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Tip revision: ea85ae35d79208706f668005cde77c98f1365826 authored by Mozilla Releng Treescript on 17 September 2024, 12:46:51 UTC
No bug - Tagging 2f6d80ae5a069caeed2c79987422bfae1d8facc3 with FIREFOX_130_0_1_RELEASE a=release CLOSED TREE DONTBUILD
Tip revision: ea85ae3
Y.js
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

// The Y combinator, applied to the factorial function.

// Return the function that is the fixed point of f.
const Y = f => (x => f(v => x(x)(v)))
               (x => f(v => x(x)(v)));

// The factorial function is the fixed point of this:
const f = fac => n => (n <= 1) ? 1 : n * fac(n - 1);

print(`5! is ${Y(f)(5)}`);
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