ycombinator.js

  (function (f) {
    return (function (g) {
      return g(g);
    })(function(h) {
      return f(function () {
        return (h(h)).apply(this, arguments);
      });
    });
  })(function(f) {
    return function (n) {
      return n === 0 ? 1 : n * f(n-1);
    };
  })(5)