/** @license MIT License (c) copyright 2010-2014 original author or authors */
/** @author Brian Cavalier */
/** @author John Hann */
/** @author Jeff Escalante */

(function(define) { 'use strict';
define(function() {

	return function fold(Promise) {

		Promise.prototype.fold = function(f, z) {
			var promise = this._beget();

			this._handler.fold(function(z, x, to) {
				Promise._handler(z).fold(function(x, z, to) {
					to.resolve(f.call(this, z, x));
				}, x, this, to);
			}, z, promise._handler.receiver, promise._handler);

			return promise;
		};

		return Promise;
	};

});
}(typeof define === 'function' && define.amd ? define : function(factory) { module.exports = factory(); }));