November 2008 - Haskell

The Monad.Reader - Issue 12: SoC Special
by Wouter Swierstra 19 Nov '08

19 Nov '08

I am pleased to announce that a new issue of The Monad.Reader is now available: http://www.haskell.org/haskellwiki/The_Monad.Reader Issue 12 is another Summer of Code special and consists of the following three articles: * Max Bolingbroke Compiler Development Made Easy * Roman Cheplyaka How to Build a Physics Engine * Neil Mitchell Hoogle Overview The Monad.Reader is a quarterly magazine about functional programming. It is less formal than a journal, but more enduring than a wiki page or blog post. If you'd like to write something for the next issue of The Monad.Reader, please get in touch. The deadline for the next issue will be February 13th. Looking forward to your submissions, Wouter This message has been checked for viruses but the contents of an attachment may still contain software viruses, which could damage your computer system: you are advised to perform your own checks. Email communications with the University of Nottingham may be monitored as permitted by UK legislation.

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ANNOUNCE: Turbinado V0.1
by Alson Kemp 18 Nov '08

18 Nov '08

I'd like to announce Turbinado, a very young and raw MVC web framework for Haskell. While the framework doesn't exactly copy Ruby on Rails, it certainly rhymes... It's very early days for Turbinado, but the framework is moving along nicely. There are still issues to be ironed out and architectural details to be decided, so help/contribution would be very much appreciated. Turbinado can be found at: http://www.turbinado.org The source can be found at: http://github.com/alsonkemp/turbinado/tree/master (see the /App directory for the code for www.turbinado.org) Turbinado: * Provides a fast web server (based on HSP; see http://turbinado.org/Home/Performance) * Provides a straightforward organization for your website (courtesy of Rails); * Uses simple HTML-like templating (courtesy of HSX); * Is easily extensible (courtesy of an Environment built out of _Map String Dynamic_, not the most type-safe of beasties; Help!); * Configurable routing (see Config/Routes.hs). Turbinado is currently lacking: * Documentation... * An easy install... * A database ORM based on HDBC (visibly incomplete and ugly in Turbinado/Database/ORM); * Many more HTML helpers; * Controllers for partials (lightweight "controls" ala ASP.NET) * Strong error reporting and handling; * Lots of functionality and plugins; * ... the favorite feature that you want to develop for Turbinado ...

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ANNOUNCE: EEConfig-1.0
by Bartosz Wójcik 18 Nov '08

18 Nov '08

ExtremlyEasyConfig ============ I've searched for simply library to read parameters from input file. I've found ConfigFile only one and during reading its docu understood, that for simple functionality I needed I'd rather write faster sth new than understood usage of this powerfull cannon. Here it is. It recognizes given parameters and their values. As input it becomes list of parameters and all their possible values in format [ParameterInput] and input String where parameters will be searched for. As output it deliveres recognized parameters and their values in format [ParameterOutput], where only these parameters are present which have been found in the input string. This format can be tranformed then to Map one and as such easy queried. Handy functions provided. Parameters in the input string have to be always given in following format: (<flagname> <parameter>)*. Anything what is not recognized as parameter or value is ignored. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/EEConfig Haddock doesn't show 2 query functions from the source, I've no idea why. Best regards, Bartek

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announcing darcs 2.1.2
by Eric Kow 17 Nov '08

17 Nov '08

Hi everybody, I am pleased to announce the release of darcs 2.1.2, which you can download from http://darcs.net/darcs-2.1.2.tar.gz This is deliberately a very modest release, containing as few changes from darcs 2.1.0 as we can manage. The changes we have included are GHC 6.10 support and a bugfix for Windows (notably, one which makes darcs help work from the DOS prompt without the need for MSYS or Cygwin). See the attached ChangeLog for details. So what's next? We have been doing a lot of work and we're eager to show you some of the results. Our next release is scheduled for January of 2009, with performance improvements from the darcs hacking sprint, improved Windows support, a new optional Cabal-based build and a first cut at libdarcs. Thanks! -- Eric Kow <http://www.nltg.brighton.ac.uk/home/Eric.Kow> PGP Key ID: 08AC04F9

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SPJ's interview for Computer World on Haskell
by Bulat Ziganshin 16 Nov '08

