B]()
+	return func(as AS) O.Option[B] {
+		count := len(as)
+		for i := 0; i < count; i++ {
+			out := pred(i, as[i])
+			if O.IsSome(out) {
+				return out
+			}
+		}
+		return none
+	}
+}
+
+// FindFirstMap finds the first element returned by an [O.Option] based selector function
+func FindFirstMap[AS ~[]A, PRED ~func(A) O.Option[B], A, B any](pred PRED) func(AS) O.Option[B] {
+	return FindFirstMapWithIndex[AS](F.Ignore1of2[int](pred))
+}
+
+// FindLastWithIndex finds the first element which satisfies a predicate (or a refinement) function
+func FindLastWithIndex[AS ~[]A, PRED ~func(int, A) bool, A any](pred PRED) func(AS) O.Option[A] {
+	none := O.None[A]()
+	return func(as AS) O.Option[A] {
+		for i := len(as) - 1; i >= 0; i-- {
+			a := as[i]
+			if pred(i, a) {
+				return O.Some(a)
+			}
+		}
+		return none
+	}
+}
+
+// FindLast finds the first element which satisfies a predicate (or a refinement) function
+func FindLast[AS ~[]A, PRED ~func(A) bool, A any](pred PRED) func(AS) O.Option[A] {
+	return FindLastWithIndex[AS](F.Ignore1of2[int](pred))
+}
+
+// FindLastMapWithIndex finds the first element returned by an [O.Option] based selector function
+func FindLastMapWithIndex[AS ~[]A, PRED ~func(int, A) O.Option[B], A, B any](pred PRED) func(AS) O.Option[B] {
+	none := O.None[B]()
+	return func(as AS) O.Option[B] {
+		for i := len(as) - 1; i >= 0; i-- {
+			out := pred(i, as[i])
+			if O.IsSome(out) {
+				return out
+			}
+		}
+		return none
+	}
+}
+
+// FindLastMap finds the first element returned by an [O.Option] based selector function
+func FindLastMap[AS ~[]A, PRED ~func(A) O.Option[B], A, B any](pred PRED) func(AS) O.Option[B] {
+	return FindLastMapWithIndex[AS](F.Ignore1of2[int](pred))
+}

array/monoid.go

@@ -18,6 +18,7 @@ package array
 import (
 	"github.com/IBM/fp-go/internal/array"
 	M "github.com/IBM/fp-go/monoid"
+	S "github.com/IBM/fp-go/semigroup"
 )
 
 func concat[T any](left, right []T) []T {
@@ -40,6 +41,10 @@ func Monoid[T any]() M.Monoid[[]T] {
 	return M.MakeMonoid(concat[T], Empty[T]())
 }
 
+func Semigroup[T any]() S.Semigroup[[]T] {
+	return S.MakeSemigroup(concat[T])
+}
+
 func addLen[A any](count int, data []A) int {
 	return count + len(data)
 }

assert/assert_test.go

@@ -0,0 +1,109 @@
+// 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 assert
+
+import (
+	"fmt"
+	"testing"
+
+	E "github.com/IBM/fp-go/either"
+	EQ "github.com/IBM/fp-go/eq"
+	"github.com/stretchr/testify/assert"
+)
+
+var (
+	errTest = fmt.Errorf("test failure")
+
+	// Eq is the equal predicate checking if objects are equal
+	Eq = EQ.FromEquals(assert.ObjectsAreEqual)
+)
+
+func wrap1[T any](wrapped func(t assert.TestingT, expected, actual any, msgAndArgs ...any) bool, t *testing.T, expected T) func(actual T) E.Either[error, T] {
+	return func(actual T) E.Either[error, T] {
+		ok := wrapped(t, expected, actual)
+		if ok {
+			return E.Of[error](actual)
+		}
+		return E.Left[T](errTest)
+	}
+}
+
+// NotEqual tests if the expected and the actual values are not equal
+func NotEqual[T any](t *testing.T, expected T) func(actual T) E.Either[error, T] {
+	return wrap1(assert.NotEqual, t, expected)
+}
+
+// Equal tests if the expected and the actual values are equal
+func Equal[T any](t *testing.T, expected T) func(actual T) E.Either[error, T] {
+	return wrap1(assert.Equal, t, expected)
+}
+
+// Length tests if an array has the expected length
+func Length[T any](t *testing.T, expected int) func(actual []T) E.Either[error, []T] {
+	return func(actual []T) E.Either[error, []T] {
+		ok := assert.Len(t, actual, expected)
+		if ok {
+			return E.Of[error](actual)
+		}
+		return E.Left[[]T](errTest)
+	}
+}
+
+// NoError validates that there is no error
+func NoError[T any](t *testing.T) func(actual E.Either[error, T]) E.Either[error, T] {
+	return func(actual E.Either[error, T]) E.Either[error, T] {
+		return E.MonadFold(actual, func(e error) E.Either[error, T] {
+			assert.NoError(t, e)
+			return E.Left[T](e)
+		}, func(value T) E.Either[error, T] {
+			assert.NoError(t, nil)
+			return E.Right[error](value)
+		})
+	}
+}
+
+// ArrayContains tests if a value is contained in an array
+func ArrayContains[T any](t *testing.T, expected T) func(actual []T) E.Either[error, []T] {
+	return func(actual []T) E.Either[error, []T] {
+		ok := assert.Contains(t, actual, expected)
+		if ok {
+			return E.Of[error](actual)
+		}
+		return E.Left[[]T](errTest)
+	}
+}
+
+// ContainsKey tests if a key is contained in a map
+func ContainsKey[T any, K comparable](t *testing.T, expected K) func(actual map[K]T) E.Either[error, map[K]T] {
+	return func(actual map[K]T) E.Either[error, map[K]T] {
+		ok := assert.Contains(t, actual, expected)
+		if ok {
+			return E.Of[error](actual)
+		}
+		return E.Left[map[K]T](errTest)
+	}
+}
+
+// NotContainsKey tests if a key is not contained in a map
+func NotContainsKey[T any, K comparable](t *testing.T, expected K) func(actual map[K]T) E.Either[error, map[K]T] {
+	return func(actual map[K]T) E.Either[error, map[K]T] {
+		ok := assert.NotContains(t, actual, expected)
+		if ok {
+			return E.Of[error](actual)
+		}
+		return E.Left[map[K]T](errTest)
+	}
+}

cli/either.go

@@ -115,16 +115,14 @@ func generateEitherize(f *os.File, i int) {
 		fmt.Fprintf(f, "t%d T%d", j, j)
 	}
 	fmt.Fprintf(f, ") Either[error, R] {\n")
-	fmt.Fprintf(f, "    return TryCatchError(func() (R, error) {\n")
+	fmt.Fprintf(f, "    return TryCatchError(f(")
-	fmt.Fprintf(f, "      return f(")
 	for j := 0; j < i; j++ {
 		if j > 0 {
 			fmt.Fprintf(f, ", ")
 		}
 		fmt.Fprintf(f, "t%d", j)
 	}
-	fmt.Fprintln(f, ")")
+	fmt.Fprintln(f, "))")
-	fmt.Fprintln(f, "    })")
 	fmt.Fprintln(f, "  }")
 	fmt.Fprintln(f, "}")
 }

constant/const.go

@@ -22,30 +22,28 @@ import (
 )
 
 type Const[E, A any] struct {
-	Value E
+	value E
 }
 
 func Make[E, A any](e E) Const[E, A] {
-	return Const[E, A]{Value: e}
+	return Const[E, A]{value: e}
 }
 
 func Unwrap[E, A any](c Const[E, A]) E {
-	return c.Value
+	return c.value
 }
 
 func Of[E, A any](m M.Monoid[E]) func(A) Const[E, A] {
-	return func(a A) Const[E, A] {
+	return F.Constant1[A](Make[E, A](m.Empty()))
-		return Make[E, A](m.Empty())
-	}
 }
 
 func MonadMap[E, A, B any](fa Const[E, A], f func(A) B) Const[E, B] {
-	return Make[E, B](fa.Value)
+	return Make[E, B](fa.value)
 }
 
 func MonadAp[E, A, B any](s S.Semigroup[E]) func(fab Const[E, func(A) B], fa Const[E, A]) Const[E, B] {
 	return func(fab Const[E, func(A) B], fa Const[E, A]) Const[E, B] {
-		return Make[E, B](s.Concat(fab.Value, fa.Value))
+		return Make[E, B](s.Concat(fab.value, fa.value))
 	}
 }
 

context/ioeither/generic/ioeither.go

@@ -19,15 +19,14 @@ import (
 	"context"
 
 	E "github.com/IBM/fp-go/either"
-	ET "github.com/IBM/fp-go/either"
 	IOE "github.com/IBM/fp-go/ioeither/generic"
 )
 
-// withContext wraps an existing IOEither and performs a context check for cancellation before delegating
+// WithContext wraps an existing IOEither and performs a context check for cancellation before delegating
 func WithContext[GIO ~func() E.Either[error, A], A any](ctx context.Context, ma GIO) GIO {
 	return IOE.MakeIO[GIO](func() E.Either[error, A] {
 		if err := context.Cause(ctx); err != nil {
-			return ET.Left[A](err)
+			return E.Left[A](err)
 		}
 		return ma()
 	})

context/reader/array.go

@@ -1,35 +0,0 @@
-//   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 reader
-
-import (
-	R "github.com/IBM/fp-go/reader/generic"
-)
-
-// TraverseArray transforms an array
-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/reader/curry.go

@@ -1,53 +0,0 @@
-//   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 reader
-
-import (
-	"context"
-
-	R "github.com/IBM/fp-go/reader/generic"
-)
-
-// these functions curry a golang function with the context as the firsr parameter into a either reader with the context as the last parameter
-// this goes back to the advice in https://pkg.go.dev/context to put the context as a first parameter as a convention
-
-func Curry0[A any](f func(context.Context) A) Reader[A] {
-	return R.Curry0[Reader[A]](f)
-}
-
-func Curry1[T1, A any](f func(context.Context, T1) A) func(T1) Reader[A] {
-	return R.Curry1[Reader[A]](f)
-}
-
-func Curry2[T1, T2, A any](f func(context.Context, T1, T2) A) func(T1) func(T2) Reader[A] {
-	return R.Curry2[Reader[A]](f)
-}
-
-func Curry3[T1, T2, T3, A any](f func(context.Context, T1, T2, T3) A) func(T1) func(T2) func(T3) Reader[A] {
-	return R.Curry3[Reader[A]](f)
-}
-
-func Uncurry1[T1, A any](f func(T1) Reader[A]) func(context.Context, T1) A {
-	return R.Uncurry1(f)
-}
-
-func Uncurry2[T1, T2, A any](f func(T1) func(T2) Reader[A]) func(context.Context, T1, T2) A {
-	return R.Uncurry2(f)
-}
-
-func Uncurry3[T1, T2, T3, A any](f func(T1) func(T2) func(T3) Reader[A]) func(context.Context, T1, T2, T3) A {
-	return R.Uncurry3(f)
-}

context/reader/from.go

@@ -1,41 +0,0 @@
-// 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 reader
-
-import (
-	"context"
-
-	R "github.com/IBM/fp-go/reader/generic"
-)
-
-// these functions curry a golang function with the context as the firsr parameter into a either reader with the context as the last parameter
-// this goes back to the advice in https://pkg.go.dev/context to put the context as a first parameter as a convention
-
-func From0[A any](f func(context.Context) A) func() Reader[A] {
-	return R.From0[Reader[A]](f)
-}
-
-func From1[T1, A any](f func(context.Context, T1) A) func(T1) Reader[A] {
-	return R.From1[Reader[A]](f)
-}
-
-func From2[T1, T2, A any](f func(context.Context, T1, T2) A) func(T1, T2) Reader[A] {
-	return R.From2[Reader[A]](f)
-}
-
-func From3[T1, T2, T3, A any](f func(context.Context, T1, T2, T3) A) func(T1, T2, T3) Reader[A] {
-	return R.From3[Reader[A]](f)
-}

context/reader/reader.go

@@ -1,66 +0,0 @@
-// 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 reader
-
-import (
-	"context"
-
-	R "github.com/IBM/fp-go/reader/generic"
-)
-
-func MonadMap[A, B any](fa Reader[A], f func(A) B) Reader[B] {
-	return R.MonadMap[Reader[A], Reader[B]](fa, f)
-}
-
-func Map[A, B any](f func(A) B) func(Reader[A]) Reader[B] {
-	return R.Map[Reader[A], Reader[B]](f)
-}
-
-func MonadChain[A, B any](ma Reader[A], f func(A) Reader[B]) Reader[B] {
-	return R.MonadChain(ma, f)
-}
-
-func Chain[A, B any](f func(A) Reader[B]) func(Reader[A]) Reader[B] {
-	return R.Chain[Reader[A]](f)
-}
-
-func Of[A any](a A) Reader[A] {
-	return R.Of[Reader[A]](a)
-}
-
-func MonadAp[A, B any](fab Reader[func(A) B], fa Reader[A]) Reader[B] {
-	return R.MonadAp[Reader[A], Reader[B]](fab, fa)
-}
-
-func Ap[A, B any](fa Reader[A]) func(Reader[func(A) B]) Reader[B] {
-	return R.Ap[Reader[A], Reader[B], Reader[func(A) B]](fa)
-}
-
-func Ask() Reader[context.Context] {
-	return R.Ask[Reader[context.Context]]()
-}
-
-func Asks[A any](r Reader[A]) Reader[A] {
-	return R.Asks(r)
-}
-
-func MonadFlap[B, A any](fab Reader[func(A) B], a A) Reader[B] {
-	return R.MonadFlap[Reader[func(A) B], Reader[B]](fab, a)
-}
-
-func Flap[B, A any](a A) func(Reader[func(A) B]) Reader[B] {
-	return R.Flap[Reader[func(A) B], Reader[B]](a)
-}

context/reader/reader_test.go

@@ -1,75 +0,0 @@
-// 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 reader
-
-import (
-	"context"
-	"fmt"
-	"strings"
-	"testing"
-
-	F "github.com/IBM/fp-go/function"
-	T "github.com/IBM/fp-go/tuple"
-	"github.com/stretchr/testify/assert"
-)
-
-func GoFunction(ctx context.Context, data string) string {
-	return strings.ToUpper(data)
-}
-
-func GoIntFunction(ctx context.Context, data string, number int) string {
-	return fmt.Sprintf("%s: %d", data, number)
-}
-
-func TestReaderFrom(t *testing.T) {
-	ctx := context.Background()
-	f := From1(GoFunction)
-
-	result := f("input")(ctx)
-
-	assert.Equal(t, result, "INPUT")
-
-}
-
-func MyFinalResult(left, right string) string {
-	return fmt.Sprintf("%s-%s", left, right)
-}
-
-func TestReadersFrom(t *testing.T) {
-	ctx := context.Background()
-
-	f1 := From1(GoFunction)
-	f2 := From2(GoIntFunction)
-
-	result1 := f1("input")(ctx)
-	result2 := f2("input", 10)(ctx)
-
-	result3 := MyFinalResult(result1, result2)
-
-	h := F.Pipe1(
-		SequenceT2(f1("input"), f2("input", 10)),
-		Map(T.Tupled2(MyFinalResult)),
-	)
-
-	composedResult := h(ctx)
-
-	assert.Equal(t, result1, "INPUT")
-	assert.Equal(t, result2, "input: 10")
-	assert.Equal(t, result3, "INPUT-input: 10")
-
-	assert.Equal(t, composedResult, "INPUT-input: 10")
-
-}

context/reader/sequence.go

@@ -1,57 +0,0 @@
-// 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 reader
-
-import (
-	R "github.com/IBM/fp-go/reader/generic"
-	T "github.com/IBM/fp-go/tuple"
-)
-
-// SequenceT converts n inputs of higher kinded types into a higher kinded types of n strongly typed values, represented as a tuple
-
-func SequenceT1[A any](a Reader[A]) Reader[T.Tuple1[A]] {
-	return R.SequenceT1[
-		Reader[A],
-		Reader[T.Tuple1[A]],
-	](a)
-}
-
-func SequenceT2[A, B any](a Reader[A], b Reader[B]) Reader[T.Tuple2[A, B]] {
-	return R.SequenceT2[
-		Reader[A],
-		Reader[B],
-		Reader[T.Tuple2[A, B]],
-	](a, b)
-}
-
-func SequenceT3[A, B, C any](a Reader[A], b Reader[B], c Reader[C]) Reader[T.Tuple3[A, B, C]] {
-	return R.SequenceT3[
-		Reader[A],
-		Reader[B],
-		Reader[C],
-		Reader[T.Tuple3[A, B, C]],
-	](a, b, c)
-}
-
-func SequenceT4[A, B, C, D any](a Reader[A], b Reader[B], c Reader[C], d Reader[D]) Reader[T.Tuple4[A, B, C, D]] {
-	return R.SequenceT4[
-		Reader[A],
-		Reader[B],
-		Reader[C],
-		Reader[D],
-		Reader[T.Tuple4[A, B, C, D]],
-	](a, b, c, d)
-}

context/readereither/exec/exec.go

@@ -34,8 +34,6 @@ var (
 
 func command(name string, args []string, in []byte) RE.ReaderEither[exec.CommandOutput] {
 	return func(ctx context.Context) E.Either[error, exec.CommandOutput] {
-		return E.TryCatchError(func() (exec.CommandOutput, error) {
+		return E.TryCatchError(GE.Exec(ctx, name, args, in))
-			return GE.Exec(ctx, name, args, in)
-		})
 	}
 }

context/readereither/reader.go

@@ -18,7 +18,6 @@ package readereither
 import (
 	"context"
 
