March 2011 - Haskell - Haskell.org

ANNOUNCE: ioctl 0.0.1
by Maciej Piechotka 13 Sep '15

13 Sep '15

A package for type-safe I/O control. Currently only ioctl is supported. Currently simply a extract from my tuntap fork TODO: - Return the integer as well as structure (will break the API) - Port for Windows Network.Socket.IOCtl (as soon as I manage to setup some sane environment on this platform) - Wrapping around DeviceIoControl Example (in hsc): data NotRead = NotRead instance NotRead Int where ioctlReq _ = #const FIONREAD notRead s = ioctlsocket' s NotRead Regards

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Announcing Djinn, version 2004-12-11, a coding wizard
by Lennart Augustsson 07 Apr '11

07 Apr '11

Howdy, y'all! I've written a small program that takes a (Haskell) type and gives you back a function of that type if one exists. It's kind of fun, so I thought I'd share it. It's probably best explained with a sample session. calvin% djinn Welcome to Djinn version 2005-12-11. Type :h to get help. # Djinn is interactive if not given any arguments. # Let's see if it can find the identity function. Djinn> f ? a->a f :: a -> a f x1 = x1 # Yes, that was easy. Let's try some tuple munging. Djinn> sel ? ((a,b),(c,d)) -> (b,c) sel :: ((a, b), (c, d)) -> (b, c) sel ((_, v5), (v6, _)) = (v5, v6) # We can ask for the impossible, but then we get what we # deserve. Djinn> cast ? a->b -- cast cannot be realized. # OK, let's be bold and try some functions that are tricky to write: # return, bind, and callCC in the continuation monad Djinn> type C a = (a -> r) -> r Djinn> returnC ? a -> C a returnC :: a -> C a returnC x1 x2 = x2 x1 Djinn> bindC ? C a -> (a -> C b) -> C b bindC :: C a -> (a -> C b) -> C b bindC x1 x2 x3 = x1 (\ c15 -> x2 c15 (\ c17 -> x3 c17)) Djinn> callCC ? ((a -> C b) -> C a) -> C a callCC :: ((a -> C b) -> C a) -> C a callCC x1 x2 = x1 (\ c15 _ -> x2 c15) (\ c11 -> x2 c11) # Well, poor Djinn has a sweaty brow after deducing the code # for callCC so we had better quit. Djinn> :q Bye. To play with Djinn do a darcs get http://darcs.augustsson.net/Darcs/Djinn or get http://darcs.augustsson.net/Darcs/Djinn/Djinn.tar.gz Then just type make. (You need a Haskell 98 implementation and some libraries.) And then start djinn. For the curious, Djinn uses a decision procedure for intuitionistic propositional calculus due to Roy Dyckhoff. It's a variation of Gentzen's LJ system. This means that (in theory) Djinn will always find a function if one exists, and if one doesn't exist Djinn will terminate telling you so. This is the very first version, so expect bugs. :) Share and enjoy. -- Lennart

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ANNOUNCE: Database Supported Haskell (DSH) 0.5.5
by George Giorgidze 31 Mar '11

31 Mar '11

I'm pleased to announce the release of DSH-0.5.5 [1]. What's new in this release -------------------- * Support for sum types * Database execution of all functions from Data.Maybe and Data.Either Cheers, George [1] http://hackage.haskell.org/package/DSH

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tfp2011: last CFP
by Henrik Nilsson 31 Mar '11

31 Mar '11

Sorry for any duplicate copies. /Henrik

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Haskell Weekly News: Issue 175
by Daniel Santa Cruz 31 Mar '11

