- Haskell-Cafe - Haskell.org

Re: [Haskell] Math behind Haskell
by Neil Mitchell 24 Sep '07

24 Sep '07

Hi The haskell-cafe@ mailing list is more appropriate for messages such as this. haskell@ is just for announcements (it should be called haskell-annouce@ !) > * Lambda calculus - the basis of functional languages > > * Category theory - where all these mysterious things like monads, > arrows, and functors come from. I'd add: * Discrete Maths - booleans, relations, functions etc. * Type theory * Logic programming (Prolog) * Semantics Most of these are computer science courses, rather than maths ones. Thanks Neil

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PROPOSAL: Rename haskell@ to haskell-announce@
by Andrzej Jaworski 24 Sep '07

24 Sep '07

Sorry guys for joining the thread of sinners on haskell@ today. Forgot to check if guests had not moved to cafe;-) It is a good example though how insufficient this verbal principles are, since I have myself raised the need to revise names of the lists here. On second thought, with rising traffic the problem should be approached by introducing AI automation - sort of scunning, learning, summerising and sending tagged abstracts onto haskel@. In other words the only possible input onto haskell list should be robotic:-) Be brave guys, you are ment to make history:-) Cheers, -Andrzej Jaworski

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Noob question and sequence of operations (print then do something else)
by John Wicket 24 Sep '07

24 Sep '07

I am still in an imperative way of thinking. In this example here; how would I call "putStrLn" and then set the function with a value. Eg: aa :: String -> IO () aa instr = do putStrLn "abc" putStrLn "abc" return "123" --- The error I am getting. Couldn't match expected type `()' against inferred type `[Char]' In the first argument of `return', namely `"123"' In the expression: return "123" In the expression: do putStrLn "abc" putStrLn "abc" return "123"

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Re: [Haskell] Re: [Haskell-cafe] PROPOSAL: Rename haskell@ to haskell-announce@
by Neil Mitchell 24 Sep '07

24 Sep '07

Hi > Forgive me, but I would much prefer a newsgroup to a mailing list. > > True, I could unsubscribe now and just browse the mailman archives - > but for posting, I'd have to temporarily re-subscribe, which is awkward. > (Indeed that's the only reason I'm not doing it.) I believe you can post from the gmane archives, and that they also offer a newsgroup feed of this list. I think the general consensus (and my personal view) is that a mailing list is the preferred mechanism for most people. Thanks Neil > > We already have comp.lang.haskell. - Best regards, > -- > -- Johannes Waldmann -- Tel/Fax (0341) 3076 6479/80 -- > ---- http://www.imn.htwk-leipzig.de/~waldmann/ ------- > > _______________________________________________ > Haskell mailing list > Haskell(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell >

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Re: [Haskell] Math behind Haskell
by Andrzej Jaworski 24 Sep '07

24 Sep '07

Tomas Caithaml wrote: > Hi all. > > When I was playing with Haskell and reading stuff about it, I noticed > that there is a lot of information in a form of research papers and a > lot of mathematics involved. I must confess that I quite like this > academic approach. > > Well, I thought that while I am still at university I could take some > math classes to help me better understand these things and > broaden my horizon. > > Any suggestion what could be relevant? > > I came up with: > > * Lambda calculus - the basis of functional languages > > * Category theory - where all these mysterious things like monads, > arrows, and functors come from. > > * Topology (?) - don't know; I thought it is important rather in > mathematical analysis (which I don't like much) but I have seen > somewhere some references to it in context of CS. > > Any other suggestions? All the advice you got was good but I will add: never go after one thing in mathematics before you really know what you are doing. Topology is probably best intellectually but must be combined with functional analysis or algebra to have something to experiment with. Similarly category theory alone will never teach you to think mathematically - to build models. For CS inclined entering into logic study is today a very rewording experiance but you must feel confident with CT for reading modern proof theory and additionally operator algebra entering into linear logic. The reward: you get closer to functional programming or quantum mechanics without even knowing that:-) Digging in Haskell can make you fluent in writing some computational stuff to experiment with, but it will most certainly follow thought experiment not vice versa. Relying on such hybrid thinking too much can be harmful though. A mathematician follows intuition, ideally he should not even plan what he will do before he spots something that will drive his attention. Programming is the opposite - planning lies at the heart of it. Even languages that fancy mathematical concepts belong still to technology and thechnology is to eliminate problems and not to investigate them. Mathematics and logic will definitelly influence CS more with each decade untill it becomes a science like phisics. However how shellow this science still is in CS today demonstrate the havoc with multicore, where linguistics, model theory, tamplet programming, object programming, Haskell(?) compete head in head to cover the bare ass... Cheers, -Andrzej Jaworski Moving to Haskell Cafe <haskell-cafe(a)haskell.org>

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Library Process (was Building "production stable" software in Haskell)
by Dominic Steinitz 24 Sep '07

24 Sep '07

This discussion has sparked a question in my mind: What is the process for the inclusion of modules / packages in ghc, hugs and other compilers & interpreters? I thought the master plan was that less would come with the compiler / interpreter and the user would install packages using cabal. I was thus mildly surprised earlier this year to find e.g. data.bytestring was included with ghc. Now that I look at the haddock, it says this is a base package but doesn't say anything about its status. On the other hand, there are lots of modules that are base packages that are experimental. Should something experimental be a base package? And shouldn't all modules that are base packages declare their status? Perhaps these are questions for the libraries mailing list but I thought I'd start here. Yours confused of Kingston.