-	R "github.com/IBM/fp-go/context/reader"
 	ET "github.com/IBM/fp-go/either"
 	O "github.com/IBM/fp-go/option"
 	RE "github.com/IBM/fp-go/readereither/generic"
@@ -32,14 +31,6 @@ func FromEither[A any](e ET.Either[error, A]) ReaderEither[A] {
 	return RE.FromEither[ReaderEither[A]](e)
 }
 
-func RightReader[A any](r R.Reader[A]) ReaderEither[A] {
-	return RE.RightReader[R.Reader[A], ReaderEither[A]](r)
-}
-
-func LeftReader[A any](l R.Reader[error]) ReaderEither[A] {
-	return RE.LeftReader[R.Reader[error], ReaderEither[A]](l)
-}
-
 func Left[A any](l error) ReaderEither[A] {
 	return RE.Left[ReaderEither[A]](l)
 }
@@ -48,10 +39,6 @@ func Right[A any](r A) ReaderEither[A] {
 	return RE.Right[ReaderEither[A]](r)
 }
 
-func FromReader[A any](r R.Reader[A]) ReaderEither[A] {
-	return RE.FromReader[R.Reader[A], ReaderEither[A]](r)
-}
-
 func MonadMap[A, B any](fa ReaderEither[A], f func(A) B) ReaderEither[B] {
 	return RE.MonadMap[ReaderEither[A], ReaderEither[B]](fa, f)
 }
@@ -84,30 +71,14 @@ func FromPredicate[A any](pred func(A) bool, onFalse func(A) error) func(A) Read
 	return RE.FromPredicate[ReaderEither[A]](pred, onFalse)
 }
 
-func Fold[A, B any](onLeft func(error) R.Reader[B], onRight func(A) R.Reader[B]) func(ReaderEither[A]) R.Reader[B] {
-	return RE.Fold[ReaderEither[A]](onLeft, onRight)
-}
-
-func GetOrElse[A any](onLeft func(error) R.Reader[A]) func(ReaderEither[A]) R.Reader[A] {
-	return RE.GetOrElse[ReaderEither[A]](onLeft)
-}
-
 func OrElse[A any](onLeft func(error) ReaderEither[A]) func(ReaderEither[A]) ReaderEither[A] {
 	return RE.OrElse[ReaderEither[A]](onLeft)
 }
 
-func OrLeft[A any](onLeft func(error) R.Reader[error]) func(ReaderEither[A]) ReaderEither[A] {
-	return RE.OrLeft[ReaderEither[A], ReaderEither[A]](onLeft)
-}
-
 func Ask() ReaderEither[context.Context] {
 	return RE.Ask[ReaderEither[context.Context]]()
 }
 
-func Asks[A any](r R.Reader[A]) ReaderEither[A] {
-	return RE.Asks[R.Reader[A], ReaderEither[A]](r)
-}
-
 func MonadChainEitherK[A, B any](ma ReaderEither[A], f func(A) ET.Either[error, B]) ReaderEither[B] {
 	return RE.MonadChainEitherK[ReaderEither[A], ReaderEither[B]](ma, f)
 }

context/readerio/array.go

@@ -1,36 +0,0 @@
-// 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 readerio
-
-import (
-	IO "github.com/IBM/fp-go/io"
-	R "github.com/IBM/fp-go/readerio/generic"
-)
-
-// TraverseArray transforms an array
-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/readerio/from.go

@@ -1,42 +0,0 @@
-// 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 readerio
-
-import (
-	"context"
-
-	IO "github.com/IBM/fp-go/io"
-	R "github.com/IBM/fp-go/readerio/generic"
-)
-
-// these functions curry a golang function with the context as the firsr parameter into a either reader with the context as the last parameter
-// this goes back to the advice in https://pkg.go.dev/context to put the context as a first parameter as a convention
-
-func From0[A any](f func(context.Context) IO.IO[A]) func() ReaderIO[A] {
-	return R.From0[ReaderIO[A]](f)
-}
-
-func From1[T1, A any](f func(context.Context, T1) IO.IO[A]) func(T1) ReaderIO[A] {
-	return R.From1[ReaderIO[A]](f)
-}
-
-func From2[T1, T2, A any](f func(context.Context, T1, T2) IO.IO[A]) func(T1, T2) ReaderIO[A] {
-	return R.From2[ReaderIO[A]](f)
-}
-
-func From3[T1, T2, T3, A any](f func(context.Context, T1, T2, T3) IO.IO[A]) func(T1, T2, T3) ReaderIO[A] {
-	return R.From3[ReaderIO[A]](f)
-}

context/readerio/reader.go

@@ -1,102 +0,0 @@
-// 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 readerio
-
-import (
-	"context"
-
-	IO "github.com/IBM/fp-go/io"
-	L "github.com/IBM/fp-go/lazy"
-	R "github.com/IBM/fp-go/readerio/generic"
-)
-
-// FromIO converts an [IO.IO] to a [ReaderIO]
-func FromIO[A any](a IO.IO[A]) ReaderIO[A] {
-	return R.FromIO[ReaderIO[A]](a)
-}
-
-func MonadMap[A, B any](fa ReaderIO[A], f func(A) B) ReaderIO[B] {
-	return R.MonadMap[ReaderIO[A], ReaderIO[B]](fa, f)
-}
-
-func Map[A, B any](f func(A) B) func(ReaderIO[A]) ReaderIO[B] {
-	return R.Map[ReaderIO[A], ReaderIO[B]](f)
-}
-
-func MonadChain[A, B any](ma ReaderIO[A], f func(A) ReaderIO[B]) ReaderIO[B] {
-	return R.MonadChain(ma, f)
-}
-
-func Chain[A, B any](f func(A) ReaderIO[B]) func(ReaderIO[A]) ReaderIO[B] {
-	return R.Chain[ReaderIO[A]](f)
-}
-
-func MonadChainIOK[A, B any](fa ReaderIO[A], f func(A) IO.IO[B]) ReaderIO[B] {
-	return R.MonadChainIOK[ReaderIO[A], ReaderIO[B]](fa, f)
-}
-
-func ChainIOK[A, B any](f func(A) IO.IO[B]) func(ReaderIO[A]) ReaderIO[B] {
-	return R.ChainIOK[ReaderIO[A], ReaderIO[B]](f)
-}
-
-func MonadChainFirstIOK[A, B any](fa ReaderIO[A], f func(A) IO.IO[B]) ReaderIO[A] {
-	return R.MonadChainFirstIOK[ReaderIO[A], ReaderIO[B]](fa, f)
-}
-
-func ChainFirstIOK[A, B any](f func(A) IO.IO[B]) func(ReaderIO[A]) ReaderIO[A] {
-	return R.ChainFirstIOK[ReaderIO[A], ReaderIO[B]](f)
-}
-
-func Of[A any](a A) ReaderIO[A] {
-	return R.Of[ReaderIO[A]](a)
-}
-
-func MonadAp[A, B any](fab ReaderIO[func(A) B], fa ReaderIO[A]) ReaderIO[B] {
-	return R.MonadAp[ReaderIO[A], ReaderIO[B]](fab, fa)
-}
-
-func Ap[A, B any](fa ReaderIO[A]) func(ReaderIO[func(A) B]) ReaderIO[B] {
-	return R.Ap[ReaderIO[A], ReaderIO[B], ReaderIO[func(A) B]](fa)
-}
-
-func Ask() ReaderIO[context.Context] {
-	return R.Ask[ReaderIO[context.Context]]()
-}
-
-// Defer creates an IO by creating a brand new IO via a generator function, each time
-func Defer[A any](gen L.Lazy[ReaderIO[A]]) ReaderIO[A] {
-	return R.Defer[ReaderIO[A]](gen)
-}
-
-// Memoize computes the value of the provided [ReaderIO] monad lazily but exactly once
-// The context used to compute the value is the context of the first call, so do not use this
-// method if the value has a functional dependency on the content of the context
-func Memoize[A any](rdr ReaderIO[A]) ReaderIO[A] {
-	return R.Memoize[ReaderIO[A]](rdr)
-}
-
-// Flatten converts a nested [ReaderIO] into a [ReaderIO]
-func Flatten[A any](mma ReaderIO[ReaderIO[A]]) ReaderIO[A] {
-	return R.Flatten[ReaderIO[A]](mma)
-}
-
-func MonadFlap[B, A any](fab ReaderIO[func(A) B], a A) ReaderIO[B] {
-	return R.MonadFlap[ReaderIO[func(A) B], ReaderIO[B]](fab, a)
-}
-
-func Flap[B, A any](a A) func(ReaderIO[func(A) B]) ReaderIO[B] {
-	return R.Flap[ReaderIO[func(A) B], ReaderIO[B]](a)
-}

context/readerio/reader_test.go

@@ -1,80 +0,0 @@
-// 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 readerio
-
-import (
-	"context"
-	"fmt"
-	"strings"
-	"testing"
-
-	F "github.com/IBM/fp-go/function"
-	IO "github.com/IBM/fp-go/io"
-	T "github.com/IBM/fp-go/tuple"
-	"github.com/stretchr/testify/assert"
-)
-
-func GoFunction(ctx context.Context, data string) IO.IO[string] {
-	return func() string {
-		return strings.ToUpper(data)
-	}
-}
-
-func GoIntFunction(ctx context.Context, data string, number int) IO.IO[string] {
-	return func() string {
-		return fmt.Sprintf("%s: %d", data, number)
-	}
-}
-
-func TestReaderFrom(t *testing.T) {
-	ctx := context.Background()
-	f := From1(GoFunction)
-
-	result := f("input")(ctx)
-
-	assert.Equal(t, result(), "INPUT")
-
-}
-
-func MyFinalResult(left, right string) string {
-	return fmt.Sprintf("%s-%s", left, right)
-}
-
-func TestReadersFrom(t *testing.T) {
-	ctx := context.Background()
-
-	f1 := From1(GoFunction)
-	f2 := From2(GoIntFunction)
-
-	result1 := f1("input")(ctx)
-	result2 := f2("input", 10)(ctx)
-
-	result3 := MyFinalResult(result1(), result2())
-
-	h := F.Pipe1(
-		SequenceT2(f1("input"), f2("input", 10)),
-		Map(T.Tupled2(MyFinalResult)),
-	)
-
-	composedResult := h(ctx)
-
-	assert.Equal(t, result1(), "INPUT")
-	assert.Equal(t, result2(), "input: 10")
-	assert.Equal(t, result3, "INPUT-input: 10")
-
-	assert.Equal(t, composedResult(), "INPUT-input: 10")
-
-}

context/readerio/sequence.go

@@ -1,57 +0,0 @@
-// 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 readerio
-
-import (
-	R "github.com/IBM/fp-go/readerio/generic"
-	T "github.com/IBM/fp-go/tuple"
-)
-
-// SequenceT converts n inputs of higher kinded types into a higher kinded types of n strongly typed values, represented as a tuple
-
-func SequenceT1[A any](a ReaderIO[A]) ReaderIO[T.Tuple1[A]] {
-	return R.SequenceT1[
-		ReaderIO[A],
-		ReaderIO[T.Tuple1[A]],
-	](a)
-}
-
-func SequenceT2[A, B any](a ReaderIO[A], b ReaderIO[B]) ReaderIO[T.Tuple2[A, B]] {
-	return R.SequenceT2[
-		ReaderIO[A],
-		ReaderIO[B],
-		ReaderIO[T.Tuple2[A, B]],
-	](a, b)
-}
-
-func SequenceT3[A, B, C any](a ReaderIO[A], b ReaderIO[B], c ReaderIO[C]) ReaderIO[T.Tuple3[A, B, C]] {
-	return R.SequenceT3[
-		ReaderIO[A],
-		ReaderIO[B],
-		ReaderIO[C],
-		ReaderIO[T.Tuple3[A, B, C]],
-	](a, b, c)
-}
-
-func SequenceT4[A, B, C, D any](a ReaderIO[A], b ReaderIO[B], c ReaderIO[C], d ReaderIO[D]) ReaderIO[T.Tuple4[A, B, C, D]] {
-	return R.SequenceT4[
-		ReaderIO[A],
-		ReaderIO[B],
-		ReaderIO[C],
-		ReaderIO[D],
-		ReaderIO[T.Tuple4[A, B, C, D]],
-	](a, b, c, d)
-}

context/readerioeither/file/file_test.go

@@ -19,9 +19,7 @@ import (
 	"context"
 	"fmt"
 
-	RIO "github.com/IBM/fp-go/context/readerio"
 	R "github.com/IBM/fp-go/context/readerioeither"
-	"github.com/IBM/fp-go/errors"
 	F "github.com/IBM/fp-go/function"
 	IO "github.com/IBM/fp-go/io"
 	J "github.com/IBM/fp-go/json"
@@ -37,20 +35,17 @@ func getData(r RecordType) string {
 
 func ExampleReadFile() {
 
-	data := F.Pipe4(
+	data := F.Pipe3(
 		ReadFile("./data/file.json"),
 		R.ChainEitherK(J.Unmarshal[RecordType]),
 		R.ChainFirstIOK(IO.Logf[RecordType]("Log: %v")),
 		R.Map(getData),
-		R.GetOrElse(F.Flow2(
-			errors.ToString,
-			RIO.Of[string],
-		)),
 	)
 
 	result := data(context.Background())
 
 	fmt.Println(result())
 
-	// Output: Carsten
+	// Output:
+	// Right[<nil>, string](Carsten)
 }

context/readerioeither/gen.go

@@ -2,7 +2,7 @@ package readerioeither
 
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-09-12 13:44:14.1022311 +0200 CEST m=+0.017763401
+// 2023-10-23 08:30:39.012572 +0200 CEST m=+0.008846101
 
 import (
 	"context"

context/readerioeither/generic/gen.go

@@ -2,7 +2,7 @@ package generic
 
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-09-12 13:44:14.1036885 +0200 CEST m=+0.019220801
+// 2023-10-23 08:30:39.012572 +0200 CEST m=+0.008846101
 
 import (
 	"context"

context/readerioeither/reader.go

@@ -19,8 +19,6 @@ import (
 	"context"
 	"time"
 
-	R "github.com/IBM/fp-go/context/reader"
-	RIO "github.com/IBM/fp-go/context/readerio"
 	G "github.com/IBM/fp-go/context/readerioeither/generic"
 	ET "github.com/IBM/fp-go/either"
 	IO "github.com/IBM/fp-go/io"
@@ -33,14 +31,6 @@ func FromEither[A any](e ET.Either[error, A]) ReaderIOEither[A] {
 	return G.FromEither[ReaderIOEither[A]](e)
 }
 
-func RightReader[A any](r R.Reader[A]) ReaderIOEither[A] {
-	return G.RightReader[ReaderIOEither[A]](r)
-}
-
-func LeftReader[A any](l R.Reader[error]) ReaderIOEither[A] {
-	return G.LeftReader[ReaderIOEither[A]](l)
-}
-
 func Left[A any](l error) ReaderIOEither[A] {
 	return G.Left[ReaderIOEither[A]](l)
 }
@@ -49,10 +39,6 @@ func Right[A any](r A) ReaderIOEither[A] {
 	return G.Right[ReaderIOEither[A]](r)
 }
 
-func FromReader[A any](r R.Reader[A]) ReaderIOEither[A] {
-	return G.FromReader[ReaderIOEither[A]](r)
-}
-
 func MonadMap[A, B any](fa ReaderIOEither[A], f func(A) B) ReaderIOEither[B] {
 	return G.MonadMap[ReaderIOEither[A], ReaderIOEither[B]](fa, f)
 }
@@ -103,30 +89,14 @@ func FromPredicate[A any](pred func(A) bool, onFalse func(A) error) func(A) Read
 	return G.FromPredicate[ReaderIOEither[A]](pred, onFalse)
 }
 
-func Fold[A, B any](onLeft func(error) RIO.ReaderIO[B], onRight func(A) RIO.ReaderIO[B]) func(ReaderIOEither[A]) RIO.ReaderIO[B] {
-	return G.Fold[RIO.ReaderIO[B], ReaderIOEither[A]](onLeft, onRight)
-}
-
-func GetOrElse[A any](onLeft func(error) RIO.ReaderIO[A]) func(ReaderIOEither[A]) RIO.ReaderIO[A] {
-	return G.GetOrElse[RIO.ReaderIO[A], ReaderIOEither[A]](onLeft)
-}
-
 func OrElse[A any](onLeft func(error) ReaderIOEither[A]) func(ReaderIOEither[A]) ReaderIOEither[A] {
 	return G.OrElse[ReaderIOEither[A]](onLeft)
 }
 
-func OrLeft[A any](onLeft func(error) RIO.ReaderIO[error]) func(ReaderIOEither[A]) ReaderIOEither[A] {
-	return G.OrLeft[ReaderIOEither[A], RIO.ReaderIO[error]](onLeft)
-}
-
 func Ask() ReaderIOEither[context.Context] {
 	return G.Ask[ReaderIOEither[context.Context]]()
 }
 
-func Asks[A any](r R.Reader[A]) ReaderIOEither[A] {
-	return G.Asks[ReaderIOEither[A]](r)
-}
-
 func MonadChainEitherK[A, B any](ma ReaderIOEither[A], f func(A) ET.Either[error, B]) ReaderIOEither[B] {
 	return G.MonadChainEitherK[ReaderIOEither[A], ReaderIOEither[B]](ma, f)
 }
@@ -164,14 +134,6 @@ func Never[A any]() ReaderIOEither[A] {
 	return G.Never[ReaderIOEither[A]]()
 }
 
