Hi Samer,
On 18/03/2014, at 18:11, Samer Abdallah <
[hidden email]> wrote:
> Hi,
> There appears to be a bug in the handling of meta-predicates that
> expect a DCG goal as an argument:
>
> :- meta_predicate foo(//,?,?).
>
> foo(G) --> phrase(G).
>
> test --> foo({writeln(hello)}).
>
> Using SWI v. 7.1.7 results in
> Warning: The predicates below are not defined. If these are defined
> Warning: at runtime using assert/1, use :- dynamic Name/Arity.
> Warning:
> Warning: {}/3, which is referenced by
> Warning: /Users/samer/src/sandpit/prolog/test.pl:4: 1-st clause of test/2
I get:
$ swipl
% /Users/pmoura/.plrc compiled 0.00 sec, 2 clauses
Welcome to SWI-Prolog (Multi-threaded, 64 bits, Version 7.1.9-53-g30fa74b-DIRTY)
Copyright (c) 1990-2014 University of Amsterdam, VU Amsterdam
SWI-Prolog comes with ABSOLUTELY NO WARRANTY. This is free software,
and you are welcome to redistribute it under certain conditions.
Please visit
http://www.swi-prolog.org for details.
For help, use ?- help(Topic). or ?- apropos(Word).
?- [user].
:- meta_predicate foo(//,?,?).
|:
|: foo(G) --> phrase(G).
|:
|: test --> foo({writeln(hello)}).
|: % user://1 compiled 0.00 sec, 6 clauses
true.
?- listing(test/2).
test(A, B) :-
foo({writeln(hello)}, A, B).
true.
?- listing(foo/3).
:- meta_predicate foo(//,?,?).
foo(A, B, C) :-
phrase(A, B, C).
true.
?- phrase(test, []).
hello
true.
If I put your code in a file and consult it I get no warnings:
$ swipl
% /Users/pmoura/.plrc compiled 0.00 sec, 2 clauses
Welcome to SWI-Prolog (Multi-threaded, 64 bits, Version 7.1.9-53-g30fa74b-DIRTY)
Copyright (c) 1990-2014 University of Amsterdam, VU Amsterdam
SWI-Prolog comes with ABSOLUTELY NO WARRANTY. This is free software,
and you are welcome to redistribute it under certain conditions.
Please visit
http://www.swi-prolog.org for details.
For help, use ?- help(Topic). or ?- apropos(Word).
?- [samer].
% samer compiled 0.00 sec, 6 clauses
true.
Are you using a different SWI-Prolgo version or testing the code in a different way?
Cheers,
Paulo
-----------------------------------------------------------------
Paulo Moura
Logtalk developer
Email: <mailto:
[hidden email]>
Web: <
http://logtalk.org/>
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