School of Computer Science
The University of Birmingham
In collaboration with
School of Cognitive and Computing Sciences,
The University of Sussex.


 This file is

Note: "POPLOG" is a trade mark of the University of Sussex.

What is POPLOG?

POPLOG is a free, open source, multi-language software development environment providing incremental compilers for a number of interactive programming languages, notably:

There is also a partial implementation of Scheme in Poplog available at the FreePoplog Site
This was developed by Robin Popplestone, at the University of Massachusetts, Amherst, USA.

Alas Robin died in 2004. See

Getting Poplog

You can get a list of versions of Poplog here.
More information about varieties of Poplog and the various packages associated with it is in Free Poplog Web Site

Poplog provides support for multi-paradigm software development in a rapid prototyping environment, because of the use of (fast) incremental compilers for all the languages.

In Poplog, all the above languages compile to a common virtual machine, which is then compiled (incrementally) to the current host machine language. Users can add new languages or extend the existing languages because the compiler development tools are made available (in the form of Pop-11 procedures).

Poplog also includes a lot of X related facilities, an integrated multi-window programmable text editor (VED), and a host of teaching material and libraries provided in source. The system was developed mainly at Sussex University, but also at Integral Solutions Ltd (ISL) between 1988 and 1998. ISL was bought by SPSS (who sell the Clementine data-mining system originally developed in Poplog by ISL).

Getting Poplog and add-ons

The main distribution site for poplog is
Warning The web site is defunct (June 2009)
This includes a number of packaged versions of Poplog of which the most popular is the version for linux+PC with extensions from Birmingham, in an easy-install bundle.

There are also various library extensions including

Some Poplog/Pop-11 History

Poplog grew out of the Pop-11 language produced at Sussex University building on the many excellent ideas in the Pop2 language, originally developed by Robin Popplestone (see below) and others at Edinburgh University in the late 1960s and early 1970s.

At Sussex Pop-11 was implemented (mainly by Steve Hardy) to run on a PDP11/40 computer running Unix, round about 1976. It was later ported to a VAX running VMS, and John Gibson was the main architect thereafter. Around 1981-2 Chris Mellish implemented a version of Prolog in Pop-11, and the combined system was then called Poplog. A few years later a "toy" Lisp system was added by Jonathan Cunningham, and after that a full Common Lisp was implemented by John Williams, with supporting changes to the Poplog virtual machine produced by John Gibson. Later Robert Duncan and Simon Nichols added an implementation of Standard ML.

One of the key features originally in Pop-11 and later in Poplog was support for e-learning. An overview of the philosophy and history of some of the features developed from 1976 at Sussex University can be found here. A central theme in all the computer-based learning techniques developed in Pop-11 and Poplog was always leaving the learner in total control.

Poplog was originally sold to commercial and academic users (at very different prices!) by Sussex University (starting around 1982), when it contained only Pop-11 and Prolog (hence the name.)

SDL (Systems Designers Ltd) took over marketing in 1983 (and had a Poplog stand at IJCAI83 in Karlsruhe). Later, following a merger, SDL grew into SD-Scicon, one of the largest software companies in the UK, which later changed its name to SD, and then became EDS

In 1989 SD decided to pull out of the AI tools market and a small group of people in the company (about 6) who had been associated with Poplog bought out the Poplog business (and also the SD-prolog business) and started ISL. At first their business was mainly selling and supporting Poplog (while Sussex University remained closely involved in development). They also provided AI services, developed various kinds of AI software.

During the 1990s ISL developed and diversified, including producing the prize winning Clementine Data Mining System, which was originally implemented mainly in Pop-11, making considerable use of Pop-11 (as did other systems produced by clients of ISL, e.g. COGSYS), and some products of Praxis.

In December 1998 SPSS bought ISL (a friendly takeover) and following that, discussions began with Sussex regarding the future of Poplog. This eventually led to the Free Poplog site.


In July 1999 it was decided that the latest version of Poplog (V15.53) including sources for all supported hardware/operating system combinations, should be made available free of charge. For information about this see

There is a smaller out of date free version of Poplog (Version 15.01), which apparently still works on SUSE Linux, though not on other recent versions of Linux. It is available by ftp from Sussex University in the Sussex Linux Poplog distribution directory:
This old version has some restrictions: it is memory-limited and you cannot create saved images. But most of the teaching material in older books on pop-11 can be used on it, though not the newer facilities at the Birmingham Poplog ftp site.


