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SketchyLISP
Reference
  Copyright (C) 2006
Nils M Holm

zero?

Conformance: R5RS

Purpose: Test a number for being zero.

Arguments:
X - number

Model:

(define (zero? x)
  (= x 0))

Implementation:

(define (zero? x)
  (letrec
    ((zerop (lambda (list-x)
      (cond ((eq? (car list-x) 0d)
          (null? (cdr list-x)))
        (#t (= x 0))))))
    (zerop (integer->list x))))

Example:

(zero? 0) 
=> #t

See also:
digits, even?, negative?, positive?.