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Re: [Haskell-cafe] Win32 Open GL / Glut Applications
by Ronald Guida 24 Sep '07

24 Sep '07

John Wicket wrote: > yea, that is probably what I need. Can you post in a step-by-step way. Here is a set of instructions for what I had to do to get FreeGLUT working with GHCi. <RANT> Just a little warning: my instructions could be wrong in some places. Normally, in order to verify my instructions, I would uninstall everything, start from scratch, follow my instructions step by step, and verify that they work. Unfortunately: * I have low confidence in the accuracy of the following instructions. * I have only one machine. * I went through lots of frustration to get freeglut to work with GHCi. * I am not willing to risk breaking my current installation. * I do not know of any easy way to preserve my current installation and still start over from scratch to test my instuctions. </RANT> If my instructions are wrong, then please let me know, and I might attempt to fix it. Although I just don't understand why freeglut, the Haskell GLUT library, and GHCi won't work together in the first place. Here's what I would have to do if I were starting from scratch: 7-Zip http://www.7-zip.org/ This is an open source file archiver for Windows that can handle *.gz and *.bz2 files. Download the Windows version and install it. GHC 6.6.1 http://haskell.org/ghc/download_ghc_661.html#windows This is the version of GHC that I'm using. Download and install it. MinGW/MSYS Download all three files, then install them in the order I have listed them. Note: MinGW and MSYS need to "live" in different directories. http://sourceforge.net/project/showfiles.php?group_id=2435 Automated MinGW installer MinGW-5.1.3.exe ** When you run the installer, it will download several more files for you. MSYS: Minimal System MSYS-1.0.10.exe http://sourceforge.net/project/showfiles.php?group_id=2435&package_id=67879 MSYS Supplementary Tools msysDTK-1.0.1.exe ** Scroll down to find "Current Release: msysDTK-1.0.1" and expand this tab. Select "msysDTK-1.0.1.exe" zlib-1.2.3 http://www.zlib.net/ The links for "zlib source code" are about halfway down the page. After downloading, the process (IIRC) is 1. Unzip the source code. 2. Start MSYS and cd to the source-code directory. 3. Execute "./configure" 4. Execute "make" 5. Execute "make install" I don't remember having any problems with zlib. cURL-7.16.4 http://curl.haxx.se/download.html Note: It appears that cURL just had a minor revision on Sept 13. I guess you can just try the latest version and see of things work. IIRC, the process is exactly the same as the zlib install process, and I didn't have any problems here either. darcs-1.0.9 http://darcs.net/darcs-1.0.9.tar.gz Dependencies that you'll need: cURL and zlib :-) Your darcs installation will have some holes, for example it won't support SSL because we didn't satisfy the SSL dependency. IIRC, the process here is 1. Unzip the source code. 2. Start MSYS and cd to the source-code directory. 3. Execute "autoconf" 4. Execute "./configure" 5. Execute "make" 6. Execute "make install" Freeglut-2.4.0 http://freeglut.sourceforge.net/index.php#download Here's where the hackery starts. 1. Download the Freeglut source code and unzip it. 2. Start MSYS and cd to the source-code directory. 3. Execute "./configure" 4. Download this custom makefile and put in in the "./src" directory. http://hpaste.org/2841 5. Download this custom def file and put in in the "./src" directory. http://hpaste.org/2842 6. Cd to the "./src" directory and then execute "make". 7. Copy the "freeglut.dll" to GHC's bin directory (ghc-6.6.1/bin). 8. Copy the *.h files from "freeglut-2.4.0/include/GL" to "ghc-6.6.1/include/mingw/GL". Note that "glut.h" will be overwritten. GLUT-2.1.1 You need to use darcs to download GLUT-2.1.1. 1. Start MSYS, create a directory for the GLUT source code, and cd to it. 2. Execute "darcs get http://darcs.haskell.org/libraries/GLUT/" and wait a while. 3. Cd to your new source directory. 4. Execute "autoreconf" and wait a while. 5. Modify "GLUT.cabal" as follows: Locate the line start starts with "build-depends:" and remove the dependencies "array" and "containers" 5. Execute "runghc Setup.hs configure" and wait. 6. Modify "GLUT-2.1.1/Graphics/UI/GLUT/Extensions.hs" as follows: Look at the last two lines: foreign import ccall unsafe "hs_GLUT_getProcAddress" hs_GLUT_getProcAddress :: CString -> IO (FunPtr a) Change "hs_GLUT_getProcAddress" to "glutGetProcAddress" 7. Modify "GLUT-2.1.1/cbits/HsGLUT.c" as follows: Look for "void* hs_GLUT_getProcAddress(char *procName)" and remove the whole function. 8. Execute "runghc Setup.hs build" and wait. 9. Execute "ghc-pkc unregister GLUT". This unregisters the existing GLUT haskell library. Also, search through GHC's directories, locate any glut library files (*.a, *.o, *.hi) that are in there and remove them. You are deleting the existing GLUT that came with GHC 6.6.1 in order to replace it with Freeglut. 10. Execute "runghc Setup.hs install". 11. In GHC's directory, there is a file named "package.conf". This file contains one extremely long line. You need to find an editor that will let you insert some text into this line without introducing any line breaks. Emacs can do this. You need to locate the text << pkgName = "GLUT" >> and then you need to locate << hsLibraries = ["HSGLUT-2.1.1"] >> to the right of there. The very next thing to the right of "hsLibraries" should be << extraLibraries = [] >>. You need to change it to << extraLibraries = ["freeglut"] >>. 12. At this point, you should be able to start GHCi, load an example that depends on freeglut, and run it from GHCi, without getting any crashes or weird errors. 13. If you want to /compile/ with GHCi, then you'll need to copy the freeglut.dll file into the same directory as your newly-compiled program.exe file. I haven't tried static linking yet; that would require recompiling freeglut as a static library instead of a DLL. Good Luck! -- Ron

