Q - Equational Programming Language

15 October 2003: Q 4.5 is now available. This release sports a new GGI (general graphics interface) module and some improvements in the debugger.

10 Dec 2003: Q goes SourceForge! As of Dec 2003, Q has now become a SourceForge-hosted project. That means that eventually this website and the download area will migrate to SourceForge, and there will also be CVS access there so that you can always get your hands on the very latest and greatest development sources. Right now neither file releases nor CVS are available yet (I hope to finish this before the end of December), but I have already set up two mailing lists for discussion of Q development and usage. Enjoy!

15 Dec 2003: The SourceForge CVS Repository is now online and file releases for the latest stable versions should soon show up in the Download Area, too!

NOTE: The software on this page is free software distributed under the GNU General Public License and can be obtained in the global Download section at the end of this page. The different packages are also listed both on the Freshmeat website and in the FSF Software Directory. Links to the Freshmeat record for each package are given in the "SEE ALSO" sections of the descriptions below. I always announce new releases on Freshmeat as soon as they become available. Thus, if you have registered a Freshmeat account and you'd like to be informed about new releases, just use the "Subscribe to new releases" option on the Freshmeat project pages.

Q

SEE ALSO:    COPYING   README    NEWS    ChangeLog    FAQ    Manual (HTML)    Manual (PDF)    Freshmeat    Download

Q is a modern functional programming language based on term rewriting. It is simple, powerful, extensible, portable, fast and easy to use:

Simple - Programs are just collections of equations which are used to evaluate expressions in a symbolic fashion.

Powerful - Despite its conceptual simplicity, Q is a full-featured functional programming language with a modern syntax, curried function applications, dynamic object-oriented typing, exception handling, POSIX style multithreading, and a comprehensive standard library.

Extensible - Q has a libtool-based C interface which makes it easy to extend the interpreter with your own primitives.

Portable - Q runs on BeOS, FreeBSD, Linux, Mac OS X, Solaris and Windows. Porting to other modern Unix-based platforms should be a piece of cake.

Fast - Well, as an interpreted language Q is certainly not as fast as native machine code, but it has an efficient interpreter which byte-compiles scripts in an eye blink and executes them about as fast as interpreted Lisp or Haskell.

Easy to use - Just throw together some equations, run the interpreter and start to evaluate expressions. Q scripts can be run from the command line or within GNU Emacs. For Windows, a graphical shell for editing and running Q scripts is also available.

As a practical programming language, Q comes with batteries included: Q's system interface comprises low-level file functions, process and thread handling, Berkeley sockets, regular expression matching, and more. Also included are interfaces to GNU dbm (simple database software), ODBC (the industry standard open database interface), John W. Eaton's GNU Octave (popular open source math software), IBM's Data Explorer (powerful scientific visualization package), GGI (a portable graphics interface) and John Ousterhout's ubiquitous Tcl/Tk (portable user interface toolkit and scripting language).

The base package includes a Q mode for GNU Emacs/XEmacs and a syntax file to enjoy syntax highlighting for the Q language in the advanced KDE editor Kate. The Windows version also provides a graphical application called Qpad for editing and running Q scripts (see below). We also have a plugin which lets you run Q sessions in GNU TeXmacs, the free scientific text editor. To install, extract this q-texmacs.tar.gz tarball into your /usr/share/TeXmacs/plugins directory.

Documentation: Full documentation can be found in the Q language manual (HTML, PDF). The HTML documentation is also available as a tarball. And there is an introductory paper on Q-Midi which includes a brief overview of Q's main features (PDF).

Qpad

SEE ALSO:    License.txt    ReadMe.txt    Download

The Qpad package is a complete binary distribution of the Q programming system for Windows. Besides the Q programming tools it also includes the Qpad application, a Windows frontend for the Q interpreter which provides a script editor and a "log" pane through which you can interact with the interpreter. You can use this application to edit and run Q scripts under Windows.

Q-Graph

SEE ALSO:    COPYING    README    NEWS    ChangeLog    Freshmeat    Download

Q-Graph is an add-on library to deal with combinatorial graphs, a data structure consisting of nodes and edges connecting the nodes. Graph theory and algorithms play a major role in countless applications such as network design and optimisation, traffic planning, routing, scheduling and visualization, and so graphs have become one of the cornerstones of applied discrete mathematics and computer science. The package implements a graph data type and the usual operations on graphs. It also contains graphed, a full-featured graph editor (requires Tcl/Tk). A sample implementation of Dijkstra's shortest path algorithm is also included. The entire package is written in Q, and thus it also provides an example of a substantial Q application.

Q-Midi

SEE ALSO:    COPYING    README    README-Player    NEWS    ChangeLog    Freshmeat    Download

Yep, Q finally plays music, too! :) More precisely, it can "talk" to MIDI, the "Musical Instrument Digital Interface". MIDI is the standard protocol for controlling synthesizers and other compatible equipment. Want to learn more about MIDI? Jeff Glatt's MIDI Technical Fanatic's Brainwashing Center is a good place to start.

Q-Midi is Q's MIDI module which allows you to write MIDI applications in the Q programming language. Q-Midi runs on top of MidiShare, Grame's excellent  "MIDI operating system" which is GPL'ed software, too. Q-Midi provides access to most basic MidiShare functionality, including realtime processing of MIDI messages and standard MIDI file access. This release of Q-Midi also includes a sample MIDI player/recorder written using Q-Midi (requires Tcl/Tk). The currently supported platforms are Linux, OS X and Windows. The Windows version has been tested on Windows 98 and 2000. An introduction to Q-Midi is now available (PDF, examples).

