CLPython - an implementation of Python in Common Lisp

CLPython is an open-source implementation of Python written in Common Lisp. With CLPython you can run Python programs in a Lisp environment. Libraries written in Lisp are available to Python code, and Python libraries can be accessed by Lisp code.

CLPython is developed by Willem Broekema and is released as open source under the LLGPL.


Please see the Introduction and Manual on


CLPython runs successfully on each of the following platforms:

There are dependencies on:


To compile and load CLPython you need asdf. First create a link from the repository to files clpython.asd and clpython-test.asd. Then load the system:

(asdf:operate 'asdf:load-op :clpython)

To run the test suite:

(asdf:operate 'asdf:test-op :clpython)

The test result printed at the end should be a message like "Errors detected in this test: 4" (which are a handful known issues) and many successes. Unintended test errors are marked as "unexpected" in the summary; please report them if they occur.

Mailing Lists

There are two mailing lists, both low-traffic: