Path: utzoo!yunexus!lethe!torsqnt!news-server.csri.toronto.edu!clyde.concordia.ca!uunet!snorkelwacker!mintaka!mintaka!weiss
From: weiss@theory.lcs.mit.edu (Paul G. Weiss)
Newsgroups: comp.lang.prolog
Subject: Re: Compiling Arity Prolog
Message-ID: <WEISS.90May29104019@toucan.lcs.mit.edu>
Date: 29 May 90 14:40:19 GMT
Article-I.D.: toucan.WEISS.90May29104019
References: <2414@aipna.ed.ac.uk>
Sender: news@mintaka.lcs.mit.edu
Organization: MIT Lab for Computer Science
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In-Reply-To: kv@aipna.ed.ac.uk's message of 27 May 90 14:18:00 GMT

Karen's program fails when it gets to the write/1 predicate.  In Arity/Prolog
we have visible declarations, which are a way to tell the interpreter which
predicates are to be visible at run-time.  Having all the builtins visible
for every standalone application would force them all to be linked in to
every standalone application, making them bigger than they would otherwise
have to be.  Therefore, we let the programmer either decide that 

(i) all builtins should be visible,  or
(ii) only selected ones (which is the default)

In the case in question, the insertion of the line:

:- visible write/1.

in the first file would cause the program to work correctly.