Language Wars - Church numerals - Scheme

languagewars-churchnumerals-scheme.scm

(define suc (lambda (a) (lambda (b) (lambda (c) (b ((a b) c))))))
(define add (lambda (a) (lambda (b) (lambda (c) (lambda (d) ((a c) ((b c) d)))))))
(define mul (lambda (a) (lambda (b) (lambda (c) (a (b c))))))
(define exp (lambda (a) (lambda (b) (b a))))
(define pre (lambda (a) (lambda (b) (lambda (c)
  (((a (lambda (d) (lambda (e) (e (d b))))) (lambda (f) c)) (lambda (g) g))))))
(define sub (lambda (a) (lambda (b) ((b pre) a))))
(define ntc (lambda (n) (if (> n 0)
  (lambda (a) (lambda (b) (a (((ntc (- n 1)) a) b))))
  (lambda (a) (lambda (b) b)))))
(define ctn (lambda (a) ((a (lambda (x) (+ x 1))) 0)))

More info: https://github.com/rsp/languagewars-churchnumerals-scheme