cho45 / jsenumerator

JSEnumerator

A light-weight library for list or enumeration.

Download

• https://raw.github.com/cho45/jsenumerator/master/jsenumerator.js

License

MIT. See header of https://raw.github.com/cho45/jsenumerator/master/jsenumerator.js

Concept

• Do not taint global.
• Infinite list functions like MochiKit.
• Enumeration method chain like Ruby 1.9.

Using method chain for generating sequence has advantages over nesting function call for writing as you think.

Sample

FizzBuzz

// normal
fizzbuzz  = E(1).countup().imap(function (i) {
	return (i % 3 == 0) ? (i % 5 == 0) ? "FizzBuzz" : "Fizz" :
						  (i % 5 == 0) ? "Buzz"     :      i ;
}).take(20);

// take some values from pre-defined sequence
fizzbuzz = E(1)
	.countup()
	.izip(
		E(["", "", "Fizz"]).cycle(),
		E(["", "", "", "", "Buzz"]).cycle())
	.imap(function (num, fizz, buzz) {
		return fizz + buzz || num;
	})
	.take(20);

with JSDeferred

function fib () {
	var p = 0, i = 1;
	return E([0, 1]).chain(E(function () {
		var ret = p + i;
		p = i;
		i = ret;
		return ret;
	}));
}

Enumerator.prototype.dloop = function (fun, n) {
	var enum = this;
	if (!n) n = 1;
	return next(function () {
		for (var  i = 0; i < n; i++) {
			fun.call(enum, enum.next());
		}
		return call(arguments.callee);
	}).error(function (e) {
		if (e != Enumerator.StopIteration) throw e;
	});
};

fib().itake(100).dloop(function (i) {
	log(i);
});