38 lines
623 B
Plaintext
38 lines
623 B
Plaintext
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% example adopted from:
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% Programming Language Prolog Part 2, Modules
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% Committee Draft - January 14, 1998 X3J17/97/5
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:- object(tracer).
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:- info([
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version is 2,
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authors is 'Paulo Moura',
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date is 2000/7/24,
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comment is 'Tracer for a goal call and exit ports.']).
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:- public(trace/1).
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:- metapredicate(trace(::)).
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:- mode(trace(+callable), zero_or_more).
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:- info(trace/1, [
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comment is '.',
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argnames is ['Goal']]).
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trace(Goal) :-
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write('call: '), writeq(Goal), nl,
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call(Goal),
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write('exit: '), writeq(Goal), nl.
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trace(Goal) :-
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write('fail: '), writeq(Goal), nl,
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fail.
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:- end_object.
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