feat(future): add zip

jklmli · Apr 20, 2018 · 5314b36 · 5314b36
1 parent ace58d8
commit 5314b36
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diff --git a/src/future/future.ts b/src/future/future.ts
@@ -171,6 +171,10 @@ class Future<A> {
     );
   }
 
+  zip<B>(that: Future<B>): Future<[A, B]> {
+    return this.flatMap((value: A) => that.map((thatValue: B) => [value, thatValue] as [A, B]));
+  }
+
 }
 
 export { Future };
diff --git a/test/future/future.ts b/test/future/future.ts
@@ -195,3 +195,14 @@ test('Future#recoverWith', async(t: ExecutionContext) => {
 
   await t.throws(failure.recoverWith((e: Error): Future<string> => { throw error; }).promise);
 });
+
+test('Future#zip', async(t: ExecutionContext) => {
+  t.plan(3);
+
+  const value: Future<number> = Future.create(10);
+  const successfulZip: [string, number] = await success.zip(value).promise;
+  t.deepEqual(successfulZip, ['hello', 10]);
+
+  await t.throws(failure.zip(value).promise);
+  await t.throws(value.zip(failure).promise);
+});