What is PyPy?
==============

- multiplatform compiler toolchain

- flexible interpreter

- an open source project

- STReP

Python - quick summary
======================

- interpreted language

- very dynamic and introspective

- diversity of implementations
  (platforms, features, JIT)

- (?)complex

Our goal
========

- write (runnable) specification in high-level
  language (RPython)

- use python as a meta-programming language
  for RPython

- reason: C is to low level to analyze
  efficiently

Single source approach
======================

- multiple backends (C, CLI, JVM coming...) [m]

- multiple interpreter (Python, Javascript, scheme...) [n]

- multiple different approaches
  (JIT, stackless, gc, threading, ...) [o]

- in summary m+n+o code, not m*n*o

Forest of flow graphs/translation
=================================

XXX interactive demo of pygame viewer

Transformation approach
=======================

- most of our optimisations/safety checks
  are done as a graph transformation

- example - stack checks

- example - gc (modeled after Jikes MMtk)

Objspace concept
================

- single place where operations on objects
  are performed

Taint objspace
==============

- intercepts all operations performed on objects

.. image:: interpreterarch.png

Multiple object implementation
==============================

- variety of different implementations per
  interpreter type

- example: multidict

- example: ropes

Transparent proxies
===================

- works as a different object implementation

- intercepts all operations on objects
  and calls app-level code

- very much like .NET transparent proxy

Custom persistance scheme
=========================

- can be implemented on top of tproxy

- using whatever storage mechanism

- with desired granularity

Sandboxing
==========

- replace all external calls by stream writing methods

- create a custom library to cope with that

- some demo?