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(defun Y (f)
(funcall
(lambda (g) (funcall g g))
(lambda (h)
(funcall f (lambda args (apply (funcall h h) args))))))
(defun fibo-impl (self)
(lambda (n)
(if (<= n 2)
1
(+ (funcall self (- n 1)) (funcall self (- n 2))))))
(defvar fibo (Y #'fibo-impl))
(assert (= 55 (funcall fibo 10)))
(defun generate-counter (init)
(let ((i init))
(lambda ()
(setq i (+ 1 i))
i)))
(let ((c (generate-counter 0)))
(assert (= 1 (funcall c)))
(assert (= 2 (funcall c)))
(assert (= 3 (funcall c))))
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