March 2009 - Haskell-Cafe

Haskell syntax highlighting support for Trac
by Manlio Perillo 22 Mar '09

22 Mar '09

Hi. I have noted that with Haskell projects that make use of Trac for issue tracking, it is not possible to have syntax highlighting for Haskell code. http://hackage.haskell.org/trac/hackage/wiki/WikiProcessors Is someone working on this? I can try to write a Trac plugin or patch to solve this. Manlio

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Google Summer of Code: Is this idea useful for the community?
by fallintothis 22 Mar '09

22 Mar '09

I'm planning on applying for the Google Summer of Code and the more I think about it, the more excited I am over a Haskell reddit-alike[1]. I'm interested in web programming, Haskell, and reddit (being an addict for some years now). There's plenty of work to be done on such a project, there are existing code bases to help along with ideas, and it doesn't require the deepest knowledge of Haskell or, say, GHC's guts (not that I don't find those interesting, I'm just no expert). The hang-up I see is that there's not too much of an immediate community benefit if reddit already exists (which, I have on good authority, it does), other than in the interest of eating (or customizing) your own dog food. Any members of the Haskell community (more involved than I am) care to comment? Would the project be useful or otherwise good as a Summer of Code idea? If people don't get too sick of my pestering, I'm also considering opening it up as a ticket on the trac to see if it gets feedback there. Thanks! [1] http://www.reddit.com/r/haskell_proposals/comments/7u48x/a_simple_redditlik…

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Haskell Logo write-in candidate
by Warren Harris 21 Mar '09

21 Mar '09

After spending a bit of time trying to decide how to vote, I ended up deciding that my favorite would be a hybrid of several of the designs (#9 & #49 FalconNL, and #50 George Pollard). It's probably too late to include this in the voting, but here it is nonetheless: (My primary criterion is "would I wear this t-shirt?") :-) Warren

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Cabal properties with conditionals
by Manlio Perillo 21 Mar '09

21 Mar '09

Hi. Assuming this configuration fragment: library xxx cc-options: -Wall if flag(HAVE_URANDOM) cc-options: -DHAVE_URANDOM In case the HAVE_URANDOM flag is defined, what will be the value of the used cc-options? 1) -DHAHE_URANDOM 2) -Wall -DHAHE_URANDOM Thanks Manlio

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New Cabal FAQ
by Duncan Coutts 21 Mar '09

21 Mar '09

Hi all, I should have done this ages ago but there's now a Cabal FAQ on the Cabal website: http://haskell.org/cabal/FAQ.html It's not linked in yet, I'm looking for feedback and patches. The Cabal website is now maintained in darcs so it's easy to send in contributions: darcs get http://haskell.org/cabal/ For new pages like the FAQ I've been using markdown via pandoc. If appropriate we can migrate old pages to use that too. The main Cabal home page needs some love. We should have the cabal-install download directly on the front page. We should have quick intro tutorials for using the cabal command line program to install packages. There's lots of good material in the user guide but it is not well sign-posted. Duncan

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ANNOUNCE: Haddock 2.4.2
by David Waern 21 Mar '09

