test.php

<?php

require_once __DIR__.'/../vendor/autoload.php';

use Amp\Loop;

Loop::run(function () {
    $messages = [];

    function receive(&$messages) {
        // static $reader;
        if (empty($messages)) {
            yield new \Amp\Success();
        }

        foreach ($messages as $message) {
            yield new \Amp\Success($message);
        }

        // $reader = new \Amp\Deferred();
        // return $reader->promise();

        $messages = [];
    }

    $message = yield receive($messages);

    if (null !== $message) {
        echo "New message $message\n";
    }

    Loop::delay(1000, function () use (&$messages) {
        $messages[] = 'Hello';
        $messages[] = 'the';
        $messages[] = 'world';
    });

    Loop::delay(5000, function () use (&$messages) {
        $messages[] = 'More';
        $messages[] = 'new';
        $messages[] = 'messages';
    });

    Loop::delay(5500, function () use (&$messages) {
        $messages[] = 'ang';
        $messages[] = 'again';
        $messages[] = 'me';
    });
});