31 Mar '11

Welcome to issue 175 of the HWN, a newsletter covering developments in the [1]Haskell community. This release covers the week of March 20 - 26. You can find the HTML version at: http://bit.ly/gs9Rr8 Announcements Wren Ng Thornton [2]announced the release of unix-bytestring: Unix/Posix-specific functions for ByteStrengs. John Lato [3]announced an incremental update to the ListLike package. "This version adds newtype wrappers for strict and lazy ByteString, CharString, and CharStringLazy..." Mario Blazevic [4]announced the release of incremental-parser, which provides the usual set of Applicative and monad combinators with a few twists that make it unique. Duncan Coutts [5]announced the release of version 0.16.3 of c2hs, the FFI preprocessor tool. Jeff Wheeler [6]announced a new release of Yi, the text editor written in and extensible in Haskell. Christiaan Baaij [7]announced an incremental upgrade to 0.1.3.0 to CLaSH. Mario Blazevic [8]announced updates to monad-parallel, monad-coroutine, and SCC (Streaming Component Combinators). John Millikin [9]announced an update to enumerator to version 0.4.8. Quotes of the Week * Squarism: wo utilizing any tricks, i want 20 miljon rabbits to mate with each other once.. how many mate event will there be * mm_freak: using combinators instead of explicit recursion can be justified with about the same reasoning as using 'while' instead of explicit 'goto' in imperative programming * monochrom: <$> is pronounced Jacquelin von Brionée * geheimdienst: what does a pirate say when starting a sentence, then suddenly being hit in the nadgers? arr- ow! * monochrom: 1985 is way more than a decade ago * copumpkin: matlab is horrible as far as language design goes[.] it's fairly convenient for doing stuff in but I need to shower after every time I use it Top Reddit Stories * Debugging trick From (self.haskell), scored 60 with 11 comments. Read on [10]reddit. * Your friendly Haskell JSON library's encoding performance just got 4x faster From (serpentine.com) scored 45 with 2 comments. Read on [12]reddit. Read the [13]original post. * A monad for deterministic parallelism (ICFP'2011 submission) From (community.haskell.org) scored 41 with 8 comments. Read on [14]reddit. Read the [15]original post. * Haskell servers benchmarked against node/ruby/python/php/java. From (docs.yesodweb.com) scored 36 with 12 comments. Read on [16]reddit. Read the [17]original post. * The Yesod Framework and the Case of the Eight Level Monad Transformer Stack From (docs.yesodweb.com) scored 35 with 16 comments. Read on [18]reddit. Read the [19]original post. * Improving Persistent Performance (Yesod Blog) From (docs.yesodweb.com) scored 29 with 1 comments. Read on [20]reddit. Read the [21]original post. * Fast, clean Haskell bindings to Google's Snappy library From (hackage.haskell.org) scored 22 with 8 comments. Read on [22]reddit. Read the [23]original post. * Open Quark on Github (Haskell like Lang on the JVM) From (github.com) scored 15 with 3 comments. Read on [24]reddit. Read the [25]original post. * EclipseFP 2.0.4 released: supports GHC 7 From (jpmoresmau.blogspot.com) scored 15 with 7 comments. Read on [26]reddit. Read the [27]original post. * Demonstrating a Time Leak in Arrowized FRP From (blog.edwardamsden.com) scored 14 with 12 comments. Read on [28]reddit. Read the [29]original post. Top StackOverflow Answers * [30]Reading large file in haskell ? votes: 19 The construct "seq x x" is always useless. If y = seq x x and I force y then this forces x then returns x. This is equivalent to y=x and forcing y. Thus "seq forceEval forceEval" does nothing more than "forceEval". The error