- Haskell-Cafe - Haskell.org

GHCi and Cairo on Windows
by smeltzek＠eecs.oregonstate.edu 06 Dec '11

06 Dec '11

In effort to keep my work cross-platform, I am trying to get GHCi and Cairo working together nicely on Windows (as a back-end to Diagrams, if it matters.) When loading the library in GHCi I get the following error: Loading package cairo-0.12.2 ... linking ... ghc: unable to load package `cairo-0.12.2' I am able to build, link, and execute successfully using 'ghc --make' so I know the libraries are installed correctly. I'm using GHC as packaged in the most recent version of the Haskell Platform and the most recent all-in-one Windows bundle of GTK. I've seen quite similar errors reported months ago with no apparent solution. Any help would be appreciated! --Karl

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Re: [Haskell-cafe] Poll: Do you want a mascot? -- please stop this
by Giovanni Tirloni 05 Dec '11

05 Dec '11

On Wed, Nov 23, 2011 at 5:52 PM, heathmatlock <heathmatlock(a)gmail.com>wrote: > On Wed, Nov 23, 2011 at 1:40 PM, Alexander Bernauer < > alex-haskell(a)copton.net> wrote: > >> Yes >> >> PS: Why not using Doodle for the poll? >> > > Email is an easy way to make sure nobody votes twice. > 1. It's unlikely to get feedback from the larger Haskell community 2. It floods people with email they don't care (unless they care to keep track of the results) 3. One can just as easily create throw-away emails, subscribe to the list and answer the poll 4. etc... My suggestion is to create a poll somewhere else and let it run for at least a month. Or a more elaborated survey with additional questions trying to capture the community's feeling toward a masket and what kind. I don't think we are in a hurry to get a mascot here so let's take the time and do it properly. -- Giovanni

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Re: [Haskell-cafe] "could not create compact unwind"
by Mark Lentczner 05 Dec '11

05 Dec '11

The ld warning is benign. You can safely ignore it. It is a known issue with GHC and the latest Mac OS X tool chain, and we are stuck with it for awhile: http://hackage.haskell.org/trac/ghc/ticket/5019 The best way to remove versions of Haskell on a Mac is now my shiny new Mac uninstaller! I just put out a "release candidate" yesterday. You can find it here: Source: UninstallHS.hs (just runhaskell this)Executable: uninstall-hs.tgz (unpack and run if your ghc is broken) Running without will just list what's there and suggest what to do next. It is "dry-run" by default. - Mark PS.: "rm -rf ~/.ghc" only removes the package databases, not the packages themselves. It also removes your ghci configuration, so I don't recommend it.

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Re: [Haskell-cafe] How to get a file path to the program invoked?
by dokondr 05 Dec '11

05 Dec '11

Balazs, thanks for your comments! The first comment works just fine. With </> operator I get this: Main System.Environment.Executable System.FilePath> "/abc" </> "/" "/" Instead of getting "/abc/" I get "/". What am I doing wrong? On Mon, Dec 5, 2011 at 6:03 PM, Balazs Komuves <bkomuves(a)gmail.com> wrote: > > Two small comments: > > 1) This should work on Windows too, if you just leave out the word "Posix" > from the source: > import System.FilePath (splitFileName) > > 2) In general when dealing with paths, use the </> operator (from > System.FilePath) > instead of ++ "/" ++ > > Balazs > > > On Mon, Dec 5, 2011 at 1:44 PM, dokondr <dokondr(a)gmail.com> wrote: > >> This is how I finally solved this problem for POSIX complaint system: >> >> -- >> -- TestRun >> -- >> module Main where >> import System.Cmd (rawSystem) >> import System.Directory (getCurrentDirectory) >> import System.Environment.Executable (ScriptPath(..), getScriptPath) >> import System.FilePath.Posix (splitFileName) >> >> main = do >> >> path <- getMyPath >> putStrLn $ "myPath = " ++ path >> let cmdLine = path ++ "args.sh" >> rawSystem cmdLine ["iphone", "test-twitts.txt"] >> >> {-- >> data ScriptPath Source >> >> Constructors: >> Executable FilePath it was (probably) a proper compiled executable >> RunGHC FilePath it was a script run by runghc/runhaskell >> Interactive we are in GHCi >> --} >> >> getMyPath = do >> curDir <- getCurrentDirectory -- from System.Directory >> scriptPath <- getScriptPath -- from System.Environment.Executable >> let path = getMyPath' scriptPath curDir >> return path >> >> getMyPath' (Executable path) _ = fst (splitFileName path) >> getMyPath' (RunGHC path) _ = fst (splitFileName path) >> getMyPath' Interactive curDir = curDir++"/" >> >> >>

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writeFile: commitBuffer: invalid argument (Illegal byte sequence)
by dokondr 05 Dec '11

05 Dec '11

Hi, In GHC 7.0.3 / Mac OS X when trying to: writeFile "someFile" "(Hoping You Have A iPhone When I Do This) Lol Sleep Is When You Close These ---> \55357\56384" I get: commitBuffer: invalid argument (Illegal byte sequence) The string I am trying to write can also be seen here: http://twitter.com/#!/search/Hoping%20You%20Have%20A%20iPhone%20When%20I%20…<http://twitter.com/#%21/search/Hoping%20You%20Have%20A%20iPhone%20When%20I%…> It looks like 'writeFile' can not write unicode characters. Any workarounds? Thanks! Dmitri

