[Haskell] How to generate a dll?

[Andreas Marth]

Hi!

> Hi, Andreas!
> Try adding these lines to your DllMain:
> 
>   if (reason == DLL_PROCESS_DETACH) {
>       shutdownHaskell();
>       return TRUE;
>   }
> 
This worked great. (At least with Excel.  I didn't test it with the VB-Project yet.)

> > If I tried to return a String (marshalled to CString) the dll just plain
> > crashed when called.
> How exactly is it marshalled?
> 
At the moment the test program is:

module Calculate where

import Foreign.C.String

foreign export stdcall calculate :: CString -> IO (CString)

calculate :: CString -> IO (CString)
calculate cs = do s <- peekCString cs
                  newCString (reverse s)


So the newCString does the marshalling. (At least I think so.)

But if I call this in VBA it crashes Excel

VBA code:
Dim helper As String
Private Declare Function calculate Lib "Calculate.dll" (ByVal x as String) As String

Sub test ()
  helper = calculate("Test")
  Debug.Print helper
End Sub


All really basic.

Does anybody know why that does not work?

Thanks for all the answers up to now.

Andreas

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