feat(iterables): Reverse

Add reverse function for iterables.

re #4

Author: danielrbradley

src/iterables.ts

@@ -305,6 +305,13 @@ export function sortByDescending<T, Key>(a: any, b?: any): any {
   return partial ? exec : exec(a)
 }
 
+export function* reverse<T>(source: Iterable<T>): Iterable<T> {
+  const asArray = Array.from(source)
+  for (let index = asArray.length - 1; index >= 0; index--) {
+    yield asArray[index]
+  }
+}
+
 export function sumBy<T>(selector: (item: T) => number): (source: Iterable<T>) => number
 export function sumBy<T>(source: Iterable<T>, selector: (item: T) => number): number
 export function sumBy<T>(a: any, b?: any): any {

test/iterable.test.ts

@@ -560,6 +560,15 @@ describe('sortByDescending', () => {
   })
 })
 
+describe('reverse', () => {
+  test('empty iterable', () => {
+    expect(Iterables.toArray(Iterables.reverse([]))).toEqual([])
+  })
+  test('reversal', () => {
+    expect(Iterables.toArray(Iterables.reverse([8, 3, 5]))).toEqual([5, 3, 8])
+  })
+})
+
 describe('sumBy', () => {
   it('sums ages', () => {
     expect(