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Haskell Weekly News: Issue 142 - December 05, 2009
by jfredett＠gmail.com 05 Dec '09

05 Dec '09

--------------------------------------------------------------------------- Haskell Weekly News http://sequence.complete.org/hwn/20091205 Issue 142 - December 05, 2009 --------------------------------------------------------------------------- Welcome to issue 142 of HWN, a newsletter covering developments in the [1]Haskell community. Occasionally, I have something silly or clever to say here. Usually I give a summary of the weeks news and end it with a bit of a cliche tagline, however, this is finals week, and as such, there is absolutely no brain cells left working to come up with any cleverness for here. I'll see you next week with (hopefully) more ability for humor. Until next week, the Haskell Weekly News! Announcements error-message. Gregory Crosswhite [2]announced a package for handling errors in haskell. To quote his message directly, 'If there is one thing that we really don't have enough of in Haskell, it is *ways to handle errors*!' atom-0.1.3. Tom Hawkins [3]announced a new version of the Atom DSL for designing hard realtime embedded software. Blueprint 0.1 -- PREVIEW. Gregory Crosswhite [4]announced a preview version of his 'Blueprint' configuration package. haskell-mode 2.7.0. Svein Ove Aas [5]announced another release of Haskell-mode for Emacs graphviz-2999.7.0.0. Ivan Lazar Miljenovic [6]announced a new version of his set of bindings to the graphviz tools for visualizing graphs. Haskell Job Openings (Pune, IN). Tom Hawkins [7]announced some job openings in Eaton's engineering center in Pune, India. SaC Tutorial at PPoPP 2010. Clemens Grelck [8]announced a tutorial to be held at PPoPP on SAC and it's auto-parallelizing compiler SAC2C. Call for papers: PAPP 2010, 7th International Workshop on Practical Aspects of High-level Parallel Programming. Clemens Grelck [9]announced a call for papers for the Seventh International Workshop on Practical Aspects of High-level Parallel Programming. PhD Studentships in Nottingham. Graham Hutton [10]announced some PhD openings at the University of Nottingham. Second Call for Copy: Monad.Reader Issue 15. Brent Yorgey [11]announced a second call for copy for the Monad.Reader. 3 full professor positions at DIKU. Fritz Henglein [12]announced three open professor positions at the the Department of Computer Science at the University of Copenhagen ([13]DIKU). Hubris 0.0.2, the Ruby-Haskell bridge. Mark Wotton [14]announced a new version of the Hubris package is now available on hackage. Discussion You are in a twisty maze of concurrency libraries, all different ... Patrick Caldon [15]asked about the 'right' concurrency package to use for his project. Greetings! 2D Graphics? M Xyz [16]asked (enthusiatically) about different ways to do 2-dimensional graphics in Haskell. Wikipedia article. Simon Marlow [17]rallied us all into fixing the (or at least starting to fix) wikipedia page for Haskell. Great Programs to Read? Michael Lesniak [18]asked about what programs were worth reading. Blog noise [19]Haskell news from the [20]blogosphere. Blog posts from people new to the Haskell community are marked with >>>, be sure to welcome them! * Michael Snoyman: [21]String-like. * Claude Heiland-Allen: [22]Heist: dataflow algebra. * Adam Jones: [23]Lambda Calculus Compiler: Part III: First-Order Functions. * Holumbus: [24]Hayoo! Update âŠ Again. * Mikael Vejdemo Johansson (Syzygy-): [25][MATH198] Lecture 10 (last lecture) posted. * Neil Brown: [26]Automated Wiring of Message-Passing Processes. * Computer Systems Design Laboratory at the University of Kansas: [27]ChalkBoard Release. * Bryan O'Sullivan: [28]Dense? Dense, you say?. * Ivan Lazar Miljenovic: [29]Waddaya know, testing WORKS!. * Ivan Lazar Miljenovic: [30]If wishes were tests, code would be perfect. * Ivan Lazar Miljenovic: [31]The Problems with Graphviz. Quotes of the Week * Badger: one does not simply >>= into mordor * Apocalisp: data CanHaz a = Haz a | ButIEatedIt * Apocalisp: You can't have your baby and eat