Welcome to Cython!

Cython (http://www.cython.org) is based on Pyrex, but supports more cutting edge functionality and optimizations.


The original Pyrex program was licensed "free of restrictions" (see below). Cython itself is licensed under the

PYTHON SOFTWARE FOUNDATION LICENSE http://www.python.org/psf/license/

There are TWO mercurial (hg) repositories included with Cython:

  • Various project files, documentation, etc. (in the top level directory)
  • The main codebase itself (in Cython/)

We keep these separate for easier merging with the Pyrex project.

To see the change history for Cython code itself, go to the Cython directory and type

$ hg log

This requires that you have installed Mercurial.

-- William Stein (wstein@gmail.com)


The following is from Pyrex:

This is a development version of Pyrex, a language for writing Python extension modules.

For more info, see:

Doc/About.html for a description of the language INSTALL.txt for installation instructions USAGE.txt for usage instructions Demos for usage examples

Comments, suggestions, bug reports, etc. are welcome!

Copyright stuff: Pyrex is free of restrictions. You may use, redistribute, modify and distribute modified versions.

The latest version of Pyrex can be found here:


Greg Ewing, Computer Science Dept, +--------------------------------------+ University of Canterbury, | A citizen of NewZealandCorp, a | Christchurch, New Zealand | wholly-owned subsidiary of USA Inc. | greg@cosc.canterbury.ac.nz +--------------------------------------+