[PPL-devel] Arithmetic evaluation bug in the CVS HEAD version of XSB

[Paul Broome]

Roberto, I agree with your sentiments and have suffered similar 
frustrations.  It indeed illustrates a significant departure from the 
expected result and will be a surprise to most new users.   Then again, 
I would say that all logic programming systems are hindered in many ways 
by the underlying operating systems.   XSB has other value.   Best 
wishes  - Paul

Roberto Bagnara wrote:

> Paul Broome wrote:
>
>> As I'm sure you know, the is/2 predicate is nonlogical.   This 
>> difference is also in previous versions of XSB.  In this instance, 
>> there is a simple alternate:
>>
>> [broome at localhost bin]$ ./xsb-bits64
>> [xsb_configuration loaded]
>> [sysinitrc loaded]
>>
>> XSB Version 3.1 (Incognito) of August 10, 2007
>> [x86_64-unknown-linux-gnu; mode: optimal; engine: slg-wam; gc: 
>> indirection; scheduling: local]
>>
>> | ?- [user].
>> [Compiling user]
>> side_step_term_as_arithmetic_argument_bug(Term,N) :-
>>   call(N is Term).
>> end_of_file.
>> [user compiled, cpu time used: 0.0090 seconds]
>> [user loaded]
>>
>> | ?- side_step_term_as_arithmetic_argument_bug(1+1+1,N).
>>
>> N = 3;
>>
>> no
>> | ?-
>> End XSB (cputime 0.02 secs, elapsetime 74.23 secs)
>>
>>
>> I hope this helps.
>
>
> Dear Paul,
>
> thanks for the workaround.  However, I don't understand how the fact that
> the is/2 predicate is nonlogical matters.  Do you agree with me that the
> behavior I indicated witnesses a (big) XSB bug?
> All the best,
>
>     Roberto
>