ft: filter, map and reduce arrays

arrays/arrays.go

@@ -0,0 +1,49 @@
+package arrays
+
+// Filter returns a new array with all elements that pass the test implemented by the provided function.
+func Filter[S ~[]E, E any](items S, fn func(E) bool) []E {
+	filteredItems := []E{}
+	for _, value := range items {
+		if fn(value) {
+			filteredItems = append(filteredItems, value)
+		}
+	}
+	return filteredItems
+}
+
+// Find returns the value of the first element in the provided array that satisfies the provided testing function.
+func Find[S ~[]E, E any](items S, fn func(E) bool) E {
+	var item E
+	for _, value := range items {
+		if fn(value) {
+			return value
+		}
+	}
+	return item
+}
+
+// Map returns a new array with the results of calling a provided function on every element in the provided array.
+func Map[S, T any](items []S, fn func(S) T) []T {
+	mappedItems := []T{}
+	for _, value := range items {
+		mappedItems = append(mappedItems, fn(value))
+	}
+	return mappedItems
+}
+
+// MapIndex returns a new array with the results of calling a provided function on every element in the provided array.
+func MapIndex[S, T any](items []S, fn func(S, int) T) []T {
+	mappedItems := []T{}
+	for index, value := range items {
+		mappedItems = append(mappedItems, fn(value, index))
+	}
+	return mappedItems
+}
+
+// Reduce applies a function against an accumulator and each element in the array (from left to right) to reduce it to a single value.
+func Reduce[S, T any](items []S, fn func(T, S) T, acc T) T {
+	for _, value := range items {
+		acc = fn(acc, value)
+	}
+	return acc
+}