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problem in using wash
by Vikrant 05 Mar '08

05 Mar '08

Hi, I was trying to use wash to learn it. I am using ubuntu and I have ghc6.6.1 installed on my system. I have also installed the package libghc6-wash-dev but in my code when i write "import WASH.CGI" it gives me following error firstCGI.hs:5:7: Could not find module `WASH.CGI': locations searched: WASH/CGI.hs WASH/CGI.lhs Failed, modules loaded: none. can somebody help me in this? Regards, Vikrant

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Haskell & Perl architecture question
by Marty Landman 04 Mar '08

04 Mar '08

I'm looking at a production system running Perl & Haskell in an Apache environment and trying to get a handle on the system architecture. Are there online resources anyone could recommend I start with? Thanks in advance, Marty -- Marty Landman, Face 2 Interface Inc. 845-679-9387 Drupal Development Blog: http://drupal.face2interface.com/ Free Database Search App: http://face2interface.com/Products/FormATable.shtml

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Markup bug in HaskellWiki
by Henning Thielemann 04 Mar '08

04 Mar '08

In the Wiki article http://haskell.org/haskellwiki/Comparison_chain there is the piece unzip">unzip which is improperly formatted.

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Annotating GHC assembler output?
by Justin Bailey 04 Mar '08

04 Mar '08

I'm interested in seeing what kind of assembler my functions turn into. Is there a means of annotating assembler output, similar to the {#- CORE -#} pragma? Is there a trickier way of doing it? Justin

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ID3 tagging
by adekoba 04 Mar '08

04 Mar '08

I was wondering if there are any haskell packages for tagging ID3 frames in mp3 files. Or perhaps if there were any plans for developing them...

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Re: static constants -- ideas?
by Don Stewart 03 Mar '08

03 Mar '08

jason.dusek: > I have an awkward programming problem -- I need to take a > dictionary, parse it, build a bunch of intermediate lists and > then make maps and tries out of the list. A "programming > problem" because it's taken me a fair amount of effort to pull > together the parser and list generator -- and "awkward" > because a 69000 item list, [(String, [(String, String)])], > does not compile under GHC (stack overflow). (It's not likely > to compile under anything else, either!) Here's an example of the approach Bryan outlined, which does seem to work for files as large as gcc can handle: * generate your big Haskell Map * serialise it with Data.Binary, and Codec.Compression.GZip to a file * compile the data into a C const array, and link that into Haskell * decode it on startup, ressurecting the Haskell data. The C source looks like: const uint8_t beowulf[] = { 31, 139, 8, 0, 0, 0, 0, 0, 0, 3, 124, 189, 75, 150, 46, 54, 93, 193, 96, 144, 241, 168, 172, 238, 214, 0, ... http://code.haskell.org/~dons/code/compiled-constants/cbits/constants.c which is the gzip, Data.Binary encoded version of a Map ByteString Int. Then the Haskell code need only access this array as a Ptr Word8, wrap that as a Bytestring, then run Data.Binary over the result to rebuild the Map. As you can see here: http://code.haskell.org/~dons/code/compiled-constants/Constants.hs I've put a couple of examples of how to access C-side serialised Haskell values in a package here: http://code.haskell.org/~dons/code/compiled-constants/ Cheers, Don

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Failing to make `par`
by Jefferson Heard 03 Mar '08

03 Mar '08

I've used Control.Parallel and Control.Parallel.Strategies extensively in the past, and I thought I knew what I was doing. I declared the following function: findSupernodes' :: S.Set Name -> Int -> Tree -> Protein.Tree -> S.Set Name findSupernodes' set size (Node i _ _ s il ir) (Protein.Node _ pl pr _ g) | S.size g > size = (Name (fromIntegral i)) `S.insert` set | otherwise = leftNodes `S.union` rightNodes where leftNodes = (findSupernodes' set size il pl) rightNodes = (findSupernodes' set size il pl) findSupernodes' set size (Leaf _ _) (Protein.Gene _ _ _) = set and then simply wrote the following as an initial stab at parallelizing it, because actually calling this function causes the program to execute an absurd number of string comparisons: findSupernodes = findSupernodes' S.empty findSupernodes' :: S.Set Name -> Int -> Tree -> Protein.Tree -> S.Set Name findSupernodes' set size (Node i _ _ s il ir) (Protein.Node _ pl pr _ g) | S.size g > size = (Name (fromIntegral i)) `S.insert` set | otherwise = leftNodes `par` rightNodes `seq` leftNodes `S.union` rightNodes where leftNodes = (findSupernodes' set size il pl) rightNodes = (findSupernodes' set size il pl) findSupernodes' set size (Leaf _ _) (Protein.Gene _ _ _) = set The thing is, these two functions don't return the same thing. The parallel version is returning an empty set, while the sequential version returns what it should return. Any clue what I did wrong? -- Jeff

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ICFP08 Final CFP
by Matthew Fluet (ICFP Publicity Chair) 03 Mar '08

03 Mar '08

Final Call for Papers ICFP 2008: International Conference on Functional Programming Victoria, BC, Canada, 22-24 September 2008 http://www.icfpconference.org/icfp2008 Submission deadline: 2 April 2008 ICFP 2008 seeks original papers on the art and science of functional programming. Submissions are invited on all topics from principles to practice, from foundations to features, from abstraction to application. The scope includes all languages that encourage functional programming, including both purely applicative and imperative languages, as well as languages with objects and concurrency. Particular topics of interest include * Applications and Domain-Specific Languages * Foundations * Design * Implementation * Transformation and Analysis * Software-development Techniques * Functional Pearls * Practice and Experience Important Dates (at 09:00 Apia time, UTC-11) ~~~~~~~~~~~~~~~ Submission: 2 April 2008 Author response: 21 May 2008 Notification: 16 June 2008 Final papers due: 7 July 2008 Call for Papers (full text) ~~~~~~~~~~~~~~~ http://www.icfpconference.org/icfp2008/cfp/cfp.html The submission URL will be available from the above page shortly. Program Chair ~~~~~~~~~~~~~ Peter Thiemann Albert-Ludwigs-Universität Georges-Köhler-Allee 079 79110 Freiburg, Germany Email: icfp08(a)informatik.uni-freiburg.de Phone: +49 761 203 8051 Fax: +49 761 203 8052 Mail sent to the address above is filtered for spam. If you send mail and do not receive a prompt response, particularly if the deadline is looming, feel free to telephone and reverse the charges.

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STAMP benchmark in Haskell?
by Tom Davies 03 Mar '08

03 Mar '08

I'm experimenting with STM (in CAL[1] rather than Haskell) and want to run the STAMP[2] benchmarks. Is there a Haskell translation available, or can anyone suggest a better/different benchmark suite for STM? Thanks, Tom [1] http://openquark.org/Open_Quark/Welcome.html [2] http://stamp.stanford.edu/

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coerce (safe!)
by Krzysztof Skrzętnicki 03 Mar '08

03 Mar '08

Well, it is simply > coerce :: a -> b > coerce _ = undefined so coerce is simply empty function. But still, it is possible to write a function of type (a->b). Well, possibly I didn't write anything particularly new, but please excuse me for I'm still in sort of a shock after I've discovered it. Yet this function reminds me how little I know so I have a question for you. I didn't took any lectures in Category Theory (for I'm still just a student, and I won't for there are none in my institute), but are there any good (e)books you would recommend for a (future) computer scientist? Regards Christopher Skrzętnicki

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