Prolog Interpreter in C++ / Java

Appeared in Volume 9/4, November 1996

rmitchle@cs.uct.ac.za
Ryan G Mitchley
10th June, 1996

I asked my lecturer if I could implement a Prolog interpreter in C++ as my CS project. His response was that he does not find Prolog "either interesting or useful". Any comments?

HSchotel@vms.uci.kun.nl
Henk Schotel
11th June 1996

Some practical Prolog applications are described at:
http://www.demon.co.uk/ar/NCSA-Mosaic/PAP96/index.html

I suggest that you use Java to implement your Prolog interpreter, not C++. This would make it platform independent, and might lead to some interesting ways of combining Prolog and the Web.

"Old" Prolog implementations are mentioned in:
http://www.cs.cmu.edu/Web/Groups/AI/html/faqs/lang/prolog/prg/top.html

For inspiration (and maybe code!) take a look at the site that is implementing Scheme in Java:
http://www.winternet.com/~sgml/kawa/

ok@goanna.cs.rmit.edu.au
Richard A. O'Keefe
12th June 1996

If I was going to implement a logic programming language in Java, I wouldn't make it Prolog. I'd move all the imperative bits to Java. I'd make the logic part just as clean and logical as I could.

Amongst other things, compiling Prolog to the JVM would not be a very good idea; ask in comp.lang.lisp what some of the problems are. (To start with, the JVM doesn't tag numbers.)

It might be worth while to consider a (polymorpic) type checked language. That might be a rather better fit to the JVM.

I've never used Smalltalk/V. Wasn't it supposed to have some sort of "Prolog" component? It might be a source of ideas.

Henk Schotel mentions http://www.winternet.com/~sgml/kawa/. Release 0.2 of Kawa was announced recently in comp.lang.scheme. It's an interpreter. Running interpreted Scheme (or an interpreted Prolog) in an interpreted interpreter does not sound like a good way to convince people that Scheme (or Prolog) can be efficient.

kohlerm@betze.bbn.hp.com
Kohler Markus
18th June 1996

An interpreter written in Java is a good starting point for compiling Prolog (or Scheme, etc.) to Java source code.

Simply use Java as a very portable assembler!

eddie@voldsboks.pvv.ntnu.no
Kjetil Valstadsve
26th August 1996

Per Bothner's Kawa scheme interpreter in Java does some compiling. As for a real compiler, we're working on it this semester, and hopefully we'll be able to come up with something. If anyone is interested, please get in touch.