it too * Dave_Benjamin: please talk to your son or daughter about parametric polymorphism * Cale: Beginners are confusing to beginners. I move that we remove them from the language altogether. * monochrom: I am 17-ary, going on 18-ary, I can take curry of you * jmillikin: [the real world is] an implementation detail of IO, pay it no mind * monochrom,ezyang: The Principle Of Idiot Savant: any sufficiently misguided opinion is indistinguishable from deep insight * Cale: I swear that most of higher-dimensional category theory must have been arrived at by some guys sitting around in a room with a blackboard and saying "What if a drew a diagram like *THIS*!?" and drawing some insane scribble up on the blackboard, and then everyone tries to figure out how to turn it into meaningful mathematics. * jbe: Here I am, happy my code compiles, and the runtime is thumbing its nose at Turing. * Ferdirand: I was TA for a C++ programming course aimed at 1st year physics once. Some girl asked for help "i wrote pseudo-code but I cannot translate it to C++". Her pseudo-code was valid haskell. I cried. * mmorrow: [regarding excessive use of categorical recursion schemes] a morphasm? * copumpkin: I'm on a rollomorphism * dons: but rumours are remarkably common when it comes to haskell * monochrom: If you read a haskell book or an FP book, by chapter 5 it's already doing data structures. It's chapter 10 in imperative books. About the Haskell Weekly News New editions are posted to [32]the Haskell mailing list as well as to [33]the Haskell Sequence and [34]Planet Haskell. [35]RSS is also available, and headlines appear on [36]haskell.org. To help create new editions of this newsletter, please see the information on [37]how to contribute. Send stories to jfredett . at . gmail . dot . com. The darcs repository is available at darcs get [38]http://patch-tag.com/r/jfredett/HWN2/pullrepo HWN2 . References 1. http://haskell.org/ 2. http://article.gmane.org/gmane.comp.lang.haskell.cafe/67149 3. http://article.gmane.org/gmane.comp.lang.haskell.cafe/67090 4. http://article.gmane.org/gmane.comp.lang.haskell.cafe/66924 5. http://article.gmane.org/gmane.comp.lang.haskell.cafe/66923 6. http://article.gmane.org/gmane.comp.lang.haskell.cafe/66920 7. http://article.gmane.org/gmane.comp.lang.haskell.cafe/66904 8. http://article.gmane.org/gmane.comp.lang.haskell.general/17661 9. http://article.gmane.org/gmane.comp.lang.haskell.general/17660 10. http://article.gmane.org/gmane.comp.lang.haskell.general/17659 11. http://article.gmane.org/gmane.comp.lang.haskell.general/17657 12. http://article.gmane.org/gmane.comp.lang.haskell.general/17656 13. http://www.diku.dk/ 14. http://article.gmane.org/gmane.comp.lang.haskell.general/17653 15. http://thread.gmane.org/gmane.comp.lang.haskell.cafe/67211 16. http://thread.gmane.org/gmane.comp.lang.haskell.cafe/67184 17. http://thread.gmane.org/gmane.comp.lang.haskell.cafe/67158 18. http://thread.gmane.org/gmane.comp.lang.haskell.cafe/66917 19. http://planet.haskell.org/ 20. http://haskell.org/haskellwiki/Blog_articles 21. http://snoyberg.wordpress.com/2009/12/04/string-like/ 22. http://claudiusmaximus.goto10.org/cm/2009-12-04_heist_dataflow_algebra.html 23. http://blog.finiteimprobability.com/2009/12/03/lambda-calculus-compiler-par… 24. http://holumbus.fh-wedel.de/blog/?p=28 25. http://blog.mikael.johanssons.org/archive/2009/12/math198-lecture-10-last-l… 26. http://chplib.wordpress.com/2009/12/02/automated-wiring-of-message-passing-… 27. http://www.ittc.ku.edu/csdlblog/?p=25 28. http://www.serpentine.com/blog/2009/12/01/dense-dense-you-say/ 29. http://ivanmiljenovic.wordpress.com/2009/11/17/waddaya-know-testing-works/ 30. http://ivanmiljenovic.wordpress.com/2009/11/26/if-wishes-were-tests-code-wo… 31. http://ivanmiljenovic.wordpress.com/2009/11/30/the-problems-with-graphviz/ 32. http://www.haskell.org/mailman/listinfo/haskell 33. http://sequence.complete.org/ 34. http://planet.haskell.org/ 35. http://sequence.complete.org/node/feed 36. http://haskell.org/ 37. http://haskell.org/haskellwiki/HWN 38. http://patch-tag.com/r/jfredett/HWN2/pullrepo%20HWN2

