- Haskell-Cafe - Haskell.org

Haskell-based iPhone development
by Conal Elliott 18 Jun '09

18 Jun '09

If you are working with Haskell and making iPhone apps, or if you intend to soon, please say so at http://haskell.org/haskellwiki/IPhone. By helping each other out, I hope we can work more productively and have more fun in the process. At this point, I'd like to find out what you'd like to share, what help you'd like from others, and generally what kind of apps you want to make. We'll see what evolves from there. - Conal

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Which windowing toolkit to use?
by Patai Gergely 18 Jun '09

18 Jun '09

Hi all, I intend to start coding the UI of the heap profiling toolkit I'm working on [1] soon. I'd be happy to get some advice on choosing the right windowing toolkit for this task. The main requirements are: - portability and native look & feel if possible - easy to distribute executables under Windows - relatively slow code rot - sane interface that doesn't need wild workarounds even if what I'm doing is not trivial or elementary - trouble-free source installation in case someone wants to contribute As I see, at the moment there's no serious alternative besides GTK and wx, so my question is which do you think is better suited to this task? I have absolutely no development experience with GTK, and while I used a bit of wx in the past (in C++), I'm not really familiar with it either, especially not the Haskell bindings. I noticed that installing the wx binding with user rights doesn't seem to work directly from hackage (doesn't pass --user to ghc-pkg?), but it looks like a problem that can be solved with some hand editing. I'm a bit more afraid of setting up a development environment under Windows; is there any major pain involved with either of these libraries if I use MinGW? And how about their interface? Is there any significant difference? I'd especially like to hear the opinion of someone who's reasonably familiar with both. Thanks, Gergely [1] http://code.google.com/p/hp2any/ -- http://www.fastmail.fm - Or how I learned to stop worrying and love email again

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Fwd: Boston Haskell June 23rd meeting: openings for Lightning Talks
by Ravi Nanavati 18 Jun '09

18 Jun '09

---------- Forwarded message ---------- From: Ravi Nanavati <ravi(a)bluespec.com> Date: Wed, Jun 17, 2009 at 3:55 PM Subject: June 23rd meeting: openings for Lightning Talks To: bostonhaskell(a)googlegroups.com Both speakers for the June 23rd meeting have let me know that they expect their presentations to be on the shorter side of the 30-45 minutes alloted, so that means we have some space in the schedule. We could just use that as additional free-form discussion and mingling time, but since I saw them be successful at ILC'2009 and at the Boston Lisp Meeting after that, I'd like to offer that space to anyone who wants to give a "Lightning Talk". I think we should use the same formula as the Lisp Meeting: strictly-timed 5-minute talks followed by 2-minutes for questions and answers from the audience. Lightning talks don't have to be Haskell-specific, as long as the topic is appropriate for the audience. If you're interested in giving a Lightning Talk at the June 23rd meeting, please contact me ( ravi(a)bluespec.com ) and let me know what you'd like to talk about. Thank you, - Ravi Nanavati

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measuring time differences between functions
by Nico Rolle 18 Jun '09

18 Jun '09

Hi everyone. I made parallel versions of my functions projection selection and sort and i wanted to test the difference in runtime. But he only printed 0.00 twice. Maybe hes just too fast? Or is it because of lazy evaluation? or is there a better way to mesure performance in execution time? regards main = do xs <- readCSV "dataconvert/lineitem.tbl" '|' start <- getCurrentTime let pnp = projection [5] xs let snp = selection (\x -> (x!!0) > (Int 17000)) pnp let sortnp = sort [0] [ASC] snp end <- getCurrentTime putStrLn $ show (end `diffUTCTime` start) start2 <- getCurrentTime let pp = pProjection [5] xs let sp = pSelection (\x -> (x!!0) > (Int 17000)) pp let sortp = pSort [0] [ASC] sp end2 <- getCurrentTime putStrLn $ show (end2 `diffUTCTime` start2) return snp

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Wiki user accounts
by Philippa Cowderoy 18 Jun '09

18 Jun '09

I'm hearing reports of people having difficulty obtaining accounts on the Haskell wiki, without which it is impossible to make edits. Currently, account creation is disabled as an anti-spam measure, and the idea is for people to mail the admin and request an account. If this is to work, accounts need to be granted reasonably quickly - so far, I'm aware of a case where after 4 days there has been no response. This is particularly problematic for Anglohaskell, as signups and the like are via the wiki page - as a temporary workaround, I'll (and anyone else willing to lend a hand who already has an account) have to make edits on others' behalf, which is a serious inconvenience for both myself and attendees, as well as something of a barrier to entry. What's going on, and how can we speed things up? -- Philippa Cowderoy <flippa(a)flippac.org>

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Start to Finish C2HS guide
by Yaakov Nemoy 18 Jun '09

18 Jun '09

Hey List, I was experimenting a bit with binding RPM in Haskell and i figured i would document the process a bit. The link below sums up from start to finish in tutorial fashion how to write bindings. http://loupgaroublond.blogspot.com/2009/06/haskell-bindings-to-c-from-start… Perhaps would it be possible to include some of this kind of information with C2HS documentation in the future? -Yaakov Nemoy

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ghc does not link after compiling
by Nico Rolle 18 Jun '09

18 Jun '09

hi I wanted to compile my little test programm so it can take advantage of a multicore system. But when i call the compiler with ghc -O2 --make Benchmark.hs -threaded it just produces a acouple of .hi and .o files but no executable. But in the documantation was written that i just need to call ghc like that and it will produce my desired executable. My version of ghc is 6.10.3 regards

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ANNOUNCE: clock 0.1 released
by Cetin Sert 17 Jun '09

17 Jun '09

clock <http://hackage.haskell.org/package/clock> is a library published under a BSD3 license that provides bindings to clock_gettime and clock_getres for monotonic, realtime, processtime and threadtime clocks from time.h <http://www.opengroup.org/onlinepubs/007908799/xsh/time.h.html>. It was implemented in response to a haskell-cafe discussion: http://www.mail-archive.com/haskell-cafe@haskell.org/msg51244.html Any suggestions for improvement, bug-fixes, joint-development offers are most welcome *^o^*!! Cetin Sert

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Android and Haskell
by Vasili I. Galchin 17 Jun '09

17 Jun '09

Hello, I was just reading a Linux Mag article on Android and scripting. The underlying OS is Linux? Python is one of the scripting languages. http://code.google.com/p/android-scripting/ ... Is Python one of the supported languages simply because it (I think) has JVM bindings? My bottom line question is what is preventing Haskell98 from running on "Android" if Python can? Regards, Vasili

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slow code
by brian 17 Jun '09

17 Jun '09

Haskell Gurus, I have tried to use profiling to tell me what's going on here, but it hasn't helped much, probably because I'm not interpreting the results correctly. Empirically I have determined that the show's are pretty slow, so an alternative to them would be helpful. I replaced the show's with "", and compiled with -O2 and not much improvement. I need to write _a lot_ of code in this style. A few words about how best to do this would be helpful. Laziness, infinite lists, uvector ?? Help... Thanks, Brian import Complex import System.IO genData :: Double -> Int -> (Double -> Complex Double) -> ([Double], [Complex Double]) genData tstop n f = let deltat = tstop / (fromIntegral n) t = [ fromIntegral(i) * deltat | i <- [0..n-1]] in (t, map f t) main = do let (t, y) = genData 100.0E-6 (2 ^ 15) (\x -> x :+ 0.0) h <- openFile "data.txt" WriteMode mapM_ (\(x, y) -> do hPutStr h (show t) hPutStr h " " hPutStrLn h (show (realPart y))) (zip t y) hClose h

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Re: [Haskell] ANN: haskell-src-exts 1.0.0 rc1 (aka 0.5.2)
by Niklas Broberg 17 Jun '09

17 Jun '09

Hi Sebastian, > This script may even simplify testing of large code bases: Thanks a lot, very useful! I'll add that to the darcs repository if you don't mind. :-) Cheers, /Niklas