16 Nov '08

Hello haskell, http://www.computerworld.com.au/index.php/id;1974033854 -- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com

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Haskell Weekly News: Issue 93 - November 15, 2008
by Brent Yorgey 15 Nov '08

15 Nov '08

--------------------------------------------------------------------------- Haskell Weekly News http://sequence.complete.org/hwn/20081115 Issue 93 - November 15, 2008 --------------------------------------------------------------------------- Welcome to issue 93 of HWN, a newsletter covering developments in the [1]Haskell community. Community News Congratulations to Ganesh (aka Heffalump) and Amanda on the [2]birth of Alexander Suresh Kerr Sittampalam! Announcements bustle-0.1. Will Thompson [3]announced the [4]release of [5]Bustle, a tool to show diagrams of D-Bus traffic for profiling purposes. It consists of a small C executable to log traffic, and a Gtk+ application which draws diagrams using Cairo. haskell-src-exts 0.4.1. Niklas Broberg [6]announced a new major release of the [7]haskell-src-exts package, an extension of the standard haskell-src package which handles most common syntactic extensions to Haskell. The new release features a cleaned up AST and names without ugly disambiguation prefixes. darcs 2.1.1rc2. Eric Kow (kowey) [8]announced the release of [9]darcs 2.1.1rc2, which adds support for GHC 6.10.1. It also includes a Windows bug fix. If you're using GHC 6.10.1 or Windows, give it a try and let the darcs development team know how it works. hpapi 0.1 release. Michael D. Adams [10]announced the first release of [11]hpapi, Performance API (PAPI) bindings for Haskell. PAPI provides access to various CPU counters such as cache-miss, instruction and pipeline stall counts. Workflow-0.1. Alberto G. Corona [12]announced the release of [13]Workflow, a library for transparent execution of computations across shutdowns and restarts. Reactive library (FRP) and mailing list. Conal Elliott [14]announced the release of [15]Reactive, a library for functional reactive programming (FRP), similar to the original [16]Fran but with a more modern interface (using standard type classes) and a hybrid push/pull implementation. It is designed to be used in a variety of contexts, such as interactive 2D and 3D graphics, graphical user interfaces, web services, and automatic recompilation/re-execution. There is also now a [17]mailing list and a [18]feature/bug tracker. ANN (sorta): OpenGL with extra type safety. Neal Alexander [19]announced a modification of the hOpenGL (and GLFW) source tree to force extra type checking on its various IO actions using the -XGeneralizedNewtypeDeriving extension. The main motivation was for writing concurrent OpenGL applications; the second motivation was to enforce static type checking on commands that can only be executed in certain OpenGL contexts (sending vertex data for example). Hopefully the code will be uploaded to Hackage as a separate package soon. FieldTrip library (functional 3D) and mailing list. Conal Elliott [20]announced the release of [21]FieldTrip, a library for functional 3D graphics. It is intended for building static, animated, and interactive 3D geometry, efficient enough for real-time synthesis and display. FieldTrip also has a [22]mailing list and a [23]feature/bug tracker. gitit 0.2 release - wiki using HAppS, git, pandoc. John MacFarlane [24]announced the upload of an early version of [25]gitit, a Haskell wiki program, to HackageDB. Gitit uses HAppS as a webserver, git for file storage, pandoc for rendering the (markdown) pages, and highlighting-kate for highlighted source code. You can [26]try it out here. Comments and patches welcome. Discussion Proof that Haskell is RT. Andrew Birkett [27]asked whether there exists a formal proof that the Haskell language is referentially transparent. Such a thing cannot exist, since Haskell has no formally defined semantics, but an interesting discussion about referential transparency and semantics ensued anyway. What *not* to use Haskell for. Dave Tapley [28]asked how people answer the question, "what does Haskell not do well?" Unfortunately, it seems that there is no good answer to this question and the thread degenerated into a discussion of all the great things you can do with Haskell. If only Haskell sucked more. Blog noise [29]Haskell news from the [30]blogosphere. * Braden Shepherdson: [31]Pimp Your XMonad #2: SmartBorders. The second in Braden's series on customising xmonad explains how to use the NoBorders extension to get rid of window borders when you don't want them. * Real-World Haskell: [32]Real World Haskell Electronic Edition Now On Sale. * Conal Elliott: [33]More beautiful fold zipping. * >>> Stephen: [34]Endless Cavern. A procedurally-generated tessellated-cavern flying game. * Twan van Laarhoven: [35]Arrays without bounds. Unbounded arrays (with O(1) amortized access) in Haskell! * "The GHC Team": [36]Comparing concurrent linked-list implementations in Haskell. * Ketil Malde: [37]454 sequencing and parsing the SFF binary format. * Tom Schrijvers: [38]Type Invariants for Haskell. Tom, Louis-Julien Guillemette, and Stefan Monnier's paper on Type Invariants for Haskell, which was recently accepted at PLPV'09. * Conal