Haskell Weekly News: January 23, 2006

Greetings, and thanks for reading the 21st issue of HWN, a weekly newsletter for the Haskell community. Each Monday, new editions are posted to the Haskell mailing list and to The Haskell Sequence. RSS is also available.

New Releases

• Haskell'

  This week Isaac Jones announced that the Haskell' standardisation process is underway. Haskell' will be a conservative refinement of Haskell 98:

  Announcing the Haskell' ("Haskell-Prime") process. A short time ago, I asked for volunteers to help with the next Haskell standard. A brave group has spoken up, and we've organized ourselves into a committee in order to coordinate the community's work. It will be the committee's task to bring together the very best ideas and work of the broader community in an "open-source" way, and to fill in any gaps in order to make Haskell' as coherent and elegant as Haskell 98.

  Read the full announcement here.

  Presently, the following resources are available:
  • The haskell-prime mailing list
  • The Haskell' issue tracking system/wiki
  • A darcs repository for larger code examples and experiments

  Please join us in making Haskell' a success.

Resources and Tools

• Cabal. Isaac Jones announced some changes to Cabal, including new changes to the `hooks' interface. Feedback is encouraged. Secondly, a move is underway to build an exhaustive list of all Cabalised packages. Add a link if you have something! Isaac is asking people to re-send any Cabal bug reports or feature requests yet to be addressed. Report them on the Cabal Wiki & Bug Tracker
• Darcs switchover GHC has switched to darcs. The era of CVS is at an end:

  From: Simon Marlow
  Subject: TAG final switch to darcs, this repo is now live
  
  Fri Jan 20 05:46:30 PST 2006  Simon Marlow  microsoft.com>
    tagged final switch to darcs, this repo is now live

Discussion

• IO Regions. Oleg Kiselyov describes a simple implementation of monadic regions. The technique provides static guarantees that neither a file handle nor any computation involving the handle can leak outside of the region that created it. The technique has no runtime overhead and induces no runtime errors. For some background, John Launchbury and Simon Peyton Jones's 94 paper Lazy Functional State Threads is useful.
• Lexically scoped type variables. Simon Peyton-Jones released a proposal to change the way in which lexically-scoped typed variables work in GHC, as part of a revision to make type inference for GADTs simpler and more uniform.
• Providing an alternative to GMP. Esa Ilari Vuokko began a discussion on modifying the GHC runtime and build system to support alternative arbtirary precision arithmetic libraries, other than the GPL'd GMP.
• Arrays interfaces. (clarification) The Haskell'98 library report contains only basic Array implementation. The Hierarchical Libraries, shipped with modern versions of GHC, Hugs and NHC, includes much richer arrays library. Bulat Ziganshin started a wiki page describing how to use these new array interfaces.

Papers

This is a new HWN section collecting paper or article abstracts on Haskell-related topics. If you have submitted a new Haskell paper, send your abstract to HWN, and the abstract will appear in the next issue.

• Ralf Lämmel. Book review, "The Haskell Road to Logic, Maths and Programming" by Kees Doets and Jan van Eijck. To appear in JoLLI journal; 13 pages. http://www.cs.vu.nl/~ralf/JoLLI06.
  The "Haskell road" is an excellent book worth considering as course material and reading anyhow. A non-Haskell road is also discussed in the review.

• Ralf Lämmel. "Google's MapReduce Programming Model -- Revisited" Draft; To be submitted; feedback appreciated; 27 pages. http://www.cs.vu.nl/~ralf/MapReduce.
  The seminal MapReduce paper had been briefly discussed at LTU without really going into technical details. The present paper discovers the concepts from a functional programming perspective. Did you ever wonder why MapReduce is called MapReduce?

Darcs Corner

• Darcs Blogging. Zooko wrote an interesting blog entry on the PR issues darcs has, and on the various activities undertaken by the darcs developers.

Quote of the Week

    <monochrom> monadic regions? sounds neat.
    <monochrom> "monadic ___" sounds neat :)
    <dons> forall a. Monad a => Neat a

Contributing to HWN

Thanks to Bulat Ziganshin and Isaac Jones for contributing material to this edition of HWN.

You can help us create new editions of this newsletter. Please see the contributing information, send stories to dons -at- cse.unsw.edu.au. The darcs repository is available at darcs get http://www.cse.unsw.edu.au/~dons/code/hwn