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BostonHaskell: Next meeting - June 23rd at MIT CSAIL Reading Room (32-G882)
by Ravi Nanavati 17 Jun '09

17 Jun '09

I'm pleased to announce the second meeting of the Boston Area Haskell Users' Group. The meeting is scheduled for Tuesday, June 23rd from 6:30pm - 8:30pm (*). It will be held in the MIT CSAIL Reading Room (32-G882, i.e. a room on the 8th floor of the Gates Tower of the MIT's Stata Center at 32 Vassar St in Cambridge, MA). We have the following two talks scheduled (each intended to be 30-45 minutes each): "Automagic Font Conversion with Haskell Typeclasses" by Frank Berthold "Intermediate Language Representations via GADTs" by Nirav Dave As in the last meeting there will be a break between the talks for discussion and mingling. As we are an informal, unsponsored group, there are no current plans to provide refreshments during the break, but I encourage people to volunteer to provide them (please contact me at ravi(a)bluespec.com so I can keep track of what to expect). I'll make sure to appropriately thank any refreshment volunteers at the meeting. If you have any questions about the meeting please send them to the BostonHaskell mailing list: bostonhaskell(a)googlegroups.com or contact me directly. I look forward to seeing many Boston area Haskellers next Tuesday! - Ravi Nanavati (*) I interpreted the silence in response to my previous email proposing June 23rd as assent. If this was a bad time or date to pick, please send your scheduling comments to the BostonHaskell list (i.e. bostonhaskell(a)googlegroups.com) so we can do a better job of picking a date and time in the future.

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PEPM'10 - First Call for Papers
by Janis Voigtlaender 16 Jun '09

16 Jun '09

=============================================================== CALL FOR PAPERS ACM SIGPLAN 2010 Workshop on Partial Evaluation and Program Manipulation (PEPM'10) Madrid, January 18-19, 2010 (Affiliated with POPL'10) http://www.program-transformation.org/PEPM10 =============================================================== IMPORTANT DATES: * Paper submission: Tue, October 6, 2009, 23:59, Apia time * Author notification: Thu, October 29, 2009 * Camera-ready papers: Mon, November 9, 2009 To facilitate smooth organization of the review process, authors are asked to submit a short abstract by October 1, 2009. SUBMISSION CATEGORIES: * Regular research papers (max. 10 pages in ACM Proceedings style) * Tool demonstration papers (max. 4 pages plus max. 6 pages appendix) SCOPE: The PEPM Symposium/Workshop series aims to bring together researchers and practitioners working in the areas of program manipulation, partial evaluation, and program generation. PEPM focuses on techniques, theory, tools, and applications of analysis and manipulation of programs. The 2010 PEPM workshop will be based on a broad interpretation of semantics-based program manipulation and continue previous years' effort to expand the scope of PEPM significantly beyond the traditionally covered areas of partial evaluation and specialization and include practical applications of program transformations such as refactoring tools, and practical implementation techniques such as rule-based transformation systems. In addition, the scope of PEPM covers manipulation and transformations of program and system representations such as structural and semantic models that occur in the context of model-driven development. In order to reach out to practitioners, there is a separate category of tool demonstration papers. Topics of interest for PEPM'10 include, but are not limited to: * Program and model manipulation techniques such as transformations driven by rules, patterns, or analyses, partial evaluation, specialization, program inversion, program composition, slicing, symbolic execution, refactoring, aspect weaving, decompilation, and obfuscation. * Program analysis techniques that are used to drive program/model manipulation such as abstract interpretation, static analysis, binding-time analysis, dynamic analysis, constraint solving, type systems, automated testing and test case generation. * Analysis and transformation for programs/models with advanced features such as objects, generics, ownership types, aspects, reflection, XML type systems, component frameworks, and middleware. * Techniques that treat programs/models as data objects including meta-programming, generative programming, deep embedded domain-specific languages, program synthesis by sketching and inductive programming, staged computation, and model-driven program generation and transformation. * Application of the above techniques including experimental studies, engineering needed for scalability, and benchmarking. Examples of application domains include legacy program understanding and transformation, DSL implementations, visual languages and end-user programming, scientific computing, middleware frameworks and infrastructure needed for distributed and web-based applications, resource-limited computation, and security. We especially encourage papers that break new ground including descriptions of how program/model manipulation tools can be integrated into realistic software development processes, descriptions of robust tools capable of effectively handling realistic applications, and new areas of application such as rapidly evolving systems, distributed and web-based programming including middleware manipulation, model-driven development, and on-the-fly program adaptation driven by run-time or statistical analysis. PROCEEDINGS: There will be formal proceedings published by ACM Press. In addition to printed proceedings, accepted papers will be included in the ACM Digital Library. Selected papers may later on be invited for a journal special issue dedicated to PEPM'10. SUBMISSION GUIDELINES: Papers should be submitted electronically via the workshop web site. Regular research papers must not exceed 10 pages in ACM Proceedings style. Tool demonstration papers must not exceed 4 pages in ACM Proceedings style, and authors will be expected to present a live demonstration of the described tool at the workshop (tool papers should include an additional appendix of up to 6 additional pages giving the outline, screenshots, examples, etc. to indicate the content of the proposed live demo at the workshop). Authors using Latex to prepare their submissions should use the new improved SIGPLAN proceedings style (sigplanconf.cls). PROGRAM CO-CHAIRS: * John Gallagher (Roskilde University, Denmark, and IMDEA Software, Spain) * Janis Voigtländer (Technische Universität Dresden, Germany) PROGRAM COMMITTEE MEMBERS: * Wei-Ngan Chin (National University of Singapore, Singapore) * Michael Codish (Ben-Gurion University of the Negev, Israel) * Jim Cordy (Queen's University, Canada) * Nate Foster (University of Pennsylvania, USA) * Haifeng Guo (University of Nebraska at Omaha, USA) * Patricia Johann (University of Strathclyde, UK) * Oleg Kiselyov (FNMOC, USA) * Günter Kniesel (University of Bonn, Germany) * Viktor Kuncak (Ecole Polytechnique Fédérale de Lausanne, Switzerland) * Yanhong Annie Liu (State University of New York at Stony Brook, USA) * Andres Löh (Utrecht University, Netherlands) * Jan Midtgaard (Roskilde University, Denmark) * David Monniaux (National Center for Scientific Research (CNRS) and VERIMAG laboratory, France) * Akimasa Morihata (University of Tokyo, Japan) * Alberto Pettorossi (Università di Roma Tor Vergata, Italy) * João Saraiva (Universidade do Minho, Portugal) * Ganesh Sittampalam (Credit Suisse, UK) * Fausto Spoto (Università di Verona, Italy) * Harald Søndergaard (University of Melbourne, Australia) * Walid Taha (Rice University, USA)

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Logo fun
by Thomas Davie 16 Jun '09

16 Jun '09

We had a lot of "fun" deciding Haskell's new logo, and while I don't agree with the final result, it would be nice if we could now start consistently using it. With that in mind, I realised that the Haskell Platform's logo is totally different, and did a quick mock up of a version reflecting the current Haskell logo. It needs someone with the original vector graphics to have a play and improve it a little bit, but hopefully you'll se a concept you like. Here's the logo, continuing on the batteries included theme: http://www.cs.kent.ac.uk/people/rpg/tatd2/HaskellBatteries.png I'd appreciate comments, suggestions, and possibly either access to the vector version of our current logo, or someone producing a nice version of this. Bob

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Parametrized monads
by Miguel Mitrofanov 16 Jun '09

