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Fwd: [Haskell-cafe] Re: ANNOUNCE: WinGhci, a GUI for GHCI on Windows
by Pepe Gallardo 26 Mar '09

26 Mar '09

2009/3/23 Andrew Butterfield <Andrew.Butterfield(a)cs.tcd.ie> > Benjamin L.Russell wrote: > >> This is wonderful--just what I was waiting for! The application looks >> beautiful, and I'm very happy that GHCi now has a matching GUI >> application along the lines of WinHugs. >> >> > Indeed - me too ! > >> It would be even better if you could provide some >> installation/uninstallation information. I unzipped the contents of >> WinGhci-1.0-bin.zip into the "C:\Documents and Settings\<username>\My >> Documents\" folder, but there was no README file. >> >> > And version information - I tried it with GHC 6.4 and it died (Not > Responding) > > What version of GHCi does it require? > > And no, I won't upgrade GHC just yet (this is the latest GHC/wxHaskell > combo that works for me with GHCi...) > >> >> >> > I have tested it with GHC 6.10.1. The latest GHC version that I have currently installed is GHC 6.6, and it seems to work too. Do you have GHC bin directory on your path? > > -- > -------------------------------------------------------------------- > Andrew Butterfield Tel: +353-1-896-2517 Fax: +353-1-677-2204 > Foundations and Methods Research Group Director. > School of Computer Science and Statistics, > Room F.13, O'Reilly Institute, Trinity College, University of Dublin > http://www.cs.tcd.ie/Andrew.Butterfield/ > -------------------------------------------------------------------- > > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe >

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Fwd: [Haskell-cafe] Re: ANNOUNCE: WinGhci, a GUI for GHCI on Windows
by Pepe Gallardo 26 Mar '09

26 Mar '09

---------- Forwarded message ---------- From: Pepe Gallardo <pepe.haskell(a)gmail.com> Date: 2009/3/25 Subject: Re: [Haskell-cafe] Re: ANNOUNCE: WinGhci, a GUI for GHCI on Windows To: "Benjamin L.Russell" <DekuDekuplex(a)yahoo.com> Hi Benjamin*,* ** The only requirement to run WinGhci is to have GHC installed and to have GHC bin directory on your path. The way to start the application is by executing winghci.exe. Install.exe is an small program that associates .hs files with WinGhci (it should be run from the same directory where WinGhci is installed). Note that this association is optional. I have added a wiki page on this. 2009/3/23 Benjamin L.Russell <DekuDekuplex(a)yahoo.com> > Just another couple of thoughts for possible additional improvement: > > 1. It would be even nicer if WinGhci added a menu entry to the > "Start" menu automatically, as WinHugs does. > > 2. For the proposed menu entry, it would also probably be a good idea > if WinGhci added a folder for that menu entry, and included a link to > a "README" file in there, as WinHugs does also. > > 3. In order to distinguish WinGhci from GHCi, it might also be > helpful if WinGhci had a different icon; the current WinGhci icon is > identical to the one for GHCi (perhaps use the forthcoming official > Haskell logo here?). > WinGhci icon is different (although quite similar) from GHCi icon, at least for medium to large icon sizes. > > Just my two cents for now.... > > -- Benjamin L. Russell > -- > Benjamin L. Russell / DekuDekuplex at Yahoo dot com > http://dekudekuplex.wordpress.com/ > Translator/Interpreter / Mobile: +011 81 80-3603-6725 > "Furuike ya, kawazu tobikomu mizu no oto." > -- Matsuo Basho^ > > _______________________________________________ > Haskell-Cafe mailing list > Haskell <Haskell-Cafe(a)haskell.org>-Cafe(a)haskell.org<Haskell-Cafe(a)haskell.org> > http://www.haskell.org/mailman/listinfo/haskell-cafe > <Haskell-Cafe(a)haskell.org> >

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a cabal package with both a library and executable programs
by Manlio Perillo 26 Mar '09

26 Mar '09

Hi. This example is taken from the Cabal documentation: Name: TestPackage ... Library Build-Depends: HUnit Exposed-Modules: A, B, C Executable program1 Main-Is: Main.hs Hs-Source-Dirs: prog1 Other-Modules: A, B Executable program2 Main-Is: Main.hs Hs-Source-Dirs: prog2 Other-Modules: A, C, Utils Here I see a small problem. Why should I explicitly declare modules from the library that are used in the executables? I would like to do, instead ... Executable program1 Main-Is: Main.hs Hs-Source-Dirs: prog1 build-depends: TestPackage Executable program2 Main-Is: Main.hs Hs-Source-Dirs: prog2 build-depends: TestPackag Other-Modules: Utils I tried this, but configuration fails, since Cabal does not find the TestPackage. It is true that it does not yet exists, but we are going to build it! Should I fill a feature request ticket, or this is how it is supposed to work? Thanks Manlio

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Learning Haskell
by Tom.Amundsen 26 Mar '09

26 Mar '09

How long did it take you to become proficient in Haskell? By that, I mean - how long until you were just as comfortable with Haskell as you were with your strongest language at that time? -- View this message in context: http://www.nabble.com/Learning-Haskell-tp22673552p22673552.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.

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Re: How to increment an Int in Haskell (stack overflow issue)
by John Lato 26 Mar '09

26 Mar '09

> From: Tim Bauer <bauertim(a)eecs.orst.edu> > > I have a program that is currently blowing out the stack, > Stack space overflow: current size 8388608 bytes. > Use `+RTS -Ksize' to increase it. > I am pretty sure I get to the end of the computation that > increments various statistic counters (lazily?) and only > when I go to print them out at the end, do things fail. > In addition to the excellent advice provided by others on this topic, you may want to look at using GHC's heap profiler if you can't track down the source of a memory issue. I've found it helpful in the past. Keep in mind that there are several different modes that may or may not be helpful for a particular problem, so you should try them all to see if you get any useful information. John

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Data Structures with Haskell
by Rohit Agrawalla 26 Mar '09

26 Mar '09

I am a beginner haskell programmer. I am interested in data structures implementation (all from basic ones like stack, queues etc. to advance ones like balanced binary trees, graphs etc.) in haskell. It would be really helpful if someone can point some good references for the same. Regards , Rohit

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ANNOUNCE: WinGhci, a GUI for GHCI on Windows
by Pepe Gallardo 26 Mar '09

26 Mar '09

Hi, I am pleased to announce the first release of WinGhci. WinGhci is a simple GUI for GHCI on Windows. It is closely based on WinHugs, and provides similar functionality. WinGhci project web page: http://code.google.com/p/winghci/<mhtml:{5097F7F7-AA40-4661-A7CF-D5EEC38F084A}mid://00000003/!x-usc:http://co…> Binaries: http://winghci.googlecode.com/files/WinGhci-1.0-bin.zip<mhtml:{5097F7F7-AA40-4661-A7CF-D5EEC38F084A}mid://00000003/!x-usc:http://wi…> Sources: http://winghci.googlecode.com/files/WinGhci-1.0-src.zip<mhtml:{5097F7F7-AA40-4661-A7CF-D5EEC38F084A}mid://00000003/!x-usc:http://wi…> Acknowledgements Much of the code in WinGhci was taken from the Winhugs project. Many thanks to Neil Mitchell for giving us permission to use his code. <mhtml:{5097F7F7-AA40-4661-A7CF-D5EEC38F084A}mid://00000003/!x-usc:http://wi…> Pepe Gallardo

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[ANN] ansi-terminal, ansi-wl-pprint - ANSI terminal support for Haskell
by Max Bolingbroke 26 Mar '09

26 Mar '09

These two packages allow Haskell programs to produce much richer console output by allowing colorisation, emboldening and so on. Both Unix-like (OS X, Linux) and Windows operating systems are supported (via a pure Haskell ANSI emulation layer for Windows). Examples, screenshots, and lots more information about how to get the packages are available at the freshly-minted homepages: http://batterseapower.github.com/ansi-terminal/ http://batterseapower.github.com/ansi-wl-pprint/ These two packages have actually been in stealth release mode on Hackage for some time. However, they seem to be getting some use and I'm not getting any bug reports, so I figure that they /must/ be stable enough to make a proper announcement :-) Cheers, Max (p.s: the GitHub "pages" feature seems to be absolutely ace - highly reccomended! http://pages.github.com/)

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How to increment an Int in Haskell (stack overflow issue)
by Tim Bauer 26 Mar '09