-func MonadChainReaderIOK[A, B any](ma ReaderIOEither[A], f func(A) RIO.ReaderIO[B]) ReaderIOEither[B] {
-	return G.MonadChainReaderIOK[ReaderIOEither[B], ReaderIOEither[A]](ma, f)
-}
-
-func ChainReaderIOK[A, B any](f func(A) RIO.ReaderIO[B]) func(ma ReaderIOEither[A]) ReaderIOEither[B] {
-	return G.ChainReaderIOK[ReaderIOEither[B], ReaderIOEither[A]](f)
-}
-
 func MonadChainIOK[A, B any](ma ReaderIOEither[A], f func(A) IO.IO[B]) ReaderIOEither[B] {
 	return G.MonadChainIOK[ReaderIOEither[B], ReaderIOEither[A]](ma, f)
 }
@@ -235,22 +197,6 @@ func Flatten[
 	return G.Flatten[ReaderIOEither[ReaderIOEither[A]]](rdr)
 }
 
-func MonadFromReaderIO[A any](a A, f func(A) RIO.ReaderIO[A]) ReaderIOEither[A] {
-	return G.MonadFromReaderIO[ReaderIOEither[A]](a, f)
-}
-
-func FromReaderIO[A any](f func(A) RIO.ReaderIO[A]) func(A) ReaderIOEither[A] {
-	return G.FromReaderIO[ReaderIOEither[A]](f)
-}
-
-func RightReaderIO[A any](ma RIO.ReaderIO[A]) ReaderIOEither[A] {
-	return G.RightReaderIO[ReaderIOEither[A]](ma)
-}
-
-func LeftReaderIO[A any](ma RIO.ReaderIO[error]) ReaderIOEither[A] {
-	return G.LeftReaderIO[ReaderIOEither[A]](ma)
-}
-
 func MonadFlap[B, A any](fab ReaderIOEither[func(A) B], a A) ReaderIOEither[B] {
 	return G.MonadFlap[ReaderIOEither[func(A) B], ReaderIOEither[B]](fab, a)
 }

di/erasure/injector.go

@@ -0,0 +1,168 @@
+// 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 erasure
+
+import (
+	A "github.com/IBM/fp-go/array"
+	"github.com/IBM/fp-go/errors"
+	F "github.com/IBM/fp-go/function"
+	I "github.com/IBM/fp-go/identity"
+	IG "github.com/IBM/fp-go/identity/generic"
+	IOE "github.com/IBM/fp-go/ioeither"
+	L "github.com/IBM/fp-go/lazy"
+	O "github.com/IBM/fp-go/option"
+	R "github.com/IBM/fp-go/record"
+	T "github.com/IBM/fp-go/tuple"
+
+	"sync"
+)
+
+func providerToEntry(p Provider) T.Tuple2[string, ProviderFactory] {
+	return T.MakeTuple2(p.Provides().Id(), p.Factory())
+}
+
+func itemProviderToMap(p Provider) map[string][]ProviderFactory {
+	return R.Singleton(p.Provides().Id(), A.Of(p.Factory()))
+}
+
+var (
+	// missingProviderError returns a [ProviderFactory] that fails due to a missing dependency
+	missingProviderError = F.Flow4(
+		Dependency.String,
+		errors.OnSome[string]("no provider for dependency [%s]"),
+		IOE.Left[any, error],
+		F.Constant1[InjectableFactory, IOE.IOEither[error, any]],
+	)
+
+	// missingProviderErrorOrDefault returns the default [ProviderFactory] or an error
+	missingProviderErrorOrDefault = F.Flow3(
+		T.Replicate2[Dependency],
+		T.Map2(Dependency.ProviderFactory, F.Flow2(missingProviderError, F.Constant[ProviderFactory])),
+		T.Tupled2(O.MonadGetOrElse[ProviderFactory]),
+	)
+
+	emptyMulti any = A.Empty[any]()
+
+	// emptyMultiDependency returns a [ProviderFactory] for an empty, multi dependency
+	emptyMultiDependency = F.Constant1[Dependency](F.Constant1[InjectableFactory](IOE.Of[error](emptyMulti)))
+
+	// handleMissingProvider covers the case of a missing provider. It either
+	// returns an error or an empty multi value provider
+	handleMissingProvider = F.Flow2(
+		F.Ternary(isMultiDependency, emptyMultiDependency, missingProviderErrorOrDefault),
+		F.Constant[ProviderFactory],
+	)
+
+	// mergeItemProviders is a monoid for item provider factories
+	mergeItemProviders = R.UnionMonoid[string](A.Semigroup[ProviderFactory]())
+
+	// mergeProviders is a monoid for provider factories
+	mergeProviders = R.UnionLastMonoid[string, ProviderFactory]()
+
+	// collectItemProviders create a provider map for item providers
+	collectItemProviders = F.Flow2(
+		A.FoldMap[Provider](mergeItemProviders)(itemProviderToMap),
+		R.Map[string](itemProviderFactory),
+	)
+
+	// collectProviders collects non-item providers
+	collectProviders = F.Flow2(
+		A.Map(providerToEntry),
+		R.FromEntries[string, ProviderFactory],
+	)
+
+	// assembleProviders constructs the provider map for item and non-item providers
+	assembleProviders = F.Flow3(
+		A.Partition(isItemProvider),
+		T.Map2(collectProviders, collectItemProviders),
+		T.Tupled2(mergeProviders.Concat),
+	)
+)
+
+// isMultiDependency tests if a dependency is a container dependency
+func isMultiDependency(dep Dependency) bool {
+	return dep.Flag()&Multi == Multi
+}
+
+// isItemProvider tests if a provivder provides a single item
+func isItemProvider(provider Provider) bool {
+	return provider.Provides().Flag()&Item == Item
+}
+
+// itemProviderFactory combines multiple factories into one, returning an array
+func itemProviderFactory(fcts []ProviderFactory) ProviderFactory {
+	return func(inj InjectableFactory) IOE.IOEither[error, any] {
+		return F.Pipe2(
+			fcts,
+			IOE.TraverseArray(I.Flap[IOE.IOEither[error, any]](inj)),
+			IOE.Map[error](F.ToAny[[]any]),
+		)
+	}
+}
+
+// MakeInjector creates an [InjectableFactory] based on a set of [Provider]s
+func MakeInjector(providers []Provider) InjectableFactory {
+
+	type Result = IOE.IOEither[error, any]
+	type LazyResult = L.Lazy[Result]
+
+	// resolved stores the values resolved so far, key is the string ID
+	// of the token, value is a lazy result
+	var resolved sync.Map
+
+	// provide a mapping for all providers
+	factoryById := assembleProviders(providers)
+
+	// the actual factory, we need lazy initialization
+	var injFct InjectableFactory
+
+	// lazy initialization, so we can cross reference it
+	injFct = func(token Dependency) Result {
+
+		key := token.Id()
+
+		// according to https://github.com/golang/go/issues/44159 this
+		// is the best way to use the sync map
+		actual, loaded := resolved.Load(key)
+		if !loaded {
+
+			computeResult := L.MakeLazy(func() Result {
+				return F.Pipe5(
+					token,
+					T.Replicate2[Dependency],
+					T.Map2(F.Flow3(
+						Dependency.Id,
+						R.Lookup[ProviderFactory, string],
+						I.Ap[O.Option[ProviderFactory]](factoryById),
+					), handleMissingProvider),
+					T.Tupled2(O.MonadGetOrElse[ProviderFactory]),
+					IG.Ap[ProviderFactory](injFct),
+					IOE.Memoize[error, any],
+				)
+			})
+
+			actual, _ = resolved.LoadOrStore(key, F.Pipe1(
+				computeResult,
+				L.Memoize[Result],
+			))
+		}
+
+		return actual.(LazyResult)()
+	}
+
+	return injFct
+}

di/erasure/provider.go

@@ -0,0 +1,174 @@
+// 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 erasure
+
+import (
+	"fmt"
+
+	A "github.com/IBM/fp-go/array"
+	E "github.com/IBM/fp-go/either"
+	F "github.com/IBM/fp-go/function"
+	I "github.com/IBM/fp-go/identity"
+	IO "github.com/IBM/fp-go/io"
+	IOG "github.com/IBM/fp-go/io/generic"
+	IOE "github.com/IBM/fp-go/ioeither"
+	IOO "github.com/IBM/fp-go/iooption"
+	Int "github.com/IBM/fp-go/number/integer"
+	O "github.com/IBM/fp-go/option"
+	R "github.com/IBM/fp-go/record"
+)
+
+type InjectableFactory = func(Dependency) IOE.IOEither[error, any]
+type ProviderFactory = func(InjectableFactory) IOE.IOEither[error, any]
+
+type paramIndex = map[int]int
+type paramValue = map[int]any
+type handler = func(paramIndex) func([]IOE.IOEither[error, any]) IOE.IOEither[error, paramValue]
+
+type Provider interface {
+	fmt.Stringer
+	// Provides returns the [Dependency] implemented by this provider
+	Provides() Dependency
+	// Factory returns s function that can create an instance of the dependency based on an [InjectableFactory]
+	Factory() ProviderFactory
+}
+
+type provider struct {
+	provides Dependency
+	factory  ProviderFactory
+}
+
+func (p *provider) Provides() Dependency {
+	return p.provides
+}
+
+func (p *provider) Factory() ProviderFactory {
+	return p.factory
+}
+
+func (p *provider) String() string {
+	return fmt.Sprintf("Provider for [%s]", p.provides)
+}
+
+func MakeProvider(token Dependency, fct ProviderFactory) Provider {
+	return &provider{token, fct}
+}
+
+func mapFromToken(idx int, token Dependency) map[int]paramIndex {
+	return R.Singleton(token.Flag()&BehaviourMask, R.Singleton(idx, idx))
+}
+
+var (
+	mergeTokenMaps = R.UnionMonoid[int](R.UnionLastSemigroup[int, int]())
+	foldDeps       = A.FoldMapWithIndex[Dependency](mergeTokenMaps)(mapFromToken)
+	mergeMaps      = R.UnionLastMonoid[int, any]()
+	collectParams  = R.CollectOrd[any, any](Int.Ord)(F.SK[int, any])
+
+	handlers = map[int]handler{
+		Identity: func(mp paramIndex) func([]IOE.IOEither[error, any]) IOE.IOEither[error, paramValue] {
+			return func(res []IOE.IOEither[error, any]) IOE.IOEither[error, paramValue] {
+				return F.Pipe1(
+					mp,
+					IOE.TraverseRecord[int](getAt(res)),
+				)
+			}
+		},
+		Option: func(mp paramIndex) func([]IOE.IOEither[error, any]) IOE.IOEither[error, paramValue] {
+			return func(res []IOE.IOEither[error, any]) IOE.IOEither[error, paramValue] {
+				return F.Pipe3(
+					mp,
+					IOG.TraverseRecord[IO.IO[map[int]E.Either[error, any]], paramIndex](getAt(res)),
+					IO.Map(R.Map[int](F.Flow2(
+						E.ToOption[error, any],
+						F.ToAny[O.Option[any]],
+					))),
+					IOE.FromIO[error, paramValue],
+				)
+			}
+		},
+		IOEither: func(mp paramIndex) func([]IOE.IOEither[error, any]) IOE.IOEither[error, paramValue] {
+			return func(res []IOE.IOEither[error, any]) IOE.IOEither[error, paramValue] {
+				return F.Pipe2(
+					mp,
+					R.Map[int](F.Flow2(
+						getAt(res),
+						F.ToAny[IOE.IOEither[error, any]],
+					)),
+					IOE.Of[error, paramValue],
+				)
+			}
+		},
+		IOOption: func(mp paramIndex) func([]IOE.IOEither[error, any]) IOE.IOEither[error, paramValue] {
+			return func(res []IOE.IOEither[error, any]) IOE.IOEither[error, paramValue] {
+				return F.Pipe2(
+					mp,
+					R.Map[int](F.Flow3(
+						getAt(res),
+						IOE.ToIOOption[error, any],
+						F.ToAny[IOO.IOOption[any]],
+					)),
+					IOE.Of[error, paramValue],
+				)
+			}
+		},
+	}
+)
+
+type Mapping = map[int]paramIndex
+
+func getAt[T any](ar []T) func(idx int) T {
+	return func(idx int) T {
+		return ar[idx]
+	}
+}
+
+func handleMapping(mp Mapping) func(res []IOE.IOEither[error, any]) IOE.IOEither[error, []any] {
+	preFct := F.Pipe1(
+		mp,
+		R.Collect(func(idx int, p paramIndex) func([]IOE.IOEither[error, any]) IOE.IOEither[error, paramValue] {
+			return handlers[idx](p)
+		}),
+	)
+	doFct := F.Flow2(
+		I.Flap[IOE.IOEither[error, paramValue], []IOE.IOEither[error, any]],
+		IOE.TraverseArray[error, func([]IOE.IOEither[error, any]) IOE.IOEither[error, paramValue], paramValue],
+	)
+	postFct := IOE.Map[error](F.Flow2(
+		A.Fold(mergeMaps),
+		collectParams,
+	))
+
+	return func(res []IOE.IOEither[error, any]) IOE.IOEither[error, []any] {
+		return F.Pipe2(
+			preFct,
+			doFct(res),
+			postFct,
+		)
+	}
+}
+
+// MakeProviderFactory constructs a [ProviderFactory] based on a set of [Dependency]s and
+// a function that accepts the resolved dependencies to return a result
+func MakeProviderFactory(
+	deps []Dependency,
+	fct func(param ...any) IOE.IOEither[error, any]) ProviderFactory {
+
+	return F.Flow3(
+		F.Curry2(A.MonadMap[Dependency, IOE.IOEither[error, any]])(deps),
+		handleMapping(foldDeps(deps)),
+		IOE.Chain(F.Unvariadic0(fct)),
+	)
+}

di/erasure/token.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 erasure
+
+import (
+	"fmt"
+
+	O "github.com/IBM/fp-go/option"
+)
+
+const (
+	BehaviourMask = 0x0f
+	Identity      = 0 // required dependency
+	Option        = 1 // optional dependency
+	IOEither      = 2 // lazy and required
+	IOOption      = 3 // lazy and optional
+
+	TypeMask = 0xf0
+	Multi    = 1 << 4 // array of implementations
+	Item     = 2 << 4 // item of a multi token
+)
+
+// Dependency describes the relationship to a service
+type Dependency interface {
+	fmt.Stringer
+	// Id returns a unique identifier for a token that can be used as a cache key
+	Id() string
+	// Flag returns a tag that identifies the behaviour of the dependency
+	Flag() int
+	// ProviderFactory optionally returns an attached [ProviderFactory] that represents the default for this dependency
+	ProviderFactory() O.Option[ProviderFactory]
+}

di/injector.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 di
+
+import (
+	DIE "github.com/IBM/fp-go/di/erasure"
+	F "github.com/IBM/fp-go/function"
+	IG "github.com/IBM/fp-go/identity/generic"
+	IOE "github.com/IBM/fp-go/ioeither"
+	RIOE "github.com/IBM/fp-go/readerioeither"
+)
+
+// Resolve performs a type safe resolution of a dependency
+func Resolve[T any](token InjectionToken[T]) RIOE.ReaderIOEither[DIE.InjectableFactory, error, T] {
+	return F.Flow2(
+		IG.Ap[DIE.InjectableFactory](asDependency(token)),
+		IOE.ChainEitherK(token.Unerase),
+	)
+}

