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From: barmar@mit-eddie.UUCP (Barry Margolin)
Newsgroups: net.lang.prolog
Subject: Re: Built In Predicates
Message-ID: <824@mit-eddie.UUCP>
Date: Tue, 18-Oct-83 01:24:15 EDT
Article-I.D.: mit-eddi.824
Posted: Tue Oct 18 01:24:15 1983
Date-Received: Tue, 18-Oct-83 23:31:25 EDT
References: <12420@sri-arpa.UUCP>
Organization: MIT, Cambridge, MA
Lines: 19

Perhaps built-in predicates should be defined as if they were:

succ (1, 2).
succ (2, 3).
.
.
.
succ (_, _):- error ().

Where error () is a built-in predicate which causes the program to abort
with an error message (perhaps a real version of this would take
arguments specifying what the message should be).

At some level, of course, you have to have primitives which really
can't be defined in the language.  I have replaced succ with error.
-- 
			Barry Margolin
			ARPA: barmar@MIT-Multics
			UUCP: ..!genrad!mit-eddie!barmar