Welcome to issue 74 of HWN, a newsletter covering developments in the Haskell community.

This week, you'll notice a bit more detail in the 'Blogs' section. I've added summaries to some of the posts, to help you decide which you might be interested to read (only a few this week, since I added them at the last minute). I've also >>> highlighted blogs not syndicated on Planet Haskell---mostly people who have just begun learning Haskell and decided to blog about it. Go show them some comment love, and invite them into the community!

Community News

Andrew Wagner (chessguy) recently flew out to Microsoft for an interview with their Live Search team. In an email to the cafe, he shares some stories from his experience and some interesting coding challenges.


HAppS self-demoing tutorial. Thomas Hartman announced a self-demoing, HStringTemplate-using intro to HAppS. Check out the live demo or obtain it from Hackage.

NWFP Interest Group. Greg Meredith announced the next monthly meeting of the NW Functional Programmers Interest group, 6:30 on June 25 at the Seattle Public Library. Greg will talk about a very cool compositional representation of graphs he's been tinkering with recently.

ICFP final call for posters. Matthew Fluet announced the final call for proposals for the ICFP 2008 poster session, which should be submitted by June 30. Let people know what you're working on!

type-level and parameterized-data packages. Alfonso Acosta announced the release of the type-level and parameterized-data packages, which provide type-level computation and parameterized types a la a dependently-typed system.

Lambda in the sun. James Iry announced the creation of Southern California Functional Programmers (SoCalFP), a group for people in LA, Orange County, and San Diego to meet to discuss, debate, present, and learn about functional programming concepts and techniques in various languages.

Real World Haskell. Bryan O'Sullivan announced the availability of ten new draft chapters of Real World Haskell, the upcoming O'Reilly book being written by Bryan, John Goerzen, and Don Stewart. In case you were worried, yes, you'll be able to have one in your Christmas stocking!

Pugs on hackage!. Audrey Tang has uploaded to Hackage version of Pugs, an implementation of Perl 6 in Haskell.

Literal programming with rst-literals. Martin Blais described a neat use of his utility rst-literals to extract Haskell code from ReST documents, enabling a different style of literate programming.

Pipe 1.0. Matti Niemenmaa announced the release of Pipe, a library for piping data through a pipeline of processes.

HUnit. Richard Giraud announced that he has improved the HUnit documentation and published the changes in a darcs repository.

hback. Norbert Wojtowicz announced a new release of hback, a Haskell implementation of the dual n-back memory game using gtk2hs.

Google Summer of Code

Progress updates from participants in the 2008 Google Summer of Code.

Hoogle 4. Neil Mitchell (ndm) is working on Hoogle 4, and recently added two new features, multi-word search and intelligent suggestions.

DPH physics engine. Roman Cheplyaka (Feuerbach) is working on a physics engine using Data Parallel Haskell. This week he intended to implement simple ad-hoc cubic collision geometry to test collisions with rotation, but the code became too cumbersome and non-extensible. He took a break to read some papers, and found a better solution.

GHC plugins. Max Bolingbroke is working on dynamically loaded plugins for GHC. This week he worked on adding arbitrary user-specified phases to GHC, implementing a control system, pipeline generation, and Template Haskell integration. Next he plans to work on a plugin annotation system.

Cabal dependency framework. Andrea Vezzosi (Saizan) is working on a make-like dependency analysis framework for Cabal. He has posted a detailed explanation of his project, some of the issues involved, and his progress so far.

Language.C. Benedikt Huber (visq) is working on Language.C, a standalone parser/pretty printer library for C99. This week he worked on AST documentation and improvements, prepared to port the AST analysis from c2hs, and worked on the pretty printer's internals.

Generic tries. Jamie Brandon is working on a library for efficient maps using generalized tries. Recently he has worked on implementing some bitpacking tools to save memory.

GHC API. Thomas Schilling (nominolo) is supposedly working on improvements to the GHC API. However, officials at HWN headquarters have begun privately speculating that Thomas does not, in fact, exist.


history of tuples vs pairs. Conal Elliott asked about the history of support for n-tuples in Haskell and ML.

hackageDB maintainer policy. Ross Paterson began a lengthy discussion towards agreeing on a policy for uploading packages to Hackage, specifying whether the package is maintained and who is maintaining it, and other related issues.

What is a rigid type variable?. Xiao-Yong Jin asked what the 'rigid type variables' are that are sometimes referred to in GHC error messages. Read the thread for a concise discussion and the solution to the original problem.

Map interface. Jamie Brandon started a thread asking for feedback on his proposed API for generic tries, and the discussion is still ongoing.

Left and right folds. George Kangas exhibited a pair of very elegant alternate definitions for left and right fold, and showed how this alternate viewpoint makes obvious several algebraic identities as well as the generalization to Data.Foldable. A must-read for the aspiring functional programmer.

ribbonsPerLine. Alfonso Acosta asked an interesting question about "ribbonsPerLine" in the Text.PrettyPrint.HughesPJ library. Do you know what it does? The answer can be found in the original paper describing the library.


PhD position at University of Strathclyde, Glasgow. Simon Marlow announced, on behalf of Patricia Johann, an open PhD position in operational and categorical approaches to parametricity. The funded position is in the newly-formed Mathematically Structured Programming group at the University of Strathclyde, comprising Neil Ghani, Patricia Johann, and Conor McBride.

Quantitative Trading Developer Position at Hutchin Hill Capital. Neil Mehra announced an open position for a Quantitative Trading Developer at Hutchin Hill Capital, a newly formed multi-strategy hedge fund located in midtown Manhattan.

Blog noise

Haskell news from the blogosphere.

Quotes of the Week

About the Haskell Weekly News

New editions are posted to the Haskell mailing list as well as to the Haskell Sequence and Planet Haskell. RSS is also available, and headlines appear on haskell.org. Headlines are available as PDF.

To help create new editions of this newsletter, please see the information on how to contribute. Send stories to byorgey at seas dot upenn dot edu. The darcs repository is available at darcs get http://code.haskell.org/~byorgey/code/hwn/ .