pypy-0.9.0: stackless, new extension compiler

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Michael Hudson

Jun 25, 2006, 8:07:29 AM6/25/06
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

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

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

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.

contact points:

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)

Monte Carlo sampling is no way to understand code.
-- Gordon McMillan, comp.lang.python

Paul Rubin

Jun 25, 2006, 10:28:04 AM6/25/06
I've been away from Usenet for a while but this is the most interesting
stuff I've seen here in ages. Way cool.

Jun 26, 2006, 6:28:52 AM6/26/06
Hi all!

Michael Hudson wrote:
> 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.

Unfortunately the download links for the release tarballs did not work
until very recently. They are now working though. You can download the
0.9 release of PyPy under:

For detailed notes about how to get started into the world of PyPy see

Sorry for the fuss and cheers,

Carl Friedrich Bolz

Carl Friedrich Bolz

Jun 26, 2006, 11:56:01 AM6/26/06
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