passing a Handle to a C function

Hal Daume
Wed, 9 Jul 2003 08:31:56 -0700

I have a C function that, for simplicity, has its definition as
something like:

> void myCFun(FILE *fd);

I have a Handle I've opened in Haskell using openFileEx and would like
to pass this to the function.  I've tried a bunch of things, the most
recent being:

> foreign import ccall "myHFile.h myCFun" c__myCFun :: Ptr CInt -> IO ()
> myCFun :: Handle -> IO ()
> myCFun (FileHandle handleMV) =3D do
>   h__ <- readMVar handleMV
>   ptr <- malloc
>   poke ptr (toCInt $ haFD h__)
>   c__initVars ptr

i've also tried it with just CInt -> IO (), without the ptr, but that
doesn't work either.

Surely someone has done this at some point...or is it even possible
(please say it is)...

 - Hal

 Hal Daume III                                   |
 "Arrest this man, he talks in maths."           |