Sunday, May 18, 2008

Berlin Sprint Day 1 + 2

After having survived the S3-Workshop which took place in Potsdam on Thursday and Friday (a blog-post about this will follow later) we are now sitting in the c-base in Berlin, happily sprinting. Below are some notes on what progress we made so far:

  • The Gameboy emulator in RPython that Camillo Bruni is working on for his Bachelor project at Uni Bern does now translate. It took him (assisted by various people) a while to figure out the translation errors (essentially because he wrote nice Python code that passed bound methods around, which the RTyper doesn't completely like). Now that is fixed and the Gameboy emulator translates and runs a test ROM. You cannot really see anything yet, because there is no graphics support in RPython.
  • To get graphics support in RPython Armin and Karl started writing SDL bindings for RPython, which both the Gameboy emulator and the SPy VM need. They have basic stuff working, probably enough to support the Gameboy already.
  • Alexander, Armin, Maciek and Samuele discussed how to approach separate compilation for RPython, which isn't easy because the RPython type analysis is a whole-program analysis.
  • Stephan, Peter and Adrian (at least in the beginning) worked on making PyPy's stackless module more complete. They added channel preferences which change details of the scheduling semantics.
  • Toon, Carl Friedrich and Adrian (a tiny bit) worked on SPy. There is a branch that Toon started a while ago which contains many improvements but is also quite unclear in many respects. There was some progress in cleaning that up. This involved implementing the Smalltalk process scheduler (Smalltalk really is an OS). There is still quite some work left though. While doing so, we discovered many funny facts about Squeak's implementation details (most of which are exposed to the user) in the process. I guess we should collect them and blog about them eventually.
  • Samuele and Maciek improved the ctypes version of pysqlite that Gerhard Häring started.
  • Armin, Samuele and Maciek found an obscure bug in the interaction between the builtin-type-shortcut that Armin recently implemented and our multimethod implementation. It's not clear which of the two are to blame, however it seems rather unclear how to fix the problem: Armin and Samuele are stuck in a discussion about how to approach a solution since a while and are hard to talk to.
  • Stijn Timbermont, a Ph.D. student at the Vrije Universiteit Brussel who is visiting the sprint for two days was first looking at how our GCs are implemented to figure out whether he can use PyPy for some experiments. The answer to that seems to be no. Today he was hacking on a Pico interpreter (without knowing too much about Python) and is making some nice progress, it seems.

Will try to blog more as the sprint progresses.

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