I am new to using the Haskell FFI, and have been trying to implement the example in section 11.6 of the GHC user’s guide. 

I have finally gotten to the point where my dll compiles (there is a missing space in the mainDll.h code at line 4:12) using GHC 6.6.1, and used the declare statement to expose the “adder” function in Excel VBA.  My VBA Code is given below:

Private Declare Function adder Lib " adder.dll" Alias "adder@8" (ByVal x As Integer, ByVal y As Integer) As Integer

Private Sub test()

Debug.Print adder(1, 2)

End Sub

My problem is this:

The function works fine (the immediate window displays 3), but when I terminate Excel, I get an application error (“The instruction at … referenced memory at … . The memory could not be read.”).  Does anyone else have any experience calling Haskell from VBA that might be relevant?