16 Jun '09

Hi! Suppose I want to create a specific monad as a combination of monad transformers - something like "StateT smth1 (ReaderT smth2 Identity)". As you can see, each transformer is parametrized with a type of kind *. I want to abstract these parameters, so that instead of "StateT smth..." I can write something like Zip (ConsT StateT (ConsT ReaderT NilT)) (ConsA smth1 (ConsA smth2 NilA)) Identity and it would be a type isomorphic to the first one. I mean, I want (ConsT StateT (ConsT ReaderT NilT))" to be a separate entity of fixed kind, so that I can, say, create a class instance for it or something. I'd be quite happy if list length appears as a separate parameter, like Zip (Succ (Succ Zero)) (ConsT ... I would NOT be happy with something like Zip (List_2 StateT ReaderT) (Arg_2 smth1 smth2) If haskell had polymorphic kinds, I'd be able to do it easily; unfortunately, it doesn't have them. Thanks

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Running Hoogle as a cgi script.
by Erik de Castro Lopo 16 Jun '09

16 Jun '09

Hi all, I'd like to run my own version of Hoogle: http://hackage.haskell.org/package/hoogle as a CGI script much like this: http://www.haskell.org/hoogle/ but there doesn't seem to be any documentation on how to do this. Clues anyone? Cheers, Erik -- ---------------------------------------------------------------------- Erik de Castro Lopo http://www.mega-nerd.com/

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Fwd: [Haskell-cafe] Logo
by Robert Greayer 16 Jun '09

16 Jun '09

Meant this to go to the list... ---------- Forwarded message ---------- From: Robert Greayer <robgreayer(a)gmail.com> To: Ashley Yakeley <ashley(a)semantic.org> For anyone concerned the Hackage icon (http://hackage.haskell.org/favicon.ico) is still the old blue lambda, not the sparkling new icon (http://haskell.org/favicon.ico) On Mon, Jun 15, 2009 at 2:39 AM, Ashley Yakeley<ashley(a)semantic.org> wrote: > Thomas Davie wrote: >> >> We had a lot of "fun" deciding Haskell's new logo, and while I don't agree >> with the final result, it would be nice if we could now start consistently >> using it. With that in mind, I realised that the Haskell Platform's logo is >> totally different, and did a quick mock up of a version reflecting the >> current Haskell logo. It needs someone with the original vector graphics to >> have a play and improve it a little bit, but hopefully you'll se a concept >> you like. > > I rather like the fact that the Haskell Platform logo is distinct from the > Haskell logo. I think it helps prevent confusion (even though the Platform > logo is based on one of the Haskell logo competition entrants). > > http://haskell.org/haskellwiki/Haskell_Platform > > By the way, when I came to replace the Haskell logo on the wiki site, since > the colours had not and still have not been officially decided on, I just > picked the same colours as the Haskell Platform logo. So for the time being, > there is a visual link between the two logos. > > -- > Ashley Yakeley > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe >

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force evaluation beginners question
by Nico Rolle 16 Jun '09

16 Jun '09

Hi there I'm trying to compile a code snipped that i've go from a tutorial which uses the function "force". But when I'm trying to compile it ghc reports an error that it couldn't find the defenition of force. my ghc verion is 6.10.3 Did they moved force out of Prelude in one of the latest updates? regards

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Re: [Haskell-cafe] Backpropagation implementation for a neural net library
by Alp Mestan 15 Jun '09

15 Jun '09

On Mon, Jun 15, 2009 at 5:00 PM, Trin Trin <trin.cz(a)gmail.com> wrote: > Hi Alp, > - even with correctly programmed back-propagation, it is usually hard to > make the net converge. > Yeah, I know, that's why we're training it until the quadratic error goes under 0.1. > - usually you initialize neuron weights with somewhat random values, when > working with back-propagation. > Yeah, that'll be done too, once the algorithm will be ready. I'll provide fancy and easy functions to create a neural net just giving the numbers of layers and their sizes. > - do some debug prints of the net error while training to see how it is > going > Good idea, yeah. > - xor function cannot be trained with a single layer neural net !!! > That's why there are 2 layers there, one hidden and the output one. I consider the "inputs" as ... inputs, not as a first layer of the NN. Thanls for your time. If you have any clues when reading the code, don't hesitate of course. -- Alp Mestan http://blog.mestan.fr/ http://alp.developpez.com/

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ANN: Haskell protocol-buffers version 1.5.0
by Chris Kuklewicz 15 Jun '09

15 Jun '09

Hello all, I have just uploaded version 1.5.0 of the Haskell version to hackage. The links for the three pieces are: http://hackage.haskell.org/package/protocol-buffers http://hackage.haskell.org/package/protocol-buffers-descriptor http://hackage.haskell.org/package/hprotoc This catches up to Google's version 2.1.0, as described below: * Support for "repeated" fields for primitive type (good arrays!). Note that using on an invalid field type will generate an error. * NO support yet for the *_FIELD_NUMBER style constants * It is now an error to define a default value for a repeated field. * Fields can now be marked deprecated (does nothing) * The type name resolver will no longer resolve type names to fields. Note that this applies to type of normal and extension fields. A lexer bug was founds and fixed by George van den Driessche, when a numeric literal in a proto file was followed immediately by a newline character. Cheers, Chris

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Backpropagation implementation for a neural net library
by Alp Mestan 15 Jun '09

15 Jun '09

Dear List, I'm working with a friend of mine on a Neural Net library in Haskell. There are 3 files : neuron.hs, layer.hs and net.hs. neuron.hs defines the Neuron data type and many utility functions, all of which have been tested and work well. layer.hs defines layer-level functions (computing the output of a whole layer of neurons, etc). Tested and working. net.hs defines net-level functions (computing the output of a whole neural net) and the famous -- but annoying -- back-propagation algorithm. You can find them there : http://mestan.fr/haskell/nn/html/ The problem is that here when I ask for final_net or test_output (anything after the train call, in net.hs), it seems to loop and loop around, as if it never gets the error under 0.1. So I was just wondering if there was one or more Neural Nets and Haskell wizard in there to check the back-propagation implementation, given in net.hs, that seems to be wrong. Thanks a lot ! -- Alp Mestan

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I need a hint in list processing
by Fernan Bolando 15 Jun '09

15 Jun '09

Hi all If I have a number of list example list1 = [2,3] list2 = [1,2] list3 = [2,3,4] list4 = [1,2,3] I want to create a list from the list above with n elements, non-repeating and each elements index represents 1 of the elements from the corresponding list so for the above input I would get. a = [3,2,4,1] ofcourse there may be several set that will satisfy the problem, so a list of list that satisfies would be good. How do I do this in haskell? or is there a code snippet that seems to work similarly? thanks fernan -- http://www.fernski.com

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graphical user interface library for editing graphs?
by Claude Heiland-Allen 15 Jun '09

15 Jun '09

Greetings, I have an idea for a project. The eventual aim is rather eccentric, but the specifications I have sketched out are roughly as follows (best viewed with fixed-width font due to diagrams): 0. the graphical user interface is entirely mouse driven, mouse position/clicks/releases are shown by [ ] 1. the world consists of empty space, nodes, and links between nodes 2. nodes may either be filled ("*") or hollow ("o"); call hollow nodes "targets", targets may be "highlighted" ("O") 3a. left-click on empty creates a filled node linked to a target: [ ] * => | o 3b. left-click on a target fills it and links it to a new target: : : [o] * => | o 4a. right-click on empty creates a filled node linked to two targets: [ ] * => / \ o o 4b. right-click on a target fills it and links it to two new targets: : : [o] * => / \ o o 5a. left-click-drag on a filled node with 1 descending link highlights all targets linked under it: : : [*] [*] : => : * * / \ / \ o o O O 5b. left-click-drag as in 5a, when released on a highlighted target, creates a "weak" link (not considered as descending for purposes of 5a) from the original node to that target. that target is filled, all other targets are unhighlighted: : : * * : => :\ * * \ / \ / \| O [O] o [*] 6a. right-click-drag from a filled node at the top of a connected component highlights all targets not in that connected component: [*] * [*] * : | => : | o O 6b. right-click-drag as in 6a, when released on a highlighted target, joins the graphs together, such that the original node fills that target, and all other targets are unhighlighted: * * * : | => | [O] [*] : 7. when a connected component has no targets, double-clicking anywhere on it will launchMissiles My question: can you suggest a library that would make implementing this specification relatively painless? OpenGL-based would be preferable, as I would like to scale the graph under construction automatically to fit the display, and launchMissiles will require something with fast rendering. Thanks, Claude -- http://claudiusmaximus.goto10.org