21 Mar '09

-------------------------------------------- -- Haddock 2.4.2 -------------------------------------------- A new version of Haddock, the Haskell documentation tool, is out. This is a bug fix release only, and it's the same version that will ship with GHC 6.10.2, unless any important problems are discovered before the GHC release. Because the .haddock file format has changed, links to previously installed documentation will not work when generating documentation using this version. Please use the bug tracker to submit bug reports or feature requests. -------------------------------------------- -- Changes in version 2.4.2 -------------------------------------------- * Support for GHC 6.10.2 * Haddock no longer crashes on Template Haskell modules (#68) (only with GHC 6.10.2 or above) * Fix problem with Template Haskell-generated declarations disappearing (#59) * Generate two anchors for each link for compatibility between IE and Opera (#45) * Improved error messages * Show re-exports from external packages again (GHC ticket #2746) * Store hidden modules in .haddock files again (needed by the haddock library) * Avoid processing boot modules * Pragmas may exist between document comments and declarations * Do not indicate that a constructor argument is unboxed * Fix problem with non-working links to ghc-prim * Allow referring to a specific section within a module in a module link (#65) * Fixes to the Hoogle backend * Improvements to the haddock library * Many other fixes (including #67, #69, #58, #57) -------------------------------------------- -- Links -------------------------------------------- Homepage: http://www.haskell.org/haddock Hackage page: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/haddock-2.4.2 Bugtracker and wiki: http://trac.haskell.org/haddock Mailing list: haddock(a)projects.haskell.org Code repository: http://code.haskell.org/haddock -------------------------------------------- -- Contributors -------------------------------------------- The following people contributed patches to this release: Joachim Breitner Roman Cheplyaka Ian Lynagh Neil Mitchell Simon Peyton-Jones Thomas Schilling David Waern -------------------------------------------- -- Get Involved -------------------------------------------- We welcome new contributors. To get involved, start by grabbing the code: http://code.haskell.org/haddock Then take a look at the bug and feature tracker for things to work on: http://trac.haskell.org/haddock

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[ANN] random-stream 0.1.1
by Manlio Perillo 21 Mar '09

21 Mar '09

I'm pleased to announce a new version of random-stream package. In this version I have rewritten the internal API. Now the package exposes a new System.Random.URandom module, with the function: urandom :: Int -> IO S.ByteString This function is an interface to the system pseudo random numbers generator. The API of the module System.Random.Stream is left unchanged, but it now uses the urandom function, internally. System.Random.Stream provides a pure interface over urandom, using a lazy ByteString of random bytes. Since it provides an infinite stream of random data, things should be ok. I have also added support to Windows (older versions may not be supported, however [1]). The package should be available on Hackage. Mercurial repository is at: http://hg.mperillo.ath.cx/haskell/random-stream/ Example usage: http://hpaste.org/fastcgi/hpaste.fcgi/view?id=2738 [1] It is possible to use OpenSSL, as a fallback. Just set the HAVE_SSL flag, during package configuration. The OpenSSL DLL should be placed where the linker can find it. I tried to test this, but without success (but I did not put much effort in it). Regards Manlio Perillo

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Data.Binary, Data.Text and errors
by Alexander Dunlap 21 Mar '09

21 Mar '09

Hi all, I have noticed that in both Data.Binary and Data.Text (which is still experimental, but still), the "decode" functions can be undefined (i.e. bottom) if they encounter malformed input. What is the preferred way to use these functions in a safe way? For example, if one writes data to a disk using Data.Binary and wants to read it back in at a later date, how can one ensure that it is valid so that Data.Binary does not hit an error? Or do you just have to catch the exception in the IO Monad? Alex

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[GSOC] About "Implementing Maps using generalized tries" project idea
by Gautam Sewani 21 Mar '09

21 Mar '09

Hi, I was looking at the list of Haskell GSOC 2009 project ideas, and I came across the one in which we have to implement maps using generalized tries. However, I also found this as one of the GSOC 2008 projects. I want to know if this project is still open, or the required work has been done last year. If it's open, what exactly needs to be done further. Regards Gautam

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Re: [Haskell-cafe] Ease of Haskell development on OS X?
by Thomas Davie 21 Mar '09

21 Mar '09

On 20 Mar 2009, at 16:56, Mark Spezzano wrote: > Hi, > > I’ve been thinking of changing over to an iMac from my crappy old PC > running Windows Vista. > > Question: Does the iMac have good support for Haskell development? As good as, if not better than other platforms I've found, you get none of the weird problems with libraries that aren't designed to run on windows, and more choice of editors than on linux. > Question: What environment setups do people commonly use (e.g. > Eclipse Xcode etc)? I use SubEthaEdit and a Terminal window, I know many people that use emacs/vi, and one or two that use TextMate. > Question: Are there any caveats I should be aware of before changing > systems (i.e. unpleasant surprises). Not particularly – it's mostly like running linux, but without the headaches when things break, and with more choice of software. > I want to be able to use the machine for Haskell OpenGL programming. Other than chose the graphics card carefully, an iMac will do you very well. Hope that helps. Bob

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