January 2008 - Haskell

ANNOUNCE: pcre-light, a light, portable regular expression library for Haskell
by Don Stewart 13 Jan '08

13 Jan '08

pcre-light A light regular expression library, using Perl 5 compatible regexes I'm pleased to announce the first release of pcre-light. This library provides a simple, efficient interface to PCRE regular expressions, via either strict ByteStrings or classical Strings. Compilation and matching of regular expressions is done via two functions: compile :: ByteString -> [PCREOption] -> Either String Regex match :: Regex -> ByteString -> [PCREExecOption] -> Maybe [ByteString] A convenience interface for 'Char8' Strings is also provided. == Examples == Although the operations by default take ByteStrings, we can avoid unnecessary 'pack' calls using GHC's support for ByteStrings literals, enabled with -XOverloadedStrings: > :m + Text.Regex.PCRE.Light > :m + Data.ByteString.Char8 > :set -XOverloadedStrings > let Right r = compile "the quick brown fox" [] > match r "the quick brown fox" [] Just ["the quick brown fox"] > match r "the quick brown FOX" [] Nothing We can also enable various matching extensions, > let Right r = compile "the quick brown fox" [caseless] > match r "the quick brown FOX" [] Just ["the quick brown FOX"] Subpatterns, and fancy Perl regex extensions are happily supported: > let Right r = compile "^(abc){1,2}zz" [] > match r "abczz" [] Just ["abczz","abc"] Where the subpattern bound by ( ) was returned as the second element of the list. > let Right r = compile "\\w+(?=\t)" [] > match r "the quick brown\t fox" [] Just ["brown"] You can do lots of silly things with this: > let Right r = compile "^(a()+)+" [] > match r "aaaa" Just ["aaaa", "a", ""] The full set of compile and runtime PCRE extensions are supported. == Get it == * Stable tarballs, (on Hackage, of course): http://hackage.haskell.org/cgi-bin/hackage-scripts/package/pcre-light * Cabal install it! Using the new 'cabal-install', you can automatically download, build and install the package: $ cabal update $ cabal install pcre-light Downloading 'pcre-light-0.1'... Configuring pcre-light-0.1... Preprocessing library pcre-light-0.1... Building pcre-light-0.1... Registering pcre-light-0.1.. And off we go! For more information about cabal-install, see the hackage page for this excellent tool. * Darcs repository: http://code.haskell.org/~dons/code/pcre-light/ * Documentation: http://code.haskell.org/~dons/docs/pcre-light/ * Stability The library takes correctness seriously, and comes with a reasonable testsuite (with plans to greatly extend it), and code coverage data for those tests (using GHC's new -fhpc flag). You can see the test coverage results here: http://code.haskell.org/~dons/tests/pcre-light/hpc_index.html Yours in code, Don P.S. I'd like to encourage other authors to distribute code coverage results for their libraries! hpc is an invaluable tool to ensure high quality libraries for the Haskell community. P.P.S. Consider consider contributing your own light bindings to useful C libraries. The more we have, the more certain and sustainable Haskell development will be :) P.P.P.S. Thanks to #haskell for testing and advice.

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ANN: Haskell Cryptographic Library 4.1.0
by Dominic Steinitz 12 Jan '08

12 Jan '08

I'd like to announce the release of a new version of the library following various contributions (contributors are bcc'd). Additions include: BubbleBabble, TEA, HMAC and more large word support. It no longer includes Base64. This is provided by http://hackage.haskell.org/cgi-bin/hackage-scripts/package/dataenc-0.10.1. Many thanks to all contributors. Dominic. PS I always mention this but the library really needs to be reviewed holistically and possibly restructured given the advent of bytestrings. If anyone would like to volunteer to do this or take over as library maintainer, please let me know.

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The Monad.Reader (10) - Second call for copy
by Wouter Swierstra 11 Jan '08

11 Jan '08

Call for Copy The Monad.Reader - Issue 10 It is not too late to consider writing something for the next issue of The Monad.Reader. The deadline for Issue 10 is ** January 25, 2007 ** It doesn't matter if you're an established academic or if you have only just started learning Haskell, if you have something to say, please write article for The Monad.Reader. The Monad.Reader is a electronic magazine about all things Haskell. It is less-formal than journal, but somehow more enduring than a wiki- page. There have been a wide variety of articles, including: exciting code fragments, intriguing puzzles, book reviews, tutorials, and even half-baked research ideas. * Submission Details * Get in touch with me if you intend to submit something -- the sooner you let me know what you're up to, the better. Please submit articles for the next issue to me by e-mail (wss at cs.nott.ac.uk). Articles should be written according to the guidelines available from http://www.haskell.org/haskellwiki/The_Monad.Reader Please submit your article in PDF, together with any source files you used. The sources will be released together with the magazine under a BSD license. If you would like to submit an article, but have trouble with LaTeX please let me know and we'll sort something out. All the best, Wouter This message has been checked for viruses but the contents of an attachment may still contain software viruses, which could damage your computer system: you are advised to perform your own checks. Email communications with the University of Nottingham may be monitored as permitted by UK legislation.

