Newsgroups: comp.lang.prolog
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From: pgweiss@netcom.com  (Paul G. Weiss)
Subject: Re: Death to Arity!
Message-ID: <pgweissD0oMDx.C0D@netcom.com>
Sender: pgweiss@netcom.com (Paul G. Weiss)
Reply-To: pgweiss@netcom.com
Organization: Arity Corporation
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References: <1994Dec5.215606.15801@bnlux1.bnl.gov> <3c0qom$eb4@hobbes.cc.uga.edu> <TOM.94Dec9150953@heather.kwi.com> <3cdl0d$1vm@hobbes.cc.uga.edu>
Date: Mon, 12 Dec 1994 05:10:45 GMT
Lines: 18

In <3cdl0d$1vm@hobbes.cc.uga.edu>, mcovingt@ai.uga.edu (Michael Covington) writes:
>Tom Howland (tom@kwi.com) wrote:
>
>: I really hate Arity Prolog. Some of the reasons include
>
>: ** doesn't have -> (if-then-else). 
>
>But they do have ifthenelse/3, don't they?  How close is it?
>I had thought the difference was only syntactic.
>

The difference between (a->b;c) and ifthenelse(a,b,c) is indeed only
syntactic.  However there is a difference between (a->b) and
ifthen(a,b):  ifthen(a,b) succeeds if the goal a fails and is therefore
more like logical implication than (a->b).

-Paul Weiss
-Arity Corporation