Poplog has, at various times, run on a variety of Unix and VMS machines, including Sun, HP, SGI, DEC Alpha, DEC Vax, Sequent Symmetry, Apollo Unix, and PC running Redhat Linux v5.2 (and maybe other versions of Linux). There is also a Windows NT version of Poplog (e.g. used in Clementine on PCs) but without graphics, unless you purchase an X window system emulator for NT.

Sources of information about Poplog

Poplog/Pop-11 History Directory

Started 15 Feb 2007 here:
Any contributions to that directory gratefully received.

Information at Sussex University

More detailed information about Pop-11, Poplog and the Poplog development team was previously available at Sussex, but appears to have been removed, unfortunately:

Robin Popplestone's Poplog-based work at University of Massachusetts at Amherst

Many of the key ideas in Pop-11 were developed in the late 1960s by Robin Popplestone, first at Manchester University, then Edinburgh University. He moved to the University of Massachusetts at Amherst in 1986. Unfortunately he died in 2004. See:
In Memoriam Professor Emeritus Robin Popplestone, 1938 - 2004
His web page included several papers relevant to the design of pop-11 and its history, especially
Early development of the POP language
Now available here:
Functional and Interactive Computer Language Design
Now available here:


Graham Higgins and Steve Knight Leach, who both previously used Poplog while working at HP research labs, have set up (now defunct apparently), a Poplog information site, which includes poplog-related and Pop-11-related information, including archives of postings to comp.lang.pop going back to about 1992, and some useful pop-11 utility libraries. Most of the material has been or will be transferred to the Birmingham site.

There is a Poplog/Pop-11 FAQ and a port of the Babylon AI development environment to Poplog Common Lisp.

Steve Leach while working at HP contributed many ideas to Poplog development and designed and implemented the first version of Objectclass the most sophisticated Object Oriented extension to Pop-11 (there were several others). See the teach, help, and ref files in this directory

WARNING The downloads of poplog installation packages at the site may be out of date. It is best to try fetching poplog from first.

Information at Reading University

Another source of information can be found at Reading University

The comp.lang.pop newsgroup

There is a news group to which questions and comments about Pop-11, Poplog and the Poplog languages may be posted: comp.lang.pop. Information about the news group is available at

The news group is gatewayed to an email list currently maintained at the University of Birmingham. If you wish to join the pop-forum email list, write to

The FreePoplog Directory at the University of Birmingham

can be examined at: .
Poplog is no longer accessible by ftp.
Most of the contents of the directory are described below and in There may be some additional information in the README file.

The directory contains code and documentation (mainly Pop-11) for use with Poplog developed at Birmingham (some of it extending work done at Sussex).

Detailed system documentation for Poplog, Pop-11 and the other Poplog languages (Prolog, Common Lisp, and Standard ML) can be found in the doc/ subdirectory.

Poplog/Pop-11 related code and documentation

The Birmingham local directories included in the FreePoplog directory contain a lot of online teaching material for an introductory AI programming course, a Ved-based net news reader, using the Pop-11 socket library, extensions to the Pop-11 RC_GRAPHIC library, and two libraries for design and development of "intelligent" agents. POPRULEBASE and SIM_AGENT. For an overview and demonstration (with movies) of the latter, see

Examples of displays produced by the "RCLIB" (relative coordinates) Graphic Library can be found in
An overview (plain text) file is here:

Fetching Birmingham utilities and teaching materials

Some of the Birmingham Pop-11 and AI teach files can be found in a convenient compressed tar file in

The Pop-11 primer

There is a Primer of pop-11 for experienced programmers now available in various formats in the FreePoplog directory including a version of the Primer in html.

The HTML version can be fetched in a tar file and unpacked for local use:
(The graphical symbols won't work, but they are inessential.)

The Computers and Thought book available online

An effective introductory book for absolute beginners in AI and Cognitive science is Computers and Thought by M.Sharples, D. Hogg, C. Hutchison, S. Torrance, D. Young, MIT Press (1989). This book relates AI to philosophy, psychology and linguistics, and includes programming examples in Pop-11,

It is available online (though without any of the diagrams alas) at

Natural language processing in Pop-11 available online

This book by Gerald Gazdar and Chris Mellish, originally published in 1989 by Addison Wesley, is available online here:

OpenPoplog development project at Sourceforge

For further information see:

This file is maintained by:
Aaron Sloman,
School of Computer Science,
The University of Birmingham

Last updated: 6 Jul 2009; 3 Dec 2010