26 Mar '09

I have a program that is currently blowing out the stack, Stack space overflow: current size 8388608 bytes. Use `+RTS -Ksize' to increase it. I am pretty sure I get to the end of the computation that increments various statistic counters (lazily?) and only when I go to print them out at the end, do things fail. I have state monad transformer (StateT) that is keeping the counters among other things. The counters are stored in a pair within a larger data structure. > data AState s a = AS { ... > asStats :: (Int,Int) > ... > } to increment them I initially just simply applied either of > incFst, incSnd :: (Int,Int) -> (Int,Int) > incFst (x,y) = (x + 1,y) > incSnd (x,y) = (x, y + 1) to the current pair. I thought this was safe since primitive arithmetic was strict, but when I go to print the counter out (evaluate it), it blows apart. I first decided this was because the addition was somehow not strict and I was getting: (0 + 1 + 1 ...millions of times..., ....) and the evaluation of that first coordinate blew things apart. So I tried was adding a strictness annotation to the arguments. > incFst (!x,y) = (x + 1,y) > incSnd (x,!y) = (x, y + 1) No dice (I also tried using seq manually all over the place to no avail). Just for fun, I tried both of > incFst _ = (0,0) > incSnd _ = (0,0) and > incFst (x,y) = (x,y) > incSnd (x,y) = (x,y) The problem goes away. But maybe an optimization is covering up the crime. So I tried > incFst (x,y) = (y,x) > incSnd (x,y) = (y,x) And indeed this again crashes. Any hints as to what is going on? If it is relevant, here is my code to access the counter within the state monad > countFst :: StateT (AState s a) IO () > countFst = modify $ \as -> as{asStats = incFst (asStats as)} and the monad transformer I am using is > import Control.Monad.State.Strict

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ghci + hopengl
by Rafael Cunha de Almeida 26 Mar '09

26 Mar '09

Hello, I'm writing a program for plotting vectorial functions and maybe something else in the future. My goal is to be able to have the following usage: Prelude> :l Galo.hs Prelude Galo> show3Dvec (\t -> (t, t, 0)) [0.0,0.01 .. 1.0] * shows graph * Prelude Galo> show3Dvec (\t -> (t, t**2, 0)) [0.0,0.01 .. 1.0] * shows new graph * I already done something, the main module can be found here: http://github.com/aflag/galo/blob/0a54a53db0f66384cfc0775f12582931d0fb4205/… The whole project is found here: http://github.com/aflag/galo/tree/master I think mainLoop is somehow responsible to exit the whole thing. I tried to even call that function through forkIO. But didn't work quite well: my terminal started behaving really weird after I closed the window. Could you explain me what is going on and what should I look into for understanding how to solve the issue? []'s Rafael

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Whats the use of "!"
by Harsh Verma 26 Mar '09

26 Mar '09

I have seen ! added in front of many values, is it related to strict evaluation? Please elaborate on it. TIA, gimli _________________________________________________________________ Windows Live Messenger. Multitasking at its finest. http://www.microsoft.com/india/windows/windowslive/messenger.aspx

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central european functional programming school
by Roman Cheplyaka 26 Mar '09

26 Mar '09

Hi, I'm interested in 3rd central european functional programming school[1]. Maybe some haskellers attended previous CEFPs and want to share (or already shared) some experience? Who also is going to attend or participate in this year's CEFP? 1. http://plcportal.inf.elte.hu/en/tfp_cefp_2009/Pages/default.aspx -- Roman I. Cheplyaka :: http://ro-che.info/ "Don't let school get in the way of your education." - Mark Twain

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Re: Exception handling in numeric computations
by John Lato 25 Mar '09

25 Mar '09

> Jake McArthur <jake(a)pikewerks.com> writes: > >> Xiao-Yong Jin wrote: >> | The problem is that there will be many functions using such >> | a function to invert a matrix, making this inversion >> | function return Either/Maybe or packing it in a monad is >> | just a big headache. >> >> I disagree. If you try to take the inverse of a noninvertable matrix, >> this is an *error* in your code. Catching an error you created in pure >> code and patching it with chewing gum it is just a hack. A monadic >> approach (I'm putting Either/Maybe under the same umbrella for brevity) >> is the only solution that makes any sense to me, and I don't think it's >> ugly as you are making it out to be. >> > > Then, why is 'div' not of type 'a -> a -> ArithExceptionMonad a' ? > Why does it throws this /ugly/ /error/ when it is applied to > 0? Why is it not using some beautiful > 'ArithExceptinoMonad'? Is 'Control.Exception' just pure > /ugly/ and doesn't make any sense? > >> >> | It is impractical to use method (a), >> | because not every function that uses 'invMat' knows how to >> | deal with 'invMat' not giving an answer. So we need to use >> | method (b), to use monad to parse our matrix around. >> | >> |> > invMat :: Matrix -> NumericCancerMonad Matrix >> | >> | It hides the exceptional nature of numerical computations >> | very well, but it is cancer in the code. Whenever any >> | function wants to use invMat, it is mutated. This is just >> | madness. You don't want to make all the code to be monadic >> | just because of singularities in numeric calculation. >> >> For functions that don't know or don't care about failure, just use fmap >> or one of its synonyms. >> >> ~ scalarMult 2 <$> invMat x >> >> See? The scalarMult function is pure, as it should be. There is no >> madness here. > > Of course, 'scalarMult' is invulnerable and free of monad. > But take a look at the following functions, > >> f1 = scalarMult 2 . invMat >> f2 l r = l `multMat` invMat r >> ff :: Matrix -> Matrix -> YetAnotherBiggerMonad Matrix >> ff x y = do let ff' = f1 x + f2 y >> put . (addMat ff') . f1 << get >> tell $ f2 ff' >> when (matrixWeDontLike (f1 ff') $ >> throwError MatrixWeDontLike >> return $ scalarMult (1/2) ff' > > Yes, I know, it's not really complicate to rewrite the above > code. But, what do I really gain from this rewrite? Apologies if this discussion has moved on, but I wanted to comment on this. You gain correctness. Any functions that need to be rewritten in this case should be rewritten anyway, because they're already wrong. Your function ff can fail for certain inputs. This statement: >> | It is impractical to use method (a), >> | because not every function that uses 'invMat' knows how to >> | deal with 'invMat' not giving an answer. So we need to use >> | method (b), to use monad to parse our matrix around. is conceptually wrong. What does it mean to multiply the inverse of a non-invertible matrix by a scalar? Obviously this is nonsensical. If a computation can fail (as this can), the type of the function should reflect it. The above functions >> f1 = scalarMult 2 . invMat >> f2 l r = l `multMat` invMat r should be f1 :: Matrix -> Maybe Matrix f1 = fmap (scalarMult 2) . invMat f2 :: Matrix -> Matrix -> Maybe Matrix f2 l r = fmap (multMat l) $ invMat r Of course these could be written with Control.Applicative as well: f1 m = scalarMult 2 <$> invMat m f2 l r = multMat l <$> invMat r >> ff :: Matrix -> Matrix -> YetAnotherBiggerMonad Matrix >> ff x y = let ff' = f1 x + f2 y ... in scalarMult (1/2) ff' (I think you may be missing an argument to f2 here.) This computation can fail as well, if the constituent parts fail. The separate parts can be combined with applicative style: ff :: Matrix -> Matrix -> Maybe Matrix ff x y = scalarMult (1/2) <$> ( (+) <$> f1 x <*> f2 y) Compare this to the same code using monadic Maybe: ff :: Matrix -> Matrix -> Maybe Matrix ff x y = do x' <- f1 x y' <- f2 y scalarMult (1/2) $ x' + y' You gain clarity and brevity. Both examples are shorter and easier to understand because you aren't messing with all the plumbing of error handling using exceptions, although I find the Applicative version especially clear. If you would like to keep track of why a computation failed, then use Either instead of Maybe with the Left carrying a reason for failure (e.g. NonInvertibleMatrix) Finally, you gain safety. When you use a function f1 :: Matrix -> Matrix, you can be assured that you will get an actual, meaningful answer. If you use a function f2 :: Matrix -> Maybe Matrix, you know that you may not get a meaningful answer, and it is simple to handle at the appropriate level of your code. I (and many other Haskell users) find this to be conceptually cleaner than throwing dynamic exceptions or using undefined. Incidentally, this is one reason why many experienced Haskellers like the applicative style. It allows you to express your computations without obtrusive error handling mixed in. It's also more general than monads, so can be applied in more instances. div (and other non-total functions in the Prelude like head), are also frequently considered ugly hacks. Just because we're stuck with something from H98 doesn't mean that it's necessarily good or elegant (the fail monad method and Functor not being a superclass of Monad come to mind). In some ways FP has moved on since Haskell was formalized. There is an alternative approach that I believe was suggested by somebody else on the list: newtype InvMatrix = Invert {unWrap :: Matrix} then you can do invertMatrix :: Matrix -> Maybe InvMatrix invertMatrix = fmap Invert . invMat If you put these in a separate module and export InvMatrix, unwrap, and invertMatrix, but not Invert, then the only way to create an InvMatrix is with invertMatrix, so any data of type InvMatrix is guaranteed to be invertible (and inverted from what you used to create it). Then your ff function becomes: ff :: InvMatrix -> InvMatrix -> Matrix the final value of the function could be InvMatrix if you can prove that it's invertible after your operations (although to be efficient, this would require exporting the Invert constructor and a proof from the programmer). This keeps ff pure; you don't even have to deal with Maybe (although there are other ramifications to doing this that should be considered). John

