Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!markh
From: markh@csd4.milw.wisc.edu (Mark William Hopkins)
Newsgroups: comp.lang.prolog
Subject: ProYACC??? (was: Pro4th???)
Keywords: forth, forlog, foobar
Message-ID: <3526@csd4.milw.wisc.edu>
Date: 25 Jul 89 23:43:20 GMT
References: <12746@well.UUCP>
Sender: news@csd4.milw.wisc.edu
Reply-To: markh@csd4.milw.wisc.edu (Mark William Hopkins)
Organization: University of Wisconsin-Milwaukee
Lines: 29

In article <12746@well.UUCP> jax@well.UUCP (Jack J. Woehr) writes:
>
>	So my son asks me last night, "Can you write a Forth in
>Prolog?"
>
>	"Yes, but it would run awfully slowly." That should have been
>that, but it got me to thinking, that would be a pretty amusing
>demo of Prolog! I seem to recall it has been done before, but don't remember
>when or by whom.

Yes it could!  Here's an outline:

(1) Set up a LR(1) parser generator in Prolog.
(2) Create a YACC-like front end, using Prolog's existing grammar
    notation and your parser generator.
(3) Write a Forth compiler using the YACC-like parser generator (choose
    your favorite target language for efficiency)
(4) Use the compiler to compile the said Forth program into the target
    language
and
(5) Run the executable code.

It's MUCH easier than expected, since Prolog is such a high-level language.

The compiler should be able to create better code since it is written in a
language that makes it easy to write better optimization rules, so the result
should be MORE(!) efficient than otherwise.

Also, steps (1) through (4) only need be done once :-).