di/provider.go

@@ -0,0 +1,166 @@
+// 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 di
+
+import (
+	A "github.com/IBM/fp-go/array"
+	DIE "github.com/IBM/fp-go/di/erasure"
+	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"
+	T "github.com/IBM/fp-go/tuple"
+)
+
+func lookupAt[T any](idx int, token Dependency[T]) func(params []any) E.Either[error, T] {
+	return F.Flow3(
+		A.Lookup[any](idx),
+		E.FromOption[any](errors.OnNone("No parameter at position %d", idx)),
+		E.Chain(token.Unerase),
+	)
+}
+
+func eraseProviderFactory0[R any](f func() IOE.IOEither[error, R]) func(params ...any) IOE.IOEither[error, any] {
+	return func(params ...any) IOE.IOEither[error, any] {
+		return F.Pipe1(
+			f(),
+			IOE.Map[error](F.ToAny[R]),
+		)
+	}
+}
+
+func eraseProviderFactory1[T1 any, R any](
+	d1 Dependency[T1],
+	f func(T1) IOE.IOEither[error, R]) func(params ...any) IOE.IOEither[error, any] {
+	ft := T.Tupled1(f)
+	t1 := lookupAt[T1](0, d1)
+	return func(params ...any) IOE.IOEither[error, any] {
+		return F.Pipe3(
+			E.SequenceT1(t1(params)),
+			IOE.FromEither[error, T.Tuple1[T1]],
+			IOE.Chain(ft),
+			IOE.Map[error](F.ToAny[R]),
+		)
+	}
+}
+
+func eraseProviderFactory2[T1, T2 any, R any](
+	d1 Dependency[T1],
+	d2 Dependency[T2],
+	f func(T1, T2) IOE.IOEither[error, R]) func(params ...any) IOE.IOEither[error, any] {
+	ft := T.Tupled2(f)
+	t1 := lookupAt[T1](0, d1)
+	t2 := lookupAt[T2](1, d2)
+	return func(params ...any) IOE.IOEither[error, any] {
+		return F.Pipe3(
+			E.SequenceT2(t1(params), t2(params)),
+			IOE.FromEither[error, T.Tuple2[T1, T2]],
+			IOE.Chain(ft),
+			IOE.Map[error](F.ToAny[R]),
+		)
+	}
+}
+
+func MakeProviderFactory0[R any](
+	fct func() IOE.IOEither[error, R],
+) DIE.ProviderFactory {
+	return DIE.MakeProviderFactory(
+		A.Empty[DIE.Dependency](),
+		eraseProviderFactory0(fct),
+	)
+}
+
+// MakeTokenWithDefault0 create a unique `InjectionToken` for a specific type with an attached default provider
+func MakeTokenWithDefault0[R any](name string, fct func() IOE.IOEither[error, R]) InjectionToken[R] {
+	return MakeTokenWithDefault[R](name, MakeProviderFactory0(fct))
+}
+
+func MakeProvider0[R any](
+	token InjectionToken[R],
+	fct func() IOE.IOEither[error, R],
+) DIE.Provider {
+	return DIE.MakeProvider(
+		token,
+		MakeProviderFactory0(fct),
+	)
+}
+
+func MakeProviderFactory1[T1, R any](
+	d1 Dependency[T1],
+	fct func(T1) IOE.IOEither[error, R],
+) DIE.ProviderFactory {
+
+	return DIE.MakeProviderFactory(
+		A.From[DIE.Dependency](d1),
+		eraseProviderFactory1(d1, fct),
+	)
+}
+
+// MakeTokenWithDefault1 create a unique `InjectionToken` for a specific type with an attached default provider
+func MakeTokenWithDefault1[T1, R any](name string,
+	d1 Dependency[T1],
+	fct func(T1) IOE.IOEither[error, R]) InjectionToken[R] {
+	return MakeTokenWithDefault[R](name, MakeProviderFactory1(d1, fct))
+}
+
+func MakeProvider1[T1, R any](
+	token InjectionToken[R],
+	d1 Dependency[T1],
+	fct func(T1) IOE.IOEither[error, R],
+) DIE.Provider {
+
+	return DIE.MakeProvider(
+		token,
+		MakeProviderFactory1(d1, fct),
+	)
+}
+
+func MakeProviderFactory2[T1, T2, R any](
+	d1 Dependency[T1],
+	d2 Dependency[T2],
+	fct func(T1, T2) IOE.IOEither[error, R],
+) DIE.ProviderFactory {
+
+	return DIE.MakeProviderFactory(
+		A.From[DIE.Dependency](d1, d2),
+		eraseProviderFactory2(d1, d2, fct),
+	)
+}
+
+// MakeTokenWithDefault2 create a unique `InjectionToken` for a specific type with an attached default provider
+func MakeTokenWithDefault2[T1, T2, R any](name string,
+	d1 Dependency[T1],
+	d2 Dependency[T2],
+	fct func(T1, T2) IOE.IOEither[error, R]) InjectionToken[R] {
+	return MakeTokenWithDefault[R](name, MakeProviderFactory2(d1, d2, fct))
+}
+
+func MakeProvider2[T1, T2, R any](
+	token InjectionToken[R],
+	d1 Dependency[T1],
+	d2 Dependency[T2],
+	fct func(T1, T2) IOE.IOEither[error, R],
+) DIE.Provider {
+
+	return DIE.MakeProvider(
+		token,
+		MakeProviderFactory2(d1, d2, fct),
+	)
+}
+
+// ConstProvider simple implementation for a provider with a constant value
+func ConstProvider[R any](token InjectionToken[R], value R) DIE.Provider {
+	return MakeProvider0[R](token, F.Constant(IOE.Of[error](value)))
+}

di/provider_test.go

@@ -0,0 +1,351 @@
+// 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 di
+
+import (
+	"fmt"
+	"testing"
+	"time"
+
+	A "github.com/IBM/fp-go/array"
+	DIE "github.com/IBM/fp-go/di/erasure"
+	E "github.com/IBM/fp-go/either"
+	F "github.com/IBM/fp-go/function"
+	IOE "github.com/IBM/fp-go/ioeither"
+	O "github.com/IBM/fp-go/option"
+	"github.com/stretchr/testify/assert"
+)
+
+var (
+	INJ_KEY2 = MakeToken[string]("INJ_KEY2")
+	INJ_KEY1 = MakeToken[string]("INJ_KEY1")
+	INJ_KEY3 = MakeToken[string]("INJ_KEY3")
+)
+
+func TestSimpleProvider(t *testing.T) {
+
+	var staticCount int
+
+	staticValue := func(value string) func() IOE.IOEither[error, string] {
+		return func() IOE.IOEither[error, string] {
+			return func() E.Either[error, string] {
+				staticCount++
+				return E.Of[error](fmt.Sprintf("Static based on [%s], at [%s]", value, time.Now()))
+			}
+		}
+	}
+
+	var dynamicCount int
+
+	dynamicValue := func(value string) IOE.IOEither[error, string] {
+		return func() E.Either[error, string] {
+			dynamicCount++
+			return E.Of[error](fmt.Sprintf("Dynamic based on [%s] at [%s]", value, time.Now()))
+		}
+	}
+
+	p1 := MakeProvider0(INJ_KEY1, staticValue("Carsten"))
+	p2 := MakeProvider1(INJ_KEY2, INJ_KEY1.Identity(), dynamicValue)
+
+	inj := DIE.MakeInjector(A.From(p1, p2))
+
+	i1 := Resolve(INJ_KEY1)
+	i2 := Resolve(INJ_KEY2)
+
+	res := IOE.SequenceT4(
+		i2(inj),
+		i1(inj),
+		i2(inj),
+		i1(inj),
+	)
+
+	r := res()
+
+	assert.True(t, E.IsRight(r))
+	assert.Equal(t, 1, staticCount)
+	assert.Equal(t, 1, dynamicCount)
+}
+
+func TestOptionalProvider(t *testing.T) {
+
+	var staticCount int
+
+	staticValue := func(value string) func() IOE.IOEither[error, string] {
+		return func() IOE.IOEither[error, string] {
+			return func() E.Either[error, string] {
+				staticCount++
+				return E.Of[error](fmt.Sprintf("Static based on [%s], at [%s]", value, time.Now()))
+			}
+		}
+	}
+
+	var dynamicCount int
+
+	dynamicValue := func(value O.Option[string]) IOE.IOEither[error, string] {
+		return func() E.Either[error, string] {
+			dynamicCount++
+			return E.Of[error](fmt.Sprintf("Dynamic based on [%s] at [%s]", value, time.Now()))
+		}
+	}
+
+	p1 := MakeProvider0(INJ_KEY1, staticValue("Carsten"))
+	p2 := MakeProvider1(INJ_KEY2, INJ_KEY1.Option(), dynamicValue)
+
+	inj := DIE.MakeInjector(A.From(p1, p2))
+
+	i1 := Resolve(INJ_KEY1)
+	i2 := Resolve(INJ_KEY2)
+
+	res := IOE.SequenceT4(
+		i2(inj),
+		i1(inj),
+		i2(inj),
+		i1(inj),
+	)
+
+	r := res()
+
+	assert.True(t, E.IsRight(r))
+	assert.Equal(t, 1, staticCount)
+	assert.Equal(t, 1, dynamicCount)
+}
+
+func TestOptionalProviderMissingDependency(t *testing.T) {
+
+	var dynamicCount int
+
+	dynamicValue := func(value O.Option[string]) IOE.IOEither[error, string] {
+		return func() E.Either[error, string] {
+			dynamicCount++
+			return E.Of[error](fmt.Sprintf("Dynamic based on [%s] at [%s]", value, time.Now()))
+		}
+	}
+
+	p2 := MakeProvider1(INJ_KEY2, INJ_KEY1.Option(), dynamicValue)
+
+	inj := DIE.MakeInjector(A.From(p2))
+
+	i2 := Resolve(INJ_KEY2)
+
+	res := IOE.SequenceT2(
+		i2(inj),
+		i2(inj),
+	)
+
+	r := res()
+
+	assert.True(t, E.IsRight(r))
+	assert.Equal(t, 1, dynamicCount)
+}
+
+func TestProviderMissingDependency(t *testing.T) {
+
+	var dynamicCount int
+
+	dynamicValue := func(value string) IOE.IOEither[error, string] {
+		return func() E.Either[error, string] {
+			dynamicCount++
+			return E.Of[error](fmt.Sprintf("Dynamic based on [%s] at [%s]", value, time.Now()))
+		}
+	}
+
+	p2 := MakeProvider1(INJ_KEY2, INJ_KEY1.Identity(), dynamicValue)
+
+	inj := DIE.MakeInjector(A.From(p2))
+
+	i2 := Resolve(INJ_KEY2)
+
+	res := IOE.SequenceT2(
+		i2(inj),
+		i2(inj),
+	)
+
+	r := res()
+
+	assert.True(t, E.IsLeft(r))
+	assert.Equal(t, 0, dynamicCount)
+}
+
+func TestEagerAndLazyProvider(t *testing.T) {
+
+	var staticCount int
+
+	staticValue := func(value string) func() IOE.IOEither[error, string] {
+		return func() IOE.IOEither[error, string] {
+			return func() E.Either[error, string] {
+				staticCount++
+				return E.Of[error](fmt.Sprintf("Static based on [%s], at [%s]", value, time.Now()))
+			}
+		}
+	}
+
+	var dynamicCount int
+
+	dynamicValue := func(value string) IOE.IOEither[error, string] {
+		return func() E.Either[error, string] {
+			dynamicCount++
+			return E.Of[error](fmt.Sprintf("Dynamic based on [%s] at [%s]", value, time.Now()))
+		}
+	}
+
+	var lazyEagerCount int
+
+	lazyEager := func(laz IOE.IOEither[error, string], eager string) IOE.IOEither[error, string] {
+		return F.Pipe1(
+			laz,
+			IOE.Chain(func(lazValue string) IOE.IOEither[error, string] {
+				return func() E.Either[error, string] {
+					lazyEagerCount++
+					return E.Of[error](fmt.Sprintf("Dynamic based on [%s], [%s] at [%s]", lazValue, eager, time.Now()))
+				}
+			}),
+		)
+	}
+
+	p1 := MakeProvider0(INJ_KEY1, staticValue("Carsten"))
+	p2 := MakeProvider1(INJ_KEY2, INJ_KEY1.Identity(), dynamicValue)
+	p3 := MakeProvider2(INJ_KEY3, INJ_KEY2.IOEither(), INJ_KEY1.Identity(), lazyEager)
+
+	inj := DIE.MakeInjector(A.From(p1, p2, p3))
+
+	i3 := Resolve(INJ_KEY3)
+
+	r := i3(inj)()
+
+	fmt.Println(r)
+
+	assert.True(t, E.IsRight(r))
+	assert.Equal(t, 1, staticCount)
+	assert.Equal(t, 1, dynamicCount)
+	assert.Equal(t, 1, lazyEagerCount)
+}
+
+func TestItemProvider(t *testing.T) {
+	// define a multi token
+	injMulti := MakeMultiToken[string]("configs")
+
+	// provide some values
+	v1 := ConstProvider(injMulti.Item(), "Value1")
+	v2 := ConstProvider(injMulti.Item(), "Value2")
+	// mix in non-multi values
+	p1 := ConstProvider(INJ_KEY1, "Value3")
+	p2 := ConstProvider(INJ_KEY2, "Value4")
+
+	// populate the injector
+	inj := DIE.MakeInjector(A.From(p1, v1, p2, v2))
+
+	// access the multi value
+	multi := Resolve(injMulti.Container())
+
+	multiInj := multi(inj)
+
+	value := multiInj()
+
+	assert.Equal(t, E.Of[error](A.From("Value1", "Value2")), value)
+}
+
+func TestEmptyItemProvider(t *testing.T) {
+	// define a multi token
+	injMulti := MakeMultiToken[string]("configs")
+
+	// mix in non-multi values
+	p1 := ConstProvider(INJ_KEY1, "Value3")
+	p2 := ConstProvider(INJ_KEY2, "Value4")
+
+	// populate the injector
+	inj := DIE.MakeInjector(A.From(p1, p2))
+
+	// access the multi value
+	multi := Resolve(injMulti.Container())
+
+	multiInj := multi(inj)
+
+	value := multiInj()
+
+	assert.Equal(t, E.Of[error](A.Empty[string]()), value)
+}
+
+func TestDependencyOnMultiProvider(t *testing.T) {
+	// define a multi token
+	injMulti := MakeMultiToken[string]("configs")
+
+	// provide some values
+	v1 := ConstProvider(injMulti.Item(), "Value1")
+	v2 := ConstProvider(injMulti.Item(), "Value2")
+	// mix in non-multi values
+	p1 := ConstProvider(INJ_KEY1, "Value3")
+	p2 := ConstProvider(INJ_KEY2, "Value4")
+
+	fromMulti := func(val string, multi []string) IOE.IOEither[error, string] {
+		return IOE.Of[error](fmt.Sprintf("Val: %s, Multi: %s", val, multi))
+	}
+	p3 := MakeProvider2(INJ_KEY3, INJ_KEY1.Identity(), injMulti.Container().Identity(), fromMulti)
+
+	// populate the injector
+	inj := DIE.MakeInjector(A.From(p1, p2, v1, v2, p3))
+
+	r3 := Resolve(INJ_KEY3)
+
+	v := r3(inj)()
+
+	assert.Equal(t, E.Of[error]("Val: Value3, Multi: [Value1 Value2]"), v)
+}
+
+func TestTokenWithDefaultProvider(t *testing.T) {
+	// token without a default
+	injToken1 := MakeToken[string]("Token1")
+	// token with a default
+	injToken2 := MakeTokenWithDefault0("Token2", F.Constant(IOE.Of[error]("Carsten")))
+	// dependency
+	injToken3 := MakeToken[string]("Token3")
+
+	p3 := MakeProvider1(injToken3, injToken2.Identity(), func(data string) IOE.IOEither[error, string] {
+		return IOE.Of[error](fmt.Sprintf("Token: %s", data))
+	})
+
+	// populate the injector
+	inj := DIE.MakeInjector(A.From(p3))
+
+	// resolving injToken3 should work and use the default provider for injToken2
+	r1 := Resolve(injToken1)
+	r3 := Resolve(injToken3)
+
+	// inj1 should not be available
+	assert.True(t, E.IsLeft(r1(inj)()))
+	// r3 should work
+	assert.Equal(t, E.Of[error]("Token: Carsten"), r3(inj)())
+}
+
+func TestTokenWithDefaultProviderAndOverride(t *testing.T) {
+	// token with a default
+	injToken2 := MakeTokenWithDefault0("Token2", F.Constant(IOE.Of[error]("Carsten")))
+	// dependency
+	injToken3 := MakeToken[string]("Token3")
+
+	p2 := ConstProvider(injToken2, "Override")
+
+	p3 := MakeProvider1(injToken3, injToken2.Identity(), func(data string) IOE.IOEither[error, string] {
+		return IOE.Of[error](fmt.Sprintf("Token: %s", data))
+	})
+
+	// populate the injector
+	inj := DIE.MakeInjector(A.From(p2, p3))
+
+	// resolving injToken3 should work and use the default provider for injToken2
+	r3 := Resolve(injToken3)
+
+	// r3 should work
+	assert.Equal(t, E.Of[error]("Token: Override"), r3(inj)())
+}