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Re: generalized shuffle
by Manlio Perillo 25 Mar '09

25 Mar '09

oleg(a)okmij.org ha scritto: > Hello! > >> The reason is that in a project I need to extract random elements >> from a list (and I need to extract a lot of them), and using "normal" >> methods [1] seems to be rather inefficient. Note that I have used an incorrect term, sorry. What I need, in detail, is to: Given a population of 100480507 elements, extract 17770 random samples, where each sample has a size between 1 and 480189. Yes, it is again my Netflix Prize project; here I'm trying to write a program to generate the entire training data set using random data. >> [1] by normal method I mean: extract a random number, in the range >> [0, n] (where n is the length of the sequence), and get the element >> indexed by that number. > > BTW, have you tried to use Data.IntMap? That is, put the sequence into > an IntMap (each element being indexed by its index) and then extract > elements at random; IntMap seems to be quite efficient... > This should be ok if I need independent random choices from a population, but I need random samples, instead, sorry for the confusion. Do you think that it is possible to further optimize your tree structure? Or to use IntMap, instead? > Cheers, > Oleg Thanks Manlio

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STM orElse semantics
by Tom Davies 25 Mar '09

25 Mar '09

I'm not 100% clear on the behaviour of the STM function orElse. The documentation says: "Compose two alternative STM actions (GHC only). If the first action completes without retrying then it forms the result of the orElse. Otherwise, if the first action retries, then the second action is tried in its place. If both actions retry then the orElse as a whole retries." What is the definition of retrying in "If the first action completes without retrying then..." -- does it mean only explicitly retrying via the retry function, or does it include a retry caused by a write conflict at commit time of the first action? That is, if the first action could complete, but doesn't simply due to interference from another transaction, does orElse run the second action, or rerun the first?

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The votes are in!
by Eelco Lempsink 25 Mar '09

25 Mar '09

The results of the Haskell logo competition are in! You can view them at http://www.cs.cornell.edu/w8/~andru/cgi-perl/civs/ results.pl?num_winners=1&id=E_d21b0256a4fd5ed7&algorithm=beatpath Congratulations Jeff Wheeler! I'll set up a page with the results visibile. -- Regards, Eelco Lempsink

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Are there performant mutable Arrays in Haskell?
by Brettschneider, Matthias 25 Mar '09

25 Mar '09

Hey There, I am trying to write a hash-algorithm that in fact is working, but as you might have guessed the problem is the performance :) At the moment I am 40 times worse than the same implementation in C. My problem is, I need mutable arrays which are the heart of that hash. The algorithm is round-based and within each round I need the value of certain positions in that array. At the moment I work with an unboxed ST-Array at the crucial part --- snip --- test list = runSTUArray $ do a_arr <- newListArray (0, 1752) list let round i = do ain <- readArray a_arr (i-n) at0 <- readArray a_arr (i-t0) at1 <- readArray a_arr (i-t1) at2 <- readArray a_arr (i-t2) at3 <- readArray a_arr (i-t3) at4 <- readArray a_arr (i-t4) let li = ls $ (i - n) mod 16 ri = rs $ (i - n) mod 16 writeArray a_arr i $ (step4 li) . (step3 ri) . (step2 at1 at2 at3 at4) $ (step1 ain at0 i) mapM_ round [n..(n+t-1)] return a_arr --- snap --- I also played around with peekElemOff and pokeElemOff, but this isn't much faster. It took ~30sec with my Haskell-Code while the C-implementation need only ~1sec. Is there someone who may have some hints for me, what I can do better, or just lead me in the right direction? :) Thanks a lot in advance -- Matthias

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Re: [Haskell-cafe] Definition of "tail recursive" wrt Folds
by Tammo Spalink (司馬泰) 25 Mar '09

25 Mar '09

wikipedia is your friend... http://en.wikipedia.org/wiki/Fold_(higher-order_function) Tammo 2009/3/25 Mark Spezzano <mark.spezzano(a)chariot.net.au>: > Hi, > > > > Just looking at the definitions for foldr and foldl I see that foldl is > (apparently) tail recursive while foldr is not. > > > > Why? > > > > Is it because foldl defers calling itself until last whereas foldr evaluates > itself as it runs? > > > > What, strictly speaking, is the definition of ”tail recursive” as opposed to > just “recursive”? > > > > Cheers, > > > > Mark Spezzano > > > > No virus found in this outgoing message. > Checked by AVG. > Version: 7.5.557 / Virus Database: 270.11.27/2021 - Release Date: 24/03/2009 > 4:00 PM > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > >

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Definition of "tail recursive" wrt Folds
by Mark Spezzano 25 Mar '09

25 Mar '09

Hi, Just looking at the definitions for foldr and foldl I see that foldl is (apparently) tail recursive while foldr is not. Why? Is it because foldl defers calling itself until last whereas foldr evaluates itself as it runs? What, strictly speaking, is the definition of ”tail recursive” as opposed to just “recursive”? Cheers, Mark Spezzano No virus found in this outgoing message. Checked by AVG. Version: 7.5.557 / Virus Database: 270.11.27/2021 - Release Date: 24/03/2009 4:00 PM

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Hugs on iPhone
by Kirk Martinez 25 Mar '09

25 Mar '09

I saw Miguel Mitrofanov ( http://www.nabble.com/Hugs-on-the-iphone-td19478992.html) successfully ported Hugs to the iPhone. I'm now wondering if anyone has tried to get Apple's blessing to put this in the App Store? It would be really great to be able to try out little Haskell ideas as the mood strikes. Of course, it's kind of essential to have an editor of some kind for more significant programs... Thanks, Kirk

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ACM Task for C++ and Java programmers in Haskell. How to make code faster?
by Vasyl Pasternak 25 Mar '09

25 Mar '09

Hi! Recently I've found interesting ACM research on C++ and Java efficiency. This task also was been solved on lisp/scheme and is described on http://www.flownet.com/ron/papers/lisp-java/ I tried to solve this task on Haskell but stuck with efficiency problems (approx in 1000 times slower and takes 20 times more memory). I hope the approach, I've used is correct and problem with data structures and implementation. It took more than 81% of time for garbage collection. I tried to use ByteStrings instead of Strings, but unfortunately it didn't help. The entire code I placed on http://hpaste.org/fastcgi/hpaste.fcgi/view?id=2764 The original instructions are on: http://www.flownet.com/ron/papers/lisp-java/instructions.html Dictionary file could be downloaded from: http://www.flownet.com/ron/papers/lisp-java/dictionary. Input data: http://www.flownet.com/ron/papers/lisp-java/input.txt Expected output: http://www.flownet.com/ron/papers/lisp-java/output.txt Could someone help me to make this code faster? I'd like to see solution that will be elegant and fast, without heavy optimizations, that will make code unreadable. Also, if it possible, prepare the program to support SMP parallelism. Very thanks in advance. Hope you'll enjoy this task :) -- Best regards, Vasyl Pasternak

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GHC 6.10.2 - PCap package - affected by the change of Finalizers?
by Neil Davies 25 Mar '09

25 Mar '09

Hi Looks like pcap package needs a little tweek for 6.10.2 - programs compiled with it bomb out with ......error: a C finalizer called back into Haskell. use Foreign.Concurrent.newForeignPtr for Haskell finalizers. Is my interpretation of this error message correct? Cheers Neil

