An addendum to my previous message:

Some preliminary benchmarks indicate that plc is a vastly faster  
execution platform than tried-and-tested (and optimized) Prolog  
engines such as SWI Prolog and Sicstus Prolog (although it currently  
only supports a restricted language).

For my example program, it is almost 12x faster than SWI and 3.7x  
faster than Sicstus.

Some details: solving the win-predicate in the attached Prolog-file  
causes a search in the space of all six-letter words (i.e. 26^6  
strings); it reports those words that are "prolog". I collected the  
following timings on my computer (Intel Core 2 Duo, MacOS X 10.4.9):

SWI-Prolog (Multi-threaded, Version 5.6.10):

$ time swipl -s prolog.pl -g true -t "win(A,B,C,D,E,F),write 
([A,B,C,D,E,F]),nl,fail"
% prolog.pl compiled 0.00 sec, 4,280 bytes
[p, r, o, l, o, g]

real    0m59.065s
user    0m58.845s
sys     0m0.073s

SICStus 4.0.1:

$ time ~/sicstus/bin/sicstus -f -l prolog.pl --goal "win 
(A,B,C,D,E,F),write([A,B,C,D,E,F]),nl,fail;halt."
% compiling /Users/bruno/my_svn/plc/prolog.pl...
% compiled /Users/bruno/my_svn/plc/prolog.pl in module user, 0 msec  
2312 bytes
SICStus 4.0.1 (i386-darwin-8.9.1): Tue May 15 14:53:23 CEST 2007
Licensed to Bruno De Fraine
[p,r,o,l,o,g]

real    0m18.474s
user    0m18.417s
sys     0m0.038s

plc and ocamlopt 3.09.3:

$ time { make prolog.cmx; make driver.cmx; ocamlopt -o driver.opt  
prolog.cmx driver.cmx; ./driver.opt; }
ocamlopt.opt -c -dtypes -pp 'camlp4 ./plc.cma pr_dump.cmo -impl' - 
impl prolog.pl
ocamlopt.opt -c -dtypes   driver.ml
prolog

real    0m5.069s
user    0m4.749s
sys     0m0.191s

Regards,
Bruno