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Fwd: [Haskell-cafe] Haskell for Physicists
by Don Stewart 05 Dec '09

05 Dec '09

Hey all, Following up on this, I'm presenting a position paper tomorrow on the use of EDSLs to improve productivity and lower cost when developing code for new high performance architectures (like GPUs). http://www.galois.com/blog/2009/10/13/domain-specific-languages-for-domain-… It advocates for Haskell + EDSLs, much as we have been discussing in this thread. -- Don

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inotify-alike for mac os x?
by Conal Elliott 05 Dec '09

05 Dec '09

I'd like to make some FRPish toys that keep files updated to have functional relationships with other files. hinotify looks like just the sort of underlying magic I could use for efficient implementation on linux. Is there any support for mac os x? Could support be either added to hinotify or maybe inotify and a mac-friendly library be abstracted into a common Haskell interface? I'm fine with an imperative interface, since I can abstract into a functional library, which I guess would be a sort of persistent simplified FRP. - Conal

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GHC magic optimization ?
by Emmanuel CHANTREAU 05 Dec '09

05 Dec '09

Hello One thing is magic for me: how GHC can know what function results to remember and what results can be forgotten ? Is it just a stupid buffer algorithm or is there some mathematics truths behind this ? I'm very happy about Haskell, it's so great to put some smart ideas in a computer. thanks -- Emmanuel Chantréau

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Re: Low Level Audio - Writing bytes to the sound card?
by John Lato 05 Dec '09

05 Dec '09

> From: M Xyz <functionallyharmonious(a)yahoo.com> > >> if you get it to work > > As a spoiled Java programmer, this new role as pioneer is a bit intimidating, but I will give it a shot. :) > > I downloaded the portaudio v19 source and I'm attempting to build it. Apparently I have to register my Visual Studio Express with Microsoft. Deeper down the rabbit hole... (Interesting aside, on the registration form under "What programming language topics are you interested in?" neither F# or Haskell are listed) For doing cross-platform development, I would strongly recommend that you use MinGW (or cygwin) in preference to Visual Studio Express. This is because most Unix/Linux packages, and thus most cross-platform packages, are designed to be built with the GNU compiler toolchain (i.e. configure, make, make install), and getting them to work with Visual Studio can be a chore. I also would use PortAudio for what you describe, and have had good experience with it on OSX. Sox is a good choice as well if you don't mind piping output to another program. *shameless plug* you could also use hCsound, although it's probably higher-level than what you're looking for. Installing on Windows is tricky too, but you only need to do so once. John

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Are there major inefficiencies in Haskell compared to OCaml?
by Casey Hawthorne 04 Dec '09

04 Dec '09

Are there major inefficiencies in Haskell compared to OCaml? If so, can something be done about them? -- Regards, Casey

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Greetings! 2D Graphics?
by M Xyz 04 Dec '09

04 Dec '09

Greetings, my name is M. This is my first time posting to a mailing list so forgive me if I've done something wrong. I just finished "Real World Haskell" and am currently working through "School of Expression". I am new to Haskell but I already love it. My question is this... I am interested in doing graphics work in Haskell, but I am lost trying to pick a library. I've been designing engineering apps in Java for 6 years and I'll admit I've been coddled by its standard library, lol. I am looking for something very lightweight with the basic capabilities of Java's Graphics2D class (antialias, composite, clipping, transformation, simple drawing primitives, gradients). I want something simple and "lightweight" because my interest is to play with building higher level abstractions myself. I use XP and Ubuntu so I'd prefer not to use the Graphics-Win32 library used by "School of Expression" if there is a platform independent library. I've read through http://www.haskell.org/haskellwiki/Applications_and_libraries/Graphics and the pertinent libraries seem to be Haven, HGL or Cairo via Gtk2Hs right? Which is the most popular/active and appropriate for a beginner to start working with? Thank you!