with your use of a fold is a common one. You are using a fold to perform a count of the bytes in the input. You should be using ... * [31]What to call a function that splits lists? votes: 12 I believe the function you're describing is breakBefore from the list-grouping package. Data.List.Grouping: http://hackage.haskell.org/packages/archive/list-grouping/0.1.1/doc/html/Da… st-Grouping.html ghci:: breakBefore even [3,1,4,1,5,9,2,6,5,3,5,8,9,7,9,3,2,3,8,4,6,2,6] [[3,1],[4,1,5,9],[2],[6,5,3,5],[8,9,7,9,3],[2,3],[8],[4],[6],[2],[6]] Top StackOverflow Questions * [32]Haskell record syntax votes: 16, answers: 1 * [33]Reading large file in haskell? votes: 12, answers: 1 * [34]Haskell laziness - how do I force the IO to happen sooner? votes: 9, answers: 3 * [35]case on monadic value votes: 7, answers: 2 * [36]Simplest way to find which data types are most garbage collected? votes: 7, answers: 2 About the Haskell Weekly News To help create new editions of this newsletter, please send stories to dstcruz(a)gmail.com. I'm in dire need of finding good "quotes of the week". If you happen to come across any, please don't hesitate to send it along. Until next time, Daniel Santa Cruz References 1. http://haskell.org/ 2. http://article.gmane.org/gmane.comp.lang.haskell.libraries/15484 3. http://article.gmane.org/gmane.comp.lang.haskell.general/18590 4. http://article.gmane.org/gmane.comp.lang.haskell.libraries/15492 5. http://article.gmane.org/gmane.comp.programming.c2hs/247 6. http://article.gmane.org/gmane.editors.yi.devel/5346 7. http://article.gmane.org/gmane.comp.lang.haskell.general/18592 8. http://article.gmane.org/gmane.comp.lang.haskell.cafe/87540 9. http://article.gmane.org/gmane.comp.lang.haskell.libraries/15506 10. http://www.reddit.com/r/haskell/comments/gbd7w/debugging_trick/ 12. http://www.reddit.com/r/haskell/comments/g8s0t/your_friendly_haskell_json_l… 13. http://www.serpentine.com/blog/2011/03/22/a-new-week-a-new-json-performance… 14. http://www.reddit.com/r/haskell/comments/gainp/a_monad_for_deterministic_pa… 15. http://community.haskell.org/~simonmar/papers/monad-par.pdf 16. http://www.reddit.com/r/haskell/comments/g7uia/haskell_servers_benchmarked_… 17. http://docs.yesodweb.com/blog/preliminary-warp-cross-language-benchmarks 18. http://www.reddit.com/r/haskell/comments/ga40w/the_yesod_framework_and_the_… 19. http://docs.yesodweb.com/blog/hamlet-lucius-widgets 20. http://www.reddit.com/r/haskell/comments/gbz43/improving_persistent_perform… 21. http://docs.yesodweb.com/blog/improving-persistent-performance 22. http://www.reddit.com/r/haskell/comments/ga080/fast_clean_haskell_bindings_… 23. http://hackage.haskell.org/package/snappy 24. http://www.reddit.com/r/haskell/comments/g7vcj/open_quark_on_github_haskell… 25. https://github.com/levans/Open-Quark 26. http://www.reddit.com/r/haskell/comments/g8du0/eclipsefp_204_released_suppo… 27. http://jpmoresmau.blogspot.com/2011/03/eclipsefp-204-released-supports-ghc-… 28. http://www.reddit.com/r/haskell/comments/g943x/demonstrating_a_time_leak_in… 29. http://blog.edwardamsden.com/2011/03/demonstrating-time-leak-in-arrowized.h… 30. http://stackoverflow.com/questions/5410777/reading-large-file-in-haskell/54… 31. http://stackoverflow.com/questions/5438558/what-to-call-a-function-that-spl… 32. http://stackoverflow.com/questions/5367167/haskell-record-syntax 33. http://stackoverflow.com/questions/5410777/reading-large-file-in-haskell 34. http://stackoverflow.com/questions/5373883/haskell-laziness-how-do-i-force-… 35. http://stackoverflow.com/questions/5395517/case-on-monadic-value 36. http://stackoverflow.com/questions/5410345/simplest-way-to-find-which-data-…

