fork(1) download
copy 
  1. ; casting out nines
  2.  
  3. (define-syntax assert
  4.   (syntax-rules ()
  5.     ((assert expr result)
  6.       (if (not (equal? expr result))
  7.           (for-each display `(
  8.             #\newline "failed assertion:" #\newline
  9.             expr #\newline "expected: " ,result
  10.             #\newline "returned: " ,expr #\newline))))))
  11.  
  12. (define (nines n)
  13.   (let loop ((n n) (s 0))
  14.     (if (< 0 n)
  15.         (let ((q (quotient n 10))
  16.               (r (remainder n 10)))
  17.           (loop q (+ r s)))
  18.         (if (< 9 s) (nines s)
  19.           (if (= 9 s) 0 s)))))
  20.  
  21. (display (do ((n 0 (+ n 1))) ((= n 1000) 'done)
  22.     (assert (nines n) (modulo n 9))))
  23. (newline)
  24.  
  25. (display
  26.   (= (nines (+ (nines  3074)
  27.                (nines  6017)
  28.                (nines 13814)
  29.                (nines  1810)
  30.                (nines    27)
  31.                (nines  3611)))
  32.      (nines           28353)))
Success #stdin #stdout 0.06s 43488KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
done
#t
https://ideone.com/sWqNxO
language:
Scheme (guile 2.2.4)
created:
6 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!