Sun, 25 Oct 2009
FP-Syd #20.
On October 22th we held the 20th meeting of FP-Syd, the Sydney Functional Programming group. The meeting was held at Google's Sydney offices and we had about 28 people show up to hear our two presenters.
First up we had Roman Leshchinskiy and his presentation "Loop Fusion in Haskell", work that is part of GHC's Data Parallel Haskell library. Loop fusion depends on the ability to convert operations on arrays into operations on streams. Then, when applying multiple stream operations, adjacent conversions to and from streams can be dropped, allowing further inlining. The real beauty of this approach is that stream operations and data parallelism can be written as a library outside of the GHC compiler and then depend on the compiler to do most of the heavy lifting. Romain then moved on to explain that this work was just as applicable to general parallel computation on multicore systems as it was to clusters and GPUs.
Our second presenter for the evening was Barry Jay who gave us an introduction to "Pattern Calculus". Barry's work on Pattern Calculus was inspired by the fact that while lambda calculus is able to adequately explain computation, it does not explain operations on data well. In particular, lambda calculus does not distinguish between variables and data constructors while in the pattern calculus constructors are treated as a separate class; matchable symbols. The ideas behind Pattern Calculus are explained more fully in Barry's book:
A big thanks to both our speakers and to Shane Stephens and Google for providing the meeting venue and the light refreshments.
![[operator<< is not my friend]](http://yosefk.com/c++fqa/images/operator.png)
