[Haskell-cafe] FFI export questions

[John Goerzen]

Hi,

I'm trying to make a Haskell binding for the FUSE library,
http://fuse.sourceforge.net/.  The FUSE concept is centered around a
struct whose members are pointers to callback functions.

Here's the problem: the functions I want to callback to have types like
this:

vGetLine :: HVFS a -> a -> IO String

Now, I can't just pass some sort of opaque pointer to C, because then
the exact type of a would be lost.

Is there any other method I might try?

Thanks,

John