Also available: Scale 1.1, a Q-Midi software for experimenting with just and microtonal tunings. This program is based on Clarence Barlow's harmonicity theory and implements several new algorithms for the rationalization and visualization of musical scales. Requires a Linux system with Octave, OpenDX and Tcl/Tk (as well as Q-Midi, of course); see the download links below. You can find a description of the algorithms and the software in this report: Musical scale rationalization (PDF).

Q-Audio

SEE ALSO:    COPYING    README    NEWS    ChangeLog    Freshmeat    Download

Q-Audio is a digital audio interface for Q. The package contains two modules which together provide the basic functionality needed to write digital audio applications in the Q programming language. The audio module implements a (near-)realtime audio interface on top of Phil Burk's PortAudio library (http://www.portaudio.com), and the sndfile module allows you to access sound files in various formats using Erik de Castro Lopo's libsndfile library (http://www.zip.com.au/~erikd/libsndfile). This package works on FreeBSD, Linux, OS X and Windows. Other UNIX systems supporting the OSS sound driver should work as well, but have not been tested yet.

Download

The Q programming system and the various add-on packages are distributed under the GNU General Public License (GPL). The relevant items can be downloaded by clicking on the appropriate links below. Both source and various binary packages are provided. All binary packages are for the x86 architecture. Please see the RELNOTES file for further information and installation instructions, and also note the requirements for each package; additional information about required third-party software can be found below. For your convenience, we also provide Linux RPMs for the GGI and MidiShare libraries required by some packages, since these libraries are only distributed as source tarballs at this time. Please note that GGI is distributed under a BSD style license by the GGI project, while MidiShare is GPL'ed software distributed by Grame.

Optional Software

Some of the packages above may require additional third-party software. Links to download these items are provided below.

• GGI: The General Graphics Interface is an open source solution for developing portable raster graphics applications. It supports a large variety of display devices on different operating systems. Q's ggi module gives you access to the basic GGI functionality from Q scripts. The GGI sources are available from www.ggi-project.org and sourceforge.net/projects/ggi. The Qpad package for Windows already includes the necessary GGI support files. For Linux we provide RPM packages in the Download section above.
  
  
• ODBC: ODBC has become the industry standard for portable and vendor independent database access. Q's odbc module lets you connect to relational databases and retrieve or modify data using SQL statements. To use this module on Unix systems, you need an ODBC driver manager such as iODBC or unixODBC, as well as the database and corresponding ODBC driver you want to use. Two popular ODBC-compatible open source databases are MySQL and PostgreSQL.
   
  
• Octave: John W. Eaton's GNU Octave is a comprehensive MATLAB-like software for performing advanced numeric computations. Octave is required for Q's octave module. It is available from www.octave.org. You can also find some additional items including information about binary packages for Windows at the GNU Octave Repository.
    
• OpenDX: IBM's Open Data Explorer is a powerful scientific data visualization software, which is required for Q's dxl module. This software needs Motif, and hence is only available for Unix/X11 based systems at this time. You can get it at www.opendx.org.
    
• Tcl/Tk: John Ousterhout's Tcl/Tk is a command language and graphical user interface toolkit. Using Q's tk module, you can employ Tcl/Tk to create high-quality graphical user interfaces which are portable across most popular operating systems and windowing environments, including Unix/X11, OS X and MS Windows. Tcl/Tk is available at www.tcl.tk. It should be included in all Linux distros. For Windows, we recommend getting ActiveState's latest binary release which also includes most popular Tcl/Tk extension packages like BWidget and Iwidgets. You can download ActiveState's free binary Tcl/Tk releases here. For OS X you currently have to compile Tcl/Tk (the Unix/X11 version) yourself; you also need Apple's rootless X server which is available here.
    
• MidiShare: Grame's MidiShare is a library for portable MIDI programming which is available for several different systems, including Linux, Mac OS, Windows and even the good ol' Atari. MidiShare, which is hosted at www.grame.fr/MidiShare/, is required for the Q-Midi package. The Windows version of Q-Midi already includes the necessary MidiShare support files. For Linux we provide RPM packages in the Download section above. For OS X you can find binary packages here. You can also grab the latest MidiShare development version from MidiShare CVS and compile it yourself.
    
• Libsndfile: Erik de Castro Lopo's libsndfile is a library to access sound files in a variety of formats. Version 1.0 (or later) of this library is required for the Q-Audio package. Most Linux distros should have this library, and the Windows package includes the necessary dll. If you want to compile it yourself, you can download it from http://www.zip.com.au/~erikd/libsndfile.

Mailing Lists

• q-lang-users is for discussing all issues related to using Q. Here you can post all your questions and comments concerning the Q interpreter, the standard library, the add-on modules, etc.
• q-lang-devel is for discussing everything that is related to the development of the Q interpreter itself. This list is intended for those who are interested in working on the interpreter and the modules.
  

More detailed information about the mailing lists and a web-based interface to subscribe to the lists can be found by following the links above.
 

Links

Here are some links to related work:

• fun->pdf: Jan Skibinski's functional interface to create PDF documents. Targets Haskell, ML and an earlier Q version. (This is a link to the WaybackMachine. Unfortunately, Jan's original website www.numeric-quest.com went offline at some time in 2001.)

Links to software which also uses term rewriting as an underlying computational model. If you have anything to add to this list please let me know.

• Mathematica: Arguably one of the most popular computer algebra systems out there.
• ELAN: An environment for specifying and prototyping deduction systems in a language based on rewrite rules controlled by strategies.
• EPIC: A reduction engine intended as a target for term rewriting compilers.
• Escher: An experimental functional+logic programming language.
• Req: Darius Bacon's calculator programmable with rewrite rules.