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SAS 2008 - Final CFP
by German Vidal 10 Jan '08

10 Jan '08

15th International Static Analysis Symposium - SAS 2008 Valencia, Spain - July 16-18 >>Just 2 days to go to the abstract submission deadline<< Important dates: Submission of abstract: January 12, 2008 Submission of full paper: January 19, 2008 Notification: March 7, 2008 Camera-ready version: April 5, 2008 Conference: July 16-18, 2008 Please see: http://www.dsic.upv.es/~sas2008/ Maria Alpuente, German Vidal (PC co-chairs) Email: sas2008(a)dsic.upv.es

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detecting existing instances
by Jorge Marques Pelizzoni 10 Jan '08

10 Jan '08

Hi, all! I guess this belongs to haskell-cafe or glasgow-haskell-users, but I've already been there and got no replies. Thanks in advance for anyone taking the time to read on. Given two type classes A t and B t, I'd like the typechecker to derive different A t instances depending exactly on whether t is an instance of B. In other words, is it possible to define a class (actually a type-level function) IsB t f such that: IsB t HTrue <=> instance (B t) exists IsB t HFalse <=> otherwise? If not, is this wish intrisically pointless? After experimenting a bit with multiparameter classes, overlapping instances and suchlike, it looks like Haskell is being purposedly designed not to support this. Yes, I believe that would require the typechecker to take a whole new theorem-proving (undecidable?) stance :o) On the other hand, any interesting type-level programming seems to require undecidable+overlapping instances, so we are usually working on undecidable grounds... Sorry if this is an overdebated matter (is it?), but searching through the endless haskell archives is not trivial. Thanks in advance for any pointers or thoughts on the matter. Cheers, Jorge.

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Problems with Unicode Symbols as Infix Function Names in Propositional Calculus Haskell DSL
by Cetin Sert 09 Jan '08

09 Jan '08

I want to design a DSL in Haskell for propositional calculus. But instead of using natural language names for functions like or, and, implies etc. I want to use Unicode symbols as infix functions ¬, ˅, ˄, →, ↔ But I keep getting error messages from the GHC parser. Is there a way to make GHC parse my source files correctly? If it is not possible yet, please consider this as a “feature request”. Best Regards, Cetin Sert INF 521, 4-6-2 69120 Heidelberg Germany http://www.corsis.de

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ANNOUNCE: Haddock version 2.0.0.0
by David Waern 09 Jan '08

09 Jan '08

Dear Haskell community, I'm proud to announce the release of Haddock 2.0.0.0! http://www.haskell.org/haddock http://hackage.haskell.org/cgi-bin/hackage-scripts/package/haddock-2.0.0.0 Changes in version 2.0.0.0: * The GHC API is used as the front-end * Haddock now understands all syntax understood by GHC 6.8.2 * Haddock can generate documentation for some of the language extensions in GHC 6.8.2 * Format of module attributes has changed. The only way of specifiying module attributes is via a new OPTIONS_HADDOCK pragma. Example: {-# OPTIONS_HADDOCK hide, prune #-} * Haddock understands literate source files * Add a small library to read Haddock's interface files * Add a flag -B for passing the path to the GHC lib dir * Add a flag --optghc for passing options to GHC * Add a flag --ghc-version for printing the GHC version * Remove --use-package, --allow-missing-html, --ghc-pkg, in favour of only supporting --read-interface * Remove --package flag, the GHC flag -package-name can be used instead * Remove --no-implicit-prelude flag, the GHC flag -XNoImplicitPrelude can be used instead * Hoogle support temporarily removed It should be noted that this version of Haddock is not compatible with interface files from previous versions. Also, currently, when Haddock comes across a GHC language extension that it doesn't know how to render as HTML, it will bail out. If this happens to you, bug me about it, or help out by sending a patch. On the development side, Haddock has been slightly refactored for easier code navigation, and has the beginnings of a test suite. Haddock also ships with (as noted in the list of changes) a small, experimental library that can be used to read its interface files. Tools and IDE-type applications can use this library to e.g. look up the documentation for identifiers. The code repository is at http://code.haskell.org/haddock. David

