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yap-6.3/Logtalk/library/natural.lgt
pmoura 75392e54c7 Logtalk 2.15.0 release files.
git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@757 b08c6af1-5177-4d33-ba66-4b1c6b8b522a
2003-02-05 00:15:28 +00:00

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:- object(natural,
extends(integer)).
:- info([
version is 1.0,
author is 'Paulo Moura',
date is 2000/7/24,
comment is 'Natural numbers data type predicates.']).
between(Lower, Upper, Integer) :-
integer(Lower),
Lower > 0,
^^between(Lower, Upper, Integer).
valid(Natural) :-
integer(Natural),
Natural > 0.
:- end_object.