Elliott: [39]Another lovely example of type class morphisms. Conal elaborates on Max Rabkin's recent post on composable folds. * Real-World Haskell: [40]Beautiful Parallelism: Harnessing Multicores with Haskell. Don Stewart will be talking about programming mainstream multicore systems with Haskell at SC'08 next week in Austin, Texas. * Luke Palmer: [41]Sketch of Udon (Version Control/Packaging system). Luke sketches a high-level design for a distributed storage system that could be used as the basis for solving a number of interesting problems. * Galois, Inc: [42]Galois awarded NASA research contract. * Mark Jason Dominus: [43]Representing ordinal numbers in the computer and elsewhere. * The GHC Team: [44]Bootstrapping cabal-install. * Jason Dagit: [45]Phantom Types, Existentials and Controlling Unification -- Part 1. * Ben Moseley: [46]Why does Functional Programming matter?. Quotes of the Week * BMeph: In a functional world, students would ask how that index shadowing works in those funny 'for' statements... * digit: i'm almost annoyed at how brilliant xmonad is. * _pizza_: i think Haskell is undoubtedly the world's best programming language for discovering the first few dozen numbers in the Fibonacci sequence over IRC. * adu: let uncat3 [] = [] ; uncat3 xs = (let (ys, zs) = splitAt 3 xs in ys : uncat3 zs) ; getFrom x y = map (x !!) $ map (fromIntegral . ((\x -> fromIntegral $ foldl (.|.) (0::Word8) (zipWith (\c n -> if c then bit n else (0::Word8)) x [0..2])) :: [Bool] -> Int)) $ reverse . uncat3 . reverse . concat . map (((\x -> map (testBit x) [7,6..0]) :: Word8 -> [Bool]) . fromIntegral . ord) $ y in getFrom " HWdelor" "e\184-\235" * Beelsebob: ((:[]) "pigs eat") <^(++)^> ((:[]) " robot monkies") About the Haskell Weekly News New editions are posted to [47]the Haskell mailing list as well as to [48]the Haskell Sequence and [49]Planet Haskell. [50]RSS is also available, and headlines appear on [51]haskell.org. To help create new editions of this newsletter, please see the information on [52]how to contribute. Send stories to byorgey at cis dot upenn dot edu. The darcs repository is available at darcs get [53]http://code.haskell.org/~byorgey/code/hwn/ . References 1. http://haskell.org/ 2. http://urchin.earth.li/aegean/baby/ 3. http://www.haskell.org//pipermail/haskell-cafe/2008-November/050626.html 4. http://people.collabora.co.uk/~wjt/bustle/releases/bustle-0.1.tar.gz 5. http://resiak.livejournal.com/59590.html 6. http://www.haskell.org//pipermail/haskell-cafe/2008-November/050634.html 7. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/haskell-src-exts… 8. http://www.haskell.org//pipermail/haskell-cafe/2008-November/050378.html 9. http://darcs.net/darcs-2.1.1rc2.tar.gz 10. http://article.gmane.org/gmane.comp.lang.haskell.general/16612 11. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hpapi 12. http://article.gmane.org/gmane.comp.lang.haskell.general/16607 13. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/Workflow 14. http://article.gmane.org/gmane.comp.lang.haskell.general/16604 15. http://haskell.org/haskellwiki/Reactive 16. http://conal.net/Fran 17. http://www.haskell.org/mailman/listinfo/reactive 18. http://trac.haskell.org/reactive 19. http://article.gmane.org/gmane.comp.lang.haskell.cafe/47458 20. http://article.gmane.org/gmane.comp.lang.haskell.cafe/47416 21. http://haskell.org/haskellwiki/FieldTrip 22. http://www.haskell.org/mailman/listinfo/FieldTrip 23. http://trac.haskell.org/FieldTrip 24. http://article.gmane.org/gmane.comp.lang.haskell.cafe/47384 25. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/gitit 26. http://johnmacfarlane.net:5001/ 27. http://thread.gmane.org/gmane.comp.lang.haskell.cafe/47569 28. http://thread.gmane.org/gmane.comp.lang.haskell.cafe/47491 29. http://planet.haskell.org/ 30. http://haskell.org/haskellwiki/Blog_articles 31. http://braincrater.wordpress.com/2008/11/15/pimp-your-xmonad-2-smartborders/ 32. http://www.realworldhaskell.org/blog/2008/11/15/real-world-haskell-electron… 33. http://feeds.feedburner.com/~r/conal/~3/453765396/ 34. http://www.maths.tcd.ie/~icecube/2008/11/endless-cavern/ 35. http://twan.home.fmf.nl/blog/haskell/UnboundedArray.details 36. http://ghcmutterings.wordpress.com/2008/11/14/comparing-concurrent-linked-l… 37. http://blog.malde.org/index.php/2008/11/14/454-sequencing-and-parsing-the-s… 38. http://tomschrijvers.blogspot.com/2008/11/type-invariants-for-haskell.html 39. http://feeds.feedburner.com/~r/conal/~3/452607365/ 40. http://www.realworldhaskell.org/blog/2008/11/12/beautiful-parallelism-harne… 41. http://lukepalmer.wordpress.com/2008/11/12/sketch-of-udon-version-controlpa… 42. http://www.galois.com/blog/2008/11/11/galois-awarded-nasa-research-contract/ 43. http://blog.plover.com/math/ordinals.html 44. http://ghcmutterings.wordpress.com/2008/11/10/bootstrapping-cabal-install/ 45. http://blog.codersbase.com/2008/11/10/phantom-types-existentials-and-contro… 46. http://nattermorphisms.blogspot.com/2008/11/why-does-functional-programming… 47. http://www.haskell.org/mailman/listinfo/haskell 48. http://sequence.complete.org/ 49. http://planet.haskell.org/ 50. http://sequence.complete.org/node/feed 51. http://haskell.org/ 52. http://haskell.org/haskellwiki/HWN 53. http://code.haskell.org/~byorgey/code/hwn/