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SOC idea ticket: Rendering Engine
by Csaba Hruska 25 Mar '09

25 Mar '09

Hi! I've created a ticket for this idea: http://hackage.haskell.org/trac/summer-of-code/ticket/1572 Please write your opinion. I also put the source code here: http://code.google.com/p/lambdacube/ svn checkout *http*://lambdacube.googlecode.com/svn/trunk/lambdacube-read-only Cheers, Csaba Hruska

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Equations for `foo' have different numbers of arguments
by Manlio Perillo 25 Mar '09

25 Mar '09

Hi. There is a limitation, in Haskell, that I'm not sure to understand. Here is an example: module Main where divide :: Float -> Float -> Float divide _ 0 = error "division by 0" divide = (/) main = do print $ divide 1.0 0.0 print $ divide 4.0 2.0 With GHC I get: Equations for `divide' have different numbers of arguments With HUGS: Equations give different arities for "divide" However the two equations really have the same number of arguments. What's the problem? Thanks Manlio Perillo

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Something wrong with happs.org?
by Vimal 25 Mar '09

25 Mar '09

Hi, http://happs.org/ has some Javascript visible as plain text. It looks like some tags are missing in the page... I hope that's the right website, because it turned up first on my Google search "happs" with a nice description too. -- Vimal

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Help on using System.Win32.Com.Automation
by Wilkes Joiner 24 Mar '09

24 Mar '09

I'm playing around with the com package, but I'm having a hard time understanding how to map a COM call to the appropriate methodN or functionN call. Does anyone have any example code that uses the method1 or higher. Any help or pointers would be appreciated. Here's the code I have so far: import System.Win32.Com import System.Win32.Com.Automation dsn = "Provider=vfpoledb.1;Data Source=C:\\SomeDirectory\\" main = coInitialize >> openConnection >>= \con -> closeConnection con openDSN :: String -> IDispatch a -> IO () openDSN dsn con = method0 "Open" [inString dsn] con openConnection :: IO (IDispatch a) openConnection = createObject "ADODB.Connection" >>= \con -> openDSN dsn con >> return con closeConnection :: IDispatch a -> IO () closeConnection = method0 "Close" [] {- Wraps ADO Connection.Execute http://msdn.microsoft.com/en-us/library/ms675023(VS.85).aspx Set recordset = connection.Execute (CommandText, RecordsAffected, Options) execute :: String -> IDispatch a -> IO a execute cmd con = method1 "Execute" [inString cmd] (inEmpty,resWord64) con -} Thank You, Wilkes

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RE: [ANN] Safe Lazy IO in Haskell
by Wei Hu 24 Mar '09

24 Mar '09

Nicolas Pouillard <nicolas.pouillard <at> gmail.com> writes: > > Hi folks, > > We have good news (nevertheless we hope) for all the lazy guys standing there. > Since their birth, lazy IOs have been a great way to modularly leverage all the > good things we have with *pure*, *lazy*, *Haskell* functions to the real world > of files. > > We are happy to present the safe-lazy-io package [1] that does exactly this > and is going to be explained and motivated in the rest of this post. Hi, Please let me know if I understood your code correctly. So, the SIO module is used only to ensure that the file processing is finished before the finalizer closes the file, right? In System.IO.Lazy.Input, run is defined as > run :: NFData sa => LI sa -> IO sa > run = run' . fmap return' Can I change it to > run = run' . fmap return ? I think the semantics is the same because run' will strictly force the processing anyway?

2 1

Don't forget to vote!
by Eelco Lempsink 24 Mar '09

24 Mar '09

In less than 4 hours the Haskell Logo poll will be closed. If you're not one of the 423 people that voted so far, please take 1-20 minutes (depending on your level of perfectionism) to support your favorite logo(s) :) -- Regards, Eelco Lempsink

1 0

generalized shuffle
by Manlio Perillo 24 Mar '09

24 Mar '09

Hi. I have implemented a generalized shuffle function, for the random-shuffle package http://hackage.haskell.org/cgi-bin/hackage-scripts/package/random-shuffle I have not yet commited the change, before that I would like to receive some feedbacks (especially by the original author of the shuffle function, in Cc) The new function is defined in this example: http://hpaste.org/fastcgi/hpaste.fcgi/view?id=2808 Note that it make use of functions not exported by the System.Random.Shuffle module. I have generalized the original shuffle function in two ways: 1) It is now possible to obtain a random "sample" from a sequence, by doing, as an example: shuffles [1..10] [2, 3, 4, 2, 1] Note that this is equivalent at taking the first 5 elements of the full shuffled sequence, and the performance are pratically the same. 2) It is now possible to pass an infinite "r-sequence" to the shuffle function, as an example: shuffles [1..10] $ cycle [9, 8 .. 1] The result is an infinite list, with elements cyclically extracted from the "r-sequence". When the "r-sequence" contains random numbers, we get an infinite sequence containing all possible random "choices" of elements in the original sequence. Why I'm doing this? The reason is that in a project I need to extract random elements from a list (and I need to extract a lot of them), and using "normal" methods [1] seems to be rather inefficient. Using the `shuffles` function should be much more efficient, since it uses a tree, and this tree is built only once. [1] by normal method I mean: extract a random number, in the range [0, n] (where n is the length of the sequence), and get the element indexed by that number. Indexing for a list if very expensive. And it is not very fast, even using arrays (unless you use non portable unsafeRead). Thanks Manlio Perillo

1 0

HSTringTemplate and syb-with-class
by Kemps-Benedix Torsten 24 Mar '09

24 Mar '09

Hello all, I'm trying to use the generic capabilities of HSTringTemplate. The documentation claims that the package is able to automatically generate instances of ToSElem if syb-with-class is installed but gives no further details. I installed syb-with-class and then installed HSTringTemplate with additional configure parameter syb-with-class=True. But when I import Text.StringTemplate.GenericWithClass and then try deriving ToSElem or $(derive ToSElem), I just get an error like "Can't make a derived instance of `ToSElem ...". Any suggestions or pointer to further docs? Kind regards Torsten

2 1

Function to cast types
by Anonymous Anonymous 24 Mar '09

24 Mar '09

Hello, I'm new to haskell, I'm wondering how can you write a function that will do the following: fromIntToString :: Int -> String this is a cast function to cast an Int to a String. I know such function exist, however let's assume it didn't exist. How would I write such function? Cause I have no idea, because there are infinity possibilities if I do it like: fromIntToString x | x == 1 = "1" | x == 2 = "2" -- And so on... I've also thinked about defining the defining the data types Int and String (I know you cannot redefine them, at least I think so), however I've no succes. Thank you in advance for answering my question! PS: if possible please do not use any casting functions that are predefined.

8 12

System.Random.Shuffle fix
by friggin friggin 24 Mar '09

24 Mar '09

I was looking for a shuffling algorithm to shuffle mp3-playlists so was very happy to see System.Random.Shuffle: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/random-shuffle-0… However I get errors,non-exhaustive patterns in function shufleTree or extractTree depending how I call it. Errors are at the bottom. I fixed it but I don't have the math skills to see if I perhaps broke it statistically ... Here is my fix, someone (don't remember who, helped me a little): http://hpaste.org/fastcgi/hpaste.fcgi/view?id=2789#a2789 the shuffle at the end is with the fix. *Freet> S.shuffle [1..10] [1..3] Loading package syb ... linking ... done. Loading package base-3.0.3.0 ... linking ... done. Loading package old-locale-1.0.0.1 ... linking ... done. Loading package old-time-1.0.0.1 ... linking ... done. Loading package random-1.0.0.1 ... linking ... done. Loading package random-shuffle-0.0.2 ... linking ... done. [2,4,6*** Exception: src\System\Random\Shuffle.hs:(52,6)-(55,30): Non-exhaustive patterns in function shuffleTree *Freet> S.shuffle [1..3] [1..10] [2,*** Exception: src\System\Random\Shuffle.hs:(66,6)-(79,27): Non-exhaustive patterns in function extractTree *Freet> :load "c:/ghc/ghc-6.10.1/progs/Mp3Player/Shuffle.hs" [1 of 1] Compiling Shuffle ( C:\ghc\ghc-6.10.1\progs\Mp3Player\Shuffle.hs, interpreted ) Ok, modules loaded: Shuffle. *Shuffle> shuffle [1..3] [1..10] [2,1,3] *Shuffle> shuffle [1..10] [1..3] [2,4,6*** Exception: C:\ghc\ghc-6.10.1\progs\Mp3Player\Shuffle.hs:(27,13)-(31,30): Non-exhaustive patterns in function shuffle' *Shuffle> shuffle [1..10] [1..10] [2,4,6,8,10,3,9,7,5,1] *Shuffle>

2 1

A small display problem using Helium
by Anonymous Anonymous 24 Mar '09

24 Mar '09

Hello, I've written something simple: main :: IO () main = do lijn <- getLine putStrLn lijn Now if I import it in Helium it will do the following: Test> main test -- (here I'm typing test) test it will be displayed two times, why? Because it displays my input and the output of the function. Now I want to write a function that does NOT display my input, any suggestions how I can achieve this? Thanks in advance!