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Haskell - string to list isusses, and more
by Gjuro Chensen 15 Jun '09

15 Jun '09

Hello everyone! Im a Haskell newbie, and Ive have few unanswered questions. For someone more experienced (at least I think so) its a very simple task, but I just cant get a grip on it and its pretty frustrating. It wouldn't be that bad if I haven't browse thru bunch of pages and tutorials and still nothing... The problem is: take a string, and if every words starts with uppercase letter then print yes, else no. Forum Text Bold -> yes Frog image File -> no Ive had my share of approaches to this, but I just cant make it work. Standard one seemed the most simple: search :: String -> String search [] = [] and then use words (splits string on space) to split the string so I could get a list and go through it recursively. But how to apply words to entered string in this form? To find the first letter I came up with: first = take 1 (head x). And compare it with elem or ASCII values to determine if its upper case. Any help, advice or suggestion is appreciated. Thanks in advance! -- View this message in context: http://www.nabble.com/Haskell---string-to-list-isusses%2C-and-more-tp240226… Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.

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Utrecht Attribute Grammar and Emacs
by Mads Lindstrøm 15 Jun '09

15 Jun '09

Hi Has anybody implemented an Emacs mode for the Utrecht Attribute Grammar System (UUAG), and is willing to share it ? Greetings, Mads Lindstrøm

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Re: [Haskell-cafe] [cabal] How to deal with build-depency that not under cabal's control?
by Roman Cheplyaka 15 Jun '09

15 Jun '09

I'm CC:ing Duncan, probably he can help. * Magicloud Magiclouds <magicloud.magiclouds(a)gmail.com> [2009-06-15 10:01:03+0800] > # ghc-pkg list gtk > /var/lib/ghc-6.10.3/./package.conf: > /home/shidaw/.ghc/i386-linux-6.10.3/package.conf: > gtk-0.10.1 > Well, still, I have the problem.... > > On Sun, Jun 14, 2009 at 6:52 PM, Roman Cheplyaka<roma(a)ro-che.info> wrote: > > * Magicloud Magiclouds <magicloud.magiclouds(a)gmail.com> [2009-06-14 18:48:26+0800] > >> My gtk2hs is install manually, `configure && make && make install`. So > > > > It's okay. > > > >> when I add gtk to build-dependency, it tells me > >> Setup.hs: At least the following dependencies are missing: > >> gtk -any > > > > Installation of gtk2hs registers these packages for you. > > Again, check `ghc-pkg list gtk`. If you installed gtk2hs, it must be > > there. If you, say, upgraded your ghc after you installed gtk2hs, you > > have to reinstall gtk2hs. > > > >> How to register my manual-installed gtk2hs to cabal? > >> > >> On Sun, Jun 14, 2009 at 6:25 PM, Roman Cheplyaka<roma(a)ro-che.info> wrote: > >> > * Magicloud Magiclouds <magicloud.magiclouds(a)gmail.com> [2009-06-14 17:30:33+0800] > >> >> Hi, > >> >> I use gtk2hs in linux. Well, I have no idea how to install gtk2hs by > >> >> cabal, but my program needs it, and I want my program cabalized. So > >> >> how to do this? > >> >> Thanks. > >> > > >> > gtk2hs consists of several cabal packages, e.g. gtk, glib and so on. > >> > (See `ghc-pkg list`) > >> > Specify those of them you need as dependencies in cabal file. > >> > > >> > -- > >> > Roman I. Cheplyaka :: http://ro-che.info/ > >> > "Don't let school get in the way of your education." - Mark Twain > >> > _______________________________________________ > >> > Haskell-Cafe mailing list > >> > Haskell-Cafe(a)haskell.org > >> > http://www.haskell.org/mailman/listinfo/haskell-cafe > >> > > >> > >> > >> > >> -- > >> 竹密岂妨流水过 > >> 山高哪阻野云飞 > > > > -- > > Roman I. Cheplyaka :: http://ro-che.info/ > > "Don't let school get in the way of your education." - Mark Twain > > > > > > -- > 竹密岂妨流水过 > 山高哪阻野云飞 -- Roman I. Cheplyaka :: http://ro-che.info/ "Don't let school get in the way of your education." - Mark Twain

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Fwd: [Haskell-cafe] curious about sum
by Alberto G. Corona 15 Jun '09

15 Jun '09

Once more I forgot to send my messages to the haskell cafe list. All the rest of the list which I´m suscribed to, send the mail replies to the list automatically, but this doesn´t. Please, can this be changed?. ---------- Forwarded message ---------- From: Alberto G. Corona <agocorona(a)gmail.com> Date: 2009/6/13 Subject: Re: [Haskell-cafe] curious about sum To: Deniz Dogan <deniz.a.m.dogan(a)gmail.com> first, I was completely wrong. It is foldl what is neccesary. sum is defined in terms of foldl: sum= foldl (+) 0 but Prelude> foldl (+) 0 [1..1000000] *** Exception: stack overflow that is not because + is non strict, but because foldl is: foldl f z0 xs0 = lgo z0 xs0 where lgo z [] = z lgo z (x:xs) = lgo (f z x) xs this version of foldl IS strict: foldlStrict f z0 xs0 = lgo z0 xs0 where lgo z [] = z lgo z (x:xs) =let t= f z x in t `seq` lgo t xs main= print $ foldlStrict (+) 0 [1..1000000] 500000500000 so the garbage collector do the job in freeing the consumed part of the list. 2009/6/13 Alberto G. Corona <agocorona(a)gmail.com> > > Prelude> let strictplus x y= let z=x +y in z `seq` z; sum1= foldr strictplus 0 in sum1[0..1000000] > *** Exception: stack overflow > I suppose that strictplus is strict, so the garbage collector would free the consumed part of the list. > Then, why the stack overflow? > 2009/6/13 Deniz Dogan <deniz.a.m.dogan(a)gmail.com> >> >> 2009/6/13 Jochem Berndsen <jochem(a)functor.nl>: >> > Keith Sheppard wrote: >> >> Is there any reason that sum isn't strict? I can't think of any case >> >> where that is a good thing. >> >> >> >> Prelude> sum [0 .. 1000000] >> >> *** Exception: stack overflow >> > >> > It is useful if the (+) is nonstrict; although I cannot think of any >> > useful mathematical structure where (+) would be nonstrict. >> >> I remember needing a non-strict sum at least once, but I do not >> remember the exact application. But imagine having a (very) long list >> of numbers and you want to do A if the sum exceeds a small number, >> otherwise B. >> >> if sum [0..100000] > 10 then A else B >> >> However, this idea didn't work, because of strictness. >> >> -- >> Deniz Dogan >> _______________________________________________ >> Haskell-Cafe mailing list >> Haskell-Cafe(a)haskell.org >> http://www.haskell.org/mailman/listinfo/haskell-cafe >

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a now abandoned experimental extension to Haskell?
by Vasili I. Galchin 15 Jun '09

15 Jun '09

Hello, In some code that I am cabalizing I ran into: type DataLiteral = <<< ref RDFgraph defs >>> type URIReference = <<< ref RDFgraph defs >>> type NonNegativeInteger = <<< ??? >>> What is this? Kind regards, Vasili

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Re: [Haskell-cafe] I need a hint in list processing
by Tony Morris 15 Jun '09

15 Jun '09

Just guessing. How do you know it's an accident? Richard O'Keefe wrote: > > On 15 Jun 2009, at 4:26 pm, Tony Morris wrote: > >> Prelude Data.List> nub . concat $ [[2, 3], [1, 2], [2, 3, 4], [1, 2, 3]] >> [2,3,1,4] > > In this particular case. But that's a lucky accident.\ > > -- Tony Morris http://tmorris.net/

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Haskell EDSL to generate SQL?
by Günther Schmidt 15 Jun '09

15 Jun '09

Hi, I tried to solve some large data processing solely in Haskell so I could avoid lots of eventually very long and complex SQL statements. Unfortunately, as was to be expected, that approach doesn't scale. So I do need an SQL backend. But I hope to be able to use an DSL from which I can automatically generate SQL-Strings instead of writing the SQL statements literally. Has anyone else taken a similar approach? Günther

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How to know the build dependencies?
by Magicloud Magiclouds 15 Jun '09

15 Jun '09

Hi, I am learning to use cabal for my code. Just when I start, I met a question, is there an easy way to find out what packages my code depends? Thanks.