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ANNOUNCE: haskell-src-exts 0.4.1
by Niklas Broberg 15 Nov '08

15 Nov '08

Fellow Haskelleers, it is my pleasure to announce the new release of the haskell-src-exts package, version 0.4.1: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/haskell-src-exts… darcs get http://code.haskell.org/HSP/haskell-src-exts This is a new "major" release, the first of the 0.4 branch, and as such it is not backwards compatible with the releases in the 0.3 branch. This is due to two major changes to the design of the library: 1) The AST has been cleaned up, by splitting Haskell expressions in the AST from the "expressions" used while parsing to represent both expressions and patterns. This means that the datatype for expressions will no longer contain constructors for things like wildcards and irrefutable patterns. It now only contains constructors for actual Haskell expressions. If you have been using haskell-src-exts previously, this change should not bite you at all unless you have abused these ugly hacks in the AST, so it is *almost* backwards compatible. However... 2) ... I've finally decided to take the plunge and get rid of the ugly prefixes on all datatypes in the AST. I am of the firm conviction that disambiguation between datatypes and functions with the same name should be handled through the module hierarchy and qualified imports, not by adding prefixes. And the longer I wait, the harder the switch. So now the datatypes that make up the AST are called things like Exp, Pat, Module (the former Module is now ModuleName), Type, QOp etc instead of HsExp, HsPat... . The migration from 0.3.x to 0.4.1 should be really simple: i) replace all occurences of Module with ModuleName ii) remove all occurences of Hs This release also contains a number of smaller, fully backwards compatible bug fixes. These are available for the 0.3 branch in the 0.3.12 release that will mark the end of that branch: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/haskell-src-exts… No further bug fixes or features will be implemented for it, and I urge you to migrate as early as possible, it really isn't hard. :-) Cheers and Happy Haskelling, /Niklas

