Add erase function (#2641)

src/prelude/array.ts

@@ -13,3 +13,7 @@ export function concat<T>(xss: T[][]): T[] {
 export function intersperse<T>(sep: T, xs: T[]): T[] {
 	return concat(xs.map(x => [sep, x])).slice(1);
 }
+
+export function erase<T>(x: T, xs: T[]): T[] {
+	return xs.filter(y => x !== y);
+}