pypy-0.99.0: new object spaces, optimizations, configuration …

Welcome to the PyPy 0.99.0 release - a major snapshot and milestone of the last 8 months of work and contributions since PyPy-0.9.0 came out in June 2006!

Main entry point for getting-started/download and documentation:

Further below you’ll find some notes about PyPy, the 0.99.0 highlights and our aims for PyPy 1.0.

have fun,

the PyPy team, Samuele Pedroni, Carl Friedrich Bolz, Armin Rigo, Michael Hudson, Maciej Fijalkowski, Anders Chrigstroem, Holger Krekel, Guido Wesdorp

and many others:

What is PyPy?

Technically, PyPy is both a Python Interpreter implementation and an advanced Compiler, actually a framework for implementing dynamic languages and generating virtual machines for them. The Framework allows for alternative frontends and for alternative backends, currently C, LLVM and .NET. For our main target “C”, we can 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 without the coding, feedback and general support from numerous people.

Formally, many of the current developers are involved in executing an EU contract with the goal of exploring and researching new approaches to Language/Compiler development and software engineering. This contract’s duration is about to end March 2007 and we are working and preparing the according final review which is scheduled for May 2007.

Key 0.99.0 Features

  • new object spaces:

    • Tainting: a 270-line proxy object space tracking and boxing sensitive information within an application. A tainted object is completely barred from crossing an I/O barrier, such as writing to files, databases or sockets. This allows to significantly reduce the effort of e.g. security reviews to the few places where objects are “declassified” in order to send information across I/O barriers.
    • Transparent proxies: allow to customize both application and builtin objects from application level code. Works as an addition to the Standard Object Space (and is translatable). For details see
  • optimizations:

    • Experimental new optimized implementations for various built in Python types (strings, dicts, lists)
    • Optimized builtin lookups to not require any dictionary lookups if the builtin is not shadowed by a name in the global dictionary.
    • Improved inlining (now also working for higher level backends) and malloc removal.
    • twice the speed of the 0.9 release, overall 2-3 slower than CPython
  • High level backends:

    • It is now possible to translate the PyPy interpreter to run on the .NET platform, which gives a very compliant (but somewhat slow) Python interpreter.
    • the JavaScript backend has evolved to a point where it can be used to write AJAX web applications with it. This is still an experimental technique, though. For demo applications see:
  • new configuration system: There is a new comprehensive configuration system that allows fine-grained configuration of the PyPy standard interpreter and the translation process.

  • new and improved modules: Since the last release, the signal, mmap, bz2 and fcntl standard library modules have been implemented for PyPy. The socket, _sre and os modules have been greatly improved. In addition we added a the pypymagic module that contains PyPy-specific functionality.

  • improved file implementation: Our file implementation was ported to RPython and is therefore faster (and not based on libc).

  • The stability of stackless features was greatly improved. For more details see:

  • RPython library: The release contains our emerging RPython library that tries to make programming in RPython more pleasant. It contains an experimental parser generator framework. For more details see:

  • improved documentation:

    The entry point to all our documentation is:

What about 1.0?

In the last week leading up to the release, we decided to go for tagging the release as 0.99.0, mainly because we have some efforts pending to integrate and complete research and coding work:

  • the JIT Compiler Generator is ready, but not fully integrated with the PyPy interpreter. As a result, the JIT does not give actual speed improvements yet, so we chose to leave it out of the 0.99 release: the result doesn’t meet yet the speed expectations that we set for ourselves - and which some blogs and people have chosen as the main criterium for looking at PyPy.
  • the extension enabling runtime changes of the Python grammar is not yet integrated. This will be used to provide Aspect-Oriented Programming extensions and Design by Contract facilities in PyPy.
  • the Logic object space, which provides Logic Variables in PyPy, needs to undergo a bit more testing. A constraint problem solver extension module is ready, and needs to be integrated with the codebase.

PyPy 0.99 is the start for getting to 1.0 end of March 2007, which we intend to become a base for a longer (and more relaxed :) time to come.

Funding partners and organizations

PyPy development and activities happen as an open source project and with the support of a consortium partially funded by a 28 months European Union IST research grant. The full partners of that consortium are:

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