array-monad.js

var apply = Function.prototype.apply;
var flatten = apply.bind([].concat, []);

Array.of = function (a) {
	return [a];
};

Array.prototype.chain = function (f) {
	return flatten(this.map(f));
};

function liftA2(f) {
	return function (a, b) {
		return a.chain(function (left) {
			return b.chain(function (right) {
				return a.constructor.of(f(left, right));
			});
		});
	};
};

var couples = liftA2(function (dude, dudette) {
	return dude + ' + ' + dudette;
})(
	['jon', 'jacob', 'jim'],
	['rachel', 'rebecca', 'rowena']
);


console.log(couples); // every male/female pairing