pypy-0.9.0: stackless, new extension compiler

The PyPy development team has been busy working and we’ve now packaged our latest improvements, completed work and new experiments as version 0.9.0, our fourth public release.

The highlights of this fourth release of PyPy are:

implementation of “stackless” features

We now support the larger part of the interface of the original Stackless Python – see for more. A significant part of this is the pickling and unpickling of a running tasklet.

These features, especially the pickling, can be considered to be a “technology preview” – they work, but for example the error handling is a little patchy in places.

The “extension compiler” is a new way of writing a C extension for CPython and PyPy at the same time. For more information, see its documentation:
Most useful in combination with the ext-compiler is the fact that our translation framework can translate code that uses the standard-in-Python-2.5 ctypes module. See its documentation for more:
framework GCs
PyPy’s interpreter can now be compiled to use a garbage collector written in RPython. This added control over PyPy’s execution makes the implementation of new and interesting features possible, apart from being a significant achievement in its own right.
The PyPy interpreter’s compatibility with CPython continues improves: now we support __del__ methods, the __subclasses__ method on types and weak references. We now pass around 95% of CPython’s core tests.
logic space preview
This release contains the first version of the logic object space, which will add logical variables to Python. See its docs for more:
high level backends preview
This release contains the first versions of new backends targeting high level languages such as Squeak and .NET/CLI and updated versions of the JavaScript and Common Lisp backends. They can’t compile the PyPy interpreter yet, but they’re getting there…
bugfixes, better performance
As you would expect, performance continues to improve and bugs continue to be fixed. The performance of the translated PyPy interpreter is 2.5-3x times faster than 0.8 (on richards and pystone), and is now stable enough to be able to run CPython’s test suite to the end.
testing refinements
py.test, our testing tool, now has preliminary support for doctests. We now run all our tests every night, and you can see the summary at:

What is PyPy (about)?

PyPy is a MIT-licensed research-oriented reimplementation of Python written in Python itself, flexible and easy to experiment with. It translates itself to lower level languages. Our goals are to target a large variety of platforms, small and large, by providing a compilation toolsuite that can produce custom Python versions. Platform, memory and threading models are to become aspects of the translation process - as opposed to encoding low level details into the language implementation itself. Eventually, dynamic optimization techniques - implemented as another translation aspect - should become robust against language changes.

Note that PyPy is mainly a research and development project and does not by itself focus on getting a production-ready Python implementation although we do hope and expect it to become a viable contender in that area sometime next year.

PyPy is partially funded as a research project under the European Union’s IST programme.

Where to start?

Getting started:

PyPy Documentation:

PyPy Homepage:

The interpreter and object model implementations shipped with the 0.9 version can run on their own and implement the core language features of Python as of CPython 2.4. However, we still do not recommend using PyPy for anything else than for education, playing or research purposes.

Ongoing work and near term goals

The Just-in-Time compiler and other performance improvements will be one of the main topics of the next few months’ work, along with finishing the logic object space.

Project Details

PyPy has been developed during approximately 20 coding sprints across Europe and the US. It continues to be a very dynamically and incrementally evolving project with many of these one-week workshops to follow.

PyPy has been a community effort from the start and it would not have got that far without the coding and feedback support from numerous people. Please feel free to give feedback and raise questions.

have fun,

the pypy team, (Armin Rigo, Samuele Pedroni, Holger Krekel, Christian Tismer, Carl Friedrich Bolz, Michael Hudson, and many others:

PyPy development and activities happen as an open source project and with the support of a consortium partially funded by a two year European Union IST research grant. The full partners of that consortium are:

Heinrich-Heine University (Germany), AB Strakt (Sweden) merlinux GmbH (Germany), tismerysoft GmbH (Germany) Logilab Paris (France), DFKI GmbH (Germany) ChangeMaker (Sweden), Impara (Germany)