yield_simple.php

<?php

/**
 * PHP 5.5.16 (cli) (built: Apr  1 2015 22:23:30)
 * Copyright (c) 1997-2014 The PHP Group
 * Zend Engine v2.5.0, Copyright (c) 1998-2014 Zend Technologies
 *     with Zend OPcache v7.0.4-dev, Copyright (c) 1999-2014, by Zend Technologies
 *     with Xdebug v2.2.5, Copyright (c) 2002-2014, by Derick Rethans
 */

function y() {
    foreach (range(0, 3) as $value) {
        yield $value;
    }
}

foreach (y() as $value) {
    echo $value . ' ';
}

#=> 0 1 2 3