March 2015 - Haskell-Cafe

Haskell development role at Standard Chartered in London
by Don Stewart 16 Mar '15

16 Mar '15

The Strats team at Standard Chartered has an open position for a typed functional programming developer to join the team in London. This is a “front office” finance role – meaning you will work on the trading floor, directly with traders, building software to automate their work and improve their efficiency. The role is highly development focused, and you will use Haskell for almost all tasks: data analysis, market data publishing, database access, web services, desktop GUIs, large parallel tasks, quantitative models, solvers, everything. This is a fast paced role – code you write today will be deployed within hours to hundreds of users and has to work. More details are in the full posting here: https://donsbot.wordpress.com/2015/03/16/haskell-development-role-in-strats…

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Re: [Haskell-cafe] [Haskell-beginners] testing IO code
by Sumit Sahrawat, Maths & Computing, IIT (BHU) 16 Mar '15

16 Mar '15

On 16 March 2015 at 19:51, Maurizio Vitale <mrz.vtl(a)gmail.com> wrote: > suppose I have a restricted IO monad, RIO that only exposes readFile. > and then I have a monad SIO that will eventually provide a virtual file > system from a map path->content, also with a readFile function returning > SIO(String). > > What is the way to write a function parseFile that can operate in both > monads so that I can use SIO for testing? should I define a third monad > CompileMonad that has instances for both RIO and SIO and then having > parseFile :: CompileMonad ast? > You might be able to do something like, class MonadIO m => ProvidesReadFile m where readFile :: FilePath -> m String instance ProvidesReadFile RIO where readFile = readFileRIO -- the RIO specific readFile instance ProvidesReadFile SIO where readFile = readFileSIO -- the SIO specific readFile parseFile :: ProvidesReadFile m => FilePath -> m ast parseFile = do f <- readFile let ast = parse f -- the pure parser return ast -- works for both monads > Thanks, > > Maurizio > > _______________________________________________ > Beginners mailing list > Beginners(a)haskell.org > http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners > > This is more suitable for the haskell-cafe. I am posting it there so that more people might comment on it. HTH. -- Regards Sumit Sahrawat

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New Functional Programming Job Opportunities
by Functional Jobs 16 Mar '15

16 Mar '15

Here are some functional programming job opportunities that were posted recently: Software Engineer at Xledger http://functionaljobs.com/jobs/8797-software-engineer-at-xledger Lead front end developer at Anchor Systems http://functionaljobs.com/jobs/8796-lead-front-end-developer-at-anchor-syst… Cheers, Sean Murphy FunctionalJobs.com

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Distributing Haskell on a cluster
by felipe zapata 16 Mar '15

16 Mar '15

Hi all, I have posted the following question on stackoverflow, but so far I have not received an answer. http://stackoverflow.com/questions/29039815/distributing-haskell-on-a-clust… I have a piece of code that process files, processFiles :: [FilePath] -> (FilePath -> IO ()) -> IO () This function spawns an async process that execute an IO action. This IO action must be submitted to a cluster through a job scheduling system (e.g Slurm). Because I must use the job scheduling system, it's not possible to use cloudHaskell to distribute the closure. Instead the program writes a new *Main.hs* containing the desired computations, that is copy to the cluster node together with all the modules that main depends on and then it is executed remotely with "runhaskell Main.hs [opts]". Then the async process should ask periodically to the job scheduling system (using *threadDelay*) if the job is done. Is there a way to avoid creating a new Main? Can I serialize the IO action and execute it somehow in the node? Best, Felipe

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is build breakage data about the main Haskell platform projects available?
by Johan Larson 15 Mar '15

15 Mar '15

Dan Luu recently dug up some build performance data about various open source projects, and found that many such projects have broken builds more than half the time. http://danluu.com/broken-builds/ Unfortunately Luu's data set doesn't include Haskell. Does anyone have the facts on this? (A brief search didn't turn up anything.) -- Johan Larson -- Toronto, Canada

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package ParsecToken
by Kattamuri Ekanadham 15 Mar '15

15 Mar '15

I am new to the community and learning Parsec, reading the tutorial "Parsec, a fast combinator Parse" by Daan Leijen. In the tutorial, the examples import the package called "ParsecToken" and I could not find this package any where (I found many variants like Text.Parsec.Token, Text.ParseCombinators.Parsec.Token etc.) So I was unable to execute those examples given there. Q1. How do I find the package name for "ParsecToken" so that I can do cabal import? Thanks.

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Wrong .hsc file paths on Windows
by Marcin Mrotek 15 Mar '15

15 Mar '15

Hello, I was trying to port some of my code to Windows. I've installed GHC with MinGHC (https://github.com/fpco/minghc) Unfortunately some packages, namely zlib and network, won't install, with the same error: getModificationTime cannot locate a file like CodecCompressionZlibStream.hsc or NetworkSocketTypes.hsc. With zlib, I figured out I just need to change mentions of "Codec/Compression/(...)" adding two slashes instead of one. Now with network I'm stuck, I can't find where the path was set at all. Is there some step I should have done prior to installation that would get the paths right? Best regards, Marcin Mrotek

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π-day
by Henk-Jan van Tuyl 14 Mar '15

14 Mar '15

Happy super pi day everybody! Henk-Jan van Tuyl -- Folding@home What if you could share your unused computer power to help find a cure? In just 5 minutes you can join the world's biggest networked computer and get us closer sooner. Watch the video. http://folding.stanford.edu/ http://Van.Tuyl.eu/ http://members.chello.nl/hjgtuyl/tourdemonad.html Haskell programming --

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Re: [Haskell-cafe] install 7.8.4 64 bits on arch linux
by Lars Hupel 14 Mar '15

14 Mar '15

> sudo pacman -S ghc > And I get the same errormessage. > Even sudo pacman -R ghc gives the same error. Odd. Before installing 'ghc', please try this: $ sudo pacman -Rucs ghc haddock haskell-ghc-paths '-Rucs' will recursively remove all existing dependencies. Please double-check the list of packages pacman prints, because they will all be removed. Cheers Lars PS: Please CC the list when you reply to messages. There might be more competent people than me lurking there :-)

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install 7.8.4 64 bits on arch linux
by Kees Bleijenberg 13 Mar '15

13 Mar '15

I want to upgrade from 7.8.3 32 bits to 7.8.4 64 bits on Arch Linux. So I removed ghc, cabal etc and followed the instruction at: http://sapiengames.com/2014/04/05/install-haskell-platform-arch-linux/ Added the lines [haskell-core] Server = http://xsounds.org/~haskell/core/$arch to pacman.conf added the pacman-key as described updated pacman and finally the fun parts should start.. $ sudo pacman -S ghc cabal-install happy alex looking for inter-conflicts... error: failed to prepare transaction (could not satisfy dependencies) :: haddock: requires ghc=7.8.3-2 :: haskell-ghc-paths: requires ghc=7.8.3-1 What is wrong and what can I do? Kees

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