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Re: [Haskell-cafe] [cabal] How to deal with build-depency that not under cabal's control?
by Roman Cheplyaka 14 Jun '09

14 Jun '09

* Magicloud Magiclouds <magicloud.magiclouds(a)gmail.com> [2009-06-14 18:48:26+0800] > My gtk2hs is install manually, `configure && make && make install`. So It's okay. > when I add gtk to build-dependency, it tells me > Setup.hs: At least the following dependencies are missing: > gtk -any Installation of gtk2hs registers these packages for you. Again, check `ghc-pkg list gtk`. If you installed gtk2hs, it must be there. If you, say, upgraded your ghc after you installed gtk2hs, you have to reinstall gtk2hs. > How to register my manual-installed gtk2hs to cabal? > > On Sun, Jun 14, 2009 at 6:25 PM, Roman Cheplyaka<roma(a)ro-che.info> wrote: > > * Magicloud Magiclouds <magicloud.magiclouds(a)gmail.com> [2009-06-14 17:30:33+0800] > >> Hi, > >> I use gtk2hs in linux. Well, I have no idea how to install gtk2hs by > >> cabal, but my program needs it, and I want my program cabalized. So > >> how to do this? > >> Thanks. > > > > gtk2hs consists of several cabal packages, e.g. gtk, glib and so on. > > (See `ghc-pkg list`) > > Specify those of them you need as dependencies in cabal file. > > > > -- > > Roman I. Cheplyaka :: http://ro-che.info/ > > "Don't let school get in the way of your education." - Mark Twain > > _______________________________________________ > > Haskell-Cafe mailing list > > Haskell-Cafe(a)haskell.org > > http://www.haskell.org/mailman/listinfo/haskell-cafe > > > > > > -- > 竹密岂妨流水过 > 山高哪阻野云飞 -- Roman I. Cheplyaka :: http://ro-che.info/ "Don't let school get in the way of your education." - Mark Twain

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[cabal] How to deal with build-depency that not under cabal's control?
by Magicloud Magiclouds 14 Jun '09

14 Jun '09

Hi, I use gtk2hs in linux. Well, I have no idea how to install gtk2hs by cabal, but my program needs it, and I want my program cabalized. So how to do this? Thanks. -- 竹密岂妨流水过山高哪阻野云飞

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install problems ...
by Vasili I. Galchin 14 Jun '09

14 Jun '09

Hello, As I have said before I a, "cabalizing" Swish (a semantic web toolkit). I have it built and have run most of the original author's tests by and they pass. There are numerous warnings which seem to be either lack of a function type signature or "unreferenced" symbols ... I will go through one-by-one and clean these up. However, now I am getting the following install-time errors .... any advice on how to track down will be greatly apprecriated .... the following is the result of "cabal build -v": Preprocessing executables for swish-0.2.1... Building swish-0.2.1... /usr/bin/ar: creating dist/build/libHSswish-0.2.1.a Warning: output was redirected with -o, but no output will be generated because there is no Main module. Installing: /home/vigalchin/.cabal/lib/swish-0.2.1/ghc-6.8.2 Installing: /home/vigalchin/.cabal/bin cabal: Error: some packages failed to install: swish-0.2.1 failed during the final install step. The exception was: dist/build/N3Parser/N3Parser: copyFile: does not exist (No such file or directory) vigalchin@ubuntu:~/FTP/Haskell/Swish-0.2.1$ Regards, Vasili

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HSH and IO ()
by Dimitry Golubovsky 14 Jun '09

14 Jun '09

John & all, I use HSH in my project where several external programs and Haskell functions need to be piped together: HSH is of great help here. I however came across the situation when one of pipe-connected functions has signature IO (), yet it reads from stdin* and writes to stdout. The documentation mentions "instance ShellCommand (Handle -> Handle -> IO ())" which could be of some help, but in the latest version of HSH on Hackage this instance is commented out. What was the reason of doing that? Is this to be expected in the upcoming versions? Thank you. ---------------------------- * I modelled that by calling getContents, but the actual program will call a foreign library that contains a C function that reads from stdin (that is, FILE *), and that cannot be changed easily. -- Dimitry Golubovsky Anywhere on the Web

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ANN: hledger 0.6 released
by Simon Michael 14 Jun '09

14 Jun '09

I'm pleased to announce the release of hledger 0.6. For docs, online demo etc., see http://hledger.org . Some pre-built binaries are now available at http://hledger.org/ binaries . Or, install with: cabal install hledger [-fhapps] [-fvty]. (Using the latest Haskell Platform, "cabal install hledger -fhapps" works on gnu/ linux, mac and windows. Hurrah!) I'd like to hear feedback, especially if you hit trouble getting started. Happy tracking! - Simon (sm) 2009/06/13 hledger 0.6 ...................... * now cabal-installable on unix, mac, and windows, with Haskell Platform * provide experimental platform binaries * parsing: fix a silly failure to open ledger file paths containing ~ * parsing: show better errors for unbalanced transaction and missing default year * parsing: allow parentheses and brackets inside account names, as ledger does * parsing: fail on empty account name components, don't just ignore * add: description passed as arguments now affects first transaction only * add: better handling of virtual postings and default amounts * print, register: show virtual accounts bracketed/parenthesised * web: improved web ui supporting full patterns & period expressions * new "stats" command reports some ledger statistics * many dev/doc/deployment infrastructure improvements * move website into darcs repo, update home page * move issue tracker to google code Release stats: * Contributors: Simon Michael * Days since last release: 21 * Commits: 94 * Lines of non-test code: 2865 * Tests: 82 * Test coverage: 53% expressions * Known errors: 3 (inconsistent eliding, vty-related failures) * Performance: similar (http://hledger.org/profs/200906131120.bench)

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Haskell Weekly News: Issue 121 - June 13, 2009
by Brent Yorgey 14 Jun '09

