Initial project import

tools/v/vlib/arrays/arrays_fold_test.v

@@ -0,0 +1,41 @@
+import arrays
+
+type MyInt = int
+
+interface FoldCyclable {
+	id() int
+}
+
+struct FoldWheel {
+	v int
+}
+
+fn (w FoldWheel) id() int {
+	return w.v
+}
+
+fn test_main() {
+	assert arrays.fold[int, []int]([1, 2, 3, 4], []int{}, fn (r []int, t int) []int {
+		return arrays.merge(r, [t])
+	}) == [1, 2, 3, 4]
+	assert arrays.fold[string, []string](['a', 'b', 'c', 'd'], []string{}, fn (r []string, t string) []string {
+		return arrays.merge(r, [t])
+	}) == ['a', 'b', 'c', 'd']
+	assert arrays.fold[bool, []bool]([true, false], []bool{}, fn (r []bool, t bool) []bool {
+		return arrays.merge(r, [t])
+	}) == [false, true]
+	assert arrays.fold[MyInt, []MyInt]([MyInt(0), 1], []MyInt{}, fn (r []MyInt, t MyInt) []MyInt {
+		return arrays.merge(r, [t])
+	}) == [MyInt(0), 1]
+	assert arrays.fold([1, 2, 3, 4], [5, 6, 7], fn (r []int, t int) []int {
+		return r.map(it * t)
+	}) == [120, 144, 168]
+}
+
+fn test_fold_with_interface_accumulator() {
+	items := [FoldWheel{1}, FoldWheel{2}]
+	result := arrays.fold[FoldWheel, FoldCyclable](items, FoldCyclable(FoldWheel{}), fn (_ FoldCyclable, elem FoldWheel) FoldCyclable {
+		return elem
+	})
+	assert result.id() == 2
+}