michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: // The Y combinator, applied to the factorial function
michael@0: 
michael@0: // Return the function that is the fixed point of f.
michael@0: var Y = f => (x => f(v => x(x)(v)))
michael@0:              (x => f(v => x(x)(v)));
michael@0: 
michael@0: // The factorial function is the fixed point of this:
michael@0: var f = fac => n => (n <= 1) ? 1 : n * fac(n - 1);
michael@0: 
michael@0: print("5! is " + Y(f)(5));