Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!ukma!gatech!udel!burdvax!armagan
From: armagan@PRC.Unisys.COM (Armagan Ozdinc)
Newsgroups: comp.lang.prolog
Subject: Re: retractall and backtracking
Message-ID: <10539@burdvax.PRC.Unisys.COM>
Date: 12 Jun 89 14:09:24 GMT
References: <575@hfserver.hfnet.bt.co.uk> <PX.89Jun9194119@uniq.unl.fctunl.rccn.pt>
Sender: news@PRC.Unisys.COM
Lines: 19

In article <PX.89Jun9194119@uniq.unl.fctunl.rccn.pt>, px@unl.fctunl.rccn.pt (Joaquim Baptista (pxQuim)) writes:
> 
> Variations on this problem also arise with asserta and assertz, as in:
> 
> /* this will loop forever, exhausting your heap space,
>    writing 1211111111... */
> 	b(1). b(2).
> 	exec2:- b(X), write(X), assertz(b(X)), fail.
> 



In Quintus Prolog 2.4, exec2 doesn't behave as you describe above. It
prints 12 and fails.


Armagan Ozdinc
Unisys Corporation
Paoli Research Center