di/token.go

@@ -0,0 +1,196 @@
+// 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 di
+
+import (
+	"fmt"
+	"strconv"
+	"sync/atomic"
+
+	DIE "github.com/IBM/fp-go/di/erasure"
+	E "github.com/IBM/fp-go/either"
+	IO "github.com/IBM/fp-go/io"
+	IOE "github.com/IBM/fp-go/ioeither"
+	IOO "github.com/IBM/fp-go/iooption"
+	O "github.com/IBM/fp-go/option"
+)
+
+// Dependency describes the relationship to a service, that has a type and
+// a behaviour such as required, option or lazy
+type Dependency[T any] interface {
+	DIE.Dependency
+	// Unerase converts a value with erased type signature into a strongly typed value
+	Unerase(val any) E.Either[error, T]
+}
+
+// InjectionToken uniquely identifies a dependency by giving it an Id, Type and name
+type InjectionToken[T any] interface {
+	Dependency[T]
+	// Identity idenifies this dependency as a mandatory, required dependency, it will be resolved eagerly and injected as `T`.
+	// If the dependency cannot be resolved, the resolution process fails
+	Identity() Dependency[T]
+	// Option identifies this dependency as optional, it will be resolved eagerly and injected as `O.Option[T]`.
+	// If the dependency cannot be resolved, the resolution process continues and the dependency is represented as `O.None[T]`
+	Option() Dependency[O.Option[T]]
+	// IOEither identifies this dependency as mandatory but it will be resolved lazily as a `IOE.IOEither[error, T]`. This
+	// value is memoized to make sure the dependency is a singleton.
+	// If the dependency cannot be resolved, the resolution process fails
+	IOEither() Dependency[IOE.IOEither[error, T]]
+	// IOOption identifies this dependency as optional but it will be resolved lazily as a `IOO.IOOption[T]`. This
+	// value is memoized to make sure the dependency is a singleton.
+	// If the dependency cannot be resolved, the resolution process continues and the dependency is represented as the none value.
+	IOOption() Dependency[IOO.IOOption[T]]
+}
+
+// MultiInjectionToken uniquely identifies a dependency by giving it an Id, Type and name.
+type MultiInjectionToken[T any] interface {
+	// Container returns the injection token used to request an array of all provided items
+	Container() InjectionToken[[]T]
+	// Item returns the injection token used to provide an item
+	Item() InjectionToken[T]
+}
+
+// makeID creates a generator of unique string IDs
+func makeId() IO.IO[string] {
+	var count atomic.Int64
+	return IO.MakeIO(func() string {
+		return strconv.FormatInt(count.Add(1), 16)
+	})
+}
+
+// genId is the common generator of unique string IDs
+var genId = makeId()
+
+type token[T any] struct {
+	name            string
+	id              string
+	flag            int
+	toType          func(val any) E.Either[error, T]
+	providerFactory O.Option[DIE.ProviderFactory]
+}
+
+func (t *token[T]) Id() string {
+	return t.id
+}
+
+func (t *token[T]) Flag() int {
+	return t.flag
+}
+
+func (t *token[T]) String() string {
+	return t.name
+}
+
+func (t *token[T]) Unerase(val any) E.Either[error, T] {
+	return t.toType(val)
+}
+
+func (t *token[T]) ProviderFactory() O.Option[DIE.ProviderFactory] {
+	return t.providerFactory
+}
+
+func makeToken[T any](name string, id string, typ int, unerase func(val any) E.Either[error, T], providerFactory O.Option[DIE.ProviderFactory]) Dependency[T] {
+	return &token[T]{name, id, typ, unerase, providerFactory}
+}
+
+type injectionToken[T any] struct {
+	token[T]
+	option   Dependency[O.Option[T]]
+	ioeither Dependency[IOE.IOEither[error, T]]
+	iooption Dependency[IOO.IOOption[T]]
+}
+
+type multiInjectionToken[T any] struct {
+	container *injectionToken[[]T]
+	item      *injectionToken[T]
+}
+
+func (i *injectionToken[T]) Identity() Dependency[T] {
+	return i
+}
+
+func (i *injectionToken[T]) Option() Dependency[O.Option[T]] {
+	return i.option
+}
+
+func (i *injectionToken[T]) IOEither() Dependency[IOE.IOEither[error, T]] {
+	return i.ioeither
+}
+
+func (i *injectionToken[T]) IOOption() Dependency[IOO.IOOption[T]] {
+	return i.iooption
+}
+
+func (i *injectionToken[T]) ProviderFactory() O.Option[DIE.ProviderFactory] {
+	return i.providerFactory
+}
+
+func (m *multiInjectionToken[T]) Container() InjectionToken[[]T] {
+	return m.container
+}
+
+func (m *multiInjectionToken[T]) Item() InjectionToken[T] {
+	return m.item
+}
+
+// makeToken create a unique `InjectionToken` for a specific type
+func makeInjectionToken[T any](name string, providerFactory O.Option[DIE.ProviderFactory]) InjectionToken[T] {
+	id := genId()
+	toIdentity := toType[T]()
+	return &injectionToken[T]{
+		token[T]{name, id, DIE.Identity, toIdentity, providerFactory},
+		makeToken[O.Option[T]](fmt.Sprintf("Option[%s]", name), id, DIE.Option, toOptionType(toIdentity), providerFactory),
+		makeToken[IOE.IOEither[error, T]](fmt.Sprintf("IOEither[%s]", name), id, DIE.IOEither, toIOEitherType(toIdentity), providerFactory),
+		makeToken[IOO.IOOption[T]](fmt.Sprintf("IOOption[%s]", name), id, DIE.IOOption, toIOOptionType(toIdentity), providerFactory),
+	}
+}
+
+// MakeToken create a unique `InjectionToken` for a specific type
+func MakeToken[T any](name string) InjectionToken[T] {
+	return makeInjectionToken[T](name, O.None[DIE.ProviderFactory]())
+}
+
+// MakeToken create a unique `InjectionToken` for a specific type
+func MakeTokenWithDefault[T any](name string, providerFactory DIE.ProviderFactory) InjectionToken[T] {
+	return makeInjectionToken[T](name, O.Of(providerFactory))
+}
+
+// MakeMultiToken creates a [MultiInjectionToken]
+func MakeMultiToken[T any](name string) MultiInjectionToken[T] {
+	id := genId()
+	toItem := toType[T]()
+	toContainer := toArrayType(toItem)
+	containerName := fmt.Sprintf("Container[%s]", name)
+	itemName := fmt.Sprintf("Item[%s]", name)
+	// empty factory
+	providerFactory := O.None[DIE.ProviderFactory]()
+	// container
+	container := &injectionToken[[]T]{
+		token[[]T]{containerName, id, DIE.Multi | DIE.Identity, toContainer, providerFactory},
+		makeToken[O.Option[[]T]](fmt.Sprintf("Option[%s]", containerName), id, DIE.Multi|DIE.Option, toOptionType(toContainer), providerFactory),
+		makeToken[IOE.IOEither[error, []T]](fmt.Sprintf("IOEither[%s]", containerName), id, DIE.Multi|DIE.IOEither, toIOEitherType(toContainer), providerFactory),
+		makeToken[IOO.IOOption[[]T]](fmt.Sprintf("IOOption[%s]", containerName), id, DIE.Multi|DIE.IOOption, toIOOptionType(toContainer), providerFactory),
+	}
+	// item
+	item := &injectionToken[T]{
+		token[T]{itemName, id, DIE.Item | DIE.Identity, toItem, providerFactory},
+		makeToken[O.Option[T]](fmt.Sprintf("Option[%s]", itemName), id, DIE.Item|DIE.Option, toOptionType(toItem), providerFactory),
+		makeToken[IOE.IOEither[error, T]](fmt.Sprintf("IOEither[%s]", itemName), id, DIE.Item|DIE.IOEither, toIOEitherType(toItem), providerFactory),
+		makeToken[IOO.IOOption[T]](fmt.Sprintf("IOOption[%s]", itemName), id, DIE.Item|DIE.IOOption, toIOOptionType(toItem), providerFactory),
+	}
+	// returns the token
+	return &multiInjectionToken[T]{container, item}
+}

di/utils.go

@@ -0,0 +1,76 @@
+// 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 di
+
+import (
+	DIE "github.com/IBM/fp-go/di/erasure"
+	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"
+	IOO "github.com/IBM/fp-go/iooption"
+	O "github.com/IBM/fp-go/option"
+)
+
+// asDependency converts a generic type to a [DIE.Dependency]
+func asDependency[T DIE.Dependency](t T) DIE.Dependency {
+	return t
+}
+
+// toType converts an any to a T
+func toType[T any]() func(t any) E.Either[error, T] {
+	return E.ToType[T](errors.OnSome[any]("Value of type [%T] cannot be converted."))
+}
+
+// toOptionType converts an any to an Option[any] and then to an Option[T]
+func toOptionType[T any](item func(any) E.Either[error, T]) func(t any) E.Either[error, O.Option[T]] {
+	return F.Flow2(
+		toType[O.Option[any]](),
+		E.Chain(O.Fold(
+			F.Nullary2(O.None[T], E.Of[error, O.Option[T]]),
+			F.Flow2(
+				item,
+				E.Map[error](O.Of[T]),
+			),
+		)),
+	)
+}
+
+// toIOEitherType converts an any to an IOEither[error, any] and then to an IOEither[error, T]
+func toIOEitherType[T any](item func(any) E.Either[error, T]) func(t any) E.Either[error, IOE.IOEither[error, T]] {
+	return F.Flow2(
+		toType[IOE.IOEither[error, any]](),
+		E.Map[error](IOE.ChainEitherK(item)),
+	)
+}
+
+// toIOOptionType converts an any to an IOOption[any] and then to an IOOption[T]
+func toIOOptionType[T any](item func(any) E.Either[error, T]) func(t any) E.Either[error, IOO.IOOption[T]] {
+	return F.Flow2(
+		toType[IOO.IOOption[any]](),
+		E.Map[error](IOO.ChainOptionK(F.Flow2(
+			item,
+			E.ToOption[error, T],
+		))),
+	)
+}
+
+// toArrayType converts an any to a []T
+func toArrayType[T any](item func(any) E.Either[error, T]) func(t any) E.Either[error, []T] {
+	return F.Flow2(
+		toType[[]any](),
+		E.Chain(E.TraverseArray(item)),
+	)
+}

di/utils_test.go

@@ -0,0 +1,83 @@
+// 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 di
+
+import (
+	"testing"
+
+	A "github.com/IBM/fp-go/array"
+	E "github.com/IBM/fp-go/either"
+	F "github.com/IBM/fp-go/function"
+	IOE "github.com/IBM/fp-go/ioeither"
+	O "github.com/IBM/fp-go/option"
+	"github.com/stretchr/testify/assert"
+)
+
+var (
+	toInt    = toType[int]()
+	toString = toType[string]()
+)
+
+func TestToType(t *testing.T) {
+	// good cases
+	assert.Equal(t, E.Of[error](10), toInt(any(10)))
+	assert.Equal(t, E.Of[error]("Carsten"), toString(any("Carsten")))
+	assert.Equal(t, E.Of[error](O.Of("Carsten")), toType[O.Option[string]]()(any(O.Of("Carsten"))))
+	assert.Equal(t, E.Of[error](O.Of(any("Carsten"))), toType[O.Option[any]]()(any(O.Of(any("Carsten")))))
+	// failure
+	assert.False(t, E.IsRight(toInt(any("Carsten"))))
+	assert.False(t, E.IsRight(toType[O.Option[string]]()(O.Of(any("Carsten")))))
+}
+
+func TestToOptionType(t *testing.T) {
+	// shortcuts
+	toOptInt := toOptionType(toInt)
+	toOptString := toOptionType(toString)
+	// good cases
+	assert.Equal(t, E.Of[error](O.Of(10)), toOptInt(any(O.Of(any(10)))))
+	assert.Equal(t, E.Of[error](O.Of("Carsten")), toOptString(any(O.Of(any("Carsten")))))
+	// bad cases
+	assert.False(t, E.IsRight(toOptInt(any(10))))
+	assert.False(t, E.IsRight(toOptInt(any(O.Of(10)))))
+}
+
+func invokeIOEither[T any](e E.Either[error, IOE.IOEither[error, T]]) E.Either[error, T] {
+	return F.Pipe1(
+		e,
+		E.Chain(func(ioe IOE.IOEither[error, T]) E.Either[error, T] {
+			return ioe()
+		}),
+	)
+}
+
+func TestToIOEitherType(t *testing.T) {
+	// shortcuts
+	toIOEitherInt := toIOEitherType(toInt)
+	toIOEitherString := toIOEitherType(toString)
+	// good cases
+	assert.Equal(t, E.Of[error](10), invokeIOEither(toIOEitherInt(any(IOE.Of[error](any(10))))))
+	assert.Equal(t, E.Of[error]("Carsten"), invokeIOEither(toIOEitherString(any(IOE.Of[error](any("Carsten"))))))
+	// bad cases
+	assert.False(t, E.IsRight(invokeIOEither(toIOEitherString(any(IOE.Of[error](any(10)))))))
+	assert.False(t, E.IsRight(invokeIOEither(toIOEitherString(any(IOE.Of[error]("Carsten"))))))
+	assert.False(t, E.IsRight(invokeIOEither(toIOEitherString(any("Carsten")))))
+}
+
+func TestToArrayType(t *testing.T) {
+	// shortcuts
+	toArrayString := toArrayType(toString)
+	// good cases
+	assert.Equal(t, E.Of[error](A.From("a", "b")), toArrayString(any(A.From(any("a"), any("b")))))
+}

either/core.go

@@ -46,12 +46,12 @@ func (s Either[E, A]) Format(f fmt.State, c rune) {
 	}
 }
 
-// IsLeft tests if the either is a left value. Rather use [Fold] if you need to access the values. Inverse is [IsRight].
+// IsLeft tests if the [Either] is a left value. Rather use [Fold] if you need to access the values. Inverse is [IsRight].
 func IsLeft[E, A any](val Either[E, A]) bool {
 	return val.isLeft
 }
 
-// IsLeft tests if the either is a right value. Rather use [Fold] if you need to access the values. Inverse is [IsLeft].
+// IsLeft tests if the [Either] is a right value. Rather use [Fold] if you need to access the values. Inverse is [IsLeft].
 func IsRight[E, A any](val Either[E, A]) bool {
 	return !val.isLeft
 }

either/either.go

@@ -120,16 +120,15 @@ func Flatten[E, A any](mma Either[E, Either[E, A]]) Either[E, A] {
 	return MonadChain(mma, F.Identity[Either[E, A]])
 }
 
-func TryCatch[FA ~func() (A, error), FE func(error) E, E, A any](f FA, onThrow FE) Either[E, A] {
+func TryCatch[FE func(error) E, E, A any](val A, err error, onThrow FE) Either[E, A] {
-	val, err := f()
 	if err != nil {
 		return F.Pipe2(err, onThrow, Left[A, E])
 	}
 	return F.Pipe1(val, Right[E, A])
 }
 
-func TryCatchError[F ~func() (A, error), A any](f F) Either[error, A] {
+func TryCatchError[A any](val A, err error) Either[error, A] {
-	return TryCatch(f, E.IdentityError)
+	return TryCatch(val, err, E.IdentityError)
 }
 
 func Sequence2[E, T1, T2, R any](f func(T1, T2) Either[E, R]) func(Either[E, T1], Either[E, T2]) Either[E, R] {
@@ -154,9 +153,7 @@ func ToOption[E, A any](ma Either[E, A]) O.Option[A] {
 
 func FromError[A any](f func(a A) error) func(A) Either[error, A] {
 	return func(a A) Either[error, A] {
-		return TryCatchError(func() (A, error) {
+		return TryCatchError(a, f(a))
-			return a, f(a)
-		})
 	}
 }
 

either/exec/exec.go

@@ -32,7 +32,5 @@ var (
 )
 
 func command(name string, args []string, in []byte) E.Either[error, exec.CommandOutput] {
-	return E.TryCatchError(func() (exec.CommandOutput, error) {
+	return E.TryCatchError(GE.Exec(context.Background(), name, args, in))
-		return GE.Exec(context.Background(), name, args, in)
-	})
 }

either/gen.go

@@ -1,6 +1,6 @@
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-09-12 13:44:15.6356542 +0200 CEST m=+0.009418901
+// 2023-10-23 08:30:40.410373 +0200 CEST m=+0.010337601
 
 package either
 
@@ -13,9 +13,7 @@ import (
 // The inverse function is [Uneitherize0]
 func Eitherize0[F ~func() (R, error), R any](f F) func() Either[error, R] {
 	return func() Either[error, R] {
-		return TryCatchError(func() (R, error) {
+		return TryCatchError(f())
-			return f()
-		})
 	}
 }
 
@@ -31,9 +29,7 @@ func Uneitherize0[F ~func() Either[error, R], R any](f F) func() (R, error) {
 // The inverse function is [Uneitherize1]
 func Eitherize1[F ~func(T0) (R, error), T0, R any](f F) func(T0) Either[error, R] {
 	return func(t0 T0) Either[error, R] {
-		return TryCatchError(func() (R, error) {
+		return TryCatchError(f(t0))
-			return f(t0)
-		})
 	}
 }
 
@@ -76,9 +72,7 @@ func TraverseTuple1[F1 ~func(A1) Either[E, T1], E, A1, T1 any](f1 F1) func(T.Tup
 // The inverse function is [Uneitherize2]
 func Eitherize2[F ~func(T0, T1) (R, error), T0, T1, R any](f F) func(T0, T1) Either[error, R] {
 	return func(t0 T0, t1 T1) Either[error, R] {
-		return TryCatchError(func() (R, error) {
+		return TryCatchError(f(t0, t1))
-			return f(t0, t1)
-		})
 	}
 }
 
@@ -126,9 +120,7 @@ func TraverseTuple2[F1 ~func(A1) Either[E, T1], F2 ~func(A2) Either[E, T2], E, A
 // The inverse function is [Uneitherize3]
 func Eitherize3[F ~func(T0, T1, T2) (R, error), T0, T1, T2, R any](f F) func(T0, T1, T2) Either[error, R] {
 	return func(t0 T0, t1 T1, t2 T2) Either[error, R] {
-		return TryCatchError(func() (R, error) {
+		return TryCatchError(f(t0, t1, t2))
-			return f(t0, t1, t2)
-		})
 	}
 }
 
@@ -181,9 +173,7 @@ func TraverseTuple3[F1 ~func(A1) Either[E, T1], F2 ~func(A2) Either[E, T2], F3 ~
 // The inverse function is [Uneitherize4]
 func Eitherize4[F ~func(T0, T1, T2, T3) (R, error), T0, T1, T2, T3, R any](f F) func(T0, T1, T2, T3) Either[error, R] {
 	return func(t0 T0, t1 T1, t2 T2, t3 T3) Either[error, R] {
-		return TryCatchError(func() (R, error) {
+		return TryCatchError(f(t0, t1, t2, t3))
-			return f(t0, t1, t2, t3)
-		})
 	}
 }
 
@@ -241,9 +231,7 @@ func TraverseTuple4[F1 ~func(A1) Either[E, T1], F2 ~func(A2) Either[E, T2], F3 ~
 // The inverse function is [Uneitherize5]
 func Eitherize5[F ~func(T0, T1, T2, T3, T4) (R, error), T0, T1, T2, T3, T4, R any](f F) func(T0, T1, T2, T3, T4) Either[error, R] {
 	return func(t0 T0, t1 T1, t2 T2, t3 T3, t4 T4) Either[error, R] {
-		return TryCatchError(func() (R, error) {
+		return TryCatchError(f(t0, t1, t2, t3, t4))
-			return f(t0, t1, t2, t3, t4)
-		})
 	}
 }
 
@@ -306,9 +294,7 @@ func TraverseTuple5[F1 ~func(A1) Either[E, T1], F2 ~func(A2) Either[E, T2], F3 ~
 // The inverse function is [Uneitherize6]
 func Eitherize6[F ~func(T0, T1, T2, T3, T4, T5) (R, error), T0, T1, T2, T3, T4, T5, R any](f F) func(T0, T1, T2, T3, T4, T5) Either[error, R] {
 	return func(t0 T0, t1 T1, t2 T2, t3 T3, t4 T4, t5 T5) Either[error, R] {
-		return TryCatchError(func() (R, error) {
+		return TryCatchError(f(t0, t1, t2, t3, t4, t5))
-			return f(t0, t1, t2, t3, t4, t5)
-		})
 	}
 }
 