14 Jun '09

--------------------------------------------------------------------------- Haskell Weekly News http://sequence.complete.org/hwn/20090613 Issue 121 - June 13, 2009 --------------------------------------------------------------------------- Welcome to issue 121 of HWN, a newsletter covering developments in the [1]Haskell community. Announcements purely functional lazy non-deterministic programming. Sebastian Fischer [2]announced the [3]explicit-sharing library, which supports lazy functional-logic programming in Haskell. nntp 0.0.1. Maciej Piechotka [4]announced the release of [5]nntp, a library to connect to nntp (i.e. mainly USENET) servers. OpenGLRaw 1.0.0.0. Sven Panne [6]announced the release of [7]OpenGLRaw, a low-level binding for OpenGL. The eventual goal is to make the OpenGL package easier to install, more modular and a bit more flexible. pgm-0.1 on Hackage. Frederick Ross [8]announced [9]pgm, a pure Haskell library to read and write PGM images. It seamlessly handles the divide between 1 and 2 byte per pixel images; reads and writes UArrays; can handle multiple PGMs concatenated one after another in a file; and encodes and decodes all comments in the PGM header, which can be used to drop arbitrary metadata into files in a human readable manner. iteratee-0.2.1 released. John Lato [10]announced the release of [11]iteratee-0.2.1, a major update to the iteratee library. This library provides types and functions for performing enumerator/iteratee based I/O operations in Haskell, as [12]described by Oleg. The new version is a large redesign, including support for resumable exceptions and a greatly simplified interface. testrunner-0.9. Reinier Lamers [13]announced [14]testrunner, a new framework for running unit test. It can run unit tests in parallel; can run QuickCheck and HUnit tests as well as simple boolean expressions; and comes with a ready-made main function for your unit test executable. serial-0.2. Frederick Ross [15]announced version 0.2 of [16]serial, a library for working with line-oriented POSIX serial ports. hunp-0.0. Deniz Dogan [17]announced [18]hunp, a command-line utility which automagically calls the right "unpacker" program for you and works on both files and directories. Nemesis : easy task management. Jinjing Wang [19]announced a new release of [20]nemesis, a simple rake-like task management tool. Data.Reify.CSE. Sebastiaan Visser [21]announced the [22]data-reify-cse module, which implements common sub-expression elimination for graphs generated by the Data.Reify package. This package might especially be useful for optimizing simple compilers for referentially transparent domain specific languages. Hac phi accommodation: register by June 15 for reduced rate! Brent Yorgey [23]reminded anyone interested in attending [24]Hac phi that Monday 15 June is the deadline for getting a special reduced hotel rate. alloy-1.0.0 (generic programming). Neil Brown [25]announced the [26]first release of the [27]Allow generic programming library. It is intended to be a fairly fast blend of several other generics approaches, such as SYB (but without the dynamic typing) and Uniplate (but allowing an arbitrary number of target types), for performing transformations on specific types in large tree structures. StrictBench 0.1 - Benchmarking code through strict evaluation. R.A. Niemeijer [28]announced the release of [29]StrictBench, a library for timing full evaluation of values. haskeem 0.7.0 uploaded to hackage. Uwe Hollerbach [30]announced [31]haskeem, a small scheme interpreter written in Haskell. numtype 1.0 -- Type-level (low cardinality) integers. Bjorn Buckwalter [32]announced the [33]Numeric.NumType module, now released as its own package, which implements a unary type-level representation of integers, supporting addition, subtraction, multiplication, and division. Google Summer of Code Progress updates from participants in the 2008 [34]Google Summer of Code. space profiling. Gergely Patai has some [35]pretty graphs generated by his profiling library. haskell-src-exts. Niklas Broberg is [36]quite close to releasing haskell-src-exts 1.0.0, as soon as he has full and correct support for (almost) everything code-related, with only a few things left to do. He also wrote [37]a post explaining the intricacies of parsing code containing the 'forall' keyword (well, whether it is a keyword depends on which extensions are enabled...) fast darcs. Petr Rockai made a bit less progress this week, with finals and other things interfering, but [38]made some progress on some documentation, tracking down a performance regression, and other things. Discussion Adding an ignore function to Control.Monad. Gwern Branwen [39]proposed adding an 'ignore' function to Control.Monad which explicitly changes an m a into a m (). Bikeshedding (and some useful discussion) ensued. Wiki user accounts. Philippa Cowderoy began a [40]discussion of what to do about the current situation with wiki user accounts (namely, that account creation is disabled due to spam, and the one maintainer of the wiki can't always respond to account creation requests instantly). Lightweight type-level dependent programming in Haskell. Ryan Ingram made an interesting [41]post about implementing lightweight closed type classes in Haskell. who's up for a hackathon? (ICFP, late Aug, early Sept). Eric Kow [42]wanted to know who would be interested in having a hackathon immediately before or after ICFP in Edinburgh. Jobs Galois is hiring functional programmers. Don Stewart [43]announced that [44]Galois is hiring! See the announcement for more details. Blog noise [45]Haskell news from the [46]blogosphere. Blog posts from people new to the Haskell community are marked with >>>, be sure to welcome them! * Niklas Broberg: [47]GSoC status report, week 3. * Joachim Breitner: [48]Introducing L-seed. * Conal Elliott: [49]Memoizing polymorphic functions - part two. * London Haskell Users Group: [50]Next Meeting: Sean Leather, Fun and generic things to do with EMGM. * David Amos: [51]It's on Hackage!. Haskell for Maths is now just a cabal-install away. * Michael Snoyman: [52]Filename encoding issues. * David Amos: [53]Permutation groups. * Edward Kmett: [54]Recursion Schemes: A Field Guide (Redux). * mightybyte: [55]Intro to HAppS-State. * Conal Elliott: [56]Memoizing polymorphic functions - part one. * Lennart Augustsson: [57]More LLVM. * Roman Cheplyaka: [58]Don't play with your monads. * Galois, Inc: [59]Tech Talk: Orc in Haskell. * Petr Rockai: [60]soc progress 3. Progress on Petr's GSoC darcs project. * Magnus Therning: [61]Using msmtp with darcs. * Erik de Castro Lopo: [62]Debian Maintainer. Erik is now a Debian maintainer, and plans to give Haskell on Debian a much-needed facelift! * Niklas Broberg: [63]What's in a forall?. More Haskell parsing fun. * Well-Typed.Com: [64]GHC, primops and exorcising GMP. * Niklas Broberg: [65]What's in a forall?. More than you might expect! * >>> Zsol: [66]Visualizing the graphrewrite process behind Haskell. Work on the [67]visual-graphrewrite package. * Eric Kow (kowey): [68]testrunner for practical quickcheck. * Sebastian Fischer: [69]Explicit sharing of monadic effects. Purely functional, lazy, non-deterministic programming! * LHC Team: [70]New backend. * >>> James McNeill: [71]Messing with Haskell. * Dan Piponi (sigfpe): [72]Hashing Molecules. * Shin-Cheng Mu: [73]Longest Segment Satisfying Suffix and Overlap-Closed Predicates. * David Amos: [74]Simple graphs with Math.Combinatorics.Graph. David shows off his Haskell for Maths library. * Gergely Patai: [75]More colourful graphs. Graphs from Gergely's GSoC project on profiling. * Bryan O'Sullivan: [76]Case conversion and text 0.3. The text module gets solid, standards-compliant case conversion. * Bjorn Buckwalter: [77]numtype 1.0: Type-level (low cardinality) integers. * >>> Jörn Dinkla: [78]Parallelization with Haskell - Easy as can be. Quotes of the Week * sjanssen: in our sub-culture, "considered harmful" means "burn it with fire" * quicksilver: after all, anyone who insists on talking about himself in the third person is clearly someone to be reckoned with. About the Haskell Weekly News New editions are posted to [79]the Haskell mailing list as well as to [80]the Haskell Sequence and [81]Planet Haskell. [82]RSS is also available, and headlines appear on [83]haskell.org. To help create new editions of this newsletter, please see the information on [84]how to contribute. Send stories to byorgey at cis dot upenn dot edu. The darcs repository is available at darcs get [85]http://code.haskell.org/~byorgey/code/hwn/ . References 1. http://haskell.org/ 2. http://article.gmane.org/gmane.comp.lang.haskell.libraries/11265 3. http://sebfisch.github.com/explicit-sharing 4. http://article.gmane.org/gmane.comp.lang.haskell.general/17271 5. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/nntp 6. http://www.haskell.org//pipermail/haskell/2009-June/021402.html 7. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/OpenGLRaw 8. http://article.gmane.org/gmane.comp.lang.haskell.general/17263 9. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/pgm 10. http://article.gmane.org/gmane.comp.lang.haskell.general/17262 11. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/iteratee 12. http://okmij.org/ftp/Streams.html#iteratee 13. http://article.gmane.org/gmane.comp.lang.haskell.general/17258 14. http://projects.haskell.org/testrunner/ 15. http://article.gmane.org/gmane.comp.lang.haskell.general/17257 16. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/serial 17. http://article.gmane.org/gmane.comp.lang.haskell.cafe/59843 18. http://hackage.haskell.org/package/hunp 19. http://article.gmane.org/gmane.comp.lang.haskell.cafe/59824 20. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/nemesis 21. http://article.gmane.org/gmane.comp.lang.haskell.cafe/59807 22. http://hackage.haskell.org/package/data-reify-cse 23. http://article.gmane.org/gmane.comp.lang.haskell.cafe/59741 24. http://haskell.org/haskellwiki/Hac_%CF%86 25. http://article.gmane.org/gmane.comp.lang.haskell.cafe/59631 26. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/alloy 27. http://twistedsquare.com/Alloy-Tutorial.pdf 28. http://article.gmane.org/gmane.comp.lang.haskell.cafe/59605 29. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/StrictBench 30. http://article.gmane.org/gmane.comp.lang.haskell.cafe/59551 31. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/haskeem 32. http://article.gmane.org/gmane.comp.lang.haskell.cafe/59543 33. http://dimensional.googlecode.com/ 34. http://hackage.haskell.org/trac/summer-of-code/wiki/SoC2008 35. http://just-bottom.blogspot.com/2009/06/more-colourful-graphs.html 36. http://nibrofun.blogspot.com/2009/06/gsoc-status-report-week-3.html 37. http://nibrofun.blogspot.com/2009/06/whats-in-forall.html 38. http://web.mornfall.net/blog/soc_progress_3.html 39. http://thread.gmane.org/gmane.comp.lang.haskell.libraries/11278 40. http://thread.gmane.org/gmane.comp.lang.haskell.cafe/59814 41. http://thread.gmane.org/gmane.comp.lang.haskell.cafe/59749 42. http://thread.gmane.org/gmane.comp.lang.haskell.cafe/59737 43. http://article.gmane.org/gmane.comp.lang.haskell.general/17264 44. http://www.galois.com/ 45. http://planet.haskell.org/ 46. http://haskell.org/haskellwiki/Blog_articles 47. http://nibrofun.blogspot.com/2009/06/gsoc-status-report-week-3.html 48. https://www.joachim-breitner.de/blog/archives/330-Introducing-L-seed.html 49. http://conal.net/blog/posts/memoizing-polymorphic-functions-part-two/ 50. http://www.londonhug.net/2009/06/12/next-meeting-sean-leather-fun-and-gener… 51. http://haskellformaths.blogspot.com/2009/06/its-on-hackage.html 52. http://blog.snoyman.com/2009/06/11/filename-encoding-issues/ 53. http://haskellformaths.blogspot.com/2009/06/permutation-groups.html 54. http://comonad.com/reader/2009/recursion-schemes/ 55. http://softwaresimply.blogspot.com/2008/02/intro-to-happs-state.html 56. http://conal.net/blog/posts/memoizing-polymorphic-functions-part-one/ 57. http://augustss.blogspot.com/2009/06/more-llvm-recently-someone-asked-me-on… 58. http://ro-che.blogspot.com/2009/06/dont-play-with-your-monads.html 59. http://www.galois.com/blog/2009/06/09/tech-talk-orc/ 60. http://web.mornfall.net/blog/soc_progress_3.html 61. http://therning.org/magnus/archives/656 62. http://www.mega-nerd.com/erikd/Blog/CodeHacking/Debian/debian_maintainer.ht… 63. http://nibrofun.blogspot.com/2009/06/whats-in-forall.html 64. http://blog.well-typed.com/2009/06/ghc-primops-and-exorcising-gmp/ 65. http://nibrofun.blogspot.com/2009/06/whats-in-forall.html 66. http://lazybottom.blogspot.com/2009/06/visualizing-graphrewrite-process-beh… 67. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/visual-graphrewr… 68. http://koweycode.blogspot.com/2009/06/testrunner-for-practical-quickcheck.h… 69. http://www-ps.informatik.uni-kiel.de/~sebf/haskell/explicit-sharing.html 70. http://lhc-compiler.blogspot.com/2009/06/new-backend.html 71. http://playtechs.blogspot.com/2009/06/messing-with-haskell.html 72. http://blog.sigfpe.com/2009/06/hashing-molecules.html 73. http://www.iis.sinica.edu.tw/~scm/2009/longest-segment-satisfying-suffix-an… 74. http://haskellformaths.blogspot.com/2009/06/simple-graphs-with-mathcombinat… 75. http://just-bottom.blogspot.com/2009/06/more-colourful-graphs.html 76. http://www.serpentine.com/blog/2009/06/07/case-conversion-and-text-03/ 77. http://flygdynamikern.blogspot.com/2009/06/announce-numtype-10-type-level-l… 78. http://blog.dinkla.net/?p=15 79. http://www.haskell.org/mailman/listinfo/haskell 80. http://sequence.complete.org/ 81. http://planet.haskell.org/ 82. http://sequence.complete.org/node/feed 83. http://haskell.org/ 84. http://haskell.org/haskellwiki/HWN 85. http://code.haskell.org/~byorgey/code/hwn/