1 0

Hackage download and popularity statistics
by Don Stewart 24 Mar '09

24 Mar '09

For the first time, we've got download and popularity statistics from Hackage: http://www.galois.com/blog/2009/03/23/one-million-haskell-downloads/ Find out if your package made the top 100, and when we reach our 1 millionth hackage download! -- Don

1 0

Hackage upload problems?
by Sebastiaan Visser 23 Mar '09

23 Mar '09

Hello, Currently I'm trying to upload a minor update of Salvia to Hackage to fix some dependency issues but Hackage times out all the time? Both the CLI tool and the web-interface do not react to my upload request. Any known problems here? Gr, Sebastiaan.

2 1

Sometimes I wish there was a global variable
by Rafael Cunha de Almeida 23 Mar '09

23 Mar '09

Hello, I am writing a OpenGL program in haskell, it can be found in: http://github.com/aflag/galo/tree/master But I hope this e-mail will be self-contained :). My main function goes like this: (...) rotX <- newIORef (0.0::GLfloat) rotY <- newIORef (0.0::GLfloat) pos <- newIORef (0.0::GLfloat, 0.0, 0.0) displayCallback $= display (map f range) rotX rotY pos keyboardMouseCallback $= Just (keyboardMouse rotX rotY pos) (...) Notice that rotX, rotY and pos are meant to be used as comunication between the keyboardMouse and display functions. They need to be set as 0 first, so display won't do anything. Only when they user press a few buttons that those values change, so display behaves accordanly. In a state-based language I would place display and keyboardMouse in one module and let them communcate to each other like they want. In haskell, I'm not quite sure how to do it except by that parameter passing style. I thought about how state-monad may help with that. But I'm not sure how I'd make the state variable to be contained inside a display/keyboardMouse module. []'s Rafael

7 7

Re: [Haskell-cafe] least fixed points above something
by Jens Blanck 23 Mar '09

23 Mar '09

> > > On Friday 20 March 2009 5:23:37 am Ryan Ingram wrote: > > On Fri, Mar 20, 2009 at 1:01 AM, Dan Doel <dan.doel(a)gmail.com> wrote: > > > However, to answer Luke's wonder, I don't think fixAbove always finds > > > fixed points, even when its preconditions are met. Consider: > > > > > > f [] = [] > > > f (x:xs) = x:x:xs > > > > > > twos = 2:twos > > > > How about > > > > > fixAbove f x = x `lub` fixAbove f (f x) > > > > Probably doesn't work (or give good performance) with the current > > implementation of "lub" :) > > > > But if "lub" did work properly, it should give the correct answer for > > fixAbove f (2:undefined). > > This looked good to me at first, too (assuming it works), and it handles my > first example. But alas, we can defeat it, too: > > f (x:y:zs) = x:y:x:y:zs > f zs = zs > > Now: > > f (2:_|_) = _|_ > f _|_ = _|_ > > fix f = _|_ > > fixAbove f (2:_|_) = 2:_|_ `lub` _|_ `lub` _|_ ... > = 2:_|_ > > Which is not a fixed point of f. But there are actually multiple choices of > fixed points above 2:_|_ > > f (2:[]) = 2:[] > forall n. f (cycle [2,n]) = cycle [2,n] > > I suppose the important distinction here is that we can't arrive at the > fixed > point simply by iterating our function on our initial value (possibly > infinitely many times). I suspect this example won't be doable without an > oracle of some kind. > > Ah well. > -- Dan > > Thanks for all comments on my question, especially those bashing my poor code. The above approach does not apply to my case. What I have is a monotone function f on a partial order satisfying f x >= x, for all x. Given that the partial order is in fact a cpo this is enough to guarantee that a least fixed point can be found above any point in the partial order simply by iterating f, although not necessarily in finite time. Taking the lub of x and the fixed point of f (over bottom) need not give a fixed point even if one exists. Think of reachability in a graph from a starting set. Let S be some fixed set, and let f return all points reachable in 0 or 1 step from the union of S and the argument to f. Then fix f is the set of points reachable from S, which is a fixed point. But adding some point x outside fix f will in general not give me a fixed point, even though a unique fixed point exists (the set reachable from the union of {x} and fix f). Jens

2 1

SoC idea: interactive profiling
by Patai Gergely 23 Mar '09

23 Mar '09

Hello all, I entered a little proposal in the issue tracker: http://hackage.haskell.org/trac/summer-of-code/ticket/1570 As I see it, the graphical part could be a warm-up exercise with an already useful product, and interaction with the rts would be the actual challenge. Reasoning about laziness is far from trivial (at least I often feel lost when trying to grok all the interaction within Reactive ;), and being able to browse profiler output on the spot is something I felt the need for a few times already. Eventually, this could be a contribution to an IDE project, even though it could as well remain a standalone application for all the emacs/vi folk. Profiling tools for parallel programs are in the make already, but I haven't seen anything more convenient than hp2ps and little add hoc solutions for analysing resource usage patterns. How do you all go about profiling? Gergely -- http://www.fastmail.fm - Does exactly what it says on the tin

5 7

MissingH bracketCD (aka bracketCWD) bug -- this is the infamous lazy io, right?
by Thomas Hartman 23 Mar '09

23 Mar '09

I got bitten by a bug (well, I call it bug) in bracketCD from HSH/MissingH demonstrated by the following code bracketCD is very useful for sysadminny one-offs, I use it all the time, but..... I suspect that unless people are very careful, this behavior will affect other users of bracketCD, in potentially very subtle and tricky ways. 1) -- is there a more elegant way to deal with lazy io than the hack below? (putStrLn the last character) 2) -- should MissingH function bracketCD be fixed, and if so how? import System.FilePath.Find (find) import System.Directory (getDirectoryContents, getCurrentDirectory, setCurrentDirectory) import System.Path (bracketCWD) -- from MissingH -- the fixed function, a more restrictive type than bracketCWD which lets you do any io, not just showables myBracketCWD :: Show a => FilePath -> IO a -> IO a myBracketCWD fp action = do oldcwd <- getCurrentDirectory setCurrentDirectory fp a <- action putStrLn $ show . last . show $ a -- force evaluation setCurrentDirectory oldcwd return a -- rather than listing "/", lists dir this module is in tWrong = bracketCWD "/" $ return . take 2 =<< listCurrentWithFind -- this lists filesystem root tRight = myBracketCWD "/" $ return . take 2 =<< listCurrentWithFind listCurrentWithFind = System.FilePath.Find.find (return True) (return True) "." -- for some reason, bracketCWD does the right thing with get tGetContents = myBracketCWD "/" $ return . take 2 =<< getDirectoryContents "." Actual code for bracketCWD in MissingH: -- this is from MissingH, seems there's a bug when attempt to wrap a find command bracketCWD :: FilePath -> IO a -> IO a bracketCWD fp action = do oldcwd <- getCurrentDirectory setCurrentDirectory fp finally action (setCurrentDiurectory oldcwd)

2 1

How to send signal from Xmonad to my app?
by Magicloud Magiclouds 23 Mar '09

23 Mar '09

Hi, I have a little program, which shows a message box when gets 'USR1' signal. This works fine when I `kill -USR1 $PID`. But my code in xmonad.hs does not work. No error throws out. And as I inspected, the "pid" is right. Only nothing happened in my app. So I wonder what is wrong? 28 , ((mod4Mask, xK_x), sendSignal2PIDinFile sigUSR1 ".sidebar.pid") 31 sendSignal2PIDinFile signal pidfile = io $ do 32 pid <- readFile pidfile 33 signalProcess signal $ read pid -- 竹密岂妨流水过山高哪阻野云飞

1 0

ANN: hranker: Basic utility for ranking a list of items (e.g. for the logo poll)
by Robin Green 23 Mar '09