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FLOPS 2012: final call for papers & deadline extension
by Tom Schrijvers 05 Dec '11

05 Dec '11

Final Call For Papers ===================== _EXTENDED SUBMISSION DEADLINE : December 16, 2011_ *Eleventh International Symposium on Functional and Logic Programming (FLOPS 2012)* May 23-25, 2012 Kobe, Japan [http://www.org.kobe-u.ac.jp/flops2012/] FLOPS is a forum for research on all issues concerning declarative programming, including functional programming and logic programming, and aims to promote cross-fertilization and integration between the two paradigms. Previous FLOPS meetings were held in Fuji Susono (1995), Shonan Village (1996), Kyoto (1998), Tsukuba (1999), Tokyo (2001), Aizu (2002), Nara (2004), Fuji Susono (2006), Ise (2008), and Sendai (2010). Topics ====== FLOPS solicits original papers in all areas of functional and logic programming, including (but not limited to): - Declarative Pearls: new and excellent declarative programs with illustrative applications. - Language issues: language design and constructs, programming methodology, integration of paradigms, interfacing with other languages, type systems, constraints, concurrency and distributed computing. - Foundations: logic and semantics, rewrite systems and narrowing, type theory, proof systems. - Implementation issues: compilation techniques, memory management, program analysis and transformation, partial evaluation, parallelism. - Applications: case studies, real-world applications, graphical user interfaces, Internet applications, XML, databases, formal methods and model checking. The proceedings will be published as an LNCS volume. The proceedings of the previous meeting (FLOPS 2010) were published as LNCS 6009. PC co-Chairs ============ - Tom Schrijvers (Ghent University, Belgium) - Peter Thiemann (University of Freiburg, Germany) PC Members ========== - Salvador Abreu (University of Evora, Portugal) - Thorsten Altenkirch (University of Nottingham, UK) - Sebastian Brand (NICTA, Australia) - Giuseppe Castagna (CNRS Univ Paris 7, France) - Sebastian Fischer (Germany) - Marco Gavanelli (University of Ferrara, Italy) - Joxan Jaffar (National University of Singapore, Singapore) - Barry Jay (University of Sydney, Australia) - Andy King (University of Kent, UK) - Claude Kirchner (INRIA, France) - Neelakantan R. Krishnaswami (Microsoft Cambridge, UK) - Yulya Lierler (University of Kentucky, USA) - Keiko Nakata (Tallinn University of Technology, Estonia) - Peter Schneider-Kamp (University of Southern Denmark, Denmark) - Olin Shivers (Northeastern University, USA) - Paul Tarau (University of Northern Texas, USA) - Kazunori Ueda (Waseda University, Japan) - Meng Wang (Chalmers Technical University, Sweden) General Chair and Local co-Chairs ================================= - Naoyuki Tamura (Kobe University, Japan) - Mutsunori Banbara (Kobe University, Japan) - Katsutoshi Hirayama (Kobe University, Japan) Submission ========== Submissions must be unpublished and not submitted for publication elsewhere. Work that already appeared in unpublished or informally published workshops proceedings may be submitted. Submissions should fall into one of the following categories: - Regular research papers: they should describe new results and will be judged on originality, correctness, and significance. - System descriptions: they should contain a link to a working system and will be judged on originality, usefulness, and design. Submissions must be written in English and can be up to 15 pages long, though pearls are typically considerably shorter. Authors are required to use LaTeX2e and the Springer llncs class file, available at [http://www.springer.de/comp/lncs/authors.html] Regular research papers should be supported by proofs and/or experimental results. In case of lack of space, this supporting information should be made accessible otherwise (e.g., a link to a web page, or an appendix). Papers should be submitted electronically at [https://www.easychair.org/conferences/?conf=flops2012] Important Dates =============== - Submission deadline : December 16, 2011 (EXTENDED) - Author notification : February 3, 2012 - Camera-ready copy : March 2, 2012 Place and Related Events ======================== Takikawa Memorial Hall, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501 Japan. The 23rd International Conference on Rewriting Techniques and Applications (RTA 2012) and satellite workshops including WFLP 2012 will be held in the week after FLOPS at Nagoya, Japan. Some Previous FLOPS =================== - FLOPS 2010, Sendai: [http://www.kb.ecei.tohoku.ac.jp/flops2010/] - FLOPS 2008, Ise: [http://www.math.nagoya-u.ac.jp/~garrigue/FLOPS2008/] - FLOPS 2006, Fuji Susono: [http://hagi.is.s.u-tokyo.ac.jp/FLOPS2006/] Sponsors ======== - Japan Society for Software Science and Technology (JSSST) SIGPPL In Cooperation with =================== - ACM SIGPLAN - Asian Association for Foundation of Software (AAFS) - Association for Logic Programming (ALP)

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Re: [Haskell-cafe] How to get a file path to the program invoked?
by dokondr 05 Dec '11

