- Haskell-Cafe - Haskell.org

Cabal and linking with static libs (.a files)
by Ketil Malde 28 Jun '06

28 Jun '06

(Reposted to café - my -libraries mail seems to have gotten lost along the way) Hi, I'm building an interface to a C library, which comes in the form of two .a files. I can't seem to get Cabal to link statically with these, so that the resulting package (libHSfoo-v.v.a) is self contained. I've tried fiddling with Cabal's ld-options and extra-libraries, but so far with no success - loading my package either results in GHC looking for (and failing to find) .so files, or "unknown symbol". Help? -k PS: did --user stop working (with GHC 20060607)? I'm adding --user to both 'configure' and 'install', but Cabal still wants to put things in /usr/local. -- If I haven't seen further, it is by standing in the footprints of giants

2 6

Are FunPtr's stable? (was: how to write an haskell binding)
by Brian Hulley 28 Jun '06

28 Jun '06

Bulat Ziganshin wrote: > Hello Brian, > > Tuesday, June 27, 2006, 2:43:15 AM, you wrote: > >> achieve a goal. One other thing to bear in mind is that foreign >> calls are extremely slow, so for example it is much faster to use the >> Foreign.Marshal.Array and Foreign.C.String functions to allocate and >> populate a temporary array with the contents of a list, and send the >> pointer to this array to C with one foreign call, than to send each >> element of the list with multiple foreign calls (eg to paste only >> 19K of text from the Windows clipboard to my app took over 1 >> minute!!! > > he-he-he :) just add "unsafe" specifier: Thanks Bulat! It turns out nearly every foreign function I'm using doesn't make callbacks into Haskell so can be marked "unsafe" so your solution has saved me an enormous amount of refactoring... :-) On a related note, as I was reading the FFI specification again, I can't find any mention of whether or not FunPtr's are stable with respect to garbage collection. I'm assuming they are but am I correct? Thanks, Brian. -- Logic empowers us and Love gives us purpose. Yet still phantoms restless for eras long past, congealed in the present in unthought forms, strive mightily unseen to destroy us. http://www.metamilk.com

3 4

closures with side effects
by tpledger＠ihug.co.nz 28 Jun '06

28 Jun '06

dkarapet wrote: > I have been trying to understand closures > in haskell and how they relate > to side effects. I have been looking > around but all I find are trivial > examples with no side effects. Please let > me know if you know of any examples. The side effects occur in the context that causes the closure to be entered. Here's a nigh-trivial example. myClosure :: IO () myClosure = putStrLn "Hello, world." main = myClosure >> myClosure When myClosure is defined, the side effect doesn't occur yet. We just have a *definition* of an IO action that hasn't yet been bound into the program's sequence of actions. When main binds myClosure into the program's sequence of actions (twice), the side effect occurs (twice). Depending on the implementation of putStrLn, it may be faster the second time because the same closure has been entered before. HTH, Tom

1 0

Re: [Haskell] Google SoC: Software Transactional Memory for Parrot
by John Meacham 28 Jun '06

28 Jun '06

On Tue, Jun 27, 2006 at 08:29:21AM -0700, Jared Updike wrote: > >Am I the only one whose first instinct upon reading this is "EW!"? > > You are not the only one, judging from my own experience. I made my > own sort of algebraic datatypes / abstract datatypes in C# by using > Enums and Objects and runtime casts. It works, but the code itself is > hairy. I guess the good news is that once I built the ADT the---in my > case, ugly---implementation is hidden. When I first started using Haskell Sather was my language of choice. As I learned Haskell and all it's cool features I kept wanting to "backport" them to Sather... Algebraic data types was one of the things I proposed to the sather community, a wacky idea for an OO language of sathers heritage. but it was not long after then that I realized I should just be using Haskell to begin with and redirected my efforts here. :) John -- John Meacham - ⑆repetae.net⑆john⑈