23 Mar '09

hranker is a fun little command-line utility I have written to help a user rank a list of items (of any type implementing Show, Eq and Ord). I hope the code is sufficiently clear that it could also serve as an educational piece of code, especially for people wanting to learn how to use the HCL library. It is now available on hackage: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hranker Just typing hranker or hranker --help will yield a usage message. Here is an example usage of the program: In the unlikely event that anyone else wants to use it to help them prepare their votes in the Haskell logo poll (which is what I used it for just now), here is what to do: 1. cabal install hranker (or download it and runhaskell Setup.lhs etc.) 2. hranker 113 (because 113 is the number of items in the poll) 3. IMPORTANT: Read the warnings the program prints on startup! 4. To control the program, enter the first character of the command you wish to perform, and then press Enter. The command you have chosen may ask you for further information. Commands generally operate on the next unranked item, apart from annotate (which can operate on ranked or unranked items), remove (which always operates on ranked items), and quit. I recommend you use the annotate command a lot - it is really helpful for this kind of situation where you have a lot of numbered items to rank. If you use the remove command, don't remove *all* ranked items, because if you do you it may terminate. 5. If you rank *everything* somehow (remember, ties are allowed), the program will print an inverse mapping (items to ranks, instead of ranks to items) before terminating. If you choose to quit before that point, you won't get that inverse mapping, unless you explicitly invoke the mapping command. There is obvious room for improvement: apart from fixing the remove bug mentioned above, there is currently no simple way to remove or annotate just *one* item at a rank when multiple items are tied at that rank. Have fun! There are some hilarious entries in the logo poll, if you haven't yet voted. -- Robin

1 0

Transforming XML using HXT, I'm confused.
by P Orrifolius 23 Mar '09

23 Mar '09

Hello, I'm trying to transform a fragment of XML using HXT, specifically I'm trying to strip out any disallowed content while retaining as much as possible. For example I might be given "<bar><evil>blah</evil></bar>". I want to get rid of the 'evil' element but retain it's content resulting in "<bar>blah</bar>", rather than just "<bar></bar>". My basic theory was to do a bottom up traversal replacing any invalid elements with their children. Unfortunately I've got myself thoroughly confused. The code below shows what I've tried so far (except the many random permutations of collapseInvalids I've tried!). I think one problem is that validElements is choosing based on the parent element but processing will just be given the child. Also I think some inputs will require multiple passes over the children during the traversal, eg given "...<baz>s6<bar>s7</bar></baz>..." I'd like "...<baz>s6s7</baz>..." but when processing the bar it is valid, it's only once you're processing the baz you see that you need to pull the s7 up. I'd really appreciate any advice, and I'm not wedded to the current code so feel free to throw it all out! :) Thanks P. ps: Is it possible to render an XmlTree as String without invoking IO? I've just been doing runLA (hread >>> collapseInvalids) frag1 and looking at the nodes. module Test where import Text.XML.HXT.Arrow --collapseInvalids = processBottomUp (processChildren ((getChildren `whenNot` validElements) `orElse` this)) -- <foo> can contain <foo>, <bar> or <baz>, not text validInFoo :: (ArrowXml a) => a XmlTree XmlTree validInFoo = foldr1 orElse ( map hasName ["foo", "bar", "baz"] ) -- <bar> can contain <foo>, <baz> or text, not <foo> validInBar :: (ArrowXml a) => a XmlTree XmlTree validInBar = foldr1 orElse ( isText : map hasName ["foo", "baz"] ) -- <baz> can only contain text validInBaz :: (ArrowXml a) => a XmlTree XmlTree validInBaz = foldr1 orElse ( isText : []) validElements :: (ArrowXml a) => a XmlTree XmlTree validElements = choiceA ( hasName "foo" :-> validInFoo : hasName "bar" :-> validInBar : hasName "baz" :-> validInBaz : isText :-> this : []) frag1 = concat ( "s1" : "<foo>" : "<bar>" : "s2" : "<evil>" : "s3" : "<baz>" : "s4" : "</baz>" : "s5" : "</evil>" : "s6" : "</bar>" : "</foo>" : "s7" : []) result1 = concat ( "s1" : "<foo>" : "<bar>" : "s2s3" : "<baz>" : "s4" : "</baz>" : "s5s6" : "</bar>" : "</foo>" : "s7" : []) frag2 = concat ( "s1" : "<foo>" : "s2" : "<evil>" : "s3" : "</evil>" : "<bar>" : "s4" : "<evil>" : "s5" : "<baz>" : "s6" : "<bar>" : "s7" : "</bar>" : "</baz>" : "s8" : "<bar>" : "s9" : "</bar>" : "</evil>" : "s10" : "</bar>" : "</foo>" : "s11" : []) result2 = concat ( "s1" : "<foo>" : "<bar>" : "s4" : "<evil>" : "s5" : "<baz>" : "s6" : "<bar>" : "s7" : "</bar>" : "</baz>" : "s8" : "<bar>" : "s9" : "</bar>" : "</evil>" : "s10" : "</bar>" : "</foo>" : "s11" : [])

1 0

Re: Re: [Haskell-cafe] [Haskell-beginners] appropriateness of haskell for GUIs
by Sanny Sanoff 23 Mar '09

23 Mar '09

Brandon S. Allbery KF8NH wrote: > > > Glade works fine if all you want is to place widgets; but it won't > generate template code in Haskell (it will for C and C++) to connect > the widgets together, which is what I understand from "you have to > type everything yourself". > > I use Template Haskell to extract information from .glade files and produce some haskell glue on the fly. So you need to declare stuff only once (in glade file). Regards, San. -- View this message in context: http://www.nabble.com/Re%3A--Haskell-beginners--appropriateness-of-haskell-… Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.

1 0

Re: [Haskell-cafe] Haskell syntax highlighting support for Trac
by Patai Gergely 23 Mar '09

23 Mar '09

I'm not sure what your problem is. I downloaded Trac not long ago, and Haskell highlighting worked out of the box for me after installing Pygments. Here's the proof (this is the wiki of a course I'm teaching): http://kfarkas.iit.bme.hu/trac/bfp/wiki/EloadasAbsztrakciok1 The code to activate it is the following: {{{ #!hs main = print "Hello world!" }}} Gergely -- http://www.fastmail.fm - One of many happy users: http://www.fastmail.fm/docs/quotes.html

2 1

Re: [Haskell-cafe] Ease of Haskell development on OS X?
by Ross Mellgren 23 Mar '09