05 Dec '11

This is how I finally solved this problem for POSIX complaint system: -- -- TestRun -- module Main where import System.Cmd (rawSystem) import System.Directory (getCurrentDirectory) import System.Environment.Executable (ScriptPath(..), getScriptPath) import System.FilePath.Posix (splitFileName) main = do path <- getMyPath putStrLn $ "myPath = " ++ path let cmdLine = path ++ "args.sh" rawSystem cmdLine ["iphone", "test-twitts.txt"] {-- data ScriptPath Source Constructors: Executable FilePath it was (probably) a proper compiled executable RunGHC FilePath it was a script run by runghc/runhaskell Interactive we are in GHCi --} getMyPath = do curDir <- getCurrentDirectory -- from System.Directory scriptPath <- getScriptPath -- from System.Environment.Executable let path = getMyPath' scriptPath curDir return path getMyPath' (Executable path) _ = fst (splitFileName path) getMyPath' (RunGHC path) _ = fst (splitFileName path) getMyPath' Interactive curDir = curDir++"/" -- All the best, Dmitri O. Kondratiev "This is what keeps me going: discovery" dokondr(a)gmail.com http://sites.google.com/site/dokondr/welcome

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Anonymous, Unique Types, maybe
by Scott Lawrence 04 Dec '11

04 Dec '11

(Sorry if this email is rather unclear - I know my desired end result, but neither how to acheive nor explain it well. Here goes.) I'm processing lists, using them sortof as streams. (Whether that's a good idea isn't the issue here - but let me know if it isn't!) Fundamentally, there are two types of operations (at least, that are relevant here) - those that change the length of the list and those that don't. Some operators might take more than one list/stream as an argument, combining them in some way or another. Obviously, if the lists were different lengths, the operator would fail. I don't want that to happen at run time, so I want to check for it statically, presumably via the type system. I could do this manually: type AList = [Event] type BList = [Event] type CList = [Event] myMapish :: AList -> AList mySelect :: AList -> (Event -> Bool) -> BList myOtherSelect :: BList -> CList but I'd rather not have to manually define a new type for every new list length: myMapish :: List a -> List a mySelect :: List a -> List ? The '?' would be an anonymous, unique type - unless there's a better way to accomplish this. Hope that was clear, and thanks (as always) for the help (and being awesome). -- Scott Lawrence

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ismzero operator possible without equal constraint
by edgar klerks 04 Dec '11

04 Dec '11

Hi list, I am using MonadSplit (from http://www.haskell.org/haskellwiki/New_monads/MonadSplit ) for a project and now I want to make a library out of it. This seems to be straightforward, but I got stuck when I tried to move miszero out of the class: miszero :: m a -> Bool It tests if the provided monad instance is empty. My naive attempt was: miszero :: (Eq (m a), MonadPlus m) => m a -> Bool miszero = ( == mzero ) This works, but not correctly. It adds an Eq constraint that is unneeded. I would prefer to have something like: miszero :: MonadPlus m => m a -> Bool Because I am not comparing the contents of the monad. I don't even touch it. Is this possible to write? with kind regards, Edgar

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ANNOUNCE: Haskell Communities and Activities Report (21st ed., November 2011)
by Janis Voigtländer 04 Dec '11

04 Dec '11

On behalf of all the contributors, I am pleased to announce that the Haskell Communities and Activities Report (21st edition, November 2011) is now available in PDF and HTML formats: http://haskell.org/communities/11-2011/report.pdf http://haskell.org/communities/11-2011/html/report.html Many thanks go to all the people that contributed to this report, both directly, by sending in descriptions, and indirectly, by doing all the interesting things that are reported. I hope you will find it as interesting a read as I did. If you have not encountered the Haskell Communities and Activities Reports before, you may like to know that the first of these reports was published in November 2001. Their goal is to improve the communication between the increasingly diverse groups, projects, and individuals working on, with, or inspired by Haskell. The idea behind these reports is simple: Every six months, a call goes out to all of you enjoying Haskell to contribute brief summaries of your own area of work. Many of you respond (eagerly, unprompted, and sometimes in time for the actual deadline to the call. The editor collects all the contributions into a single report and feeds that back to the community. When I try for the next update, six months from now, you might want to report on your own work, project, research area or group as well. So, please put the following into your diaries now: ========================================= End of April 2012: target deadline for contributions to the May 2012 edition of the HC&A Report ========================================= Unfortunately, many Haskellers working on interesting projects are so busy with their work that they seem to have lost the time to follow the Haskell related mailing lists and newsgroups, and have trouble even finding time to report on their work. If you are a member, user or friend of a project so burdened, please find someone willing to make time to report and ask them to "register" with the editor for a simple e-mail reminder in April (you could point me to them as well, and I can then politely ask if they want to contribute, but it might work better if you do the initial asking). Of course, they will still have to find the ten to fifteen minutes to draw up their report, but maybe we can increase our coverage of all that is going on in the community. Feel free to circulate this announcement further in order to reach people who might otherwise not see it. Enjoy! Janis Voigtlaender <hcar at haskell.org>

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