Haskell function with String arguments in DLL

[Christian Lescher]

I'm trying to build a DLL with a Haskell function of type String ->
String, that should be called from outside (e.g. VBA), but it still
doesn't work.

I'm afraid I need an example or some kind of 'step by step instruction'.
Who can help me? (I use GHC 4.08.1.)

Christian