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ANNOUNCE: hunp-0.0
by Deniz Dogan 14 Jun '09

14 Jun '09

Inspired by the CLI utility "unp", which was nice but lacked some DWIM functionality, I developed hunp (or hünp, but pronounced hump because it's easier). It automagically calls the right "unpacker" program for you and works on both files and directories: $ hunp ~/download/something/ ...finds ~/download/something/hello.r00 and calls "unrar x ~/download/something/hello.r00". $ hunp ~/howdy.tar.gz ...calls "tar zxvf ~/howdy.tar.gz" Get it from http://hackage.haskell.org/package/hunp or from git://github.com/skorpan/hunp.git Enjoy! -- Deniz Dogan PS. I was unable to find the thread on how to properly announce things on the mailing lists, so I hope everyone is okay with this going only to Haskell café.

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Check out my photos on Facebook
by Rakesh Malik 14 Jun '09

14 Jun '09

Hi haskell-cafe(a)haskell.org, I set up a Facebook profile where I can post my pictures, videos and events and I want to add you as a friend so you can see it. First, you need to join Facebook! Once you join, you can also create your own profile. Thanks, Rakesh To sign up for Facebook, follow the link below: http://www.facebook.com/p.php?i=898160075&k=Z5E62YTRPW2CUGGAX144X3&r haskell-cafe(a)haskell.org was invited to join Facebook by Rakesh Malik. If you do not wish to receive this type of email from Facebook in the future, please click on the link below to unsubscribe. http://www.facebook.com/o.php?k=917e28&u=531922198&mid=9dcc69G1fb47d16G0G8 Facebook's offices are located at 1601 S. California Ave., Palo Alto, CA 94304.

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Haskell Meetup groups in Glasgow
by A Smith 13 Jun '09

13 Jun '09

Do any Haskell Meetup groups exist in or around Glasgow, an informal get-to-gether in a pub,cafe or wherever ? I'm in Edinburgh, and on my own have been desperately trying to rewire my brain from Perl to Haskell without much success for most of this year. I posted the meetup group question a few weeks ago for Edinburgh but got no response. -- Andrew

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Atom - help.
by Radamés Ajna 13 Jun '09

13 Jun '09

hi there, I've been working with haskell and atom dsl, however I'm new to haskell.. John Van Enk inspired me with programming arduino->atmegas , with haskell, So here is my problem. With an action , action :: ([String] -> String) -> [UE] -> Atom () , it's possible make calls to some precoded C functions like, setLED v = action (\[x] -> "setLED(" ++ x ++ ")") [v'] where v' = ue . value $ v where setLed is a precode function. I want call a precoded C function that returns some value, but action always give me Atom () , that's I would like to do but I don't know how .. Atom (V Int8) < ---- "int read()" thanks... related links http://hackage.haskell.org/package/atom-0.0.5 http://blog.sw17ch.com/wordpress/?p=111 http://leepike.wordpress.com/2009/05/05/an-atomic-fibonacci-server-explorin… Radamés

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[ANN] Nemesis : easy task management
by Jinjing Wang 13 Jun '09

