added filling and reduction to iterators

src/lib.ts

@@ -2,7 +2,7 @@
 export type { Arr, ClassOf, Constructible, Function, InstanceOf, KeyOfType, Tail } from "./lib/types.ts";
 
 // functions
-export { all, chunk, enumerate, filter, filter_map, it, Iter, map, window, zip } from "./lib/iter.ts";
+export { all, chunk, enumerate, fill, filter, filter_map, fold, it, Iter, map, window, zip } from "./lib/iter.ts";
 export { log_from, next, split_promise, wait } from "./lib/utils.ts";
 
 // Structures

src/lib/iter.ts

@@ -67,6 +67,16 @@ export function* window<T>(iter: Iterable<T>, size: number, incomplete = false):
 	}
 }
 
+export function* fill<I, O>(iter: Iterable<I>, value: O) {
+	for (const _item of iter) yield value;
+}
+
+export function fold<I, O>(iter: Iterable<I>, init: O, reduction: (item: I, acc: O) => O) {
+	let accumulator = init;
+	for (const item of iter) accumulator = reduction(item, accumulator);
+	return accumulator;
+}
+
 export class Iter<T> {
 	iter;
 	[Symbol.iterator] = () => this.iter[Symbol.iterator]();
@@ -121,6 +131,14 @@ export class Iter<T> {
 	all(predicate: (item: T) => boolean) {
 		return all(this, predicate);
 	}
+
+	fill<O>(value: O) {
+		return fill(this, value);
+	}
+
+	fold<O>(init: O, reduction: (item: T, acc: O) => O) {
+		return fold(this, init, reduction);
+	}
 }
 
 Deno.test("test_comon", async () => {