23 Mar '09

(back to the list) Answers inline: On Mar 21, 2009, at 2:42 PM, Colin Adams wrote: > Yes, that was the problem, and swapping the PATH order does the trick. > Thanks. no prob. > I must still have the macports stuff installed. Can you tell me how to > get rid of it? if you really want to get rid of it I believe you just have to rm -rf / opt/local and remove any initialization hooks for /opt/local out of / etc/profile and ~/.bash_profile > However I still can't install my program - I get missing dependencies > for gtk glib cairo and svgcairo. I'm not really that savvy with the package registration magics -- on my system after doing sudo make install for gtk2hs, I get the packages properly registered. You can check the registered packages with ghc- pkg list. It could be that the package is registered local for your user, but the cabal install line you're using for the application includes --global (or your cabal configuration) so it won't look in the user config. I think Duncan answered some questions about this same problem recently, though I don't have a mailing list reference. > I tried some of the gtk2hs demos - they work, but, for instance, the > actionmenu demo does not put the menus up at the top of the screen, so > it doesn't look like the framework integration has worked. Even with the integration everything is still GTK-ish. There's a separate framework that comes with the .dmg called ige-mac-integration that allows applications to meld with the mac environment better, but no gtk2hs bindings for this exist at the moment. Bindings would have to be created, and then you'd have to modify the application to make use of them (presumably with CPP or similar switch to control whether you want mac support, or just plain GTK) -Ross > 2009/3/21 Ross Mellgren <rmm-haskell(a)z.odi.ac>: >> I think there must be a version inconsistency with your GLib >> framework -- >> either not the most recent copy of the GTK+ DMG, or your path is >> flipped >> around and you're using a ports version. >> >> Run glib-mkenums --version to see what version you have... I have >> >> rmm@Hugo:~/tmpgtk/GLib.framework/Resources/dev/bin$ ./glib-mkenums >> --version >> glib-mkenums version glib-2.18.1 >> glib-mkenums comes with ABSOLUTELY NO WARRANTY. >> You may redistribute copies of glib-mkenums under the terms of >> the GNU General Public License which can be found in the >> GLib source package. Sources, examples and contact >> information are available at http://www.gtk.org >> >> Particularly, the error you're getting is because your version of >> glib-mkenums doesn't expand @ENUMPREFIX@ -- if I run glib-mkenums >> with no >> arguments, my version reports @ENUMPREFIX@ as a valid subtitution: >> >> rmm@Hugo:~/tmpgtk/GLib.framework/Resources/dev/bin$ ./glib-mkenums >> Usage: glib-mkenums [options] [files...] >> --fhead <text> output file header >> --fprod <text> per input file production >> --ftail <text> output file trailer >> --eprod <text> per enum text (produced prior to value >> itarations) >> --vhead <text> value header, produced before iterating >> over >> enum values >> --vprod <text> value text, produced for each enum value >> --vtail <text> value tail, produced after iterating >> over enum >> values >> --comments <text> comment structure >> --template file template file >> -h, --help show this help message >> -v, --version print version informations >> Production text substitutions: >> @EnumName@ PrefixTheXEnum >> @enum_name@ prefix_the_xenum >> @ENUMNAME@ PREFIX_THE_XENUM >> @ENUMSHORT@ THE_XENUM >> @ENUMPREFIX@ PREFIX >> @VALUENAME@ PREFIX_THE_XVALUE >> @valuenick@ the-xvalue >> @type@ either enum or flags >> @Type@ either Enum or Flags >> @TYPE@ either ENUM or FLAGS >> @filename@ name of current input file >> >> >> Does yours? >> >> You might try moving /Library/Frameworks/GLib.framework/Resources/ >> dev/bin to >> the front of your path before make'ing pango -- >> >> cd pango-1.24.0 >> export PATH=/Library/Frameworks/GLib.framework/Resources/dev/bin: >> $PATH >> make >> >> Hope this helps, >> >> -Ross >> >> On Mar 21, 2009, at 1:52 PM, Colin Adams wrote: >> >>> Attached. >>> >>> >>> >>> 2009/3/21 Ross Mellgren <rmm-haskell(a)z.odi.ac>: >>>> >>>> (taking this off list, to avoid noise) >>>> >>>> Could you attach pango-1.24.0/pango/pango-enum-types.h? Something >>>> hokey >>>> is >>>> going on -- this file is shipped with pango-1.24.0 but may be >>>> overwritten >>>> if >>>> your glib-mkenums does it differently. In any case, since it's >>>> (possibly) >>>> machine generated I would have to see what's going on at those >>>> lines to >>>> make >>>> progress. >>>> >>>> Also, if you could cd pango-1.24.0/pango, and run: >>>> >>>> gcc -E -DHAVE_CONFIG_H -I. -I.. -DG_LOG_DOMAIN=\"Pango\" >>>> -DPANGO_ENABLE_BACKEND -DPANGO_ENABLE_ENGINE >>>> -DSYSCONFDIR=\"/usr/local/etc\" >>>> -DLIBDIR=\"/usr/local/lib\" -I.. -DG_DISABLE_CAST_CHECKS >>>> -I/Library/Frameworks/GLib.framework/Headers >>>> -I/Library/Frameworks/Cairo.framework/Headers -I/usr/X11/ >>>> include >>>> -DFC_WEIGHT_EXTRABLACK=215 -Wall -MT fonts.lo -MD -MP -MF >>>> .deps/fonts.Tpo >>>> -c -o fonts.i fonts.c >>>> >>>> and attach fonts.i, that might shed more light. However, since >>>> the error >>>> you're getting is a preprocessor one, gcc -E may fail as well. >>>> >>>> -Ross >>>> >>>> On Mar 21, 2009, at 1:37 PM, Colin Adams wrote: >>>> >>>>> In file included from ../pango/pango.h:31, >>>>> from pango-impl-utils.h:28, >>>>> from fonts.c:30: >>>>> ../pango/pango-enum-types.h:12:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:14:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:17:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:19:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:22:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:25:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:27:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:29:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:31:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:33:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:36:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:38:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:41:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:43:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:45:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:48:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:51:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:54:9: error: macro names must be >>>>> identifiers >>>>> In file included from ../pango/pango.h:31, >>>>> from pango-impl-utils.h:28, >>>>> from glyphstring.c:26: >>>>> ../pango/pango-enum-types.h:12:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:14:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:17:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:19:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:22:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:25:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:27:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:29:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:31:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:33:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:36:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:38:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:41:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:43:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:45:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:48:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:51:9: error: macro names must be >>>>> identifiers >>>>> ../pango/pango-enum-types.h:54:9: error: macro names must be >>>>> identifiers >>>>> >>>>> >>>>> 2009/3/21 Ross Mellgren <rmm-haskell(a)z.odi.ac>: >>>>>> >>>>>> I didn't get any errors like that (nor do I remember ever >>>>>> having them), >>>>>> though if you want to paste them here maybe I can help with them. >>>>>> >>>>>> -Ross >>>>>> >>>>>> On Mar 21, 2009, at 1:27 PM, Colin Adams wrote: >>>>>> >>>>>>> If I try this, pango fails to compile with lots of error >>>>>>> messages >>>>>>> about error: macro names must be identifiers. >>>>>>> >>>>>>> I think I've seen this before - some well-known Mac OSX >>>>>>> problem? (I'm >>>>>>> a linux man myself - so I'm not used to the mac) >>>>>>> >>>>>>> 2009/3/21 Ross Mellgren <rmm-haskell(a)z.odi.ac>: >>>>>>>> >>>>>>>> I tried making this work, but librsvg requires pango, and >>>>>>>> pango is a >>>>>>>> huge >>>>>>>> pain in the ass -- I managed to get the whole thing to >>>>>>>> compile, but >>>>>>>> now >>>>>>>> it >>>>>>>> can't find any fonts, apparently due to some dynaloading >>>>>>>> issues. >>>>>>>> >>>>>>>> I think if you need any of the extended modules (e.g. >>>>>>>> svgcairo, gl) >>>>>>>> that >>>>>>>> the >>>>>>>> DMG doesn't directly support then you're best served by >>>>>>>> shedding a >>>>>>>> couple >>>>>>>> tears and going with macports. >>>>>>>> >>>>>>>> The steps I used to get the broken version were (FYI -- doing >>>>>>>> this >>>>>>>> causes >>>>>>>> all fonts to load as the no-character square in all gtk2hs >>>>>>>> apps): >>>>>>>> >>>>>>>> export >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> PKG_CONFIG_PATH=/usr/X11/lib/pkgconfig:/usr/local/lib/ >>>>>>>> pkgconfig:/Library/Frameworks/Cairo.framework/Resources/dev/ >>>>>>>> lib/pkgconfig:/Library/Frameworks/GLib.framework/Resources/ >>>>>>>> dev/lib/pkgconfig:/Library/Frameworks/Gtk.framework/Resources/ >>>>>>>> dev/lib/pkgconfig >>>>>>>> >>>>>>>> export >>>>>>>> PATH=$PATH:/Library/Frameworks/GLib.framework/Resources/dev/bin >>>>>>>> >>>>>>>> cd pango-1.24.0 >>>>>>>> CFLAGS="-DFC_WEIGHT_EXTRABLACK=215" ./configure --prefix=/usr/ >>>>>>>> local >>>>>>>> make -j4 >>>>>>>> sudo make install >>>>>>>> >>>>>>>> cd librsvg-2.26.0 >>>>>>>> ./configure --prefix=/usr/local >>>>>>>> make -j4 >>>>>>>> sudo make install >>>>>>>> >>>>>>>> cd gtk2hs-0.10.0 >>>>>>>> ./configure --disable-gio >>>>>>>> make -j4 >>>>>>>> sudo make install >>>>>>>> >>>>>>>> Running apps linked with this version of gtk2hs gets: >>>>>>>> >>>>>>>> (svgviewer:43314): Pango-CRITICAL **: No modules found: >>>>>>>> No builtin or dynamically loaded modules were found. >>>>>>>> PangoFc will not work correctly. >>>>>>>> This probably means there was an error in the creation of: >>>>>>>> '/usr/local/etc/pango/pango.modules' >>>>>>>> You should create this file by running: >>>>>>>> pango-querymodules > '/usr/local/etc/pango/pango.modules' >>>>>>>> >>>>>>>> (svgviewer:43314): Pango-WARNING **: failed to choose a font, >>>>>>>> expect >>>>>>>> ugly >>>>>>>> output. engine-type='PangoRenderATSUI', script='latin' >>>>>>>> >>>>>>>> So if anyone knows what Pango is trying to do, maybe they >>>>>>>> could help >>>>>>>> resolve >>>>>>>> this. >>>>>>>> >>>>>>>> I'm probably going to ditch the use of GTK in my own project >>>>>>>> and use >>>>>>>> FFI >>>>>>>> bindings to Carbon/Win32, since I don't really need widgets >>>>>>>> for my >>>>>>>> own >>>>>>>> stuff >>>>>>>> and the whole family of GTK related packages is a total pain >>>>>>>> in the >>>>>>>> ass >>>>>>>> (as >>>>>>>> are most things in the GNU family of software, IMO) >>>>>>>> >>>>>>>> -Ross >>>>>>>> >>>>>>>> On Mar 21, 2009, at 10:13 AM, Colin Paul Adams wrote: >>>>>>>> >>>>>>>>>>>>>> "Ross" == Ross Mellgren <rmm-haskell(a)z.odi.ac> writes: >>>>>>>>> >>>>>>>>> Ross> While there is not a .dmg for Gtk2Hs, you can use >>>>>>>>> a .dmg >>>>>>>>> Ross> installed GHC with a .dmg installed Gtk, and then build >>>>>>>>> Ross> gtk2hs straight on top of that, without having to >>>>>>>>> deal with >>>>>>>>> Ross> the dual-GHC macports mess.. >>>>>>>>> >>>>>>>>> Ross> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> http://www.haskell.org/haskellwiki/Gtk2hs#Using_the_GTK.2B_OS_X_Framework >>>>>>>>> >>>>>>>>> I just tried this. >>>>>>>>> >>>>>>>>> The configure enables cairo, but does not enable svgcairo. >>>>>>>>> Is there >>>>>>>>> anyway round this, or do I have to revert to the macports >>>>>>>>> gtk? (my >>>>>>>>> application uses svgcairo) >>>>>>>>> -- >>>>>>>>> Colin Adams >>>>>>>>> Preston Lancashire >>>>>>>> >>>>>>>> _______________________________________________ >>>>>>>> Haskell-Cafe mailing list >>>>>>>> Haskell-Cafe(a)haskell.org >>>>>>>> http://www.haskell.org/mailman/listinfo/haskell-cafe >>>>>>>> >>>>>> >>>>>> >>>> >>>> >>> <pango-enum-types.h> >> >>