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Haskell Weekly News: September 23, 2007
by Don Stewart 24 Sep '07

24 Sep '07

--------------------------------------------------------------------------- Haskell Weekly News http://sequence.complete.org/hwn/20070923 Issue 65 - September 23, 2007 --------------------------------------------------------------------------- Welcome to issue 65 of HWN, a newsletter covering developments in the [1]Haskell community. This episode comes to you live from Portland, Oregon, where the HWN automaton now lives, running on a virtual host at Galois, Inc. 1. http://haskell.org/ Announcements Cabal 1.2.0 released. Thomas Schilling [2]announced that [3]Cabal version 1.2.0 is available. The major new feature in this release is support for Cabal configurations. This allows package authors to more easily adopt their package descriptions to different system parameters such as operating system, architecture, or compiler. In addition, some optional features may be enabled or disabled explicitly by the package user. 2. http://article.gmane.org/gmane.comp.lang.haskell.libraries/7491 3. http://www.haskell.org/cabal SparseCheck. Matthew Naylor [4]announced SparseCheck, a library for typed, depth-bounded logic programming in Haskell allowing convenient expression of test-data generators for properties with sparse domains. More information on the [5]home page. 4. http://article.gmane.org/gmane.comp.lang.haskell.general/15593 5. http://www.cs.york.ac.uk/~mfn/sparsecheck/ monadLib 3.3.0. Iavor Diatchki [6]announced a new version of monadLib, adding the identiy transformer, and a family of deriving functions. 6. http://article.gmane.org/gmane.comp.lang.haskell.general/15586 ListLlke. John Goerzen [7]announced ListLike, a generic interface to the various list-like structures in Haskell. 7. http://article.gmane.org/gmane.comp.lang.haskell.general/15582 HaL2: Meeting Haskell in Leipzig 2: videos. Klaus Meier [8]announced that the videos and presentations of the talks given at HaL2 are [9]now online. 8. http://article.gmane.org/gmane.comp.lang.haskell.general/15565 9. http://iba-cg.de/haskell.html The Monad.Reader: Issue 8. Wouter Swierstra [10]announced that the latest issue of The Monad.Reader is [11]now available. Issue 8 consists of the following two articles: Brent Yorgey on 'Generating Multiset Partitions' and Conrad Parker's 'Type-Level Instant Insanity' 10. http://article.gmane.org/gmane.comp.lang.haskell.general/15554 11. http://www.haskell.org/haskellwiki/The_Monad.Reader Haskell mode plugins for Vim. Claus Reinke [12]announced improved [13]haskell mode plugins for vim. 12. http://article.gmane.org/gmane.comp.lang.haskell.general/15553 13. http://article.gmane.org/gmane.comp.lang.haskell.general/15553 hstats-0.1. Marshall Beddoe [14]announced a statistical computing module for Haskell. 14. http://article.gmane.org/gmane.comp.lang.haskell.cafe/28973 HIntegerByInt. Isaac Dupree [15]announced a [16]reimplementation, in Haskell, of the Integer type that Haskell provides in its Prelude. It is designed in mind of being actually usable as the implementation of that type, for compilers. It is also a module that exports a working Integer type. It is in terms of only basic Prelude functions, lists, and Int. It is NOT a purely inductive definition, because Int is much faster than a purely inductive definition would allow, and nevertheless often easier to come by (more portable, license-wise, size-wise, nuisance-wise...) than GMP or other C bignum libraries. 15. http://thread.gmane.org/gmane.comp.lang.haskell.libraries/7285 16. http://isaac.cedarswampstudios.org/2007/HIntegerByInt OzHaskell: Australian Haskell Programmers Group. Manuel Chakravarty [17]started organising OzHaskell, and Australian Haskell user's group. 17. http://article.gmane.org/gmane.comp.lang.haskell.cafe/28883 Israeli Haskell Programmers Group. B K [18]also seeks to form an Israeli Haskell user's group 18. http://article.gmane.org/gmane.comp.lang.haskell.cafe/28877 xmonad 0.3. Don Stewart [19]announced the 0.3 release of [20]xmonad. xmonad is a tiling window manager for X. Windows are arranged automatically to tile the screen without gaps or overlap, maximising screen use. 19. http://article.gmane.org/gmane.comp.lang.haskell.cafe/28425 20. http://xmonad.org/ HPDF 1.0. alpheccar [21]announced version 1.0 of the [22]HPDF library. 21. http://article.gmane.org/gmane.comp.lang.haskell.cafe/28371 22. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/HPDF-1.0 pcap: user-level network packet capture. Bryan O'Sullivan [23]announced the release of pcap 0.3.1 23. http://article.gmane.org/gmane.comp.lang.haskell.cafe/28139 Gtk2Hs Tutorial. Hans van Thiel [24]announced a port of the GTK2 [25]tutorial by Tony Gail and Ian Main to Haskell's gtk2hs. 24. http://article.gmane.org/gmane.comp.lang.haskell.cafe/27954 25. http://tinyurl.com/yrbtsu An efficient lazy suffix tree library. Bryan O'Sullivan [26]posted a [27]suffix tree library to hackage. It implements Giegerich and Kurtz's lazy construction algorithm, with a few tweaks for better performance and resource usage. 26. http://article.gmane.org/gmane.comp.lang.haskell.cafe/27891 27. http://www.serpentine.com/software/suffixtree/ Bay Area Functional Programmers. Keith Fahlgren [28]announced the formation of the [29]Bay Area Functional Programmers group. This group is for anyone using or interested in functional programming and functional programming languages, particularly strongly typed languages such as Haskell, OCaml and SML. 28. http://article.gmane.org/gmane.comp.lang.haskell.cafe/27860 29. http://bayfp.org/ Haskell irc channel reaches 400 users. Don Stewart [30]noticed that, five and a half years after its inception, under the guiding hand of Shae Erisson (aka shapr), the [31]Haskell IRC channel on freenode has reached 400 users! 