Merge from vscode cfc1ab4c5f816765b91fb7ead3c3427a7c8581a3

src/vs/base/common/iterator.ts

@@ -34,6 +34,28 @@ export interface NativeIterator<T> {
 	next(): NativeIteratorResult<T>;
 }
 
+export namespace Iterable {
+
+	export function first<T>(iterable: Iterable<T>): T | undefined {
+		return iterable[Symbol.iterator]().next().value;
+	}
+
+	export function some<T>(iterable: Iterable<T>, predicate: (t: T) => boolean): boolean {
+		for (const element of iterable) {
+			if (predicate(element)) {
+				return true;
+			}
+		}
+		return false;
+	}
+
+	export function* map<T, R>(iterable: Iterable<T>, fn: (t: T) => R): IterableIterator<R> {
+		for (const element of iterable) {
+			return yield fn(element);
+		}
+	}
+}
+
 export module Iterator {
 	const _empty: Iterator<any> = {
 		next() {