5 19

about beta NF in lambda calculus
by Algebras Math 22 Mar '09

22 Mar '09

hi, What is the different between 'in beta normal form' and 'has beta normal form' ? Does the former means the current form of the term is already in normal form but the latter means that it is not a normal form yet and can be reduced to be normal form? Like \x.x is in NF and (\x.x) (\x.x) has NF? If above is true, I am confused why we have to distinguish the terms which have NF and be in NF? isn't the terms have NF will eventually become in NF? or there are some way to avoid them becoming in NF? Thanks Alg

5 5

ANN: regex-tdfa 1.1.1
by ChrisK 22 Mar '09

22 Mar '09

This is both a bug fix release and a feature release. The bug fix is a bit embarrassing, the indices were correct but the captured text was wrong in version 1.1.0. Oops. As of version 1.1.1 the following GNU extensions are recognized, all anchors: \` at beginning of entire text \' at end of entire text \< at beginning of word \> at end of word \b at either beginning or end of word \B at neither beginning nor end of word There is a "newSyntax" field of CompOptions that can enable/disable this syntax. These were requested by users of the Yi project. The "home page" is on the wiki and UPDATED a bit at http://haskell.org/haskellwiki/Regular_expressions#regex-tdfa The HADDOCK fails on hackage for now, but is up at http://darcs.haskell.org/packages/regex-unstable/regex-tdfa/doc/html/regex-… The released code is on hackage at http://hackage.haskell.org/cgi-bin/hackage-scripts/package/regex-tdfa The darcs repository is at http://darcs.haskell.org/packages/regex-unstable/regex-tdfa/ Cheers, Chris

1 0

Completely confused by cabal
by Colin Paul Adams 22 Mar '09

22 Mar '09

[colin@susannah ghc]$ ghc-pkg list /usr/local/lib/ghc-6.11.20090319/./package.conf: Cabal-1.7.0, array-0.2.0.1, base-3.0.3.0, base-4.0.0.0, bytestring-0.9.1.4, containers-0.2.0.1, directory-1.0.0.2, (dph-base-0.4.0), (dph-par-0.4.0), (dph-prim-interface-0.4.0), (dph-prim-par-0.4.0), (dph-prim-seq-0.4.0), (dph-seq-0.4.0), editline-0.2.1.0, ffi-1.0, filepath-1.1.0.1, gconf-0.10.0, (ghc-6.11.20090319), ghc-prim-0.1.0.0, gio-0.10.0, glib-0.10.0, haskell98-1.0.1.0, hpc-0.5.0.2, integer-0.1.0.0, old-locale-1.0.0.1, old-time-1.0.0.1, packedstring-0.1.0.1, pretty-1.0.1.0, process-1.0.1.1, random-1.0.0.1, rts-1.0, syb-0.1.0.0, template-haskell-2.3.0.0, unix-2.3.1.0 /home/colin/.ghc/x86_64-linux-6.11.20090319/package.conf: EdisonAPI-1.2.1, EdisonCore-1.2.1.3, HUnit-1.2.0.3, QuickCheck-1.2.0.0, cairo-0.10.0, game-tree-0.1.0.0, gconf-0.10.0, gio-0.10.0, glade-0.10.0, glib-0.10.0, gnomevfs-0.10.0, gstreamer-0.10.0, gtk-0.10.0, gtkglext-0.10.0, mozembed-0.10.0, mtl-1.1.0.2, parallel-1.1.0.0, parsec-2.1.0.1, parsec-3.0.0, soegtk-0.10.0, sourceview-0.10.0, svgcairo-0.10.0, time-1.1.2.3 [colin@susannah ghc]$ su -c 'cabal install parsec --global' Password: Warning: The package list for 'hackage.haskell.org' does not exist. Run 'cabal update' to download it. cabal: There is no package named parsec [colin@susannah ghc]$ su -c 'cabal install parsec-2.0.0 --global' Password: Warning: The package list for 'hackage.haskell.org' does not exist. Run 'cabal update' to download it. cabal: There is no package named parsec [colin@susannah ghc]$ cabal update Downloading the latest package list from hackage.haskell.org [colin@susannah ghc]$ su -c 'cabal install parsec-2.0.0 --global' Password: Warning: The package list for 'hackage.haskell.org' does not exist. Run 'cabal update' to download it. cabal: There is no package named parsec [colin@susannah ghc]$ cabal update --global unrecognized option `--global' Why does cabal install nearly everything in the user repository rather than the global repository? -- Colin Adams Preston Lancashire

4 11

Haskell syntax highlighting support for Trac
by Manlio Perillo 22 Mar '09

22 Mar '09

Hi. I have noted that with Haskell projects that make use of Trac for issue tracking, it is not possible to have syntax highlighting for Haskell code. http://hackage.haskell.org/trac/hackage/wiki/WikiProcessors Is someone working on this? I can try to write a Trac plugin or patch to solve this. Manlio

1 0

Google Summer of Code: Is this idea useful for the community?
by fallintothis 22 Mar '09

22 Mar '09

I'm planning on applying for the Google Summer of Code and the more I think about it, the more excited I am over a Haskell reddit-alike[1]. I'm interested in web programming, Haskell, and reddit (being an addict for some years now). There's plenty of work to be done on such a project, there are existing code bases to help along with ideas, and it doesn't require the deepest knowledge of Haskell or, say, GHC's guts (not that I don't find those interesting, I'm just no expert). The hang-up I see is that there's not too much of an immediate community benefit if reddit already exists (which, I have on good authority, it does), other than in the interest of eating (or customizing) your own dog food. Any members of the Haskell community (more involved than I am) care to comment? Would the project be useful or otherwise good as a Summer of Code idea? If people don't get too sick of my pestering, I'm also considering opening it up as a ticket on the trac to see if it gets feedback there. Thanks! [1] http://www.reddit.com/r/haskell_proposals/comments/7u48x/a_simple_redditlik…

2 1