php collections interfaces

List.php

<?php

/**
 * An ordered collection.
 *
 * could call it "Sequence"
 *
 * @generic V
 */
interface List extends Collection {
  /**
   * or nth, getNth, ...
   *
   * @param int $index
   *
   * @return V
   */
  function getAt($index);

  /** @return V */
  function last();
}

Map.php

<?php

/**
 * A collection where each item has a key.
 * 
 * aka Dictionary
 *
 * @generics K, V 
 */
interface Map extends Collection {
  /**
   * @param K $key
   *
   * @return V
   */
  function get($key);

  /** @return Set<K> */
  function keys();
}

Queue.php

<?php

/**
 * Typically FIFO, but could be implemented
 * as LIFO to make a Stack.
 */
interface Queue extends List {
  /** @return T */
  function peek();

  /** @return T */
  function pop();

  /** @param T $item */
  function push($item);
}