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The real Monad Transformer
by Henning Thielemann 13 Nov '08

13 Nov '08

It was argued that people avoid Haskell because of terms from Category theory like 'Monad'. This problem can now be solved by a wrapper which presents all the WWW without monads! Start e.g. at http://saxophone.jpberlin.de/MonadTransformer?source=http%3A%2F%2Fwww%2Ehas… Of course the tool is written in Haskell, that is, Haskell helps solving problems which only exist because of Haskell. Bug reports and feature requests can be tracked at https://sourceforge.net/projects/parallelweb

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XOSD x Haskell
by Roy Lanek 13 Nov '08

13 Nov '08

Hi, I am looking for XOSD (X On Screen Display) library bindings for Haskell, of the kind of X::Osd [Perl]. I haven't been able to find anything on XOSD _and_ Haskell around, who knows better? Thank you and cheers, /Roy Lanek (West Sumatra) -- ______________________________________ # _ a@@ @[ # @#@@ @ _____ ___]F ___ ___ ___ __ __ ___ __ ___ # #@_# @ ^@###@ ###@]@@@@* ##* "*#_'#@###_ ""#@##F#W"7@ # __ "@ @ @ dE #" "]F 7@ @ dL @ #F @ #" F __# @## ]L @ @ @ # ][ # @ dL @ # # # @ #WW B @ _@___#@ #___@@ #L " _# 7@@@@L@__#" 7@___@ # #@@_ # 7#@#*"##*@@@ *##^@M @@@ @@E @@@"dL###" 7##W#@ # @__@+ # d@ #@L #"#* # #MMMMMMMMM Slackware Linux MMMMMMMMMMM

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ANNOUNCE: hpapi 0.1 release
by Michael D. Adams 12 Nov '08

12 Nov '08

I am pleased to announce the first release of hpapi, Performance API (PAPI) bindings for Haskell. The release is on Hackage: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hpapi The source repository is at: http://code.haskell.org/hpapi/ Please send bug reports to <adamsmd [AT] cs.indiana.edu> What is it ========== This is a simple set of bindings for the Performance API (PAPI). PAPI provides access to various CPU counters such as cache-miss, instruction and pipeline stall counts. The easiest way to use this library is the withCounts function: withCounts :: [EventCode] -> IO a -> IO (a, [Integer]) Given a list of events to count and an IO operation it will run the operation and return the resulting counts. So you could do something like: main = do [l1,tlb,fp] <- withCounters [papi_l1_dcm, papi_tlb_dm, papi_fp_ins] ioOperationToMeasure printLn (l1, tlb, fp) To use it one will of course need the PAPI C library and any necessary kernel modifications installed. Status ====== The High Level interface (which will be sufficient for most people's needs) should be usable, but the low level interface is still alpha quality. That is to say, it is ready for people to start banging on it, but it is largely untested and the modules/interfaces may be reorganized based on user feedback. All of PAPI is supported with the exception of the following "advanced" features: - Multiplexing - Threads - Locks - Overflow - Statistical Profiling Future Directions ================= Future directions will be determined largely by user feedback. Principal areas that I am looking for feedback on are: - documentation - module organization - the handling of PAPI errors (currently it throws an IO error) - the design of the Haskell interface build on top of the C level PAPI_get_opt and PAPI_set_opt - what advanced features of PAPI to build bindings for next Comparison with GHC's built-in PAPI =================================== GHC supports a built-in version of PAPI (see http://hackage.haskell.org/trac/ghc/wiki/PAPI) This system is different in a few ways. First, hpapi allows you to measure specific parts of a program while GHCI's PAPI only does whole program measurement Second, since hpapi is a library you can have fine grained and sophisticated control over how things are measured. On the other hand GHC's PAPI as part of the RTS gives you less control, but on the plus side doesn't require any modification to the program. Finally, GHC's PAPI splits apart the counts that come from the garbage collector from those that come from the mutator, while hpapi combines them. This is a limitation of hpapi we hope to correct some time in the future. It remains to be seen whether it would be worth while to unify these two systems. ================ Bug reports as well as suggestions, feedback or contributions to the API or the documentation most welcome. Michael D. Adams

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