fix: add Zip and ZipWith to iterators

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

array/generic/zip.go

@@ -0,0 +1,52 @@
+// Copyright (c) 2023 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package generic
+
+import (
+	F "github.com/IBM/fp-go/function"
+	N "github.com/IBM/fp-go/number"
+	T "github.com/IBM/fp-go/tuple"
+)
+
+// ZipWith applies a function to pairs of elements at the same index in two arrays, collecting the results in a new array. If one
+// input array is short, excess elements of the longer array are discarded.
+func ZipWith[AS ~[]A, BS ~[]B, CS ~[]C, FCT ~func(A, B) C, A, B, C any](fa AS, fb BS, f FCT) CS {
+	l := N.Min(len(fa), len(fb))
+	res := make(CS, l)
+	for i := l - 1; i >= 0; i-- {
+		res[i] = f(fa[i], fb[i])
+	}
+	return res
+}
+
+// Zip takes two arrays and returns an array of corresponding pairs. If one input array is short, excess elements of the
+// longer array are discarded
+func Zip[AS ~[]A, BS ~[]B, CS ~[]T.Tuple2[A, B], A, B any](fb BS) func(AS) CS {
+	return F.Bind23of3(ZipWith[AS, BS, CS, func(A, B) T.Tuple2[A, B]])(fb, T.MakeTuple2[A, B])
+}
+
+// Unzip is the function is reverse of [Zip]. Takes an array of pairs and return two corresponding arrays
+func Unzip[AS ~[]A, BS ~[]B, CS ~[]T.Tuple2[A, B], A, B any](cs CS) T.Tuple2[AS, BS] {
+	l := len(cs)
+	as := make(AS, l)
+	bs := make(BS, l)
+	for i := l - 1; i >= 0; i-- {
+		t := cs[i]
+		as[i] = t.F1
+		bs[i] = t.F2
+	}
+	return T.MakeTuple2(as, bs)
+}