🚀 go-pugleaf

For what it's worth, as far as I know BNR Prolog doesn't do
last-call optimization and doesn't garbage collect.  It was
designed with failure-driven loop style programming in mind,
and data-base operations are supposed to be reasonably efficient.
(Perhaps Andre' Vellino can set me straight if I'm wrong here).

Despite these drawbacks I find it a very useful little system.
I especially like the fact that it has freeze, and that I can
copy graphics I create with it into Word documents in the standard
Mac fashion.  When I give it around 8 Mb of memory the lack of
last call optimization and garbage collection doesn't seem so
serious, at least for the smallish programs I usually write.

In general, I am very disappointed with the Prologs available for
the Mac.  I have four or five Prologs for the Mac, and they are all
poor, in my mind.  Doing a decent job on a Mac interface seems
to be beyond most Mac prolog implementors capabilities.  I strongly
recommend that any Mac prolog implementor study the way that 
the user interaction in Apple MacIntosh Lisp (MCL) (or when running
Prolog as a subprocess under Epsilon on a PC) is organized:
e.g. you need to keep track of *two* points in the Listener window,
(where the user's cursor is currently located, and where the 
Prolog interpreter is currently reading from and writing to).  But
all Mac prologs I know of only use one point, with the result that user
interaction is just a mess.  I think anybody implementing a
prolog on the Mac should be forced to sit down and study MCL;
these guys have figured out how to implement a user interface
that is an order of magnitude better than any Mac prolog I have
seen, and there is no reason to reinvent the wheel.  But I'm
afraid that the fact that MCL is a Lisp implementation is enough
to put off most prolog implementors - so smug are they in their
monolingual viewpoint.

Second, just about all Mac prolog implementors seem to feel the
need to "improve" on the Edinburgh standard in some incompatible
way.  These "improvements" usually suffice to break most standard
programs.

Sorry for the strong remarks, but I'm sick and tired of all these
half-baked prologs for the Mac.  This is one case where I would
truly like to be shown to be wrong...

Mark
--
Mark Johnson
Institut fuer maschinelle Sprachverarbeitung - Computerlinguistik
Universitaet Stuttgart
Keplerstrasse 17
D-7000 Stuttgart 1
West Germany.  (you need "West" otherwise mail from the US is not delivered!)
work phone: 0711 - 121 3132.

On leave until mid July 1991 from:
	Cognitive and Linguistic Sciences, Box 1978
	Brown University
	Providence, RI 02912
	USA

email addresses: 
	mark@adler.philosophie.uni-stuttgart.de
	mj@cs.brown.edu