1 0

Re: Haskell-Cafe Digest, Vol 34, Issue 45
by Jason Dagit 27 Jun '06

27 Jun '06

On 6/27/06, Jeremy O'Donoghue <jeremy.odonoghue(a)gmail.com> wrote: > Hi Jason. > > My $0.02 > > On 27/06/06, haskell-cafe-request(a)haskell.org > <haskell-cafe-request(a)haskell.org> wrote: > > ---------- Forwarded message ---------- > > From: "Jason Dagit" <dagit(a)eecs.oregonstate.edu> > > > Requirements: > > Okay, so now that you know why I'm here, let me give you an idea of > > what my *ideal* GUI library would be for this project (roughly in > > order of importance): > > 1) Doesn't require the end user to install anything (no dependencies) > > 2) Looks and feels like windows > > 3) Robust (or mature) > > 4) A pleasure to program (boo @ swing) > > 5) ?? > > > > I don't really know the landscape, but this is my (uneducated) idea of > > my options: > > A) wxWidgets > > B) gtk2hs > > C) win32 api > > D) write the gui in C or C++ and use the FFI to invoke it > > E) write the gui in scala or java and use FFI + JNI to invoke it > > F) ?? you tell me > > > > I think (although I have yet to verify) that (A) satisfies #1-4, but > > (B) doesn't satisfy #1. Is this true? I tried to install wxHaskell > > but it turned out to be a real pain. I'm using visual haskell so that > > I have COM support (I need the version of H/Direct that ships with > > VisualHaskell and VisuallHaskell only ships with ghc 6.5) and that > > means I have to compile the less mainstream haskell libraries myself. > > I have yet to successfully install wxHaskell on my dev machine at > > work. > > I've developed a couple of projects with wxHaskell, along with a > couple using the lablGtk2 library for Ocaml - in fact, the whole > clunkiness and lack of Windows and (especially) Mac native feel of GTK > on non-Linux platforms is a large part of what brought me to Haskell > :-) > > My applications are mainly for internal use at my workplace, and come > with Windows installers (I use Inno setup with wxHaskell - never > managed to make it work with GTK2, so these applications were > delivered as zip files which just had to be unzipped in a certain > place). Do you have any advice about using Inno with haskell? Have you tried wix at all? http://sourceforge.net/projects/wix/ Maybe you have a developer blog I could read? > To distribute wxHaskell applications you need only two DLLs and an > executable. All can be in the same directory. I think this covers 1) Yes, I would say that's almost ideal. (Ideally the user wouldn't even have to install my progam it would 'just work' ;) > Look and feel is Windows native. As an added bonus (for me, at least) > it also looks native on Mac and Linux. That's 2) Yes, I've used wxPython in the past very successfully. It's fast, easy to use, tends to look right. (in my narrow opinion) > wxHaskell is fairly robust, but you need to be aware that it does not > have complete coverage of the wxWindows library. I have found layout > behaviour to be incomprehensible at times (although I found this to be > somewhat true of the native wxWindows sizers on which layout is > built). Some of the more exotic widgets (Scintilla, wxGrid) are either > not wrapped, or the wrapping is incomplete. I have not succeeded, in > the general case, in getting sash wiondows to work as I would like > them to (it's possible for some limiting cases, but that is not enough > for my needs) Hmm...Yes I've fought extensively with the layout managers for Java that come with the Net Beans IDE. I think using a layout manager is a great idea, but then I'll spend several hours fighting with getting just one screen to layout correctly and never want to use layout managers again. Perhaps I'm just dense, but the Matisse gui builder in Net Beans is really frustrating for me. > My impression, sadly, is that little development now goes on on > wxHaskell. The last compiled binaries available from the website are > over a year old now and, as you've already discovered, it's really > quite difficult to get wxHaskell to compile on Windows. For what it's > worth, I gave up on 2.6.x and reverted to 2.4.2, which compiled > cleanly for me. I took a hint here and downloaded 2.4.2, followed the instructions to the letter and got things almost working. It seems that I had spaces in my paths. VisualHaskell installed to: C:\Program Files\Visual Haskell When I came to the step of compiling wxHaskell I needed to run configure with these options: ./configure --libdir=C:/Progra~1/Visual~1 The two important things here are: 1) You must use the forward slash and 2) you cannot use spaces. After it installed I started getting panics from 'ghc -package wx': http://www.haskell.org/pipermail/glasgow-haskell-bugs/2005-October/005632.h… And I found a solution here: http://www.haskell.org/pipermail/glasgow-haskell-bugs/2005-October/005639.h… Next I found that I needed to add C:\Program Files\Visual Haskell to my path so that the wxHaskell dlls could be located by windows. Now I'm at the point where I can compile and run wxHaskell programs (yay!). > > Because of the appearance that it's withering on the vine, I would be > reluctant to recommend wxHaskell. However, despite the gripes above, I > think it's a superb piece of work. I have managed to produce some very > high performance applications with it - users assumed that I had > written in hand-optimized C (FastPackedStrings also had a big hand in > the performance). If the project were better documented, I really > believe that there's a chance that the project would take off. As an > example, I easily have the knowledge of C/C++ needed to contribute, > and the Haskell is getting there, but the (lack of) documentation > makes it hard for the end user at times - let alone the wannabe > developer. When I used wxPython I was often referencing the C++ docs and I didn't mind as I'm reasonably fluent in C++. So (hopefully) this will not slow me down when using wxHaskell. > wxHaskell programming is something of a mix of Haskell idioms (layout, > in particular) and C style imperative programming (in IO monad). In > some respects the UI code looks quite similar to wxPython, but at > least you get Haskell goodness for everything else. This is a big > plus. This is something I'm looking forward to. A little bit of not-as-pretty Haskell with lots of typical Haskell to support it. I think it will make my project fun to work on as well as giving me certain bonuses in the software engineering department (go referential transparency!). [snipped testimonials about gtk2hs] Thanks for the info about gtk2hs. I feel like GTK is great and I would gladly use it on an open source project but I think given my target audience and my requirements it's not right for this project. > > I can't really comment on your other potential solutions. Hopefully I won't need them now :) Thanks, this was very helpful, Jason

