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From: fjh@mundil.cs.mu.OZ.AU (Fergus Henderson)
Subject: Re: numbervars/3 bug in Quintus and Sicstus
Message-ID: <9430005.4768@mulga.cs.mu.OZ.AU>
Sender: news@cs.mu.OZ.AU
Organization: Computer Science, University of Melbourne, Australia
References: <38jqt7$5bn@coli-gate.coli.uni-sb.de> <PEREIRA.94Oct25231821@alta.research.att.com> <38lgc9$m8k@coli-gate.coli.uni-sb.de>
Date: Wed, 26 Oct 1994 19:17:35 GMT
Lines: 28

erbach@coli.uni-sb.de (Gregor Erbach) writes:

>pereira@alta.research.att.com (Fernando Pereira) writes:
>
>>erbach@coli.uni-sb.de (Gregor Erbach) writes:
>>> The Sicstus manual states that numbervars(Term,FirstVar,LastVar)
>>>
>>>    Unifies each of the variables in term @var{Term} with a special term ...
>>>
>>> Consider what happens when I call
>>>
>>>    ?- numbervars('$VAR'(X),0,N).
>>>
>>> The solution I get is X = 0, N = 1; instead 
>>> of the expected X = '$VAR'(0), N = 1. 
>
>>> I consider this a bug that should be fixed

I agree.  In fact every other Prolog system I had on hand (SWI-Prolog,
NU-Prolog, and Aquarius Prolog) has the behaviour you expect, not the
Sicstus Prolog behaviour.

>>Unfortunately, almost everyone else wants the implemented behavior,

This seems unlikely, given that other Prolog systems don't have that behaviour.

-- 
Fergus Henderson - fjh@munta.cs.mu.oz.au
