My program creates a Windows dll. The calling program calls a function with strings as parameters. Works fine.

I want to add a extra parameter. This extra parameter is a callback:  a function Int -> Int: stdcall. In Haskell I want to call this function.  So I have to convert the pointer to a (formal) Haskell function.

In the examples for the FFI, Haskell provides the callback. I need an example or documentation.

Kees