1 0

Re: Haskell-Cafe Digest, Vol 34, Issue 45
by Jeremy O'Donoghue 27 Jun '06

27 Jun '06

Hi Jason. My $0.02 On 27/06/06, haskell-cafe-request(a)haskell.org <haskell-cafe-request(a)haskell.org> wrote: > ---------- Forwarded message ---------- > From: "Jason Dagit" <dagit(a)eecs.oregonstate.edu> > Requirements: > Okay, so now that you know why I'm here, let me give you an idea of > what my *ideal* GUI library would be for this project (roughly in > order of importance): > 1) Doesn't require the end user to install anything (no dependencies) > 2) Looks and feels like windows > 3) Robust (or mature) > 4) A pleasure to program (boo @ swing) > 5) ?? > > I don't really know the landscape, but this is my (uneducated) idea of > my options: > A) wxWidgets > B) gtk2hs > C) win32 api > D) write the gui in C or C++ and use the FFI to invoke it > E) write the gui in scala or java and use FFI + JNI to invoke it > F) ?? you tell me > > I think (although I have yet to verify) that (A) satisfies #1-4, but > (B) doesn't satisfy #1. Is this true? I tried to install wxHaskell > but it turned out to be a real pain. I'm using visual haskell so that > I have COM support (I need the version of H/Direct that ships with > VisualHaskell and VisuallHaskell only ships with ghc 6.5) and that > means I have to compile the less mainstream haskell libraries myself. > I have yet to successfully install wxHaskell on my dev machine at > work. I've developed a couple of projects with wxHaskell, along with a couple using the lablGtk2 library for Ocaml - in fact, the whole clunkiness and lack of Windows and (especially) Mac native feel of GTK on non-Linux platforms is a large part of what brought me to Haskell :-) My applications are mainly for internal use at my workplace, and come with Windows installers (I use Inno setup with wxHaskell - never managed to make it work with GTK2, so these applications were delivered as zip files which just had to be unzipped in a certain place). To distribute wxHaskell applications you need only two DLLs and an executable. All can be in the same directory. I think this covers 1) Look and feel is Windows native. As an added bonus (for me, at least) it also looks native on Mac and Linux. That's 2) wxHaskell is fairly robust, but you need to be aware that it does not have complete coverage of the wxWindows library. I have found layout behaviour to be incomprehensible at times (although I found this to be somewhat true of the native wxWindows sizers on which layout is built). Some of the more exotic widgets (Scintilla, wxGrid) are either not wrapped, or the wrapping is incomplete. I have not succeeded, in the general case, in getting sash wiondows to work as I would like them to (it's possible for some limiting cases, but that is not enough for my needs) My impression, sadly, is that little development now goes on on wxHaskell. The last compiled binaries available from the website are over a year old now and, as you've already discovered, it's really quite difficult to get wxHaskell to compile on Windows. For what it's worth, I gave up on 2.6.x and reverted to 2.4.2, which compiled cleanly for me. Because of the appearance that it's withering on the vine, I would be reluctant to recommend wxHaskell. However, despite the gripes above, I think it's a superb piece of work. I have managed to produce some very high performance applications with it - users assumed that I had written in hand-optimized C (FastPackedStrings also had a big hand in the performance). If the project