@@ -376,9 +362,7 @@ func TraverseTuple6[F1 ~func(A1) Either[E, T1], F2 ~func(A2) Either[E, T2], F3 ~
 // The inverse function is [Uneitherize7]
 func Eitherize7[F ~func(T0, T1, T2, T3, T4, T5, T6) (R, error), T0, T1, T2, T3, T4, T5, T6, R any](f F) func(T0, T1, T2, T3, T4, T5, T6) Either[error, R] {
 	return func(t0 T0, t1 T1, t2 T2, t3 T3, t4 T4, t5 T5, t6 T6) Either[error, R] {
-		return TryCatchError(func() (R, error) {
+		return TryCatchError(f(t0, t1, t2, t3, t4, t5, t6))
-			return f(t0, t1, t2, t3, t4, t5, t6)
-		})
 	}
 }
 
@@ -451,9 +435,7 @@ func TraverseTuple7[F1 ~func(A1) Either[E, T1], F2 ~func(A2) Either[E, T2], F3 ~
 // The inverse function is [Uneitherize8]
 func Eitherize8[F ~func(T0, T1, T2, T3, T4, T5, T6, T7) (R, error), T0, T1, T2, T3, T4, T5, T6, T7, R any](f F) func(T0, T1, T2, T3, T4, T5, T6, T7) Either[error, R] {
 	return func(t0 T0, t1 T1, t2 T2, t3 T3, t4 T4, t5 T5, t6 T6, t7 T7) Either[error, R] {
-		return TryCatchError(func() (R, error) {
+		return TryCatchError(f(t0, t1, t2, t3, t4, t5, t6, t7))
-			return f(t0, t1, t2, t3, t4, t5, t6, t7)
-		})
 	}
 }
 
@@ -531,9 +513,7 @@ func TraverseTuple8[F1 ~func(A1) Either[E, T1], F2 ~func(A2) Either[E, T2], F3 ~
 // The inverse function is [Uneitherize9]
 func Eitherize9[F ~func(T0, T1, T2, T3, T4, T5, T6, T7, T8) (R, error), T0, T1, T2, T3, T4, T5, T6, T7, T8, R any](f F) func(T0, T1, T2, T3, T4, T5, T6, T7, T8) Either[error, R] {
 	return func(t0 T0, t1 T1, t2 T2, t3 T3, t4 T4, t5 T5, t6 T6, t7 T7, t8 T8) Either[error, R] {
-		return TryCatchError(func() (R, error) {
+		return TryCatchError(f(t0, t1, t2, t3, t4, t5, t6, t7, t8))
-			return f(t0, t1, t2, t3, t4, t5, t6, t7, t8)
-		})
 	}
 }
 
@@ -616,9 +596,7 @@ func TraverseTuple9[F1 ~func(A1) Either[E, T1], F2 ~func(A2) Either[E, T2], F3 ~
 // The inverse function is [Uneitherize10]
 func Eitherize10[F ~func(T0, T1, T2, T3, T4, T5, T6, T7, T8, T9) (R, error), T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, R any](f F) func(T0, T1, T2, T3, T4, T5, T6, T7, T8, T9) Either[error, R] {
 	return func(t0 T0, t1 T1, t2 T2, t3 T3, t4 T4, t5 T5, t6 T6, t7 T7, t8 T8, t9 T9) Either[error, R] {
-		return TryCatchError(func() (R, error) {
+		return TryCatchError(f(t0, t1, t2, t3, t4, t5, t6, t7, t8, t9))
-			return f(t0, t1, t2, t3, t4, t5, t6, t7, t8, t9)
-		})
 	}
 }
 

either/http/request.go

@@ -35,17 +35,13 @@ var (
 func bodyRequest(method string) func(string) func([]byte) E.Either[error, *http.Request] {
 	return func(url string) func([]byte) E.Either[error, *http.Request] {
 		return func(body []byte) E.Either[error, *http.Request] {
-			return E.TryCatchError(func() (*http.Request, error) {
+			return E.TryCatchError(http.NewRequest(method, url, bytes.NewReader(body)))
-				return http.NewRequest(method, url, bytes.NewReader(body))
-			})
 		}
 	}
 }
 
 func noBodyRequest(method string) func(string) E.Either[error, *http.Request] {
 	return func(url string) E.Either[error, *http.Request] {
-		return E.TryCatchError(func() (*http.Request, error) {
+		return E.TryCatchError(http.NewRequest(method, url, nil))
-			return http.NewRequest(method, url, nil)
-		})
 	}
 }

either/resource_test.go

@@ -25,20 +25,14 @@ import (
 
 func TestWithResource(t *testing.T) {
 	onCreate := func() Either[error, *os.File] {
-		return TryCatchError(func() (*os.File, error) {
+		return TryCatchError(os.CreateTemp("", "*"))
-			return os.CreateTemp("", "*")
-		})
 	}
 	onDelete := F.Flow2(
 		func(f *os.File) Either[error, string] {
-			return TryCatchError(func() (string, error) {
+			return TryCatchError(f.Name(), f.Close())
-				return f.Name(), f.Close()
-			})
 		},
 		Chain(func(name string) Either[error, any] {
-			return TryCatchError(func() (any, error) {
+			return TryCatchError(any(name), os.Remove(name))
-				return name, os.Remove(name)
-			})
 		}),
 	)
 

either/variadic.go

@@ -17,80 +17,60 @@ package either
 
 func Variadic0[V, R any](f func([]V) (R, error)) func(...V) Either[error, R] {
 	return func(v ...V) Either[error, R] {
-		return TryCatchError(func() (R, error) {
+		return TryCatchError(f(v))
-			return f(v)
-		})
 	}
 }
 
 func Variadic1[T1, V, R any](f func(T1, []V) (R, error)) func(T1, ...V) Either[error, R] {
 	return func(t1 T1, v ...V) Either[error, R] {
-		return TryCatchError(func() (R, error) {
+		return TryCatchError(f(t1, v))
-			return f(t1, v)
-		})
 	}
 }
 
 func Variadic2[T1, T2, V, R any](f func(T1, T2, []V) (R, error)) func(T1, T2, ...V) Either[error, R] {
 	return func(t1 T1, t2 T2, v ...V) Either[error, R] {
-		return TryCatchError(func() (R, error) {
+		return TryCatchError(f(t1, t2, v))
-			return f(t1, t2, v)
-		})
 	}
 }
 
 func Variadic3[T1, T2, T3, V, R any](f func(T1, T2, T3, []V) (R, error)) func(T1, T2, T3, ...V) Either[error, R] {
 	return func(t1 T1, t2 T2, t3 T3, v ...V) Either[error, R] {
-		return TryCatchError(func() (R, error) {
+		return TryCatchError(f(t1, t2, t3, v))
-			return f(t1, t2, t3, v)
-		})
 	}
 }
 
 func Variadic4[T1, T2, T3, T4, V, R any](f func(T1, T2, T3, T4, []V) (R, error)) func(T1, T2, T3, T4, ...V) Either[error, R] {
 	return func(t1 T1, t2 T2, t3 T3, t4 T4, v ...V) Either[error, R] {
-		return TryCatchError(func() (R, error) {
+		return TryCatchError(f(t1, t2, t3, t4, v))
-			return f(t1, t2, t3, t4, v)
-		})
 	}
 }
 
 func Unvariadic0[V, R any](f func(...V) (R, error)) func([]V) Either[error, R] {
 	return func(v []V) Either[error, R] {
-		return TryCatchError(func() (R, error) {
+		return TryCatchError(f(v...))
-			return f(v...)
-		})
 	}
 }
 
 func Unvariadic1[T1, V, R any](f func(T1, ...V) (R, error)) func(T1, []V) Either[error, R] {
 	return func(t1 T1, v []V) Either[error, R] {
-		return TryCatchError(func() (R, error) {
+		return TryCatchError(f(t1, v...))
-			return f(t1, v...)
-		})
 	}
 }
 
 func Unvariadic2[T1, T2, V, R any](f func(T1, T2, ...V) (R, error)) func(T1, T2, []V) Either[error, R] {
 	return func(t1 T1, t2 T2, v []V) Either[error, R] {
-		return TryCatchError(func() (R, error) {
+		return TryCatchError(f(t1, t2, v...))
-			return f(t1, t2, v...)
-		})
 	}
 }
 
 func Unvariadic3[T1, T2, T3, V, R any](f func(T1, T2, T3, ...V) (R, error)) func(T1, T2, T3, []V) Either[error, R] {
 	return func(t1 T1, t2 T2, t3 T3, v []V) Either[error, R] {
-		return TryCatchError(func() (R, error) {
+		return TryCatchError(f(t1, t2, t3, v...))
-			return f(t1, t2, t3, v...)
-		})
 	}
 }
 
 func Unvariadic4[T1, T2, T3, T4, V, R any](f func(T1, T2, T3, T4, ...V) (R, error)) func(T1, T2, T3, T4, []V) Either[error, R] {
 	return func(t1 T1, t2 T2, t3 T3, t4 T4, v []V) Either[error, R] {
-		return TryCatchError(func() (R, error) {
+		return TryCatchError(f(t1, t2, t3, t4, v...))
-			return f(t1, t2, t3, t4, v...)
-		})
 	}
 }

erasure/erasure.go

@@ -16,6 +16,8 @@
 package erasure
 
 import (
+	E "github.com/IBM/fp-go/either"
+	"github.com/IBM/fp-go/errors"
 	F "github.com/IBM/fp-go/function"
 )
 
@@ -29,6 +31,15 @@ func Unerase[T any](t any) T {
 	return *t.(*T)
 }
 
+// SafeUnerase converts an erased variable back to its original value
+func SafeUnerase[T any](t any) E.Either[error, T] {
+	return F.Pipe2(
+		t,
+		E.ToType[*T](errors.OnSome[any]("Value of type [%T] is not erased")),
+		E.Map[error](F.Deref[T]),
+	)
+}
+
 // Erase0 converts a type safe function into an erased function
 func Erase0[T1 any](f func() T1) func() any {
 	return F.Nullary2(f, Erase[T1])

function/binds.go

@@ -1,6 +1,6 @@
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-09-12 13:44:23.4226437 +0200 CEST m=+0.011841001
+// 2023-10-23 08:30:44.6474482 +0200 CEST m=+0.150851901
 
 package function
 

function/flip.go

@@ -0,0 +1,25 @@
+// Copyright (c) 2023 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package function
+
+// Flip reverses the order of parameters of a curried function
+func Flip[T1, T2, R any](f func(T1) func(T2) R) func(T2) func(T1) R {
+	return func(t2 T2) func(T1) R {
+		return func(t1 T1) R {
+			return f(t1)(t2)
+		}
+	}
+}

function/flip_test.go

@@ -13,14 +13,24 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// Package readerio implements a specialization of the ReaderIO monad assuming a golang context as the context of the monad
+package function
-package readerio
 
 import (
-	"context"
+	"fmt"
+	"testing"
 
-	R "github.com/IBM/fp-go/readerio"
+	"github.com/stretchr/testify/assert"
 )
 
-// ReaderIO is a specialization of the ReaderIO monad assuming a golang context as the context of the monad
+func TestFlip(t *testing.T) {
-type ReaderIO[A any] R.ReaderIO[context.Context, A]
+
+	x := Curry2(func(a, b string) string {
+		return fmt.Sprintf("%s:%s", a, b)
+	})
+
+	assert.Equal(t, "a:b", x("a")("b"))
+
+	y := Flip(x)
+
+	assert.Equal(t, "b:a", y("a")("b"))
+}

function/gen.go

@@ -1,6 +1,6 @@
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-09-12 13:44:17.0002767 +0200 CEST m=+0.008233101
+// 2023-10-23 08:30:41.7972101 +0200 CEST m=+0.008029101
 
 package function
 

function/generic/switch.go

@@ -0,0 +1,28 @@
+// 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
+
+// Switch applies a handler to different cases. The handers are stored in a map. A key function
+// extracts the case from a value.
+func Switch[HF ~func(T) R, N ~map[K]HF, KF ~func(T) K, K comparable, T, R any](kf KF, n N, d HF) HF {
+	return func(t T) R {
+		f, ok := n[kf(t)]
+		if ok {
+			return f(t)
+		}
+		return d(t)
+	}
+}

function/switch.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 function
+
+import (
+	G "github.com/IBM/fp-go/function/generic"
+)
+
+// Switch applies a handler to different cases. The handers are stored in a map. A key function
+// extracts the case from a value.
+func Switch[K comparable, T, R any](kf func(T) K, n map[K]func(T) R, d func(T) R) func(T) R {
+	return G.Switch(kf, n, d)
+}

go.mod

@@ -8,7 +8,7 @@ require (
 )
 
 require (
-	github.com/cpuguy83/go-md2man/v2 v2.0.2 // indirect
+	github.com/cpuguy83/go-md2man/v2 v2.0.3 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/russross/blackfriday/v2 v2.1.0 // indirect

go.sum

@@ -1,5 +1,5 @@
-github.com/cpuguy83/go-md2man/v2 v2.0.2 h1:p1EgwI/C7NhT0JmVkwCD2ZBK8j4aeHQX2pMHHBfMQ6w=
+github.com/cpuguy83/go-md2man/v2 v2.0.3 h1:qMCsGGgs+MAzDFyp9LpAe1Lqy/fY/qCovCm0qnXZOBM=
-github.com/cpuguy83/go-md2man/v2 v2.0.2/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
+github.com/cpuguy83/go-md2man/v2 v2.0.3/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=

http/utils.go

@@ -68,10 +68,8 @@ const (
 
 // ParseMediaType parses a media type into a tuple
 func ParseMediaType(mediaType string) E.Either[error, ParsedMediaType] {
-	return E.TryCatchError(func() (ParsedMediaType, error) {
+	m, p, err := mime.ParseMediaType(mediaType)
-		m, p, err := mime.ParseMediaType(mediaType)
+	return E.TryCatchError(T.MakeTuple2(m, p), err)
-		return T.MakeTuple2(m, p), err
-	})
 }
 
 func GetHeader(resp *H.Response) H.Header {

identity/gen.go

@@ -1,6 +1,6 @@
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-09-12 13:44:24.9409324 +0200 CEST m=+0.008573601
+// 2023-10-23 08:30:50.5492271 +0200 CEST m=+0.023274501
 
 package identity
 

identity/generic/identity.go

@@ -57,6 +57,6 @@ func MonadFlap[GAB ~func(A) B, A, B any](fab GAB, a A) B {
 	return FC.MonadFlap(MonadMap[func(GAB) B, GAB, B], fab, a)
 }
 
-func Flap[GAB ~func(A) B, A, B any](a A) func(GAB) B {
+func Flap[GAB ~func(A) B, B, A any](a A) func(GAB) B {
 	return F.Bind2nd(MonadFlap[GAB, A, B], a)
 }

internal/apply/gen.go

@@ -1,6 +1,6 @@
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-09-12 13:44:26.2499883 +0200 CEST m=+0.007601301
+// 2023-10-23 08:30:54.1909432 +0200 CEST m=+0.014252201
 
 package apply
 

internal/array/array.go

@@ -51,6 +51,24 @@ func ReduceWithIndex[GA ~[]A, A, B any](fa GA, f func(int, B, A) B, initial B) B
 	return current
 }
 
+func ReduceRight[GA ~[]A, A, B any](fa GA, f func(A, B) B, initial B) B {
+	current := initial
+	count := len(fa)
+	for i := count - 1; i >= 0; i-- {
+		current = f(fa[i], current)
+	}
+	return current
+}
+
+func ReduceRightWithIndex[GA ~[]A, A, B any](fa GA, f func(int, A, B) B, initial B) B {
+	current := initial
+	count := len(fa)
+	for i := count - 1; i >= 0; i-- {
+		current = f(i, fa[i], current)
+	}
+	return current
+}
+
 func Append[GA ~[]A, A any](as GA, a A) GA {
 	return append(as, a)
 }
@@ -88,6 +106,15 @@ func MonadMap[GA ~[]A, GB ~[]B, A, B any](as GA, f func(a A) B) GB {
 	return bs
 }
 
+func MonadMapWithIndex[GA ~[]A, GB ~[]B, A, B any](as GA, f func(idx int, a A) B) GB {
+	count := len(as)
+	bs := make(GB, count)
+	for i := count - 1; i >= 0; i-- {
+		bs[i] = f(i, as[i])
+	}
+	return bs
+}
+
 func ConstNil[GA ~[]A, A any]() GA {
 	return (GA)(nil)
 }

internal/file/file.go

@@ -46,9 +46,7 @@ func MakeReader(ctx context.Context, rdr io.Reader) io.Reader {
 
 // ReadAll reads the content of a reader and allows it to be canceled
 func ReadAll(ctx context.Context, rdr io.Reader) E.Either[error, []byte] {
-	return E.TryCatchError(func() ([]byte, error) {
+	var buffer bytes.Buffer
-		var buffer bytes.Buffer
+	_, err := io.Copy(&buffer, MakeReader(ctx, rdr))
-		_, err := io.Copy(&buffer, MakeReader(ctx, rdr))
+	return E.TryCatchError(buffer.Bytes(), err)
-		return buffer.Bytes(), err
-	})
 }

io/gen.go

@@ -1,6 +1,6 @@
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-09-12 13:44:27.9813739 +0200 CEST m=+0.011088001
+// 2023-10-23 08:30:56.7105551 +0200 CEST m=+0.011255201
 
 package io
 

io/generic/gen.go

@@ -1,6 +1,6 @@
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-09-12 13:44:27.9813739 +0200 CEST m=+0.011088001
+// 2023-10-23 08:30:56.7105551 +0200 CEST m=+0.011255201
 package generic
 
 import (

io/generic/traverse.go

@@ -57,7 +57,7 @@ func SequenceArray[GA ~func() A, GAS ~func() AAS, AAS ~[]A, GAAS ~[]GA, A any](t
 }
 