30. http://article.gmane.org/gmane.comp.lang.haskell.cafe/27826 31. http://www.haskell.org/haskellwiki/IRC_channel Guihaskell and PropLang 0.1. Asumu Takikawa [32]announced the results of his Google Summer of Code project: Guihaskell, a graphical REPL using PropLang and work on PropLang, a GUI library built on Gtk2hs that allows for high level design. 32. http://article.gmane.org/gmane.comp.lang.haskell.cafe/27598 HAppS-Data 0.9: XML, Pairs, HList, deriveAll. Alex Jacobson [33]announced that the components of [34]HAppS are being released as individual useful packages. HAppS-Data is the first in a series, and provides useful operations on XML data. 33. http://article.gmane.org/gmane.comp.lang.haskell.cafe/27597 34. http://happs.org/ Introduction to proving Haskell code. Tim Newsham [35]put together [36]a small intro lesson on proving Haskell code using quickcheck, equational reasoning and Isabelle/HOL. 35. http://article.gmane.org/gmane.comp.lang.haskell.cafe/27523 36. http://www.thenewsh.com/%7Enewsham/formal/reverse/ Very Fast Searching of ByteStrings. Chris Kuklewicz [37]announced a Boyer-Moore algorithm implemented for strict and lazy bytestrings (and combinations thereof). It finds all the overlapping instances of the pattern inside the target. 37. http://article.gmane.org/gmane.comp.lang.haskell.libraries/7363 Infinity 0.1. Austin Seipp [38]announced Infinity v0.1. an IRC bot in the essence of lambdabot; that is, it should be extendable through plugins and plugins should be easy to write, modify and contribute. 38. http://article.gmane.org/gmane.comp.lang.haskell.cafe/27445 Haskell' This section covers the [39]Haskell' standardisation process. * [40]Instances of Read on bounded integral types should detect overflow 39. http://hackage.haskell.org/trac/haskell-prime 40. http://article.gmane.org/gmane.comp.lang.haskell.prime/2302 Libraries This week's proposals and extensions to the [41]standard libraries. * [42]Add &&& and *** to Data.Tuple * [43]Add System.Info.isWindows * [44]Make arrays safer * [45]GenT monad transformer variant of Gen * [46]Test.HUnit documentation * [47]Data.List.groupBy with non-transitive equality predicate * [48]Add dropped STM invariants functions * [49]Add Data.Eq.equating to match Data.Ord.comparing * [50]Fix abstract unix sockets 41. http://haskell.org/haskellwiki/Library_submissions 42. http://thread.gmane.org/gmane.comp.lang.haskell.libraries/7550 43. http://thread.gmane.org/gmane.comp.lang.haskell.libraries/7261 44. http://thread.gmane.org/gmane.comp.lang.haskell.libraries/7283 45. http://article.gmane.org/gmane.comp.lang.haskell.libraries/7294 46. http://article.gmane.org/gmane.comp.lang.haskell.libraries/7394 47. http://article.gmane.org/gmane.comp.lang.haskell.libraries/7400 48. http://article.gmane.org/gmane.comp.lang.haskell.libraries/7598 49. http://article.gmane.org/gmane.comp.lang.haskell.libraries/7594 50. http://article.gmane.org/gmane.comp.lang.haskell.libraries/7544 Hackage This week's new libraries in [51]the Hackage library database. 51. http://hackage.haskell.org/ * numbers-2007.9.23. Lennart Augustsson. [52]numbers: instances of the numerical classes for a variety of different numbers. 52. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/numbers-2007.9.23 * hmp3 1.3. Don Stewart. [53]hmp3: An mp3 player with a curses frontend. 53. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hmp3-1.3 * utf-string 0.2. Eric Mertens. [54]utf8-string: A UTF8 layer for IO and Strings. 54. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/utf8-string-0.2 * hstats 0.1. Marshall Beddoe. [55]hstats: A library of commonly used statistical functions. 55. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hstats-0.1 * sparsecheck 0.2. Matthew Naylor. [56]SparseCheck: a library for logic programming in Haskell that allows convenient description of test-data generators. 56. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/sparsecheck-0.1 * monadLib 3.3.0. Iavor Diatchki. [57]monadLib: A collection of monad transformers. 57. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/monadLib-3.3.0 * ListLike 1.0.0. John Goerzen. [58]ListLike: Generic support for list-like structures in Haskell. 58. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/ListLike-1.0.0 * cabal-test 0.1. David Himmelstrup. [59]cabal-test: Cabal-test is a tool for testing cabal projects. 59. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/cabal-test-0.1 * HPDF 1.1. alpheccar. [60]HPDF: a PDF library. 60. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/HPDF-1.1 * hxt 7.3. Uwe Schmidt. [61]hxt: The Haskell XML Toolbox. 61. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hxt-7.3 * irc 0.1. Trevor Elliott. [62]irc: A small library for parsing IRC messages 62. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/irc-0.1 * hsdns 1.0. Peter Simons. [63]hsdns: an asynchronous DNS resolver based on GNU ADNS. 63. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hsdns-1.0 * streamproc 1.0. Peter Simons. [64]streamproc: Stream Processer Arrow 64. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/streamproc-1.0 * hsemail 1.0. Peter Simons. [65]hsemail: Parsers for the syntax defined in RFC2821 and 2822 65. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hsemail-1.0 * funcmp 1.0. Peter Simons. [66]funcmp: Functional MetaPost is a Haskell frontend to the MetaPost language 66. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/funcmp-1.0 * cabal-rpm 0.3.1. Bryan OSullivan. [67]cabal-rpm: This package turns Haskell Cabal source packages into source and binary RPM packages. 67. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/cabal-rpm-0.3.1 * Finance-Quote-Yahoo 0.3. Brad Clawsie. [68]Finance-Quote-Yahoo: Obtain quote data from finance.yahoo.com 68. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/Finance-Quote-Ya… * xmonad 0.3. Spencer Janssen. [69]xmonad: a minimalist tiling window manager for X 69. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/xmonad-0.3 * hint 0.1. Daniel Gorin. [70]hint: an interpreter monad for Haskell expressions based on ghc-api 70. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hint-0.1 * ipprint 0.2. Gleb Alexeyev. [71]ipprint: Tiny helper for pretty-printing values in ghci console 71. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/ipprint-0.2 * pandoc 0.44. John MacFarlane. [72]pandoc: Conversion between markup formats 72. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/pandoc-0.44 * X11-extras 0.3. Spencer Janssen. [73]X11-extras: Missing bindings to the X11 graphics library 73. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/X11-extras-0.3 * dsp 0.2. Matthew Donadio. [74]dsp: Digital Signal Processing, Fourier Transform, Filter design, Frequency estimation, Interpolation, Linear Algebra, Polynomials 74. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/dsp-0.2 * c2hs 0.15.0. Manuel Chakravarty. [75]c2hs: C->Haskell assists in the development of Haskell bindings to C libraries. 75. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/c2hs-0.15.0 * regex-base 0.92. Chris Kuklewicz. [76]regex-base: Interface API for regex-posix,pcre,parsec,tdfa,dfa 76. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/regex-base-0.92 * soegtk 0.9.12.2. Duncan Coutts. [77]soegtk: SOE api for gtk2hs 77. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/soegtk-0.9.12.2 * hsns 0.5.3. Austin Seipp. [78]hsns: a miniature network sniffer 78. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hsns-0.5.3 * anydbm 1.0.4. John Goerzen. [79]anydbm: Interface for DBM-like database systems 79. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/anydbm-1.0.4 * suffixtree 0.2.1. Bryan O'Sullivan [80]suffixtree: An efficient, lazy suffix tree implementation. 80. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/suffixtree-0.2.1 Discussion A regressive view of support for imperative programming in Haskell. Paul Hudak [81]sparked an interesting thread about the effect on the language of rich support for imperative programming. 81. http://thread.gmane.org/gmane.comp.lang.haskell.cafe/27214 Conference roundup * [82]Sydney Area Programming Language INterest Group: Call for Abstracts 82. http://article.gmane.org/gmane.comp.lang.haskell.cafe/29046 Jobs A top tier Investment bank is looking for a Haskell developer. Kyle McBeath [83]announced that there is a available a permanent position in London, joining a cross asset team. You will be able to use Haskell commercially everyday, be generously compensated and be on the forefront of technology in banking. This is a great opportunity for PhD students or above with proven experience of Haskell programming. 83. http://article.gmane.org/gmane.comp.lang.haskell.general/15552 Postdoctoral Fellowship in Functional Programming. Graham Hutton [84]announced that applications are invited for a 3-year postdoctoral research fellowship in functional programming, to work on the EPSRC-funded project 'Reasoning About Exceptions and Interrupts'. 84. http://article.gmane.org/gmane.comp.lang.haskell.general/15600 Blog noise [85]Haskell news from the [86]blogosphere. * [87]Peano induction for binary numbers * [88]Simple proof of stack correctness for a tiny language (in Agda) * [89]Peano, episode 3 * [90]Proving Haskell programs correct with QuickCheck and Isabelle/HOL * [91]Coq and simple group theory * [92]Coq and The Monad Laws: Introduction * [93]Coq and The Monad Laws: The First and Second * [94]Coq and The Monad Laws: The Third * [95]Revisiting board-building in chess * [96]Monads * [97]A Monad Tutorial for Ocaml * [98]Learning about (Computational) Monads * [99]I Wasn't Joking about One-Argument Haskell Functions * [100]Mapping Programming Language IRC Channels 85. http://planet.haskell.org/ 86. http://haskell.org/haskellwiki/Blog_articles 87. http://sneezy.cs.nott.ac.uk/fplunch/weblog/?p=70 88. http://sneezy.cs.nott.ac.uk/fplunch/weblog/?p=71 89. http://sneezy.cs.nott.ac.uk/fplunch/weblog/?p=72 90. http://www.thenewsh.com/%7Enewsham/formal/reverse/ 91. http://blog.mikael.johanssons.org/archive/2007/08/coq-and-simple-group-theo… 92. http://sequence.complete.org/node/358 93. http://sequence.complete.org/node/359 94. http://sequence.complete.org/node/360 95. http://sequence.complete.org/node/361 96. http://www.bofh.org.uk/articles/2007/08/07/monads 97. http://enfranchisedmind.com/blog/archive/2007/08/06/307 98. http://dailykibitz.blogspot.com/2007/08/learning-about-computational-monads… 99. http://www.oreillynet.com/onlamp/blog/2007/08/i_wasnt_joking_about_oneargum… 100. http://chneukirchen.org/blog/archive/2007/08/mapping-programming-language-i… * [101]ASCII Rave in Haskell * [102]Today is similar to the programming languages situation of twenty years ago * [103]Haskell - the videos * [104]QuickCheck : Why Testing code should be Laissez-faire * [105]Rationals! * [106]Grass-Roots Functional Languages? * [107]Programming in C, ummm, Haskell * [108]And what about C arrays? * [109]Real Quicksort in