were better documented, I really believe that there's a chance that the project would take off. As an example, I easily have the knowledge of C/C++ needed to contribute, and the Haskell is getting there, but the (lack of) documentation makes it hard for the end user at times - let alone the wannabe developer. In short, I'm not sure about 3). wxHaskell programming is something of a mix of Haskell idioms (layout, in particular) and C style imperative programming (in IO monad). In some respects the UI code looks quite similar to wxPython, but at least you get Haskell goodness for everything else. This is a big plus. Back in the day when I was using the Ocaml GTK2 binding, the following observations were true. I suspect they may be true of GTK2Hs (as they are mainly observations on GTK2 on Windows per se), but I am not certain. Installation of GTK2 on Windows is nothing short of revolting. It's a completely manual set of 'work out which DLL or library to download from where and install it in a suitable directory. Building from source is worse. I never managed to work out a small, sane set of DLLs which could just be packaged with the executable I was delivering. It may be possible, but I didn't manage it. That's a fail on 1), I suspect. Look and feel is adequate on Windows, for the most part. However, the file dialog, in particular, caused my users (mainly engineers, so pretty switched on, on the whole) no end of confusion, and was a major driver to my dropping Ocaml for this type of work. That's a failure on 2), at least for me. However, in its defence, GTK2 is stable and capable on Windows. I also have the impression that GTK2Hs is much more actively developed than wxHaskell, and this may be a good reason to choose it if what you are producing is a prototype which will not have wide distribution. I think you'd have to give GTK2Hs a good rating for 3). I can't really comment on your other potential solutions. Regards Jeremy

1 0

RE: [Haskell-cafe] A question about stack overflow
by voigt.16734551＠bloglines.com 27 Jun '06

27 Jun '06

--- Huazhi (Hank) Gong" <hankgong(a)nm.gist.ac.kr wrote: > Thank you very much for introducing tail recursion. > It's my first time to hear this. :) > However, I'm wondering whether every loop structure from C like language can > be translated to this kind of tail recursion? Yes, as discovered by John McCarthy almost 50 years ago in "Recursive functions of symbolic expressions and their computation by machine. Communications of the ACM, 3:184-195, 1960". Ciao, Janis Voigtlaender.

1 0

[GHC/Base.A_o] Error 1
by gaa＠cin.ufpe.br 27 Jun '06

27 Jun '06

Anyone can help me? I did some changes in the .mk and makefile files in order to integrate it with the Haskell.NET code generator but when I try to compile the following error appears: ../../ghc/compiler/ghc-inplace -H32m -O -W -fno-warn-unused-matches > -fwarn-unuse > d-imports -fglasgow-exts -cpp -Iinclude -#include HsBase.h -Icbits/regex > -funbox > -strict-fields -package-name base -O -dcore-lint -W > -fno-warn-unused-matches -fw > arn-unused-imports -fglasgow-exts -keep-msil-files -fvia-il -hisuf A_hi > -hcsuf > A_hc -osuf A_o -fvia-il -keep-msil-file -c GHC/Base.lhs -o GHC/Base.A_o > -ohi > GHC/Base.A_hi > GHC/Base.lhs:296: parse error on input `.' > make[3]: *** [GHC/Base.A_o] Error 1 > make[2]: *** [all] Error 1 > make[1]: *** [all] Error 1 > make[1]: Leaving directory `/cygdrive/c/Guilherme/ghc-6.2.2/libraries' > make: *** [build] Error 1 > > > > Thanks, Guilherme A. Avelino

