Path: utzoo!attcan!uunet!husc6!mailrus!purdue!decwrl!sun!quintus!ok From: ok@quintus.uucp (Richard A. O'Keefe) Newsgroups: comp.lang.prolog Subject: Re: Survey of Prologs for VMS VAX Message-ID: <153@quintus.UUCP> Date: 4 Jul 88 00:54:22 GMT References: <536@dcl-csvax.comp.lancs.ac.uk> Sender: news@quintus.UUCP Reply-To: ok@quintus.UUCP (Richard A. O'Keefe) Organization: Quintus Computer Systems, Inc. Lines: 37 In article <536@dcl-csvax.comp.lancs.ac.uk> simon@comp.lancs.ac.uk (Simon Brooke) provides some information about Prolog systems for VAX VMS. I'd like to correct some of it. (1) If 'Edinburgh' Prolog is still the same system that its designer called NIP, it is a compiler. A key feature of the original design was that there was to be no distinction between compiled and interpreted code: clause/2, retract/1, listing/1 and so on work by running the compiled code in a special mode (ALS also use this technique; I do not know whether they were aware of the Clocksin/Byrd/Bowen work). (2) PopLog does in fact compile Prolog all the way to actual VAX instructions. (3) InterFace Prolog does have a C interface. I don't particularly like it, but they've had it for years. (4) The speed figures make Quintus Prolog look reasonably good, but I have to warn you that naive reverse is almost totally useless as a predictor of performance on real applications. The ability of a system to keep its working set small can be of greater consequence. (5) The VMS version of Quintus Prolog has the same foreign interface as the UNIX version, plus there are a couple of extra VMS-specific functions provided by Quintus Prolog to user C code. It's all in the "System- Dependent Features Manual -- VMS Version". (6) Quintus has a UNIX interface to Unify and Oracle. Potential VMS customers: please let us know which data-base systems you would prefer a VMS interface to (RDB? whatever?) so that we can plan which one to do first. (7) A general observation: anyone considering buying Quintus Prolog can get a 30-day evaluation copy (in Europe, check with AI Ltd) and find out exactly what it's like and how it performs. I imagine that other Prolog companies make a similar offer. There is no substitute for actually trying a product on the actual hardware and operating system version you intend to use.