t3x.org / sketchy / library / naturalp.html
SketchyLISP
Reference
  Copyright (C) 2007
Nils M Holm

natural?

Conformance: SketchyLISP Core

Purpose: Test whether a number is a natural number or zero.

Implementation:

(define natural? non-negative?)

Example:

(natural? 567) 
=> #t

See also:
digits, natural, integer?.