Haskell * [110]Pointer tagging * [111]n00b Thoughts on Haskell * [112]'The way forward involves functional programming' * [113]Does Syntax Matter? * [114]A bright future: security and modern type systems * [115]Making the transition from sequential to implicit parallel programming: How sequential languages obscure parallelism * [116]Software Transactional Memory - Making multithreading easier * [117]Roman Numerals in Haskell * [118]A history of monad tutorials * [119]Java Becoming Solution for Safety-Critical Applications * [120]Dunno (about STM) 101. http://doc.gold.ac.uk/~ma503am/alex/asciirave 102. http://pinderkent.blogsavy.com/archives/97 103. http://www.elbeno.com/blog/?p=353 104. http://disparatemathematician.blogspot.com/2007/08/why-testing-code-should-… 105. http://byorgey.wordpress.com/2007/08/13/rationals/ 106. http://www.falvotech.com/blog/index.php?/archives/68-Grass-Roots-Functional… 107. http://augustss.blogspot.com/2007/08/programming-in-c-ummm-haskell-heres.ht… 108. http://augustss.blogspot.com/2007/08/what-about-arrays-after-doing-my-littl… 109. http://augustss.blogspot.com/2007/08/quicksort-in-haskell-quicksort-is.html 110. http://community.livejournal.com/evan_tech/229988.html 111. http://dumpendebat.net/2007/08/14/n00b-thoughts-on-haskell/ 112. http://notes-on-haskell.blogspot.com/2007/08/haskell-more-than-just-hype.ht… 113. http://notes-on-haskell.blogspot.com/2007/08/does-syntax-matter.html 114. http://blog.moertel.com/articles/2007/08/15/a-bright-future-security-and-mo… 115. http://www.embedded.com/design/multicore/201500267 116. http://weblogs.asp.net/ralfw/archive/2007/07/03/software-transactional-memo… 117. http://fawcett.blogspot.com/2007/08/roman-numerals-in-haskell.html 118. http://koweycode.blogspot.com/2007/08/history-of-monad-tutorials.html 119. http://www.sdtimes.com/article/latestnews-20070815-04.html 120. http://patricklogan.blogspot.com/2007/08/dunno.html * [121]A thesis about language niches * [122]Thoughts on Scheme from a Haskeller * [123]Arrow Transformers for sample rate conversion * [124]Playing with Propositional Logic in Haskell * [125]Programmer productivity, feature set implementation, and runtime performance * [126]Anatomy of a new monad * [127]Welcome to Haskell for Maths Blog * [128]Monadic Parser Combinators using C# 3.0 * [129]Blog Rewrite - I'm giving up * [130]Implementing The Kelly Criterion * [131]Universal Floating Point Errors * [132]Polyglot Programming - is it all Greek to you? * [133]Factor with a dash of curry * [134]How to learn to program * [135]I dated Haskell Curry's daughter * [136]Importance and Prominence and the wave: FP * [137]A Beautiful Regex Matcher... In Haskell * [138]San Francisco Bay Area FP Group * [139]AngloHaskell: The Aftermath * [140]Leibniz Equality, Decomposition, and Definability 121. http://utcc.utoronto.ca/~cks/space/blog/programming/LanguageNiches 122. http://overwatering.blogspot.com/2007/08/thoughts-on-scheme.html 123. http://www.blurty.com/users/claudiusmaximus/day/2007/08/18 124. http://www.present-tense.org/2007/08/18/playing-with-propositional-logic/ 125. http://pinderkent.blogsavy.com/archives/107 126. http://paulspontifications.blogspot.com/2007/08/anatomy-of-new-monad.html 127. http://polyomino.blogspot.com/2007/08/welcome.html 128. http://blogs.msdn.com/lukeh/archive/2007/08/19/monadic-parser-combinators-u… 129. http://lukeplant.me.uk/blog.php?id=1107301674 130. http://r6.ca/blog/20070820T175938Z.html 131. http://notes-on-haskell.blogspot.com/2007/08/universal-floating-point-error… 132. http://grahamis.com/blog/2007/08/21/polyglot-programming-is-it-all-greek-to… 133. http://useless-factor.blogspot.com/2007/08/factors-curry.html 134. http://madhadron.auditblogs.com/2007/08/21/how-to-learn-to-program/ 135. http://importantshock.wordpress.com/2007/08/21/haskell-curry-yes-i-dated-hi… 136. http://balasubramanians.com/blog/?p=312 137. http://www.oreillynet.com/onlamp/blog/2007/08/a_beautiful_regex_matcher_in_… 138. http://kfahlgren.com/blog/2007/08/21/san-francisco-bay-area-fp-group/ 139. http://neilmitchell.blogspot.com/2007/08/anlgohaskell-aftermath.html 140. http://blog.jbapple.com/2007/08/leibniz-equality-decomposition-and.html * [141]Word ladder in Haskell * [142]Existential Data Constructors in Haskell and Qi * [143]Sun slots transactional memory into Rock * [144]Haskell for pluggable apps, with the GHC API * [145]Yoda Speaks Haskell: A Tutorial * [146]Haskell Syntax Gem * [147]ClusterBy: a handy little function for the toolbox * [148]Squarefree numbers in Haskell * [149]Overloading functional references * [150]Haskell PDF 1.0 * [151]More fun with randoms * [152]Learn Haskell in 5 minutes a day: lesson 1 * [153]Destructive Quicksort in Haskell * [154]Tries and their derivatives * [155]Haskell HMAC * [156]Solving the word numbers problem: part 2 * [157]Solving the word numbers problem: part 3 * [158]Functional Forth * [159]F#'s monadic syntax * [160]The Actors Model and Haskell 141. http://gbacon.blogspot.com/2007/08/word-ladder-in-haskell.html 142. http://programmingkungfuqi.blogspot.com/2007/08/existential-data-constructo… 143. http://www.theregister.com/2007/08/21/sun_transactional_memory_rock/ 144. http://austin.youareinferior.net/?q=node/29 145. http://www.kirit.com/Yoda%20speaks%20Visual%20Haskell 146. http://www.joachim-breitner.de/blog/archives/262-Haskell-Syntax-Gem.html 147. http://blog.moertel.com/articles/2007/09/01/clusterby-a-handy-little-functi… 148. http://byorgey.wordpress.com/2007/09/01/squarefree-numbers-in-haskell/ 149. http://twan.home.fmf.nl/blog/haskell/overloading-functional-references.deta… 