Y combinator in various Lisps

y-combinator-common-lisp.lisp

(defun factorial-y-combinator (n)
  (funcall
   (Y (lambda (f n)
	(if (zerop n)
	    1
	    (* n (funcall f f (1- n))))))
   n))

(defun tail-factorial-y-combinator (n)
  (funcall
   (Y (lambda (f n acc)
	(if (zerop n)
	    acc
	    (funcall f f (1- n) (* n acc)))))
   n 1))

(defun Y (proc)
  (lambda (&rest arg)
    (apply proc proc arg)))

y-combinator-elisp.el

;; -*- lexical-binding: t -*-

(cl-defun Y (proc)
  (lambda (&rest arg)
    (apply proc proc arg)))

(cl-defun factorial-y-combinator (n)
  (funcall
   (Y (lambda (f n)
	(if (zerop n)
	    1
	  (* n (funcall f f (1- n))))))
   n))

(cl-defun tail-factorial-y-combinator (n)
  (funcall
   (Y (lambda (f n acc)
	(if (zerop n)
	    acc
	  (funcall f f (1- n) (* n acc)))))
   n 1))

y-combinator-guile.scm

(define (Y proc)
  (lambda (. arg)
    (apply proc proc arg)))

(define (factorial-y-combinator n)
  ((Y (lambda (f n)
	(if (zero? n)
	  1
	  (* n (f f (- n 1)))))) n))

(define (tail-factorial-y-combinator n acc)
  ((Y (lambda (f n acc)
	(if (zero? n)
	  acc
	  (f f (- n 1) (* n acc))))) n acc))