[Haskell] How to generate a dll?

Hallo! I want to make my Haskell program usable from Visual Basic. What is the way to go? (I tried the way the user guide for ghc 6.4.2 describes but the resulting dll was not stable.) While I don't have any clues about language interoperation I guess it is a task that is done many times before. So I would appreciate any pointers. Thanks for any help, Andreas