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; Copyright (c) 1993-2008 by Richard Kelsey. See file COPYING.
(xodd? 10)
(xodd? 5)
(define-local-syntax (define-primitive id nargs)
(let ((args (reverse (list-tail '(z y x) (- '3 nargs)))))
`(define (,id . ,args)
(call-primitively ,id . ,args))))
(define-primitive + 2)
(define-primitive - 2)
(define-primitive * 2)
(define-primitive < 2)
(define-primitive = 2)
(define (xodd? x)
(cond ((= 0 x)
#f)
((< 100 x) ; efficiency hack
(goto odd? (- x 100)))
((< 1000 x) ; efficiency hack
(goto xodd? (- x 100)))
(else
(goto xeven? (- x 1)))))
(define (xeven? x)
(cond ((= 0 x)
#t)
((< 100 x) ; efficiency hack
(goto xeven? (- x 100)))
(else
(goto xodd? (- x 1)))))
(define (odd? x)
(cond ((= 0 x)
#f)
((< 100 x) ; efficiency hack
(goto odd? (- x 100)))
(else
(goto even? (- x 1)))))
(define (even? x)
(cond ((= 0 x)
#t)
((< 100 x) ; efficiency hack
(goto even? (- x 100)))
(else
(goto odd? (- x 1)))))
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