Possible PHP data-structure outline

<?php
/**
 * The purpose of this document is to brainstorm a possible inheritance scheme
 * usable for a new set of PHP data-structures.  It is by no means final.
 */
namespace Spl;

/**
 * By Collection, we do not mean the same thing as a Java collection. It is
 * simply a name by which we can give generic properties to.
 *
 *
 */
interface Collection extends \Countable, \Iterator, \Serializable {
    function clear();
    function contains($item);
    function isEmpty();
}

interface Vector extends Collection, \ArrayAccess {

}

class ArrayList implements Vector {

}

class LinkedList implements Vector {

}

class Stack implements \Collection  {

    function peek();
    function pop();
    function push($item);

}

?>