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From: alf@sics.se (Thomas Sj|land)
Newsgroups: comp.lang.prolog
Subject: Re: What does/should your Prolog make of this ?
Message-ID: <1990Mar7.104021.28421@sics.se>
Date: 7 Mar 90 10:40:21 GMT
References: <1990Mar1.210219.5687@Neon.Stanford.EDU> <1557@maestro.htsa.aha.nl>
	<1990Mar6.132958.6258@sics.se>
Sender: news@sics.se
Organization: Swedish Institute of Computer Science, Kista
Lines: 51
In-Reply-To: roland@sics.se's message of Tue, 6 Mar 90 13:29:58 GMT

Roland Karlsson wrote:
> In SICStus Prolog there is a sound implementation of assert after call.
			       ^^^^^	

Please, do not misuse the terminology like this. This problem has nothing
to do with "soundness" in the logical sense. Use "healthy" or "nice"
or "good" or whatever you like.

----

Another issue that has come up and which could interest this group 
relates to  bagof(setof)-semantics : 

What should be the behaviour of the following queries (in the program 'p(X)') ?

?- freeze(X,write(foo)), bagof(_,(X=1 ; X=2),L).

?- Y=1,
   bagof((X,Y),p(X),L).

?- bagof((X,Y),p(X),L), 
   Y=1.

The behaviour in SICStus seems unintuitive to many. One would perhaps 
want to have a less "operational" view on bagof/setof

Is there a need for more versions of findall/bagof/setof ?
Are there efficiently implementable alternatives ?

	/Thomas Sjvland, 
		(look, I can write my name on a SUN with ISO standard 8859 !)

PS.	
	This is what I get easily into gnu-emacs using C-Q M-<key> !!
	1234567890-=\`	!@#$%^&*()_+|~
	qwertyuyuiop[]	QWERTYUIOP{}
	asdghjklkl;'	ASDFGHJKL:"
	zxcvbnm,./	ZXCVBNM<<>?

	? Doesn't it look nice ?

Ought we not to think about bigger character sets for Prolog 
including Europe and Japan and also FULL (complete, :-)) English 
in the syntax ?
DS.

--
Thomas Sjoeland
SICS, PO Box 1263, S-164 28 KISTA, SWEDEN
Tel: +46 8 752 15 42	Ttx: 812 61 54 SICS S	Fax: +46 8 751 72 30
Internet: alf@sics.se or {mcvax,munnari,ukc,unido}!enea!sics.se!alf