Make async return a callable

src/functions.php

@@ -14,14 +14,13 @@
  * Execute an async Fiber-based function to "await" promises.
  *
  * @param callable(mixed ...$args):mixed $function
- * @param mixed ...$args Optional list of additional arguments that will be passed to the given `$function` as is
- * @return PromiseInterface<mixed>
+ * @return callable(): PromiseInterface<mixed>
  * @since 4.0.0
  * @see coroutine()
  */
-function async(callable $function, mixed ...$args): PromiseInterface
+function async(callable $function): callable
 {
- return new Promise(function (callable $resolve, callable $reject) use ($function, $args): void {
+ return static fn (mixed ...$args): PromiseInterface => new Promise(function (callable $resolve, callable $reject) use ($function, $args): void {
  $fiber = new \Fiber(function () use ($resolve, $reject, $function, $args): void {
  try {
  $resolve($function(...$args));

tests/AsyncTest.php

@@ -15,7 +15,7 @@ public function testAsyncReturnsPendingPromise()
  {
  $promise = async(function () {
  return 42;
- });
+ })();
 
  $promise->then($this->expectCallableNever(), $this->expectCallableNever());
  }
@@ -24,7 +24,7 @@ public function testAsyncReturnsPromiseThatFulfillsWithValueWhenCallbackReturns(
  {
  $promise = async(function () {
  return 42;
- });
+ })();
 
  $value = await($promise);
 
@@ -35,7 +35,7 @@ public function testAsyncReturnsPromiseThatRejectsWithExceptionWhenCallbackThrow
  {
  $promise = async(function () {
  throw new \RuntimeException('Foo', 42);
- });
+ })();
 
  $this->expectException(\RuntimeException::class);
  $this->expectExceptionMessage('Foo');
@@ -51,7 +51,7 @@ public function testAsyncReturnsPromiseThatFulfillsWithValueWhenCallbackReturnsA
  });
 
  return await($promise);
- });
+ })();
 
  $value = await($promise);
 
@@ -66,15 +66,15 @@ public function testAsyncReturnsPromiseThatFulfillsWithValueWhenCallbackReturnsA
  });
 
  return await($promise);
- });
+ })();
 
- $promise2 = async(function () {
- $promise = new Promise(function ($resolve) {
- Loop::addTimer(0.11, fn () => $resolve(42));
+ $promise2 = async(function (int $theAnswerToLifeTheUniverseAndEverything): int {
+ $promise = new Promise(function ($resolve) use ($theAnswerToLifeTheUniverseAndEverything): void {
+ Loop::addTimer(0.11, fn () => $resolve($theAnswerToLifeTheUniverseAndEverything));
  });
 
  return await($promise);
- });
+ })(42);
 
  $time = microtime(true);
  $values = await(all([$promise1, $promise2]));

tests/AwaitTest.php

@@ -160,6 +160,6 @@ public function testAwaitShouldNotCreateAnyGarbageReferencesForPromiseRejectedWi
  public function provideAwaiters(): iterable
  {
  yield 'await' => [static fn (React\Promise\PromiseInterface $promise): mixed => React\Async\await($promise)];
- yield 'async' => [static fn (React\Promise\PromiseInterface $promise): mixed => React\Async\await(React\Async\async(static fn(): mixed => $promise))];
+ yield 'async' => [static fn (React\Promise\PromiseInterface $promise): mixed => React\Async\await(React\Async\async(static fn(): mixed => $promise)())];
  }
 }