Thank you Krzystof! This did the trick. Now I also have a better understanding what is going on. Great.
Kees
Van: Krzysztof Skrzętnicki [mailto:gtener@gmail.com]
Verzonden: woensdag 29 mei 2013 11:58
Aan: Kees Bleijenberg
Onderwerp: Re: [Haskell-cafe] using a win32 dll
Oh, I didn't mean kernel32. And -L provides search path not the actual library. The idea was to use -l , so it would be -lpngDLL.dll, provided it is in library search path. If not use -Ldirectory-with-dll -lpngDLL.dll
On Wed, May 29, 2013 at 11:49 AM, Kees Bleijenberg wrote:
I’ve tried to compile it with –l kernel32, but nothing changed. I’ve also tried -LpngDll.dll but that didn’t work either.
Kees
My first guess would be missing -l parameter. The examples you have linked read:
ghc --make compname.hs -lkernel32
Best regards,
Krzysztof Skrzętnicki
On Wed, May 29, 2013 at 9:13 AM, Kees Bleijenberg wrote:
I made a Delphi dll (32 bits windows). This dll exports a function named getPngVersion. This is a function with no arguments that returns a pointer to a array of chars.
If I examine the dll with a tools like tdump, I can see the function getPngVersion on index 1.
Now I want to use this dll in Haskell:
{-# LANGUAGE ForeignFunctionInterface #-}
module Main(
main
)
where
import Control.Monad
import Foreign.C
import Foreign.Marshal.Alloc
import Foreign.Marshal.Array
import System.Win32.Types
foreign import stdcall "glasPng getPngVersion" getPngDllVersion :: IO CString
main :: IO ()
main = do
s <- getPngDllVersion
putStrLn (show s)
Compiling this with ghc --make glasPng.hs gives:
GlasPng.o: fake: (.text +0x82): undefined reference to ‘getPngVersion@0’ collect2 : Id returned 1 exit status
I wonder what went wrong. In the foreign import line I use “glasPng…. “ to tell ghc, it has to searh in glasPng.dll (changing glasPng to glasPng.dll doesn’t help). I’ve changed the name of the function in the dll to getPngVersion@0 but no luck. I’ve read and tested the last example at http://stackoverflow.com/questions/1027246/haskell-foreign-import-stdcall-on... (win32_getComputername, this works!). I wonder how haskell knows which dll to use in this example?)
Probably I’am doing something wrong with the way I tell ghc which dll to link or….
Any ideas?
Kees
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