LPA Win-Prolog: A professional Prolog compiler with unique features

In early 2001, I had the pleasure of working closely together with a friendly bunch of people, the creators of LPA Win-Prolog, for a a period of a few months: This company, who made LPA Win-Prolog is “Logic Programming Associates“, a group of dedicated developers and computer scientists led by Brian Steel, who also happens to be a musician and an orchestra conductor. A long time ago (in the eighties) Brian Steel had caused quite a stir in the so-called “home computer” industry, by writing the first Prolog compiler that could run on a ZX Spectrum, a machine with only 48Kb of RAM and a Z80 8-bit processor. At that embryonic stage of the computer industry’s evolution, it was considered impossible to cram a working Prolog compiler in only so little RAM and in such a slow computer. However, Brian Steel was also an Assembly Language programmer (just like me -although long before my time). He still writes very efficient Assembly Language code (today for Intel Pentiums – 32-bit and 64-bit code) which empowers today’s LPA compiler with a tremendous speed, compared to its rivals. Brian also thought deeply about the best way to implement certain commonly needed operations (such as string search) and so he set out to improve the ISO-prolog-compatible LPA compiler with special and unique instructions that increase its speed and efficiency even more (e.g. the multi-faceted predicate “find/3“).

Well, I am still using LPA Win-Prolog, ever since that happy period of a few months I spent in the UK, back in 2001, as an employee of LPA Ltd. In fact, I was forced to return to Greece because of a bad accident (a broken tendon in a foot), otherwise I’d rather stay in the UK and work with LPA… forever! BTW, Brian Steel is also -like me- a winter swimmer, in the English sea (in Cornwall) making it even more apealling for me -at the time- to… follow his example. 🙂

The latest versions of LPA Prolog (version 4.6 is the one I use at the moment) are full of extra goodies, such as a coloured syntax editor, a nice dialog editor (for the visual design of menus, windows, dialog boxes, etc), and so on. (Not to mention several good extra packages, included in the compiler, such as Flex, Datamite, Proweb, Chimaira Agents, and so on; you can read all about them in LPA Prolog’s site, here).

My only complaint is that (at the moment) the LPA package does not include a Constraints programming extension, (such as CLP, CLP/fd, CHR, etc). However, I plan to adapt some open source code for such extensions and include it inside LPA Prolog, in the near future. Unless -of course- this innovative company has already embarked on a similar project, adding to their compiler Constraints handling extensions. Finally, the very latest (recently announced) next version of LPA Prolog includes something very special, which is useful to musically inclined programmers and hobbyists: A midi interface!

I was probably among those people who first proposed to Brian Steel -back in 2001- that a midi interface would prove to be very popular, as well as a way to expand LPA’s customer base even further. At the time (2001), most of their customers were academics, universities and serious professional people. Today (2007) my guess is that their clients begin to be also musically oriented hobbyists and computer-literate composers. I -for one- (as a composer and remixer) can’t wait to get my hands on this new version of their compiler, since it’s the best way to experiment with L-systems for computer music generation, Prolog-based grammars for parsing and analysing existing MIDI music pieces, and so on.

However, now that the MIDI music Logic Programming client-base of LPA Prolog is beginniing to grow, the issue of Constraints extensions can no longer be neglected. Some of the best work in musical Artificial Intelligence is already using Constraints programming methods.

In this blog, I hope to write quite often about programming projects and experiments with LPA Win-Prolog, including my own (public domain) source-code. In addition, you can browse some professional projects implemented with LPA Prolog in recent years (2001-2005), in my source-code and programming projects’ page.

Finally, there are some rather unusual web-pages I wrote a few years ago, with tips and free code to combine LPA Win-Prolog, with… one of its rivals (PDC/Visual Prolog). At the time, it became evident that it was perfectly possible to combine the best features of both these professional compilers, so the title of the main web-page about this work was “A tale of Two Prologs“.