150. http://www.alpheccar.org/en/posts/show/80 151. http://osfameron.vox.com/library/post/more-random-fun.html 152. http://learnhaskell.blogspot.com/2007/09/lesson-1-hello-world.html 153. http://jputnam.livejournal.com/42065.html 154. http://sigfpe.blogspot.com/2007/09/tries-and-their-derivatives_08.html 155. http://scsibug.com/2007/09/16/haskell-hmac/ 156. http://conway.rutgers.edu/~ccshan/wiki/blog/posts/WordNumbers2/ 157. http://conway.rutgers.edu/~ccshan/wiki/blog/posts/WordNumbers3/ 158. http://wiki.forthfreak.net/index.cgi?FunForth 159. http://blogs.msdn.com/dsyme/archive/2007/09/22/some-details-on-f-computatio… 160. http://lstephen.wordpress.com/2007/09/08/the-actors-model-and-haskell/ * [161]Haskell and the South African Computing Olympiad * [162]The Power of Folds * [163]Folding Incremental Averages in Haskell * [164]OpenGL tetris in Haskell * [165]Learn Haskell in 5 minutes a day: Lesson 1: Hello, World! * [166]Learn Haskell in 5 minutes a day: Lesson 2: Input and Output, Variable Binding, and more * [167]Learn Haskell in 5 minutes a day: Lesson 3: case * [168]Break a string into groups of characters * [169]A news aggregator * [170]Haskell elevator pitch * [171]Do Notation and Sequence Operator * [172]Part 1: How sequential languages obscure parallelism * [173]Part 2: How to achieve parallel execution * [174]Part 3: Explicit parallel programming with threads and locks * [175]Part 4: Explicit parallelism: message-passing programming * [176]Part 5: Implicit parallel programming: Declarative languages * [177]Part 6: So, why aren't we using functional languages yet? * [178]More articles about multicores and multiprocessors 161. http://squing.blogspot.com/2007/09/haskelling-saco-1.html 162. http://www.sftank.net/?q=node/11 163. http://kraeutler.net/vincent/essays/Folding%20Incremental%20Averages%20in%2… 164. http://myawesomeblag.blogspot.com/2007/03/opengl-tetris-in-haskell.html 165. http://learnhaskell.blogspot.com/2007/09/lesson-1-hello-world.html 166. http://learnhaskell.blogspot.com/2007/09/lesson-2-input-and-output-variable… 167. http://learnhaskell.blogspot.com/2007/09/lesson-3-case-3.html 168. http://www.perlmonks.org/?node_id=632023 169. http://www.b7j0c.org/content/haskell-newspage.html 170. http://nickmudge.info/?post=51 171. http://nickmudge.info/?post=56 172. http://www.embedded.com/design/multicore/201500267 173. http://www.embedded.com/showArticle.jhtml?articleID=201801070 174. http://www.embedded.com/showArticle.jhtml?articleID=201802337 175. http://www.embedded.com/design/multicore/201803783?_requestid=708481 176. http://www.embedded.com/design/multicore/201804960?_requestid=708724 177. http://www.embedded.com/design/multicore/201806715 178. http://www.embedded.com/design/multicore/173400008 Quotes of the Week * nomeata: Haskell is basically Swiss: Small, Efficient, and it is fun to explore the higher parts. * Tom Moertel: In the not-too-distant future, perhaps, we might look back in amazement at the days when important security properties were neither free nor guaranteed but expensive and uncertain, underwritten only by the heroic efforts of individual programmers, struggling against impossible odds to achieve inhuman perfection. * Adam Turoff: In any case, Simon Peyton Jones is right -- the way forward involves functional programming, whether it means choosing a language like Haskell, or integrating ideas from Haskell into your language of choice. * bootslack: Once, around the time of the discovery of fire, there was a large population of people that thought mastering fire would be too difficult so they didn't. The rest of us killed them, cooked them and ate them. Code Watch Notable new features and bug fixes to the Haskell compilers. Thu Sep 6 09:19:48 PDT 2007. Norman Ramsey . [179]massive changes to add a 'zipper' representation of C-- 179. http://article.gmane.org/gmane.comp.lang.haskell.cvs.ghc/23114 Tue Aug 14 03:36:23 PDT 2007. Ben Lippmeier. Add graph coloring register allocator. Refactored linear allocator into separate liveness annotation and allocation stages. Added graph coloring allocator, use -fregs-graph to enable. New dump flags are -ddump-asm-native -- output of cmm -> native transform. -ddump-asm-liveness -- code annotated with register liveness info -ddump-asm-coalesce -- output of register move coalescing (this is a separate pass when using the coloring allocator) (this could change in the future) -ddump-asm-regalloc -- code after register allocation -ddump-asm-regalloc-stages -- blocks after each build/spill stage of coloring allocator -ddump-asm-conflicts -- a global register liveness graph in graphviz format The new register allocator will allocate some registers, but it's not quite ready for prime-time yet. The spill code generator needs some work. About the Haskell Weekly News New editions are posted to [180]the Haskell mailing list as well as to [181]the Haskell Sequence and [182]Planet Haskell. [183]RSS is also available, and headlines appear on [184]haskell.org. Headlines are available as [185]PDF. To help create new editions of this newsletter, please see the [186]contributing information. Send stories to dons at galois.com. The darcs repository is available at darcs get [187]http://www.cse.unsw.edu.au/~dons/code/hwn References 180. http://www.haskell.org/mailman/listinfo/haskell 181. http://sequence.complete.org/ 182. http://planet.haskell.org/ 183. http://sequence.complete.org/node/feed 184. http://haskell.org/ 185. http://www.cse.unsw.edu.au/~dons/code/hwn/archives/20070923.pdf 186. http://haskell.org/haskellwiki/HWN 187. http://www.cse.unsw.edu.au/~dons/code/hwn