 // MonadTraverseRecord transforms a record using an IO transform an IO of a record
-func MonadTraverseRecord[GB ~func() B, GBS ~func() MB, MA ~map[K]A, MB ~map[K]B, K comparable, A, B any](ma MA, f func(A) GB) GBS {
+func MonadTraverseRecord[GBS ~func() MB, MA ~map[K]A, GB ~func() B, MB ~map[K]B, K comparable, A, B any](ma MA, f func(A) GB) GBS {
 	return RR.MonadTraverse[MA](
 		Of[GBS, MB],
 		Map[GBS, func() func(B) MB, MB, func(B) MB],
@@ -67,7 +67,7 @@ func MonadTraverseRecord[GB ~func() B, GBS ~func() MB, MA ~map[K]A, MB ~map[K]B,
 }
 
 // TraverseRecord transforms a record using an IO transform an IO of a record
-func TraverseRecord[GB ~func() B, GBS ~func() MB, MA ~map[K]A, MB ~map[K]B, K comparable, A, B any](f func(A) GB) func(MA) GBS {
+func TraverseRecord[GBS ~func() MB, MA ~map[K]A, GB ~func() B, MB ~map[K]B, K comparable, A, B any](f func(A) GB) func(MA) GBS {
 	return RR.Traverse[MA](
 		Of[GBS, MB],
 		Map[GBS, func() func(B) MB, MB, func(B) MB],
@@ -87,5 +87,5 @@ func TraverseRecordWithIndex[GB ~func() B, GBS ~func() MB, MA ~map[K]A, MB ~map[
 }
 
 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])
+	return MonadTraverseRecord[GAS](tas, F.Identity[GA])
 }

io/sync.go

@@ -19,10 +19,9 @@ import (
 	"context"
 
 	G "github.com/IBM/fp-go/io/generic"
-	L "github.com/IBM/fp-go/lazy"
 )
 
 // WithLock executes the provided [IO] operation in the scope of a lock
-func WithLock[A any](lock L.Lazy[context.CancelFunc]) func(fa IO[A]) IO[A] {
+func WithLock[A any](lock IO[context.CancelFunc]) func(fa IO[A]) IO[A] {
 	return G.WithLock[IO[A]](lock)
 }

io/traverse.go

@@ -41,13 +41,13 @@ func SequenceArray[A any](tas []IO[A]) IO[[]A] {
 }
 
 func MonadTraverseRecord[K comparable, A, B any](tas map[K]A, f func(A) IO[B]) IO[map[K]B] {
-	return G.MonadTraverseRecord[IO[B], IO[map[K]B]](tas, f)
+	return G.MonadTraverseRecord[IO[map[K]B]](tas, f)
 }
 
 // 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)
+	return G.TraverseRecord[IO[map[K]B], map[K]A, IO[B]](f)
 }
 
 // TraverseRecordWithIndex applies a function returning an [IO] to all elements in a record and the

ioeither/gen.go

@@ -1,6 +1,6 @@
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-09-12 13:44:29.4935658 +0200 CEST m=+0.015377401
+// 2023-10-23 08:30:58.6457744 +0200 CEST m=+0.080336501
 
 package ioeither
 

ioeither/generic/gen.go

@@ -1,6 +1,6 @@
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-09-12 13:44:29.4935658 +0200 CEST m=+0.015377401
+// 2023-10-23 08:30:58.6556525 +0200 CEST m=+0.090214601
 package generic
 
 import (

ioeither/generic/ioeither.go

@@ -19,7 +19,6 @@ import (
 	"time"
 
 	ET "github.com/IBM/fp-go/either"
-	"github.com/IBM/fp-go/errors"
 	F "github.com/IBM/fp-go/function"
 	C "github.com/IBM/fp-go/internal/chain"
 	"github.com/IBM/fp-go/internal/eithert"
@@ -184,12 +183,15 @@ func Flatten[GA ~func() ET.Either[E, A], GAA ~func() ET.Either[E, GA], E, A any]
 
 func TryCatch[GA ~func() ET.Either[E, A], E, A any](f func() (A, error), onThrow func(error) E) GA {
 	return MakeIO(func() ET.Either[E, A] {
-		return ET.TryCatch(f, onThrow)
+		a, err := f()
+		return ET.TryCatch(a, err, onThrow)
 	})
 }
 
 func TryCatchError[GA ~func() ET.Either[error, A], A any](f func() (A, error)) GA {
-	return TryCatch[GA](f, errors.IdentityError)
+	return MakeIO(func() ET.Either[error, A] {
+		return ET.TryCatchError(f())
+	})
 }
 
 // Memoize computes the value of the provided IO monad lazily but exactly once
@@ -273,6 +275,27 @@ func ChainFirstIOK[GA ~func() ET.Either[E, A], GIOB ~func() B, E, A, B any](f fu
 	)
 }
 
+// MonadChainFirstEitherK runs the monad returned by the function but returns the result of the original monad
+func MonadChainFirstEitherK[GA ~func() ET.Either[E, A], E, A, B any](first GA, f func(A) ET.Either[E, B]) GA {
+	return FE.MonadChainFirstEitherK(
+		MonadChain[GA, GA, E, A, A],
+		MonadMap[func() ET.Either[E, B], GA, E, B, A],
+		FromEither[func() ET.Either[E, B], E, B],
+		first,
+		f,
+	)
+}
+
+// ChainFirstEitherK runs the monad returned by the function but returns the result of the original monad
+func ChainFirstEitherK[GA ~func() ET.Either[E, A], E, A, B any](f func(A) ET.Either[E, B]) func(GA) GA {
+	return FE.ChainFirstEitherK(
+		MonadChain[GA, GA, E, A, A],
+		MonadMap[func() ET.Either[E, B], GA, E, B, A],
+		FromEither[func() ET.Either[E, B], E, B],
+		f,
+	)
+}
+
 // Swap changes the order of type parameters
 func Swap[GEA ~func() ET.Either[E, A], GAE ~func() ET.Either[A, E], E, A any](val GEA) GAE {
 	return MonadFold(val, Right[GAE], Left[GAE])
@@ -313,3 +336,14 @@ func MonadFlap[GEAB ~func() ET.Either[E, func(A) B], GEB ~func() ET.Either[E, B]
 func Flap[GEAB ~func() ET.Either[E, func(A) B], GEB ~func() ET.Either[E, B], E, B, A any](a A) func(GEAB) GEB {
 	return FC.Flap(MonadMap[GEAB, GEB], a)
 }
+
+func ToIOOption[GA ~func() O.Option[A], GEA ~func() ET.Either[E, A], E, A any](ioe GEA) GA {
+	return F.Pipe1(
+		ioe,
+		IO.Map[GEA, GA](ET.ToOption[E, A]),
+	)
+}
+
+func FromIOOption[GEA ~func() ET.Either[E, A], GA ~func() O.Option[A], E, A any](onNone func() E) func(ioo GA) GEA {
+	return IO.Map[GA, GEA](ET.FromOption[A](onNone))
+}

ioeither/http/request.go

@@ -20,54 +20,94 @@ import (
 	"net/http"
 
 	B "github.com/IBM/fp-go/bytes"
-	ER "github.com/IBM/fp-go/errors"
 	F "github.com/IBM/fp-go/function"
+	H "github.com/IBM/fp-go/http"
 	IOE "github.com/IBM/fp-go/ioeither"
 	IOEF "github.com/IBM/fp-go/ioeither/file"
 	J "github.com/IBM/fp-go/json"
+	T "github.com/IBM/fp-go/tuple"
 )
 
-type Client interface {
+type (
-	Do(req *http.Request) IOE.IOEither[error, *http.Response]
+	// Requester is a reader that constructs a request
-}
+	Requester = IOE.IOEither[error, *http.Request]
 
-type client struct {
+	Client interface {
-	delegate *http.Client
+		Do(Requester) IOE.IOEither[error, *http.Response]
-}
+	}
 
-func (client client) Do(req *http.Request) IOE.IOEither[error, *http.Response] {
+	client struct {
-	return IOE.TryCatch(func() (*http.Response, error) {
+		delegate *http.Client
-		return client.delegate.Do(req)
+		doIOE    func(*http.Request) IOE.IOEither[error, *http.Response]
-	}, ER.IdentityError)
+	}
+)
+
+var (
+	// MakeRequest is an eitherized version of [http.NewRequest]
+	MakeRequest = IOE.Eitherize3(http.NewRequest)
+	makeRequest = F.Bind13of3(MakeRequest)
+
+	// specialize
+	MakeGetRequest = makeRequest("GET", nil)
+)
+
+func (client client) Do(req Requester) IOE.IOEither[error, *http.Response] {
+	return F.Pipe1(
+		req,
+		IOE.Chain(client.doIOE),
+	)
 }
 
 func MakeClient(httpClient *http.Client) Client {
-	return client{delegate: httpClient}
+	return client{delegate: httpClient, doIOE: IOE.Eitherize1(httpClient.Do)}
 }
 
-func ReadAll(client Client) func(*http.Request) IOE.IOEither[error, []byte] {
+// ReadFullResponse sends a request,  reads the response as a byte array and represents the result as a tuple
-	return func(req *http.Request) IOE.IOEither[error, []byte] {
+func ReadFullResponse(client Client) func(Requester) IOE.IOEither[error, H.FullResponse] {
-		return IOEF.ReadAll(F.Pipe2(
+	return F.Flow3(
-			req,
+		client.Do,
-			client.Do,
+		IOE.ChainEitherK(H.ValidateResponse),
-			IOE.Map[error](func(resp *http.Response) io.ReadCloser {
+		IOE.Chain(func(resp *http.Response) IOE.IOEither[error, H.FullResponse] {
-				return resp.Body
+			return F.Pipe1(
-			}),
+				F.Pipe3(
-		),
+					resp,
-		)
+					H.GetBody,
-	}
+					IOE.Of[error, io.ReadCloser],
+					IOEF.ReadAll[io.ReadCloser],
+				),
+				IOE.Map[error](F.Bind1st(T.MakeTuple2[*http.Response, []byte], resp)),
+			)
+		}),
+	)
 }
 
-func ReadText(client Client) func(*http.Request) IOE.IOEither[error, string] {
+// ReadAll sends a request and reads the response as bytes
+func ReadAll(client Client) func(Requester) IOE.IOEither[error, []byte] {
+	return F.Flow2(
+		ReadFullResponse(client),
+		IOE.Map[error](H.Body),
+	)
+}
+
+// ReadText sends a request, reads the response and represents the response as a text string
+func ReadText(client Client) func(Requester) IOE.IOEither[error, string] {
 	return F.Flow2(
 		ReadAll(client),
 		IOE.Map[error](B.ToString),
 	)
 }
 
-func ReadJson[A any](client Client) func(*http.Request) IOE.IOEither[error, A] {
+// ReadJson sends a request, reads the response and parses the response as JSON
-	return F.Flow2(
+func ReadJson[A any](client Client) func(Requester) IOE.IOEither[error, A] {
-		ReadAll(client),
+	return F.Flow3(
-		IOE.ChainEitherK(J.Unmarshal[A]),
+		ReadFullResponse(client),
+		IOE.ChainFirstEitherK(F.Flow2(
+			H.Response,
+			H.ValidateJsonResponse,
+		)),
+		IOE.ChainEitherK(F.Flow2(
+			H.Body,
+			J.Unmarshal[A],
+		)),
 	)
 }

ioeither/http/retry_test.go

@@ -23,7 +23,6 @@ import (
 
 	AR "github.com/IBM/fp-go/array"
 	E "github.com/IBM/fp-go/either"
-	HE "github.com/IBM/fp-go/either/http"
 	"github.com/IBM/fp-go/errors"
 	F "github.com/IBM/fp-go/function"
 	IOE "github.com/IBM/fp-go/ioeither"
@@ -53,17 +52,16 @@ func TestRetryHttp(t *testing.T) {
 	client := MakeClient(&http.Client{})
 
 	action := func(status R.RetryStatus) IOE.IOEither[error, *PostItem] {
-		return F.Pipe2(
+		return F.Pipe1(
-			HE.GetRequest(urls[status.IterNumber]),
+			MakeGetRequest(urls[status.IterNumber]),
-			IOE.FromEither[error, *http.Request],
+			ReadJson[*PostItem](client),
-			IOE.Chain(ReadJson[*PostItem](client)),
 		)
 	}
 
 	check := E.Fold(
 		F.Flow2(
 			errors.As[*net.DNSError](),
-			O.Fold(F.Constant(false), F.Constant1[*net.DNSError](true)),
+			O.IsSome[*net.DNSError],
 		),
 		F.Constant1[*PostItem](false),
 	)

ioeither/ioeither.go

@@ -19,6 +19,7 @@ import (
 	ET "github.com/IBM/fp-go/either"
 	I "github.com/IBM/fp-go/io"
 	G "github.com/IBM/fp-go/ioeither/generic"
+	IOO "github.com/IBM/fp-go/iooption"
 	L "github.com/IBM/fp-go/lazy"
 	O "github.com/IBM/fp-go/option"
 )
@@ -63,6 +64,10 @@ func FromOption[A, E any](onNone func() E) func(o O.Option[A]) IOEither[E, A] {
 	return G.FromOption[IOEither[E, A]](onNone)
 }
 
+func FromIOOption[A, E any](onNone func() E) func(o IOO.IOOption[A]) IOEither[E, A] {
+	return G.FromIOOption[IOEither[E, A], IOO.IOOption[A]](onNone)
+}
+
 func ChainOptionK[A, B, E any](onNone func() E) func(func(A) O.Option[B]) func(IOEither[E, A]) IOEither[E, B] {
 	return G.ChainOptionK[IOEither[E, A], IOEither[E, B]](onNone)
 }
@@ -125,10 +130,29 @@ func MonadAp[B, E, A any](mab IOEither[E, func(A) B], ma IOEither[E, A]) IOEithe
 	return G.MonadAp[IOEither[E, B]](mab, ma)
 }
 
+// Ap is an alias of [ApPar]
 func Ap[B, E, A any](ma IOEither[E, A]) func(IOEither[E, func(A) B]) IOEither[E, B] {
 	return G.Ap[IOEither[E, B], IOEither[E, func(A) B]](ma)
 }
 
+func MonadApPar[B, E, A any](mab IOEither[E, func(A) B], ma IOEither[E, A]) IOEither[E, B] {
+	return G.MonadApPar[IOEither[E, B]](mab, ma)
+}
+
+// ApPar applies function and value in parallel
+func ApPar[B, E, A any](ma IOEither[E, A]) func(IOEither[E, func(A) B]) IOEither[E, B] {
+	return G.ApPar[IOEither[E, B], IOEither[E, func(A) B]](ma)
+}
+
+func MonadApSeq[B, E, A any](mab IOEither[E, func(A) B], ma IOEither[E, A]) IOEither[E, B] {
+	return G.MonadApSeq[IOEither[E, B]](mab, ma)
+}
+
+// ApSeq applies function and value sequentially
+func ApSeq[B, E, A any](ma IOEither[E, A]) func(IOEither[E, func(A) B]) IOEither[E, B] {
+	return G.ApSeq[IOEither[E, B], IOEither[E, func(A) B]](ma)
+}
+
 func Flatten[E, A any](mma IOEither[E, IOEither[E, A]]) IOEither[E, A] {
 	return G.Flatten(mma)
 }
@@ -192,6 +216,14 @@ func ChainFirst[E, A, B any](f func(A) IOEither[E, B]) func(IOEither[E, A]) IOEi
 	return G.ChainFirst[IOEither[E, A]](f)
 }
 
+func MonadChainFirstEitherK[A, E, B any](ma IOEither[E, A], f func(A) ET.Either[E, B]) IOEither[E, A] {
+	return G.MonadChainFirstEitherK[IOEither[E, A]](ma, f)
+}
+
+func ChainFirstEitherK[A, E, B any](f func(A) ET.Either[E, B]) func(ma IOEither[E, A]) IOEither[E, A] {
+	return G.ChainFirstEitherK[IOEither[E, A]](f)
+}
+
 // MonadChainFirstIOK runs [IO] the monad returned by the function but returns the result of the original monad
 func MonadChainFirstIOK[E, A, B any](ma IOEither[E, A], f func(A) I.IO[B]) IOEither[E, A] {
 	return G.MonadChainFirstIOK(ma, f)
@@ -239,3 +271,8 @@ func MonadFlap[E, B, A any](fab IOEither[E, func(A) B], a A) IOEither[E, B] {
 func Flap[E, B, A any](a A) func(IOEither[E, func(A) B]) IOEither[E, B] {
 	return G.Flap[IOEither[E, func(A) B], IOEither[E, B]](a)
 }
+
+// ToIOOption converts an [IOEither] to an [IOO.IOOption]
+func ToIOOption[E, A any](ioe IOEither[E, A]) IOO.IOOption[A] {
+	return G.ToIOOption[IOO.IOOption[A]](ioe)
+}

ioeither/sync.go

@@ -18,11 +18,11 @@ package ioeither
 import (
 	"context"
 
+	IO "github.com/IBM/fp-go/io"
 	G "github.com/IBM/fp-go/ioeither/generic"
-	L "github.com/IBM/fp-go/lazy"
 )
 
