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jiamo/Ycombinator1.rkt

Last active September 20, 2018 10:43
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Ycombinator1
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Ycombinator1.rkt
#lang racket
(define (factorial n)
(if (= n 0)
1
(* n (factorial (- n 1)))))
(define factorial_lambda
(lambda (n)
(if (= n 0)
1
(* n (factorial_lambda (- n 1))))))
(define almost-factorial
(lambda (f)
(lambda (n)
(if (= n 0)
1
(* n ((f f) (- n 1))))))) ;; the (f f) is so important to understand
(define sort-of-factorial
(lambda (n)
(if (= n 0)
1
(* n ((almost-factorial almost-factorial) (- n 1))))))
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