This is a longstanding bug with XSB's compiler. I tried fixing it 4-5 years ago, but my fix caused problems with some optimizations that XSB performs with arithmetic expressions, so the fix was never adopted.
But you're right -- it is a big (though localized) bug and we should fix it. Do you have a work-around for the immediate future?
Terry
On Sun, 23 Sep 2007, 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@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-- Prof. Roberto Bagnara Computer Science Group Department of Mathematics, University of Parma, Italy http://www.cs.unipr.it/~bagnara/ mailto:bagnara@cs.unipr.it
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