 // WithLock executes the provided IO operation in the scope of a lock
-func WithLock[E, A any](lock L.Lazy[context.CancelFunc]) func(fa IOEither[E, A]) IOEither[E, A] {
+func WithLock[E, A any](lock IO.IO[context.CancelFunc]) func(fa IOEither[E, A]) IOEither[E, A] {
 	return G.WithLock[IOEither[E, A]](lock)
 }

iooption/gen.go

@@ -1,6 +1,6 @@
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-09-12 13:44:32.1514823 +0200 CEST m=+0.098931001
+// 2023-10-23 08:31:01.9227118 +0200 CEST m=+0.009977901
 
 package iooption
 

iooption/generic/gen.go

@@ -1,6 +1,6 @@
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-09-12 13:44:32.1546277 +0200 CEST m=+0.102076401
+// 2023-10-23 08:31:01.9227118 +0200 CEST m=+0.009977901
 package generic
 
 import (

iooption/generic/iooption.go

@@ -64,13 +64,6 @@ func FromEither[GA ~func() O.Option[A], E, A any](e ET.Either[E, A]) GA {
 	)
 }
 
-func FromIOEither[GA ~func() O.Option[A], GEA ~func() ET.Either[E, A], E, A any](ioe GEA) GA {
-	return F.Pipe1(
-		ioe,
-		IO.Map[GEA, GA](ET.ToOption[E, A]),
-	)
-}
-
 func MonadMap[GA ~func() O.Option[A], GB ~func() O.Option[B], A, B any](fa GA, f func(A) B) GB {
 	return optiont.MonadMap(IO.MonadMap[GA, GB, O.Option[A], O.Option[B]], fa, f)
 }

iooption/iooption.go

@@ -18,7 +18,6 @@ package iooption
 import (
 	ET "github.com/IBM/fp-go/either"
 	I "github.com/IBM/fp-go/io"
-	IOE "github.com/IBM/fp-go/ioeither"
 	G "github.com/IBM/fp-go/iooption/generic"
 	O "github.com/IBM/fp-go/option"
 )
@@ -129,11 +128,6 @@ func Defer[A any](gen func() IOOption[A]) IOOption[A] {
 	return G.Defer[IOOption[A]](gen)
 }
 
-// FromIOEither converts an [IOEither] into an [IOOption]
-func FromIOEither[E, A any](ioe IOE.IOEither[E, A]) IOOption[A] {
-	return G.FromIOEither[IOOption[A]](ioe)
-}
-
 // FromEither converts an [Either] into an [IOOption]
 func FromEither[E, A any](e ET.Either[E, A]) IOOption[A] {
 	return G.FromEither[IOOption[A]](e)

iooption/sync.go

@@ -18,11 +18,11 @@ package iooption
 import (
 	"context"
 
+	IO "github.com/IBM/fp-go/io"
 	G "github.com/IBM/fp-go/iooption/generic"
-	L "github.com/IBM/fp-go/lazy"
 )
 
 // WithLock executes the provided IO operation in the scope of a lock
-func WithLock[E, A any](lock L.Lazy[context.CancelFunc]) func(fa IOOption[A]) IOOption[A] {
+func WithLock[E, A any](lock IO.IO[context.CancelFunc]) func(fa IOOption[A]) IOOption[A] {
 	return G.WithLock[IOOption[A]](lock)
 }

iterator/stateless/any.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"
+)
+
+// Any returns `true` if any element of the iterable is `true`. If the iterable is empty, return `false`
+// Similar to the [https://docs.python.org/3/library/functions.html#any] function
+func Any[U any](pred func(U) bool) func(ma Iterator[U]) bool {
+	return G.Any[Iterator[U]](pred)
+}

iterator/stateless/any_test.go

@@ -0,0 +1,38 @@
+// Copyright (c) 2023 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package stateless
+
+import (
+	"testing"
+
+	A "github.com/IBM/fp-go/array"
+	F "github.com/IBM/fp-go/function"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestAny(t *testing.T) {
+
+	anyBool := Any(F.Identity[bool])
+
+	i1 := FromArray(A.From(false, true, false))
+	assert.True(t, anyBool(i1))
+
+	i2 := FromArray(A.From(false, false, false))
+	assert.False(t, anyBool(i2))
+
+	i3 := Empty[bool]()
+	assert.False(t, anyBool(i3))
+}

iterator/stateless/example_test.go

@@ -0,0 +1,55 @@
+// Copyright (c) 2023 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package stateless
+
+import (
+	"fmt"
+
+	A "github.com/IBM/fp-go/array"
+	F "github.com/IBM/fp-go/function"
+	O "github.com/IBM/fp-go/option"
+)
+
+func Example_any() {
+	// `Any` function that simply returns the boolean identity
+	anyBool := Any(F.Identity[bool])
+
+	fmt.Println(anyBool(FromArray(A.From(true, false, false))))
+	fmt.Println(anyBool(FromArray(A.From(false, false, false))))
+	fmt.Println(anyBool(Empty[bool]()))
+
+	// Output:
+	// true
+	// false
+	// false
+}
+
+func Example_next() {
+
+	seq := MakeBy(F.Identity[int])
+
+	first := seq()
+
+	value := F.Pipe1(
+		first,
+		O.Map(Current[int]),
+	)
+
+	fmt.Println(value)
+
+	// Output:
+	// Some[int](0)
+}

iterator/stateless/generic/any.go

@@ -0,0 +1,31 @@
+// Copyright (c) 2023 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package generic
+
+import (
+	F "github.com/IBM/fp-go/function"
+	O "github.com/IBM/fp-go/option"
+	T "github.com/IBM/fp-go/tuple"
+)
+
+// Any returns `true` if any element of the iterable is `true`. If the iterable is empty, return `false`
+func Any[GU ~func() O.Option[T.Tuple2[GU, U]], FCT ~func(U) bool, U any](pred FCT) func(ma GU) bool {
+	return F.Flow3(
+		Filter[GU](pred),
+		First[GU],
+		O.IsSome[U],
+	)
+}

iterator/stateless/generic/dropwhile.go

@@ -41,7 +41,7 @@ func DropWhile[GU ~func() O.Option[T.Tuple2[GU, U]], U any](pred func(U) bool) f
 		return F.Pipe2(
 			t,
 			fromPred,
-			O.Fold(recurse(t.F1), O.Of[T.Tuple2[GU, U]]),
+			O.Fold(recurse(Next(t)), O.Of[T.Tuple2[GU, U]]),
 		)
 	})
 

iterator/stateless/generic/iterator.go

@@ -26,6 +26,16 @@ import (
 	T "github.com/IBM/fp-go/tuple"
 )
 
+// Next returns the iterator for the next element in an iterator `T.Tuple2`
+func Next[GU ~func() O.Option[T.Tuple2[GU, U]], U any](m T.Tuple2[GU, U]) GU {
+	return T.First(m)
+}
+
+// Current returns the current element in an iterator `T.Tuple2`
+func Current[GU ~func() O.Option[T.Tuple2[GU, U]], U any](m T.Tuple2[GU, U]) U {
+	return T.Second(m)
+}
+
 // From constructs an array from a set of variadic arguments
 func From[GU ~func() O.Option[T.Tuple2[GU, U]], U any](data ...U) GU {
 	return FromArray[GU](data)
@@ -56,8 +66,8 @@ func reduce[GU ~func() O.Option[T.Tuple2[GU, U]], U, V any](as GU, f func(V, U)
 	current := initial
 	for ok {
 		// next (with bad side effect)
-		current = f(current, next.F2)
+		current = f(current, Current(next))
-		next, ok = O.Unwrap(next.F1())
+		next, ok = O.Unwrap(Next(next)())
 	}
 	return current
 }
@@ -199,8 +209,8 @@ func FilterMap[GV ~func() O.Option[T.Tuple2[GV, V]], GU ~func() O.Option[T.Tuple
 	m = O.Fold(
 		Empty[GV](),
 		func(t T.Tuple2[GU, U]) O.Option[T.Tuple2[GV, V]] {
-			r := recurse(t.F1)
+			r := recurse(Next(t))
-			return O.MonadFold(f(t.F2), r, F.Flow2(
+			return O.MonadFold(f(Current(t)), r, F.Flow2(
 				F.Bind1st(T.MakeTuple2[GV, V], r),
 				O.Some[T.Tuple2[GV, V]],
 			))

iterator/stateless/iterator.go

@@ -26,6 +26,16 @@ import (
 // Iterator represents a stateless, pure way to iterate over a sequence
 type Iterator[U any] L.Lazy[O.Option[T.Tuple2[Iterator[U], U]]]
 
+// Next returns the [Iterator] for the next element in an iterator `T.Tuple2`
+func Next[U any](m T.Tuple2[Iterator[U], U]) Iterator[U] {
+	return G.Next(m)
+}
+
+// Current returns the current element in an [Iterator] `T.Tuple2`
+func Current[U any](m T.Tuple2[Iterator[U], U]) U {
+	return G.Current(m)
+}
+
 // Empty returns the empty iterator
 func Empty[U any]() Iterator[U] {
 	return G.Empty[Iterator[U]]()

json/json.go

@@ -23,16 +23,12 @@ import (
 
 // Unmarshal parses a JSON data structure from bytes
 func Unmarshal[A any](data []byte) E.Either[error, A] {
-	return E.TryCatchError(func() (A, error) {
+	var result A
-		var result A
+	err := json.Unmarshal(data, &result)
-		err := json.Unmarshal(data, &result)
+	return E.TryCatchError(result, err)
-		return result, err
-	})
 }
 
 // Marshal converts a data structure to json
 func Marshal[A any](a A) E.Either[error, []byte] {
-	return E.TryCatchError(func() ([]byte, error) {
+	return E.TryCatchError(json.Marshal(a))
-		return json.Marshal(a)
-	})
 }

lazy/traverse.go

@@ -41,13 +41,13 @@ func SequenceArray[A any](tas []Lazy[A]) Lazy[[]A] {
 }
 
 func MonadTraverseRecord[K comparable, A, B any](tas map[K]A, f func(A) Lazy[B]) Lazy[map[K]B] {
-	return G.MonadTraverseRecord[Lazy[B], Lazy[map[K]B]](tas, f)
+	return G.MonadTraverseRecord[Lazy[map[K]B]](tas, f)
 }
 
 // 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) Lazy[B]) func(map[K]A) Lazy[map[K]B] {
-	return G.TraverseRecord[Lazy[B], Lazy[map[K]B], map[K]A](f)
+	return G.TraverseRecord[Lazy[map[K]B], map[K]A, Lazy[B]](f)
 }
 
 // TraverseRecord applies a function returning an [IO] to all elements in a record and the

magma/magma.go

@@ -33,7 +33,7 @@ func MakeMagma[A any](c func(A, A) A) Magma[A] {
 
 func Reverse[A any](m Magma[A]) Magma[A] {
 	return MakeMagma(func(x A, y A) A {
-		return m.Concat(y, y)
+		return m.Concat(y, x)
 	})
 }
 

optics/traversal/array/const/traversal.go

@@ -22,7 +22,7 @@ import (
 	G "github.com/IBM/fp-go/optics/traversal/generic"
 )
 
-// FromArray returns a traversal from an array for the identity monad
+// FromArray returns a traversal from an array for the identity [Monoid]
 func FromArray[E, A any](m M.Monoid[E]) G.Traversal[[]A, A, C.Const[E, []A], C.Const[E, A]] {
 	return AR.FromArray[[]A, E, A](m)
 }

option/gen.go

@@ -1,6 +1,6 @@
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-09-12 13:44:34.2077257 +0200 CEST m=+0.023541001
+// 2023-10-23 08:31:07.8687134 +0200 CEST m=+0.012222901
 
 package option
 

option/option.go

@@ -82,6 +82,10 @@ func Fold[A, B any](onNone func() B, onSome func(a A) B) func(ma Option[A]) B {
 	}
 }
 
+func MonadGetOrElse[A any](fa Option[A], onNone func() A) A {
+	return MonadFold(fa, onNone, F.Identity[A])
+}
+
 func GetOrElse[A any](onNone func() A) func(Option[A]) A {
 	return Fold(onNone, F.Identity[A])
 }

reader/gen.go

@@ -1,6 +1,6 @@
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-09-12 13:44:36.1655251 +0200 CEST m=+0.010000501
+// 2023-10-23 08:31:13.0131834 +0200 CEST m=+0.010996501
 
 package reader
 

reader/generic/gen.go

@@ -1,6 +1,6 @@
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-09-12 13:44:36.166526 +0200 CEST m=+0.011001401
+// 2023-10-23 08:31:13.0131834 +0200 CEST m=+0.010996501
 package generic
 
 // From0 converts a function with 1 parameters returning a [R] into a function with 0 parameters returning a [GRA]

readereither/sequence_test.go

@@ -25,58 +25,58 @@ import (
 )
 
 var (
-	testError = fmt.Errorf("error")
+	errFoo = fmt.Errorf("error")
 )
 
 func TestSequenceT1(t *testing.T) {
 
 	t1 := Of[MyContext, error]("s1")
-	e1 := Left[MyContext, string](testError)
+	e1 := Left[MyContext, string](errFoo)
 
 	res1 := SequenceT1(t1)
 	assert.Equal(t, E.Of[error](T.MakeTuple1("s1")), res1(defaultContext))
 
 	res2 := SequenceT1(e1)
-	assert.Equal(t, E.Left[T.Tuple1[string]](testError), res2(defaultContext))
+	assert.Equal(t, E.Left[T.Tuple1[string]](errFoo), res2(defaultContext))
 }
 
 func TestSequenceT2(t *testing.T) {
 
 	t1 := Of[MyContext, error]("s1")
-	e1 := Left[MyContext, string](testError)
+	e1 := Left[MyContext, string](errFoo)
 	t2 := Of[MyContext, error](2)
-	e2 := Left[MyContext, int](testError)
+	e2 := Left[MyContext, int](errFoo)
 
 	res1 := SequenceT2(t1, t2)
 	assert.Equal(t, E.Of[error](T.MakeTuple2("s1", 2)), res1(defaultContext))
 
 	res2 := SequenceT2(e1, t2)
-	assert.Equal(t, E.Left[T.Tuple2[string, int]](testError), res2(defaultContext))
+	assert.Equal(t, E.Left[T.Tuple2[string, int]](errFoo), res2(defaultContext))
 
 	res3 := SequenceT2(t1, e2)
-	assert.Equal(t, E.Left[T.Tuple2[string, int]](testError), res3(defaultContext))
+	assert.Equal(t, E.Left[T.Tuple2[string, int]](errFoo), res3(defaultContext))
 }
 
 func TestSequenceT3(t *testing.T) {
 
 	t1 := Of[MyContext, error]("s1")
-	e1 := Left[MyContext, string](testError)
+	e1 := Left[MyContext, string](errFoo)
 	t2 := Of[MyContext, error](2)
-	e2 := Left[MyContext, int](testError)
+	e2 := Left[MyContext, int](errFoo)
 	t3 := Of[MyContext, error](true)
-	e3 := Left[MyContext, bool](testError)
+	e3 := Left[MyContext, bool](errFoo)
 
 	res1 := SequenceT3(t1, t2, t3)
 	assert.Equal(t, E.Of[error](T.MakeTuple3("s1", 2, true)), res1(defaultContext))
 
 	res2 := SequenceT3(e1, t2, t3)
-	assert.Equal(t, E.Left[T.Tuple3[string, int, bool]](testError), res2(defaultContext))
+	assert.Equal(t, E.Left[T.Tuple3[string, int, bool]](errFoo), res2(defaultContext))
 
 	res3 := SequenceT3(t1, e2, t3)
-	assert.Equal(t, E.Left[T.Tuple3[string, int, bool]](testError), res3(defaultContext))
+	assert.Equal(t, E.Left[T.Tuple3[string, int, bool]](errFoo), res3(defaultContext))
 
 	res4 := SequenceT3(t1, t2, e3)
-	assert.Equal(t, E.Left[T.Tuple3[string, int, bool]](testError), res4(defaultContext))
+	assert.Equal(t, E.Left[T.Tuple3[string, int, bool]](errFoo), res4(defaultContext))
 }
 
 func TestSequenceT4(t *testing.T) {

readerioeither/gen.go

@@ -1,6 +1,6 @@
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-09-12 13:44:37.5566477 +0200 CEST m=+0.009011201
+// 2023-10-23 08:31:16.2414489 +0200 CEST m=+0.013052301
 
 package readerioeither
 

readerioeither/generic/gen.go

@@ -1,6 +1,6 @@
 // Code generated by go generate; DO NOT EDIT.
 // This file was generated by robots at
-// 2023-09-12 13:44:37.5566477 +0200 CEST m=+0.009011201
+// 2023-10-23 08:31:16.241979 +0200 CEST m=+0.013582401
 package generic
 
 import (

record/generic/record.go

@@ -99,6 +99,14 @@ func Collect[M ~map[K]V, GR ~[]R, K comparable, V, R any](f func(K, V) R) func(M
 	return F.Bind2nd(collect[M, GR, K, V, R], f)
 }
 
+func CollectOrd[M ~map[K]V, GR ~[]R, K comparable, V, R any](o ord.Ord[K]) func(f func(K, V) R) func(M) GR {
+	return func(f func(K, V) R) func(M) GR {
+		return func(r M) GR {
+			return collectOrd[M, GR](o, r, f)
+		}
+	}
+}
+
 func Reduce[M ~map[K]V, K comparable, V, R any](f func(R, V) R, initial R) func(M) R {
 	return func(r M) R {
 		return G.Reduce(r, f, initial)