For some time ago, there was here in this  newsgroup some discussion
concerning Mats Carlsson's YAQ (Yet Another Qlog) which was a simple
but nice Prolog interpreter written in Maclisp.  Converted to the
Common LISP that program could indeed  be a nice educational and
instructional tool.

The Wizard Himself, ie. Mats, told that he measured YAQ as 4 LIPS, I
think in a mainframe Maclisp implementation.  I wrote my Special
Project in Computer Science ("tietojenkäsittelyopin erikoistyö") about
the implementation of Prolog, and converted Carlsson's YAQ first to
Symbolics 3600 Zetalisp and after that to VAX/VMUNIX Franzl.  I
actually got the YAQ to run a about 200 LIPS in the VAX/750 we had,
and even qucker in the Symbolics 3600 LISP Machine.

I started converting the YAQ to Commmon LISP, but decided to post here
in the 'Net merely a partially-debugged partially-converted version of
the 1983/1985 YAQ, partially done because I have significantly more
important things to do -- and converting a program to (LET + dynamic
scope) => (SETF + lexical scope) ; and noticing that CCL nreverse
works just a little bit differently from Maclisp nreverse ; and a
zillion similar itsy bitsy teenie weenie details -- was too time
consuming.

Moreover, I no more have the tapes, I only have the paper printed
listing - and typing a long LISP program from a bad printout is a
horrifying task, eg. the printer does not differentiate backquote from
ordinary quote, and other idiosyncracies.

But if somebody wants to get the abovementioned source of the
1983/1985 part-debugged part-converted YAQ then it is available at

http://www.tkk.fi/~ajy/yaq85/yaq83.lsp

in the free domain for educational and instructional purposes.

As I said, it is a partially converted and partially debugged version
-- if somebody actually wants to use the YAQ then the conversion and
debugging must be completed, which is not very much work -- but as I
said it is a very itsy bitsy teenie weenie kind of thing.

Commercial use would necessitate a written explicit permission from
the author, ie. Mars Carlsson, and the editor/debugger, ie. me.

kind regards; Antti J Ylikoski
Helsinki, Finland, the EU