January 2004 - Glasgow-haskell-users

Concurrent Haskell on Win32?
by Stefan Reich 24 Jan '04

24 Jan '04

I am confused about the state of Concurrent Haskell on Win32. I remember it didn't work in the past because of I/O blocking issues. IIRC, I actually verified this by compiling a Haskell web server on both Linux and Windows. Has this been fixed in the meantime? If not, it would be great to mention this in the GHC release notes in order to prevent people from figuring this out the hard way. Fixing concurrency would expand Haskell's potential range of applications tremendously... I'd really love to see that happen. -Stefan Reich (addicted Haskell programmer)

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Generics...(ish)
by MR K P SCHUPKE 21 Jan '04

21 Jan '04

I am currently using template haskell to generate code to work on a record data type... This however is not very pretty, and I wondered if there was another way to do what I want in GHC. I need to iterate over the contents of a record for example: data Test = Test { a :: Int, b :: String, c :: Float } If I derive Typeable, I can compare the data-type, but not decompose it, I don't know much about generics, and was wondering if I might be able to do it that way... The functionality I need is equivalent to being able to compare to instances, for example, consider the type above, and the type below: data Test2 = Test2 { x :: Int, y :: String, z :: Float, zz :: String } i need to construct a function that could output the differenc between the types, position at a time, so for the above the output would be: Test2 contains extra String field. or if "y" was to have the type Float, Position 2 : Types differ (Test has String, Test2 has Float) Test2 contains extra String field. I could do this easily if Typeable was a concrete type just by using case statements... Regards, Keean Schupke.

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RE: "Talking" with the compiler
by Simon Marlow 21 Jan '04

21 Jan '04

> Am 18.01.2004 um 11:31 schrieb Ketil Malde: > > > HNBeck(a)t-online.de (Hans Nikolaus Beck) writes: > > > >> in order to build a programming environement, it would be > nice to ask > >> the GHC about symbols etc found in a given Haskell program. > > > > I suppose a programming environment could talk to GHCi > (which provides > > commands like :type, :info, :browse to explore the currently defined > > symbols)? > > I've look shortly at the GHCi documentation. So I think it would be > possible to include a "GHC engine" into a IDE application by > redirecting input and output from GHCi to pipes (I rembemer > that emacs > used something similar for doing it's compile stuff). But that's > hardcore UNIX, I've forgot how to do that :-((( For the Visual Studio plugin we're going to need to talk to GHCi. We plan to do this by designing an appropriate API for GHCi and calling it directly; you *could* do it by talking over a pipe, but it's going to be a lot of work (and slow). If you want to do this, please talk to us about what API you'd like to see, and we can hopefully implement something that will be generally useful. Cheers, Simon

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ghc-6.2/opengl
by mai99dnn＠studserv.uni-leipzig.de 20 Jan '04

20 Jan '04

Hi there... The following problem was posted to the haskell-users list: We can not build a opengl application with hopengl. We get this error message: Linking ... Undefined first referenced symbol in file glXGetProcAddressARB /usr/local/share/ghc/lib/ghc-6.2/libHSOpenGL_cbits.a(HsOpenGL.o) glXGetProcAddressARB is a function that returns just a pointer to another function. It is used to find out what special gl features your graphiccard or mesa provides. If there isn't that feature you want, this function returns a NULL pointer. I hope I'm right so far. Our system is a "SunOS 5.8 Generic_108528-27 sun4u sparc SUNW,Ultra-60". I looked around, but I was unable to find any libglX, where this function normally appears. One way to make this all running is to write a foo-bar-glXGetProcAddressARB function that returns everytime the NULL-pointer. But how can I compile this together with the haskell source? Or must I build a *.so library? Or is there a much much easier way to solve this? Cheers Patrick -------------------------------- RockMe http://www.yoursort.de Anikas Pharmaziestudium-Seite http://www.pharmazie.net.ms

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ghc-6.2/opengl
by Johannes Waldmann 20 Jan '04

20 Jan '04

we have compiled ghc-6.2 --enable-hopengl from source (with ghc-6.0) on SunOS userv2 5.8 Generic_108528-27 sun4u sparc SUNW,Ultra-60. it installs and compiles fine but not for programs that use OpenGL: ghc --make -Wall -fglasgow-exts -package OpenGL ... we get this linker error: Linking ... Undefined first referenced symbol in file glXGetProcAddressARB /usr/local/share/ghc/lib/ghc-6.2/libHSOpenGL_cbits.a(HsOpenGL.o) any ideas? -- -- Johannes Waldmann, Tel/Fax: (0341) 3076 6479 / 6480 -- ------ http://www.imn.htwk-leipzig.de/~waldmann/ ---------

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RE: -fglasgow-exts -fno-th does not turn off Template Haskell
by Simon Marlow 19 Jan '04

19 Jan '04

> not sure if this is a bug or a feature, but on my ghc 6.2, > -fglasgow-exts > -fno-th still allows Template Haskell. > > Is that the correct way for ghc to behave? It doesn't do that for me (and it shouldn't). Could you give more details? Cheers, Simon

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Non-exhaustive patterns in basicTypes/Var.lhs
by Peter Simons 18 Jan '04

18 Jan '04

QuickCheck's 'generate' function works fine in GHCi, but only for the _first_ time I call it. After that, I get an error: | Ok, modules loaded: Main. | *Main> generate 3 (mkStdGen 28) (return 'x') | Loading package QuickCheck ... linking ... done. | 'x' | | *Main> generate 3 (mkStdGen 28) (return 'x') | *** Exception: basicTypes/Var.lhs:226:32-58: Non-exhaustive | patterns in record update Peter

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"Talking" with the compiler
by HNBeck＠t-online.de 18 Jan '04

18 Jan '04

Hi, in order to build a programming environement, it would be nice to ask the GHC about symbols etc found in a given Haskell program. I've read that GHC has a interface, which was originally intended to plug in other backends. But I've never found a detailed description or API.... Can someone help me ? Thanks Hans

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-fglasgow-exts -fno-th does not turn off Template Haskell
by Shae Matijs Erisson 18 Jan '04

18 Jan '04

not sure if this is a bug or a feature, but on my ghc 6.2, -fglasgow-exts -fno-th still allows Template Haskell. Is that the correct way for ghc to behave? -- Shae Matijs Erisson - 2 days older than RFC0226 #haskell on irc.freenode.net - We Put the Funk in Funktion 10 PRINT "HELLO" 20 GOTO 10 ; putStr $ fix ("HELLO\n"++)

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RE: docs bug - on Data.Int doc page, UArray points to imaginary Data.Array.Base.html
by Simon Marlow 16 Jan '04

16 Jan '04

> On this page: > http://www.haskell.org/ghc/docs/latest/html/libraries/base/Dat > a.Int.html > the links to IArray and UArray point to > http://www.haskell.org/ghc/docs/latest/html/libraries/base/Dat > a.Array.Base.html#t%3AIArray > which doesn't exist. > > Not sure if this is a haddock bug or a missing file or what. That looks like a bug - Data.Array.Base is hidden so we shouldn't get any links to it. Thanks for spotting it. Cheers, Simon

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