<?php

namespace PhatCats\ObjectTypeclass;

trait ObjectTraversable {

/**

* @param $f A callable of a single parameter that returns some Monad.

* @param $monad (Monad) An instance of the desired context. This Monad

* should be of the same type as that returned by $f. This Monad can

* be any value of a given Monad (e.g., can be `Nothing` or `Just` in

* the case that a `Maybe` is desired); it is only used so that the

* appropriate implementation of `pure` may be called.

* @return A single "wrapped" array whose elements are the same type as

* those wrapped by the return value of $f.

*/

abstract function traverse(callable $f, $monad);

/**

* @param $monad (Monad) An instance of the desired context. This Monad

* should be of the same type as the implementor of `sequence`. This

* Monad can be any value of a given Monad (e.g., can be `Nothing`

* or `Just` in the case that a `Maybe` is desired); it is only used

* so that the appropriate implementation of `pure` may be called.

* @return A single "wrapped" array whose elements are the same type as

* those wrapped by the elements of the input array.

*/

function sequence($monad) {

$id = function ($i) { return $i; };

return $this->traverse($id, $monad);

}

}