1. Cat's Eye Technologies
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Thue /

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The Thue Programming Language

This is Cat's Eye Technologies' distribution of Thue, an esoteric programming language designed by John Colagioia. Thue is a non-deterministic string-rewriting language, based on a formalism called a semi-Thue system, but also including some programming-oriented features, like input and output.

The specification can be found in the file thue.txt in the doc directory.

John's implementation of the language, in C, is in the file thue.c in the src directory, and can, for all intents and purposes, be considered the reference implementation.

In the src directory, there are also two other implementation of Thue:

  • thue.py, in Python, written by Frédéric van der Plancke
  • thue.rb, in Ruby, written by Chris Pressey

There is an assortment of example Thue programs in the eg directory. The credits for these are as follows:

  • add_bin.t: Frédéric van der Plancke
  • edgcase?.t: Chris Pressey
  • truth-machine.t: Keymaker
  • all others: John Colagioia

More information on Thue can be found on the esolangs.org wiki entry for Thue.


All files in this distribution are "essentially in the public domain".

John's original license text can be found in doc/license.txt. (In it, the phrase "this file" referred to the archive in which all the Thue files were distributed.) He placed the files he wrote (implementation, spec, and examples) basically into the public domain, with the proviso that he be contacted by anyone who wanted to do "anything interesting" with the files, including modifying them.

Unfortunately, the email address he left for this purpose, with the claim that it would be kept current, is no longer active. Thus, one can probably reasonably assume that he is no longer interested in what happens to his Thue sources, and that they are unconditionally in the public domain; however, I am not a lawyer, etc. etc.

Frédéric's implementation, and example source, are much less questionably in the public domain; his only proviso is that he be given credit for what he wrote (and not be given credit for any changes or additions that he did not write.) Actually, as I understand it (but again, I am not a lawyer etc etc), putting something into the public domain does not take away one's moral rights to proper credit, so this isn't very much (if at all) different from just being in the public domain.

I, Chris Pressey, hereby place my implementation in Ruby, my example Thue programs in eg, and the contents of this README, into the public domain, under the Creative Commons CC0 1.0 Public Domain Dedication.

The following example files were taken from the esolangs.org wiki, and are thus also under the CC0 1.0 Public Domain Dedication:

  • truth-machine.t