%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  This file is part of Logtalk <https://logtalk.org/>
%  Copyright 1998-2021 Paulo Moura <pmoura@logtalk.org>
%  SPDX-License-Identifier: Apache-2.0
%
%  Licensed under the Apache License, Version 2.0 (the "License");
%  you may not use this file except in compliance with the License.
%  You may obtain a copy of the License at
%
%      http://www.apache.org/licenses/LICENSE-2.0
%
%  Unless required by applicable law or agreed to in writing, software
%  distributed under the License is distributed on an "AS IS" BASIS,
%  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%  See the License for the specific language governing permissions and
%  limitations under the License.
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%



:- object(natural,
	extends(integer)).

	:- info([
		version is 1:1:0,
		author is 'Paulo Moura',
		date is 2009-3-6,
		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.

	check(Term) :-
		this(This),
		sender(Sender),
		(	integer(Term), Term > 0 ->
			true
		;	var(Term) ->
			throw(error(instantiation_error, This::check(Term), Sender))
		;	throw(error(type_error(This, Term), This::check(Term), Sender))
		).

:- end_object.
