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/* 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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