13 Jun '09

You can have a description file named Nemesis, with content nemesis = do clean [ "**/*.hi" , "**/*.o" , "manifest" ] task "dist" $ do sh "cabal clean" sh "cabal configure" sh "cabal sdist" task "i" (sh "ghci -isrc src/System/Nemesis.hs") task "manifest" $ do sh "find . | grep 'hs$' > manifest" then after run `nemesis`, there will be a compiled bin `nem` in your local path, which allows you to do `nem clean` Install with `cabal install nemesis` Cheers, -- jinjing

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ghci and applicative
by Paul Keir 13 Jun '09

13 Jun '09

Hi, I'm finding that some data types which use Applicative to instantiate the Num class, give responses I wasn't expecting at the ghci prompt. A simple example is list: import Control.Applicative instance (Num a) => Num [a] where as + bs = (+) <$> as <*> bs (*) = undefined; abs = undefined signum = undefined; fromInteger = undefined f1 = let op = (+) in [1,2,3] `op` [1,1,1] f2 = let op = (+) in op [1,2,3] [1,1,1] Functions f1 and f2 give no problems at the ghci prompt. However if I instead type the body of either interactively, I get an error: *Main> let op = (+) *Main> [1,2,3] `op` [1,1,1] <interactive>:1:0: Couldn't match expected type `Integer' against inferred type `[a]' In the first argument of `op', namely `[1, 2, 3]' In the expression: [1, 2, 3] `op` [1, 1, 1] In the definition of `it': it = [1, 2, 3] `op` [1, 1, 1] I get the same error message with op [1,2,3] [1,1,1]. Any thoughts? Thanks, Paul

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Debugging misbehaving multi-threaded programs
by Evan Klitzke 12 Jun '09

12 Jun '09

I've written a multi-threaded Haskell program that I'm trying to debug. Basically what's happening is the program runs for a while, and then at some point one of the threads goes crazy and spins the CPU while allocating memory; this proceeds until the system runs out of available memory. I can't fix this without figuring out what code is being executed in the loop (or at least which thread is misbehaving, which would narrow things down a lot). I was hopeful that I could compile the program with profiling support and then use +RTS -M100M along with some of the RTS profiling options and get profiling information on CPU and memory usage at the time that my program runs out of memory. The thinking here is that nearly all of the CPU time and heap space will be from the misbehaving thread, so at that point I could do more investigation into exactly what is happening. Unfortunately, this doesn't seem to work; whenever the program terminates due to running out of heap space, the generated .prof file is empty. Another strategy I tried was running the program in ghci and use -fbreak-on-exception and :trace; by hitting Ctrl-C I was hopeful I'd stop the program in whatever is looping (this is all described and suggested in the ghc docs). Unfortunately, this also didn't seem to work, because the Ctrl-C only stops the main thread. Does anyone have any tips for dealing this? Have other people run into similar problems? I'm out of ideas, so I'm open to any suggestions. -- Evan Klitzke <evan(a)eklitzke.org> :wq

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Why do ghc-built binaries use timer_create?
by Maurício 12 Jun '09

12 Jun '09

This comes from an issue in haskell-beginner, although it have already been touched here. If you use recent versions of ghc to build a program and try the resulting binary on an old linux distro, you may get a message about timer_create receiving the wrong parameters. Curiously, as sugested in the other thread, it seems building with ghc -threaded solves the problem. So, I'm just curious: how is timer_create used, and why maybe it's not used with -threaded? Thanks, Maurício

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Software Transactional Memory and LWN
by Ketil Malde 12 Jun '09

12 Jun '09

Hi, Browsing LWN, I ran across this comment: http://lwn.net/Articles/336039/ The author makes a bunch of unsubstantiated claims about STM, namely that all implementations use locking under the hood, and that STM can live- and deadlock. I've seen a lot of similar sentiments in other places as well (comp.arch springs to mind). Now, I'm no expert on STM, but I was pretty sure these are incorrect, and I certainly had the impression that Haskell's STM guarantees some progress - which it couldn't in a deadlock situation. Am I wrong? -k -- If I haven't seen further, it is by standing in the footprints of giants

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[ANN] Data.Reify.CSE
by Sebastiaan Visser 12 Jun '09

12 Jun '09

Hi all, This module[1] implements common sub-expression elimination for graphs generated by the Data.Reify package. (Which is a really neat tool!) The algorithm performs a simple fixed point iteration and is not (consciously) optimized for speed. This package might especially be useful for optimizing simple compilers for referential transparent domain specific languages. Which is exactly the reason I've written this code. An example of the usage is included in the Haddock documentation. Gr, -- Sebastiaan Visser [1] http://hackage.haskell.org/package/data-reify-cse

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Documentation bug -- building ghc from darcs sources
by Michael Vanier 12 Jun '09

12 Jun '09

I've been trying to build ghc head from the darcs repo using these instructions: http://hackage.haskell.org/trac/ghc/wiki/Building/GettingTheSources Unfortunately, when I do ./darcs-all --extra get as described under "Getting more packages" it fails because the darcs-all script doesn't recognize the --extra option. Was this removed recently, and if so, how do I achieve the same effect? TIA, Mike

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exporting Data.ByteString functions via FFI
by kenny lu 12 Jun '09

12 Jun '09

Hi, I was trying to write a FFI wrapper for my Haskell program which manipulates ByteString. But I am unable to compile/link it. Here is the toy program. {-# LANGUAGE ForeignFunctionInterface #-} module B where import Foreign.C.Types import Foreign.C.String import qualified Data.ByteString as BS rev :: BS.ByteString -> BS.ByteString rev bstr = BS.reverse bstr rev_hs :: CString -> IO CString rev_hs cstr = do { bstr <- BS.packCString cstr ; let bstr' = rev bstr ; cstr' <- newCString (show bstr') ; return cstr' } foreign export ccall rev_hs :: CString -> IO CString And here is the C counter-part. #include "B_stub.h" #include <stdio.h> int main(int argc, char *argv[]) { char *str; hs_init(&argc, &argv); str = rev_hs("it works."); printf("Rev: %s\n", str); hs_exit(); return 0; } Compiling B.hs alone seems fine, but errors popped up when I was trying to compile/link it with C. $ ghc -c -O B.hs $ ghc -optc-O test_b.c B.o B_stub.o -o test_b Undefined symbols: "___stginit_bytestringzm0zi9zi1zi4_DataziByteString_", referenced from: ___stginit_Lib_ in B.o "_bytestringzm0zi9zi1zi4_DataziByteString_zdwreverse_info", referenced from: _s19w_info in B.o "_bytestringzm0zi9zi1zi4_DataziByteStringziInternal_zdwshowsPrec_info", referenced from: _s19v_info in B.o "_bytestringzm0zi9zi1zi4_DataziByteStringziInternal_zdwshowsPrec_closure", referenced from: _Lib_zdwa_srt in B.o "_bytestringzm0zi9zi1zi4_DataziByteString_zdwa4_info", referenced from: _Lib_zdwa_info in B.o "_bytestringzm0zi9zi1zi4_DataziByteString_reverse_info", referenced from: _Lib_rev_info in B.o ld: symbol(s) not found collect2: ld returned 1 exit status If I replace ByteString with the ordinary String, the above programs can be compiled and linked. Can someone tell me what I did wrong here? -Kenny

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Re: [Haskell] ANNOUNCE: OpenGLRaw 1.0.0.0
by Felipe Lessa 12 Jun '09

12 Jun '09

On Thu, Jun 11, 2009 at 06:56:01PM +0200, Sven Panne wrote: > Version 1.0.0.0 covers the OpenGL 3.1 core, all ARB extensions > and all EXT extensions. What about OpenGL 2.1? As I understand, Linux won't have OpenGL 3.0 or 3.1 for at least some months, $ glxinfo | grep 'OpenGL version' OpenGL version string: 2.1 Mesa 7.5-rc3 Thanks! -- Felipe.

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