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From: bimbart@kulcs.uucp (Bart Demoen)
Newsgroups: comp.lang.prolog
Subject: setof / ,/2
Message-ID: <1411@kulcs.kulcs.uucp>
Date: 26 Aug 88 07:05:51 GMT
Reply-To: bimbart@kulcs.UUCP (Bart Demoen)
Organization: Katholieke Universiteit Leuven, Dept. Computer Science
Lines: 36

In article <301@quintus.UUCP> ok@quintus.uucp (Richard A. O'Keefe) writes:

> Well, no.  That was just one example.  Let me provide another example:
>         | ?- A = 1, B = 1,
>         |    setof(X, (X = A ; X = B), L).
> Result: L = [1]
> 
>         | ?- setof(X, (X = A ; X = B), L),
>         |    A = 1, B = 1.
> Result: L = [1,1]

I will try one more time: if setof/3 is non-logical when its solutions are not
ground, that is because @</2 (and its sisters) are non-logical for non-ground
arguments; after all, setof/3 tries to order with @</2 or doesn't it ?


In article <307@quintus.UUCP> ok@quintus.uucp (Richard A. O'Keefe) writes:

> {I claim that clause((_,_), _) SHOULD report an error in every Prolog;
>  (_,_) has a definition, it's just that the Prolog system refuses to
>  show it do you.}

sounds as if ok@quintus wants to tell us that (_,_) actually has a Prolog
definition, but that his favourite Prolog doesn't want to show it by means
of clause/2 ... a disease inherited from Edinburgh ?
I am amazed: there is no reason why 'every Prolog' should have a Prolog
definition of (_,_); on the contrary
,/2 is a syntactic construct, with a semantics, but it is not a builtin
predicate, nor a predicate defined in Prolog

bimbart@kulcs.uucp
Bart Demoen
Dept. of Computer Science
Celestijnenlaan 200A
B-3030 Leuven
Belgium