title: array_map on collection with array interfaces?
body: <p>I have a class called <code>Collection</code> which stores objects of same type.
  <code>Collection</code> implements array interfaces: <code>Iterator</code>, <code>ArrayAccess</code>, <code>SeekableIterator</code>, and <code>Countable</code>.</p>
  
  <p>I'd like to pass a <code>Collection</code> object as the array argument to the <a href="http://php.net/manual/en/function.array-map.php" rel="noreferrer"><code>array_map</code></a> function. But this fails with the error</p>
  
  <blockquote>
    <p>PHP Warning:  array_map(): Argument #2 should be an array</p>
  </blockquote>
  
  <p>Can I achieve this by implementing other/more interfaces, so that <code>Collection</code> objects are seen as arrays?</p>