Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!apple!usc!bbn.com!nic!bunny!newshost!bs30 From: bs30@sirius.gte.com (Bernard Silver) Newsgroups: comp.lang.prolog Subject: Re: Standards question: behavior of arg/3 Message-ID: Date: 23 Oct 90 19:27:33 GMT References: <9888@bunny.GTE.COM> <3992@goanna.cs.rmit.oz.au> <1753@ecrc.de> <4055@goanna.cs.rmit.oz.au> Sender: news@GTE.COM Organization: GTE Laboratories Incorporated Lines: 40 In-reply-to: ok@goanna.cs.rmit.oz.au's message of 23 Oct 90 08:20:20 GMT In article <4055@goanna.cs.rmit.oz.au> ok@goanna.cs.rmit.oz.au (Richard A. O'Keefe) writes: [I hope someone on the ANSI or ISO committees is keeping a copy of this stuff.] Yes, I am! I also received a lot of email on the original question of arg/3. As you might expect, there are several different points of view: some support the infinite table approach, others view arg(N, Term, Arg) ("extra" spaces for Richard) with N greater than the arity of Term as a grave error, similar to exceeding the bounds of an array, and thus must be reported. To answer Richard's original ``attack'' on my posting: I agree that it is not a good idea to have a separate convention for each predicate. However, that is the way the standard has evolved (and I don't accept the blame for this as I have only joined recently!) I feel that very few people involved would agree to redo the predicates in accordance with your (or someone else's) design methodology. So, one viable possibility is to try to replace the particular definitions that we do not like. We decided to post the arg/3 question to get feedback to that specific issue, and also to see if people were interested in commenting on standards in general. In the past, Richard has been accused the standards bodies of not caring about existing practice, suggesting that they are isolated from the real user community. This was a small attempt to address such concerns. I got lots of feedback on arg/3 and related issues, so if the rest of ANSI agrees, we may post other questions in future, hopefully in a more structured context. Richard, if you can send me two free plane tickets to IJCAI, I'll be willing to forget your attack (and I'll put spaces after commas). -- Bernard Silver GTE Laboratories bsilver@gte.com (617) 466-2663