PyPy 1.1: Compatibility & Consolidation

Welcome to the PyPy 1.1 release - the first release after the end of EU funding. This release focuses on making PyPy’s Python interpreter more compatible with CPython (currently CPython 2.5) and on making the interpreter more stable and bug-free.

Download page:

PyPy’s Getting Started lives at:

Highlights of This Release

Other Changes

What is PyPy?

Technically, PyPy is both a Python interpreter implementation and an advanced compiler, or more precisely a framework for implementing dynamic languages and generating virtual machines for them.

The framework allows for alternative frontends and for alternative backends, currently C, Java and .NET. For our main target “C”, we can “mix in” different garbage collectors and threading models, including micro-threads aka “Stackless”. The inherent complexity that arises from this ambitious approach is mostly kept away from the Python interpreter implementation, our main frontend.

Socially, PyPy is a collaborative effort of many individuals working together in a distributed and sprint-driven way since 2003. PyPy would not have gotten as far as it has without the coding, feedback and general support from numerous people.

Have fun,

the PyPy release team, [in alphabetical order]

Amaury Forgeot d’Arc, Anders Hammerquist, Antonio Cuni, Armin Rigo, Carl Friedrich Bolz, Christian Tismer, Holger Krekel, Maciek Fijalkowski, Samuele Pedroni

and many others: https://codespeak.net/pypy/dist/pypy/doc/contributor.html