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MSFP call for papers
by Venanzio Capretta 09 Jan '08

09 Jan '08

CALL FOR PAPERS Second Workshop on MATHEMATICALLY STRUCTURED FUNCTIONAL PROGRAMMING 6 July 2008, Reykjavik - Iceland A satellite workshop of ICALP 2008 PRESENTATION The workshop on Mathematically Structured Functional Programming is devoted to the derivation of functionality from structure. It is a celebration of the direct impact of Theoretical Computer Science on programs as we write them today. Modern programming languages, and in particular functional languages, support the direct expression of mathematical structures, equipping programmers with tools of remarkable power and abstraction. Monadic programming in Haskell is the paradigmatic example, but there are many more mathematical insights manifest in programs and in programming language design: Freyd-categories in reactive programming, symbolic differentiation yielding context structures, and comonadic presentations of dataflow, to name but three. This workshop is a forum for researchers who seek to reflect mathematical phenomena in data and control. The first MSFP workshop was held in Kuressaare, Estonia, in July 2006. An associated special issue of the Journal of Functional Programming is in preparation. SUBMISSIONS Electronic Notes in Theoretical Computer Science have provisionally agreed to publish the proceedings of MSFP 2008. ENTCS require submissions in LaTeX, formatted according to their guidelines (http://www.entcs.org/prelim.html) Papers must report previously unpublished work and not be submitted concurrently to another conference with refereed proceedings. Programme Committee members, barring the co-chairs, may (and indeed are encouraged) to contribute. Accepted papers must be presented at the workshop by one of the authors. There is no specific page limit, but authors should strive for brevity. We are using the EasyChair software to manage submissions. To submit a paper, please log in at: http://www.easychair.org/conferences/?conf=msfp2008. TIMELINE: Submission of abstracts: 4 April Submission of papers: 11 April Notification: 16 May Final versions due: 13 June Workshop: 6 July For more information about the workshop, go to: http://msfp.org.uk/ Programme Committee * Yves Bertot, INRIA, Sophia-Antipolis, France * Venanzio Capretta (co-chair), Radboud University, Nijmegen, The Netherlands * Jacques Carette, McMaster University, Hamilton, Ontario, Canada * Thierry Coquand, Chalmers University, Göteborg, Sweden * Andrzej Filinski, DIKU, University of Copenhagen, Denmark * Jean-Christophe Filliâtre, LRI, Université Paris Sud, France * Jeremy Gibbons, Oxford University, England * Andy Gill, Galois Inc., Portland, Oregon, USA * Peter Hancock, University of Nottingham, England * Oleg Kiselyov, FNMOC, Monterey, California, USA * Paul Blain Levy, University of Birmingham, England * Andres Löh, Utrecht University, The Netherlands * Marino Miculan, Università di Udine, Italy * Conor McBride (co-chair), Alta Systems, Northern Ireland * James McKinna, Radboud University, Nijmegen, The Netherlands * Alex Simpson, University of Edinburgh, Scotland * Tarmo Uustalu, Institute of Cybernetics, Tallinn, Estonia

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2nd ANNOUNCE: HCAR 12/2007
by Andres Loeh 09 Jan '08

09 Jan '08

Hi everyone. [For everyone who missed the first announcement because they were already in the holidays ...] The December 2007 edition of the Haskell Communities and Activities Report is out and available for download from http://haskell.org/communities Cheers, Andres -- Andres Loeh, Universiteit Utrecht mailto:andres@cs.uu.nl mailto:mail@andres-loeh.de http://www.andres-loeh.de

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What dates are best for a hackathon in Gothenburg?
by Bjorn Bringert 08 Jan '08

08 Jan '08

We are planning to hold the 4th Haskell Hackathon in Gothenburg in April. If you would be at all interested in coming, please indicate which of the three candidate dates Apr 4-6, Apr 11-13, or Apr 18-20 suit you by editing: http://www.haskell.org/haskellwiki/Hac_2008/Dates If you haven't been to a Haskell Hackathon before, check out the web page from the 3rd hackathon which was held in Freiburg in October: http://www.haskell.org/haskellwiki/Hac_2007_II /Björn

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