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seems like I'm on the wrong track
by Michael P Mossey 04 Dec '09

04 Dec '09

Perhaps someone could either (1) help me do what I'm trying to do, or (2) show me a better way. I have a problem that is very state-ful and I keep thinking of it as OO, which is driving me crazy. Haskell is several times harder to use than Python in this instance, probably because I'm doing it wrong. To give you a larger context, this problem is essentially compiling a description of music (my own) into a kind of music-machine-language (CSound). CSound is relatively untidy. In this one example, in a OO way of thinking, I have data called AssignedNumbers that assigns integers to unique strings and keeps track of the used integers and next available integer (the choice of available integer could follow a number of conventions so I wanted to hide that in an ADT.) So it has an associated function: getNumber :: String -> AssignedNumbers -> (Int,AssignedNumbers) What getNumber does is: - check if the string already has a number assigned to it. If so, return that number. - if not, pick the next available number. - in all cases, return the possibly changed state of AssignedNumbers Then in a larger data structure, it contains fields of type AssignedNumbers. Like data MusicStuff = MusicStuff { oscillatorNumbers :: AssignedNumbers , tableNumbers :: AssignedNumbers , ... } I'm using MusicStuff in a State monad, so I might write a function like doSomeMusicStuff :: String -> String -> State MusicStuff (Int,Int) doSomeMusicStuff aString1 aString2 = do ms <- get (o1,newOscNums) = getNumber aString1 (oscillatorNumbers ms) (t1,newTabNums) = getNumber aString2 (tableNumbers ms) put ms { oscillatorNumbers = newOscNums , tableNumbers = newTabNums } return (o1,t1) For what it does, this is extremely verbose and filled with distracting visual content. And this is just a very simple example---my real problem is several times more state-ful. Is there a better way? Note that in Python it would be a method def doMusicStuff( self, s1, s2 ) : return (self.oscillatorNumbers.next(s1), self.oscillatorNumbers.next(s2))

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Optimization with Strings ?
by John D. Earle 04 Dec '09

04 Dec '09

Dear Emmanuel Chantréau, You may want to look into Objective CAML http://caml.inria.fr/ which is a French product as you can see from the Internet address. It is likely better suited to the task than Haskell and has a reputation for speed. For those who prefer object oriented programming it has facilities for that which may ease your transition from C++. The Microsoft F# language is based on Objective CAML. Haskell has a problem with its type system and is not rigorous. Haskell is not a suitable language for proof assistants and so I would advise you to stay clear of Haskell. Standard ML was engineered with the needs of proof assistants in mind and so you may want to look into Standard ML, but you should be very happy with Objective CAML. It has an excellent reputation. The Coq proof assistant which is another French product is based on Objective CAML. If you do decide that Haskell is the way, it will help ease your transition to Haskell. There is nothing that says you can't keep your fingers in several pies at once.

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FFI and ghci
by Patrick LeBoutillier 04 Dec '09

04 Dec '09

Hi all, I have a small FFI-based library that I like to test like this: $ ghci -I../c -L../c/.libs -lmlp t.hs GHCi, version 6.10.1: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer ... linking ... done. Loading package base ... linking ... done. Loading object (dynamic) mlp ... done final link ... done [1 of 9] Compiling MLP ( MLP.hs, interpreted ) [2 of 9] Compiling MLP.Error ( MLP/Error.hs, interpreted ) [3 of 9] Compiling MLP.Context ( MLP/Context.hs, interpreted ) [4 of 9] Compiling MLP.Runtime ( MLP/Runtime.hs, interpreted ) [5 of 9] Compiling MLP.Object ( MLP/Object.hs, interpreted ) [6 of 9] Compiling MLP.Type ( MLP/Type.hs, interpreted ) [7 of 9] Compiling MLP.Value ( MLP/Value.hs, interpreted ) [8 of 9] Compiling MLP.Language ( MLP/Language.hs, interpreted ) [9 of 9] Compiling Main ( t.hs, interpreted ) Ok, modules loaded: MLP, MLP.Object, Main, MLP.Runtime, MLP.Context, MLP.Error, MLP.Value, MLP.Type, MLP.Language. *Main> main Note: Inside libmlp.so, another shared object is loaded using dlopen(). When running this test program I get some sporadic segmentation faults, which seem to always occur at entrypoint to the shared object that is loaded with dlopen(). But when I compile it with ghc, i.e. $ ghc --make -I../c -L../c/.libs -lmlp t.hs I can't reproduce crash. Can anyone see why this could be happening? It's quite possible that there is really a bug in the C code, but if someone knows about a bug or something in ghci that can cause this behaviour I can stop looking... Thanks a lot, Patrick -- ===================== Patrick LeBoutillier Rosemère, Québec, Canada

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