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SLE 2011 - Deadline extension
by João Fernandes 30 Mar '11

30 Mar '11

============================================================ * DEADLINE EXTENSION * SLE 2011 4th International Conference on Software Language Engineering Braga, Portugal, 3-6 July 2011 http://planet-sl.org/sle2011/ ============================================================= PAPER SUBMISSION DEADLINE EXTENSION The paper submission deadline has been *extended* and is now set to April, 15th --------------------------------------------------------- INVITED SPEAKERS SLE 2011 is proud to announce the following invited speakers. Krzysztof Czarnecki is associate professor at the University of Waterloo and industrial research chair at Bank of Nova Scotia / NSERC. Before coming to Waterloo, he spent eight years at DaimlerChrysler Research working on the practical applications of generative programming. His current work focuses on realizing the synergies between generative and model-driven software development. Paul Klint is head of the software engineering department at Centrum Wiskunde en Informatica in Amsterdam, full professor in Computer Science at the University of Amsterdam and theme leader of Software Analysis and Transformation at CWI. His research interests include generic language technology, domain-specific languages, software renovation, and technology transfer. --------------------------------------------------------- CO-LOCATED EVENTS The following events will take place together with SLE 2011: Summer School on Generative and Transformational Techniques in Software Engineering (GTTSE) * http://gttse.wikidot.com/2011 Coupled Software Transformations Workshop (CSXW) * http://www.di.univaq.it/CSXW2011/ Industry Track of Software Language Engineering (ITSLE) * http://planet-sl.org/itsle2011/ Workshop on Transforming and Weaving Ontologies and MDE (TWOMDE) * http://planet-sl.org/twomde2011/ ------------------------------------------------------------ SLE 2011 COMITTEES GENERAL CHAIR João Saraiva Universidade do Minho, Portugal jas(a)di.uminho.pt PROGRAM CO-CHAIRS Uwe Aßmann Dresden University of Technology, Germany uwe.assmann(a)tu-dresden.de Anthony Sloane Macquarie University, Australia anthony.sloane(a)mq.edu.au DOCTORAL SYMPOSIUM CHAIRS Perdita Stevens University of Edinburgh, UK perdita.stevens(a)ed.ac.uk Eric Van Wyk University of Minnesota, USA evw(a)cs.umn.edu PROGRAM COMITTEE Adrian Johnstone, University of London, UK Aldo Gangemi, Semantic Technology Laboratory, Italy Alexander Serebrenik, Eindhoven University of Technology, Netherlands Ana Moreira, FCT/UNL, Portugal Anthony Cleve, University of Namur, Belgium Anya Helene Bagge, University of Bergen, Norway Bernhard Rumpe, Aachen University, Germany Bijan Parsia, University of Manchester, UK Brian Malloy, Clemson University, USA Bruno Oliveira, Seoul National University, Korea Chiara Ghidini, FBK-irst, Italy Daniel Oberle, SAP Research, Germany Eelco Visser, Delft University of Technology, Netherlands Eric Van Wyk, University of Minnesota, USA Fernando Pereira, Federal University of Minas Gerais, Brasil Fernando Silva Parreiras, University of Koblenz-Landau, Germany Friedrich Steimann, University of Hannover, Germany Görel Hedin, Lund University, USA Ivan Kurtev, University of Twente, Netherlands James Power, National University of Ireland, Ireland Jean-Marie Favre, OneTree Technologies, France Jeff Gray, University of Alabama, USA Jeff Z. Pan, University of Aberdeen, UK João Paulo Fernandes, Univ. of Minho& Univ. of Porto, Portugal John Boyland, University of Wisconsin-Milwaukee, USA John Grundy, Swinburne University of Technology, Australia Jordi Cabot, École des Mines de Nantes, France Jurgen Vinju, CWI, Netherlands Laurence Tratt, Middlesex University, UK Marjan Mernik, University of Maribor, Slovenia Mark van den Brand, Eindhoven University of Technology, Netherlands Michael Collard, University of Akron, USA Nicholas Kraft, University of Alabama, USA Paul Klint, CWI, Netherlands Paulo Borba, Federal University of Pernambuco, Brazil Peter Haase, University of Karlsruhe, Germany Peter Mosses, Swansea University, UK Ralf Möller, Hamburg University of Technology, Germany Silvana Castano, University of Milan, Italy Steffen Zschaler, Lancaster University, UK York Sure, University of Koblenz-Landau, Germany Zhenjiang Hu, National Institute of Informatics, Japan ORGANIZATION COMMITTEE José Creissac Campos (Finance Chair) Universidade do Minho, Portugal João Paulo Fernandes (Web and Publicity co-Chair) Universidade do Porto& Universidade do Minho, Portugal Jurgen Vinju (Workshop Selection Chair) CWI, The Netherlands Vadim Zaytsev (Publicity co-Chair) CWI, The Netherlands

