First day, Discussions

Bern Sprint, First Day, October 22

So, it seems customary for the Squeak community to use such incredibly advanced technology as RSS feeds and blogs to disseminate their sprint reports, which means us old-fashioned PyPyers just have to follow suit.

Today started the first ever Pypy-Squeak-collaboration sprint, kindly hosted in Bern by the Software Composition Group. The sprint aims to bring people from two different communities together (not without the unavoidable clash of culture, the first wars on zero- versus one-based indexing were already fought today) to learn about each others projects and to explore collaboration possibilies.

Morning was spent setting up the sprint room and general computer infrastructure like Squeak's VMMaker and Pypy. It seems that bootstrapping Squeak is certainly faster then bootstrapping Pypy (and uses way less memory) but not without certain problems. Adrian Kuhn tried to distribute an USB stuck containing a zip archive created under Windows. This turned out to be a bad idea, as obviously the notion of execution access permission is not known to Windows but crucial for Unices. In the end we finally succeeded. The PyPy checkouts of the Squeak guys on the other hand went quite smooth. Nobody tried to translate PyPy yet, though.

After lunch, Armin and Carl Friedrich gave various talks and demo for the SCG crowd (including some increasingly confused students). The first talk covered sprint-driven development in a two-slide presentation, including visualizations of software evolution, then we delved into the technical topics by re-giving our Dyla talk and demos.

After a break, we started brainstorming. We identified the following options as possible main goals for this week's sprint

* to implement a Squeak-bytecode interpreter in RPython

* to define and implement an RSqueak as PyPy frontend

* to write a Squeak backend for PyPy

even though option 2 was favoured as long term goal, we decided to go for the first option. To complete the second option, we felt, that we miss yet an understanding of the second option's trade-offs. Now, we do option one to gain insight into and a feel for the second option. We broke the first option down into smaller steps, as shown on this picture

Next Carl Friedrich quickly introduced the Squeak crowd to RPython, whereas Adrian Kuhn gave a quick and dirty introduction into the Smalltalk object model: "objects all the way down".

Finally, everyone gathered around Armin's laptop, who started hacking the very beginning of said object model into a set of RPython classes. Always writing tests first, true to Test Driven Development (while the rest of the crowed watched in amazement how the svn comments are announced live on PyPy's IRC channel). If you are interested in this very first prototype, please refer to the svn repo.

Please stay tuned for more news tomorrow.

Carl Friedrich Bolz and Adrian Kuhn