fix: add samples for Any and Next to iterator package (#78)

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

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.Fold(F.ConstFalse, F.Constant1[U](true)),
+	)
+}

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)
-		next, ok = O.Unwrap(next.F1())
+		current = f(current, Current(next))
+		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)
-			return O.MonadFold(f(t.F2), r, F.Flow2(
+			r := recurse(Next(t))
+			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]]()

test.bat

@@ -1,3 +1,3 @@
 @echo off
 mkdir build 2> NUL
-gotip test .\... && go1.20.5 test .\... && go test -v -coverprofile build/cover.out -coverpkg=./... -covermode=atomic .\...
+gotip test .\... && go1.20.11 test .\... && go test -v -coverprofile build/cover.out -coverpkg=./... -covermode=atomic .\...