Feedback update

lib/Internal/EmitSource.php

@@ -21,6 +21,9 @@ use React\Promise\PromiseInterface as ReactPromise;
  */
 final class EmitSource
 {
+    /** @var Success */
+    private static $success;
+
     /** @var Promise|null */
     private $result;
 
@@ -61,7 +64,7 @@ final class EmitSource
      */
     public function continue(): Promise
     {
-        return $this->next(new Success);
+        return $this->next(self::$success ?? (self::$success = new Success));
     }
 
     /**

lib/functions.php

@@ -714,50 +714,13 @@ namespace Amp\Iterator
             }
         }
 
-        $emitter = new Emitter;
+        return new Producer(function (callable $emit) use ($iterators) {
-        $previous = [];
+            foreach ($iterators as $iterator) {
-        $promise = Promise\all($previous);
-
-        $coroutine = coroutine(static function (Iterator $iterator, callable $emit) {
                 while (yield $iterator->advance()) {
                     yield $emit($iterator->getCurrent());
                 }
+            }
         });
-
-        foreach ($iterators as $iterator) {
-            $emit = coroutine(static function ($value) use ($emitter, $promise) {
-                static $pending = true, $failed = false;
-
-                if ($failed) {
-                    return;
-                }
-
-                if ($pending) {
-                    try {
-                        yield $promise;
-                        $pending = false;
-                    } catch (\Throwable $exception) {
-                        $failed = true;
-                        return; // Prior iterator failed.
-                    }
-                }
-
-                yield $emitter->emit($value);
-            });
-            $previous[] = $coroutine($iterator, $emit);
-            $promise = Promise\all($previous);
-        }
-
-        $promise->onResolve(static function ($exception) use ($emitter) {
-            if ($exception) {
-                $emitter->fail($exception);
-                return;
-            }
-
-            $emitter->complete();
-        });
-
-        return $emitter->iterate();
     }
 
     /**
@@ -840,6 +803,7 @@ namespace Amp\Stream
     use Amp\Promise;
     use Amp\Stream;
     use Amp\StreamSource;
+    use React\Promise\PromiseInterface as ReactPromise;
     use function Amp\call;
     use function Amp\coroutine;
     use function Amp\Internal\createTypeError;
@@ -869,18 +833,17 @@ namespace Amp\Stream
             throw createTypeError(["array", "Traversable"], $iterable);
         }
 
-        if ($delay) {
         return new AsyncGenerator(static function (callable $yield) use ($iterable, $delay) {
             foreach ($iterable as $value) {
+                if ($delay) {
                     yield new Delayed($delay);
-                    yield $yield($value instanceof Promise ? yield $value : $value);
-                }
-            });
                 }
 
-        return new AsyncGenerator(static function (callable $yield) use ($iterable) {
+                if ($value instanceof Promise || $value instanceof ReactPromise) {
-            foreach ($iterable as $value) {
+                    $value = yield $value;
-                yield $yield($value instanceof Promise ? yield $value : $value);
+                }
+
+                yield $yield($value);
             }
         });
     }
@@ -988,50 +951,13 @@ namespace Amp\Stream
             }
         }
 
-        $source = new StreamSource;
+        return new AsyncGenerator(function (callable $emit) use ($streams) {
-        $previous = [];
+            foreach ($streams as $stream) {
-        $promise = Promise\all($previous);
+                while ($value = yield $stream->continue()) {
-
+                    yield $emit($value);
-        $coroutine = coroutine(static function (Stream $stream, callable $yield) {
+                }
-            while (null !== $value = yield $stream->continue()) {
-                yield $yield($value);
             }
         });
-
-        foreach ($streams as $iterator) {
-            $emit = coroutine(static function ($value) use ($source, $promise) {
-                static $pending = true, $failed = false;
-
-                if ($failed) {
-                    return;
-                }
-
-                if ($pending) {
-                    try {
-                        yield $promise;
-                        $pending = false;
-                    } catch (\Throwable $exception) {
-                        $failed = true;
-                        return; // Prior iterator failed.
-                    }
-                }
-
-                yield $source->emit($value);
-            });
-            $previous[] = $coroutine($iterator, $emit);
-            $promise = Promise\all($previous);
-        }
-
-        $promise->onResolve(static function ($exception) use ($source) {
-            if ($exception) {
-                $source->fail($exception);
-                return;
-            }
-
-            $source->complete();
-        });
-
-        return $source->stream();
     }
 
     /**