Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!cs.utexas.edu!sdd.hp.com!elroy.jpl.nasa.gov!mahendo!seila!johnt
From: johnt@seila.UUCP (john grant)
Newsgroups: comp.lang.prolog
Subject: Re: Arity Prolog
Message-ID: <626@seila.UUCP>
Date: 4 May 90 23:18:30 GMT
References: <10830@sun.udel.edu>
Reply-To: johnt@seila.UUCP (john grant)
Organization: SEI Information Technology, LA, CA
Lines: 21


	Arity Corporation are, on the whole, pleasant to deal with and do
listen to suggestions/bug reports, but their PC Prolog has a nasty limitation.
The stacks and trail are limited to 64Kbytes each, this is also true of the
OS/2 version - you can reduce the allocation (!) by using an "environment"
file.  The database is for all intents and purposes limitless, it will swap
itself on & off disk very happily, as long as all predicates are less than
4Kbytes long, if they're larger it will bomb.  It seems strange that they are
quite happy to give you all this database space, but won't allow you to really
use it by limiting the stacks.

	The OS/2 port is just that, a straight port of the DOS code, ie the
same limitations exist, however the 'windows' and mouse support have been 
removed - it uses the VIO model for its I/O.  There is no PM support, 
if you want PM you must write your own C/Pascal/Whatever and then tuck the 
Prolog into that.  Having said that, I believe that they are the only OS/2 
choice available.

	I have been using both the DOS & OS/2 versions for over a year, but 
during that time there has been little in the way of enhancements, so the
field is open for other vendors - Quintus take note.