Xref: utzoo comp.lang.functional:154 comp.lang.prolog:2760 Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!uunet!mcsun!ukc!edcastle!aipna!rjc From: rjc@uk.ac.ed.cstr (Richard Caley) Newsgroups: comp.lang.functional,comp.lang.prolog Subject: Re: Pattern matching considered harmful Message-ID: Date: 4 Jun 90 13:46:59 GMT References: <2584@skye.ed.ac.uk> <3077@goanna.cs.rmit.oz.au> <2790@syma.sussex.ac.uk> Sender: news@aipna.ed.ac.uk Organization: Center for Speech Technology Research Lines: 14 In-reply-to: aarons@syma.sussex.ac.uk's message of 2 Jun 90 15:57:33 GMT In article <2790@syma.sussex.ac.uk> aarons@syma.sussex.ac.uk (Aaron Sloman) writes: I don't see any difference between this problem and the problem arising in any programming language where you define procedures or functions with arguments of certain types and then have to invoke them by giving the right number of arguments in the right order. One can change the implementation of a function without changing its calling sequence, one can not change the structure of a data object without changing the pattern used to match it. It would be nice this was possible. declare a dtat type ad declare a `picture' of it which is what the outside world sees.