Merge pull request #4 from N8Brooks/optional_permutations_r

fix(permutations): allow r to not be passed

Author: N8Brooks

permutations.ts

@@ -21,7 +21,7 @@
  */
 export function* permutations<T>(
   iterable: Iterable<T>,
-  r: number | undefined,
+  r?: number,
 ): Generator<T[]> {
   const pool = Array.from(iterable);
   const n = pool.length;

permutations_test.ts

@@ -76,12 +76,12 @@ Deno.test("n = r", () => {
 });
 
 Deno.test("r = undefined (0)", () => {
-  const actual = [...permutations("", undefined)];
+  const actual = [...permutations("")];
   assertEquals(actual, [[]]);
 });
 
 Deno.test("r = undefined (n)", () => {
-  const actual = [...permutations("abc", undefined)];
+  const actual = [...permutations("abc")];
   const expected = [
     ["a", "b", "c"],
     ["a", "c", "b"],