2 1

Win32 GUI bindings
by Jason Dagit 27 Jun '06

27 Jun '06

I'm looking for recommendations (testimonials?) for GUI libraries for haskell (ghc 6.5) on the win32 platform that meet my requirements below. But first, I try to motivate my question. Bit of background: I work at a smallish software company and I've been given a project where I'm supposed to create a prototype which will later be scraped and a new version will be written that is part of our main product. The prototype will only ever run on windows and it will be distributed to customers for a year or two before it is assimilated. I've used python a bit to prototype the prototype and figure out some of the basics. I'll need a small GUI (maybe one or two dialogs), an XML library, a few small parsers and COM support. I was going to put Haskell back on the shelf and use either python or scala for this project because of the COM requirement but just today I made a major breakthrough with H/Direct and it looks like Haskell is back in the running. So far I plan to use HaXml, parsec and H/Direct but I still need some way to create a gui. This project is fairly representative of all the work we do at my company so I feel if I find a good solution this time it's probably what I'll focus on using in the future. That's part of the reason I'm trying out python, Haskell and scala. (Perhaps the real reason is just that I like playing with languages ;). Requirements: Okay, so now that you know why I'm here, let me give you an idea of what my *ideal* GUI library would be for this project (roughly in order of importance): 1) Doesn't require the end user to install anything (no dependencies) 2) Looks and feels like windows 3) Robust (or mature) 4) A pleasure to program (boo @ swing) 5) ?? I don't really know the landscape, but this is my (uneducated) idea of my options: A) wxWidgets B) gtk2hs C) win32 api D) write the gui in C or C++ and use the FFI to invoke it E) write the gui in scala or java and use FFI + JNI to invoke it F) ?? you tell me I think (although I have yet to verify) that (A) satisfies #1-4, but (B) doesn't satisfy #1. Is this true? I tried to install wxHaskell but it turned out to be a real pain. I'm using visual haskell so that I have COM support (I need the version of H/Direct that ships with VisualHaskell and VisuallHaskell only ships with ghc 6.5) and that means I have to compile the less mainstream haskell libraries myself. I have yet to successfully install wxHaskell on my dev machine at work. I think that (C) is going to violate #4 and maybe #3 depending on how much code I need to write to get the bare windows api to do what I want. Plus I doubt this makes sense for a long term solution. I think (D) makes less sense than (C) and I doubt it's a nice way to do things, I'm probably better off with (C). As for (E), why don't I just do the whole thing in scala if I'm requiring the GUI to be in scala? Advice? Thanks, Jason

3 3

Simple matrix
by Atila Romero 26 Jun '06

26 Jun '06

I made a very simple matrix module that implements matrix sum and multiplication. It does not require any especific type since it uses Num [[a]]. So instead of typing something like Matrix [[1,0],[0,2]] * Matrix [[1,2],[3,4]] you can just type [[1,0],[0,2]]*[[1,2],[3,4]] It needs -fglasgow-exts Atila module SimpleMatrix where instance Num a => Num [[a]] where fromInteger x = [[fromInteger x]] abs x = map (map abs) x (+) [ ] y = y (+) x [ ] = x (+) x y = zipWith (zipWith (+)) x y (*) x y = map (matrixXvector x) y where -- matrixXvector :: Num a => [[a]] -> [a] -> [[a]] matrixXvector m v = foldl vectorsum [] $ zipWith vectorXnumber m v -- vectorXnumber :: Num a => [a] -> a -> [a] vectorXnumber v n = map (n*) v -- vectorsum :: [a] -> [a] -> [a] vectorsum [] y = y vectorsum x [] = x vectorsum x y = zipWith (+) x y _______________________________________________________ Novidade no Yahoo! Mail: receba alertas de novas mensagens no seu celular. Registre seu aparelho agora! http://br.mobile.yahoo.com/mailalertas/

8 17