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ANNOUNCE: enumerator 0.4.8
by John Millikin 29 Mar '11

29 Mar '11

----------------------------------------------------------------------------------------------------------------------------------------------------- Enumerators are an efficient, predictable, and safe alternative to lazy I/O. Discovered by Oleg Kiselyov, they allow large datasets to be processed in near–constant space by pure code. Although somewhat more complex to write, using enumerators instead of lazy I/O produces more correct programs. http://hackage.haskell.org/package/enumerator http://john-millikin.com/software/enumerator/ ----------------------------------------------------------------------------------------------------------------------------------------------------- Hello -cafe, It's been a while since the last point release of enumerator. This one is sufficiently large that I think folks might want to know about it, and since I try not to spam too many announcements, I'll give a quick rundown on major changes in other 0.4.x versions as well. First, most of what I call "list analogues" -- enumerator-based versions of 'head', 'take', 'map', etc -- have been separated into three modules (Data.Enumerator.List, .Binary, and .Text) depending on what sorts of data they operate on. This separation has been an ongoing process throughout 0.4.x releases, and I think it's now complete. The old names in Data.Enumerator will continue to exist in 0.4.x versions, but will be removed in 0.5. Second, Gregory Collins and Ertugrul Soeylemez found a space leak in Iteratee's (>>=), which could cause eventual space exhaustion in some circumstances. If you use enumerators to process very large or infinite streams, you probably want to upgrade to version 0.4.7 or higher. Third, the source code PDF has seen some substantial improvement -- if you're interested in how the library is implemented, or have insomnia, read it at < http://john-millikin.com/software/enumerator/enumerator_0.4.8.pdf > Finally, there is a known issue in the current encoding of iteratees -- if an iteratee yields extra data but never consumed anything, that iteratee will violate the monad law of associativity. Oleg has updated his implementations to fix this problem, but since it would break a *lot* of dependent libraries, I'm holding off until the vague future of version 0.5. Since iteratees that yield extra data they didn't consume are invalid anyway, I hope this problem will not cause too much inconvenience. New features ----------------- * Range-limited binary file enumeration (requested + initial patch by Bardur Arantsson). * splitWhen , based on the "split" package < http://hackage.haskell.org/package/split > * 0.4.6: Typeable instances for most types (requested by Michael Snoyman) * 0.4.5: joinE , which simplifies enumerator/enumeratee composition (requested by Michael Snoyman)

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ANN: Yi 0.6.3
by Jeff Wheeler 29 Mar '11

