What is it?

Pythran is an ahead of time compiler for a subset of the Python language, with a focus on scientific computing. It takes a Python module annotated with a few interface descriptions and turns it into a native Python module with the same interface, but (hopefully) faster.

It is meant to efficiently compile scientific programs, and takes advantage of multi-cores and SIMD instruction units.

Until 0.9.5 (included), Pythran was supporting Python 3 and Python 2.7. It now only supports Python 3.


Pythran sources are hosted on

Pythran releases are hosted on

Pythran is available on conda-forge on


Using pip

  1. Gather dependencies:

    Pythran depends on a few Python modules and several C++ libraries. On a debian-like platform, run:

    $> sudo apt-get install libatlas-base-dev
    $> sudo apt-get install python-dev python-ply python-numpy
  2. Install with pip:

    $> pip install pythran

Using mamba or conda

  1. Using mamba ( or conda (

  2. Run:

    $> mamba install -c conda-forge pythran


    $> conda install -c conda-forge pythran


Using brew (

$> pip install pythran
$> brew install openblas
$> printf '[compiler]\nblas=openblas\ninclude_dirs=/usr/local/opt/openblas/include\nlibrary_dirs=/usr/local/opt/openblas/lib' > ~/.pythranrc

Depending on your setup, you may need to add the following to your ~/.pythranrc file:



Using pacman:

$> pacman -S python-pythran


Using dnf:

$> dnf install pythran


Windows support is on going and only targets Python 3.5+ with either Visual Studio 2017 or, better, clang-cl:

$> pip install pythran

Note that using clang-cl.exe is the default setting. It can be changed through the CXX and CC environment variables.

Other Platform

See MANUAL file.

Basic Usage

A simple pythran input could be

Naive dotproduct! Pythran supports
#pythran export dprod(int list, int list)
def dprod(l0,l1):
    """WoW, generator expression, zip and sum."""
    return sum(x * y for x, y in zip(l0, l1))

To turn it into a native module, run:

$> pythran

That will generate a native that can be imported just like the former module:

$> python -c 'import dprod' # this imports the native module instead


The user documentation is available in the MANUAL file from the doc directory.

The developer documentation is available in the DEVGUIDE file from the doc directory. There is also a TUTORIAL file for those who don’t like reading documentation.

The CLI documentation is available from the pythran help command:

$> pythran --help

Some extra developer documentation is also available using pydoc. Beware, this is the computer science incarnation for the famous Where’s Waldo? game:

$> pydoc pythran
$> pydoc pythran.typing
$> pydoc -b  # in the browser


See the pythran/tests/cases/ directory from the sources.


Praise, flame and cookies:

The mailing list archive is available at


If you need to cite a Pythran paper, feel free to use

  title={Pythran: Enabling static optimization of scientific python programs},
  author={Guelton, Serge and Brunet, Pierrick and Amini, Mehdi and Merlini,
                  Adrien and Corbillon, Xavier and Raynaud, Alan},
  journal={Computational Science \& Discovery},
  publisher={IOP Publishing}


See AUTHORS file.


See LICENSE file.