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Re: [Haskell-cafe] what is f=f (not) doing ?
by Ronald Guida 24 Sep '07

24 Sep '07

Miguel Mitrofanov wrote: >> A deadlock happens whenever two (or more) threads are blocked on each >> other. Deadlocks can be extremely hard to detect, especially if they >> occur intermittently. > > Isn't that so much different from garbage collection? Replace > "thread" with "chunk of data", and "waits for" with "has a pointer > to" and these two problems look very similar. And we all know there > ARE efficient garbage collectors. Actually, I think the two problems look /extremely/ similar. When doing garbage collection, one BIG problem is determining what's really a pointer and what's just data. There are conservative garbage collectors that assume just about anything can be a pointer, and then there are precise garbage collectors that use knowledge of the layout of "chunks of data" to identify the pointers to follow. All garbage collectors have one thing in common, though. They all depend on being able to identify, for each chunk of data, what else it has pointers to. If all else fails, a conservative GC can simply assume that everything is potentially a pointer and try to follow it. Now, a deadlock detector would need to be able to identify, for each blocked thread, what that thread is waiting for. The OS already tracks this information and uses it to determine when a blocked thread becomes un-blocked and ready to run. Now, if we could make sure that /all/ locks go through the OS, then the OS would be able to build a complete dependency table. When a deadlock is about to occur, the OS would be able to detect it immediately. Back to reality: Not all locks go through the OS. Suppose I'm using fibers. That means I have one OS thread running many routines at the same time, and I'm doing my own cooperative multitasking. GHC does this. The OS has no idea what's going on. Even if I had an OS that could track all locks, I can still get into deadlock situations. Suppose I have a programming error that causes two of my threads to deadlock. Furthermore, suppose that when the deadlock is detected, I make both threads roll back and start again with the same pre- conditions. Now they will go back into the same deadlock. This cycle will repeat indefinitely, and it's beyond the OS's ability to detect. Regarding deadlock detection, I think the real questions to ask are (1) Do deadlocks occur often enough for us to care? (2) When they do occur, are they severe enough for us to care? If the answers are both "no", then deadlock detection is not worth the trouble of implementation. My opinion is that for typical commercial end-user software, the answers are both "no". For "critical" computing systems, like flight computers and life support systems, the answers are obviously "yes"; a deadlock that occurs once per million years is still a problem if it can bring down a multi-million dollar aircraft with hundreds of passengers on board. For these types of systems, the developers tend to spend extra development resources to try to design fool-proof systems. In some cases, they may even go to heroic lengths to /prove/ that their software is correct. It /is/ possible to design a system that cannot deadlock. It turns out that one of the necessary conditions for deadlock is the hold and wait condition. If a process that's already holding resources is /not/ allowed to request additional resources, then deadlocks are impossible. If we really, absolutely don't want any deadlocks, then we can design a system in which a process that needs a resource is required to release all its resources and then re-allocate its updated list of resources. -- Ron

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what is f=f (not) doing ?
by Pasqualino 'Titto' Assini 23 Sep '07

23 Sep '07

Hi, if I define: f = f and then try to evaluate 'f' in GHCi, as one would expect, the interpreter never returns an answer. The funny thing is that, while it is stuck in an infinite loop, GHCi doesn't seem to use any CPU time at all. How is this possible? Thanks titto

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