feat(all): add type-narrowing signature

Author: djcsdy

index.test.ts

@@ -328,6 +328,18 @@ test("any", t => {
 test("all", t => {
     t.true(all([1, 2, 3], e => e < 4));
     t.false(all([1, 2, 3], e => e > 2));
+
+    const mixed1: Array<string | number> = [1, 2, "hello", 3, "goodbye"];
+    const mixed2: Array<string | number> = [1, 2, 3];
+
+    const acceptNumbers = (array: readonly number[]): boolean => true;
+    const isNumber = (v: unknown): v is number => typeof v === "number";
+
+    t.false(all(mixed1, isNumber));
+    t.true(all(mixed2, isNumber));
+
+    t.false(all(mixed1, isNumber) ? acceptNumbers(mixed1) : false);
+    t.true(all(mixed2, isNumber) ? acceptNumbers(mixed2) : false);
 });
 
 test("concat", t => {

index.ts

@@ -665,13 +665,31 @@ export function anyFn<T>(
     return array => any(array, predicate);
 }
 
+export function all<T, U extends T>(
+    array: readonly T[],
+    predicate: (element: T, index: number) => element is U
+): array is readonly U[];
+export function all<T, U extends T>(
+    array: ArrayLike<T>,
+    predicate: (element: T, index: number) => element is U
+): array is ArrayLike<U>;
+export function all<T>(
+    array: ArrayLike<T>,
+    predicate: (element: T, index: number) => boolean
+): boolean;
 export function all<T>(
     array: ArrayLike<T>,
     predicate: (element: T, index: number) => boolean
 ): boolean {
     return !any(array, (element, index) => !predicate(element, index));
 }
 
+export function allFn<T, U extends T>(
+    predicate: (element: T, index: number) => element is U
+): (array: ArrayLike<T>) => array is ArrayLike<U>;
+export function allFn<T>(
+    predicate: (element: T, index: number) => boolean
+): (array: ArrayLike<T>) => boolean;
 export function allFn<T>(
     predicate: (element: T, index: number) => boolean
 ): (array: ArrayLike<T>) => boolean {