var match = function (...vals) {
	return {
		when(...args) {
			var patterns = _(args).dropRight().take(vals.length);
			var values = _(vals).take(args.length-1);

			var satisfy = patterns
					.zip(values.value())
					.every(([p,v]) => p(v));

			if (satisfy) {
				this.result = _.last(args);
				this.when = function () { return this; }
			}
			return this;
		},
		done () {
			return this.result;
		},
	}
}

var m = function(n) { return (x => x > n) };
var e = function(n) { return (x => x == n) };
var t = match(0,1,2)
	.when(m(0), e(1), e(2), 'a')
	.when(e(0), e(1),		'b')
	.when(e(0), e(1), e(2), 'c')
	.done()
console.log(t);