Skip to content
Fetching contributors…
Cannot retrieve contributors at this time
122 lines (75 sloc) 3.49 KB


What is Cython?

Cython is a programming language based on Python with extra syntax to provide static type declarations.

What Does It Do?

It takes advantage of the benefits of Python while allowing one to achieve the speed of C.

How Exactly Does It Do That?

The source code gets translated into optimized C/C++ code and compiled as Python extension modules.

This allows for both very fast program execution and tight integration with external C libraries, while keeping up the high programmer productivity for which the Python language is well known.

Tell Me More!

The Python language is well known.

The primary Python execution environment is commonly referred to as CPython, as it is written in C. Other major implementations use:

Java:Jython [1]
C#:IronPython [2])
Python itself:PyPy [3]

Written in C, CPython has been conducive to wrapping many external libraries that interface through the C language. It has, however, remained non trivial to write the necessary glue code in C, especially for programmers who are more fluent in a high-level language like Python than in a do-it-yourself language like C.

Originally based on the well-known Pyrex [4], the Cython project has approached this problem by means of a source code compiler that translates Python code to equivalent C code. This code is executed within the CPython runtime environment, but at the speed of compiled C and with the ability to call directly into C libraries.

At the same time, it keeps the original interface of the Python source code, which makes it directly usable from Python code. These two-fold characteristics enable Cython’s two major use cases:

  1. Extending the CPython interpreter with fast binary modules, and
  2. Interfacing Python code with external C libraries.

While Cython can compile (most) regular Python code, the generated C code usually gains major (and sometime impressive) speed improvements from optional static type declarations for both Python and C types. These allow Cython to assign C semantics to parts of the code, and to translate them into very efficient C code.

Type declarations can therefore be used for two purposes:

  1. For moving code sections from dynamic Python semantics into static-and-fast C semantics, but also for..
  2. Directly manipulating types defined in external libraries. Cython thus merges the two worlds into a very broadly applicable programming language.

Where Do I Get It?

Well.. at of course!

How Do I Report a Bug?

I Want To Make A Feature Request!

Is There a Mail List? How Do I Contact You?


[1]Jython: J. Huginin, B. Warsaw, F. Bock, et al., Jython: Python for the Java platform,
[2]IronPython: Jim Hugunin et al.,
[3]PyPy: The PyPy Group, PyPy: a Python implementation written in Python,
[4]Pyrex: G. Ewing, Pyrex: C-Extensions for Python,
Something went wrong with that request. Please try again.