Subtracting a number: `sub'

The expression $m - n$ is evaluated by decrementing $m$ $n$-times.

(define sub 
   (lambda (m n)
      ((n pred) m)))

(ndisp! (sub three two))
                             --> 1
(ndisp! (sub four two))
                             --> 2

Georg P. Loczewski 2004-03-05

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