29 Mar '11

Hi all, I'm very excited to announce the first release of Yi since last summer. It is relatively light on new features, but it finally should compile nicely on friendly machines. This means, for the most part, machines with the latest Haskell Platform installed. (Windows, unfortunately, has not been tested all that much. See details below, though, for install info.) ## What's new? * New vte UI. This is a terminal UI inside a GUI, much like gvim. It depends on Gtk2Hs for the GUI, and then launches the vty UI inside the terminal. * Compatibility with the latest Haskell Platform release * Start yi-contrib package. We intend to move more stuff here, to clean up the core yi package. * We're now on GitHub (and mirrored on Google Code)! See below for info. ## What's Yi? Yi is a text editor written in Haskell and extensible in Haskell. The long-term goal of the Yi project is to provide the editor of choice for Haskell programmers. Yi now works relatively well in the terminal, using the vty package, and also has Gtk frontends using vte (which interfaces with the terminal interface) and a Pango frontend. There is also a Cocoa frontend under (slow) development. ## Installation Using cabal install: $ cabal update $ cabal install yi The default UI depends on the vty package, which will only compile with the ncurses development headers available. On Ubuntu, you need to install the `libncurses5-dev` package. On Windows, you'll need to disable the default vty terminal UI, and use a Gtk UI instead (the vte UI requires vty, so you can't install that either): $ cabal install yi -f-vty -fpango (Windows support is not well-tested, though.) Optionally also install the contrib package: $ cabal install yi-contrib ## Features * A purely functional editor core * Key-bindings written as parsers of the input * Emacs, Vim and (partial) Cua emulations provided by default * Console front-end (Gtk2Hs and Cocoa front-ends in development) * Static configuration (XMonad style) for fast load * Haskell support: * Lexical highlighting and (unicode-based) beautification. * Layout-aware parenthesis-matching * Auto-indentation * cabal-build within the editor * Syntax highlighting for a number of other languages (latex, python, perl, ...) ## More Info Read the README [1] on GitHub for more information. The source code [2] is also hosted there. ## Credits This release is brought to you by: * Alexey Levan * Gwern Branwen * Issac Trotts * Jean-Philippe Bernardy * Jeff Wheeler * Jeremy Wall * Maciej Piechotka * Malte Sommerkorn and all the contributors to the previous versions. Also, Yi would not exist without all the work put into the Haskell platform. [1] https://github.com/yi-editor/yi/blob/master/README.md [2] https://github.com/yi-editor/yi -- Jeff Wheeler Undergraduate, Electrical Engineering University of Illinois at Urbana-Champaign

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Fwd: ANN: Yi 0.6.3
by Robby Findler 29 Mar '11

29 Mar '11

On Mon, Mar 28, 2011 at 8:39 PM, Brandon S Allbery KF8NH <allbery.b(a)gmail.com> wrote: > Somehow the Haskell community is hellbent on repeating the mistakes every > other community learned about the hard way years ago, especially in the area > of dependencies (first refusing to acknowledge the need for upper dependency > limits, more recently trying to avoid adding an epoch — and I'm not counting > how packages included with the compiler but not recognized as such by Cabal > lead directly to Cabal introducing diamond dependency failures). Is this > *really* necessary, or should those of us who've seen it before just sit > back and watch you all ram your heads against the same brick walls? > > (Why no, it doesn't look like a brick wall now; that's the point. It > *will*. Learn *before* it happens.) Hi Brandon: are any of these lessons written up somewhere? (I'd love to be able to read about what the important ones are, their rationale, etc.) Thanks, Robby

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ANNOUNCE: aivika 0.1
by David Sorokin 28 Mar '11

28 Mar '11

------------------------------------------------------------------------ Aivika is a multi-paradigm simulation library. It allows us to integrate a system of ordinary differential equations. Also it can be applied to the Discrete Event Simulation. It supports the event-oriented, process-oriented and activity-oriented paradigms. Aivika also supports the Agent-based Modeling. Finally, it can be applied to System Dynamics. The library widely uses monads. The dynamic system is represented as a computation in the Dynamics monad. There is also the DynamicsProc monad to represent the discontinuous processes which can be suspended at any time and then resumed later. Everything else is expressed through these two monads, including the events, agent handlers and even integrals. http://hackage.haskell.org/package/aivika ------------------------------------------------------------------------ Hello, I'm glad to announce a Haskell port of my F# simulation library written in 2009, 2010. The method is very simple but general and powerful. Perhaps the discrete event simulation is mostly well done. The package contains a PDF document with the corresponded description. Best regards, David Sorokin

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