Re: [Info-gnuprologjava] Getting some irritating error (procedure "list" does not exist?)

[Daniel Thomas]

On Sat, 2011-04-16 at 13:08 +0200, Daniel Warzecha wrote:
> Hello,
> 
> I'm trying to execute some Prolog code with GNU Prolog for Java.
> 
> The standalone GNU Prolog interpreter throws no errors, yet GPJ says
> "list" doesn't exist. Any ideas?
> 
> Bye,
> Daniel W.

Hello,

What code are you trying to execute? Exactly what does it say (can I
have the full output of whatever error was given)?

You might want to file a bug:
https://savannah.gnu.org/bugs/?func=additem&group=gnuprologjava with
these details on it. The standalone GNU Prolog interpreter and GPJ have
entirely independent implementations, GNU Prolog is more mature and so
more likely to be correct (though iirc there are a fair number of edge
cases where it does not comply with the ISO standard and GPJ does).

The procedure list/1 which determines whether its argument is a list is
in GNU Prolog but not in the ISO standard. However the procedure
is_list/1 is in GPJ so you could try using that instead or adding:
list(T) :- is_list(T).
which is a little bit of a hack. If you want list/1 to be in GPJ file a
bug and I will put it in the next release. Unfortunately is_list/1 is
not in GNU Prolog though it is in SWI-Prolog (which aiui is more mature
than GNU Prolog).

Daniel T.

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