Re: Cut(!) and fail inside nested once/1 calls?

Hi Dave

Le 21/09/2012 20:14, Dave Sworin a écrit :

Please advise whether the following
behavior is a bug.

Test platforms tried: 1) Ubuntu 10.10
64-bit gprolog 1.3.1 and 2) Mint 13 64-bit gprolog 1.4.1

once((

(once(((4 == 5) ; (!,fail)))) ;

(write(a))

)).

This query writes the letter a to the
standard output. (I hope I typed all the parentheses
correctly!)

Correct behavior.

If I remove the once/1 call inside the
outer once/1, the cut(!) and fail works as expected.

once((

((((4 == 5) ; (!,fail)))) ;

(write(a))

)).

This query fails with a "no".

Correct behavior.

Is the cut(!) and fail scope limited
inside the once/1 call?

You said it :-) once/1 is a built-in predicate (it is not a control
construct). So it is not transparent to cut (i.e. the scope of cut
is the Goal of once/1).

Daniel

Dave

PS: Everything seems to work fine in
gprolog 1.4.1 but in the debugger I experienced segmentation

violations debugging after consulting a
very large prolog file bug exact same thing works fine in

gprolog 1.3.1. Have other people
experienced this too. I do not have a small example.

PS: I would be interested in getting this large file. Can I get by
ftp (or other) a zipped version of this file ?

(you can write to me directly: [email protected] )

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