Hi Stefan, In that case, how do I marshall [String] to Ptr (Ptr CChar)? Thanks -John On 2/6/07, Stefan O'Rear wrote:

You have to use a type that C's tiny brain understains. IANAWP but I'm guessing you want:

type ServiceMainClosure = DWORD -> Ptr (Ptr CChar) -> IO ()

foreign import ccall "wrapper" mkServiceMainClosure :: ServiceMainClosure -> IO (FunPtr ServiceMainClosure)

Actually, what I need to do is a fair bit more complex than string marshalling. It feels like I'll need to pull together a number of different concepts so I may as well describe the problem directly. The C function I want to call is StartServiceCtrlDispatcher: *BOOL* *StartServiceCtrlDispatcher(* *const LPSERVICE_TABLE_ENTRY* *lpServiceTable** **);* It takes an array of SERVICE_TABLE_ENTRY structures: typedef struct _SERVICE_TABLE_ENTRY { LPTSTR lpServiceName; LPSERVICE_MAIN_FUNCTION lpServiceProc; } SERVICE_TABLE_ENTRY, *LPSERVICE_TABLE_ENTRY; The typedef LPSERVICE_MAIN_FUNCTION is something like: *typedef (VOID WINAPI* *ServiceMain)(* *DWORD* *dwArgc**, * *LPTSTR** *lpszArgv** **);* It seems to me that I'll need to learn how to do the following: * Represent SERVICE_TABLE_ENTRY AND LPSERVICE_TABLE_ENTRY structs as a haskell type. * Create an array of SERVICE_TABLE_ENTRY structs. * Populate the array (they're null terminated). * Do all sorts of elaborate marshalling so that the end product is a sensibly typed Haskell function like this: data ServiceTableEntry = ServiceTableEntry { serviceName :: String serviceProc :: [String] -> IO () } startServiceCtrlDispatcher :: [ServiceTableEntry] -> IO () That's quite a lot to chew on and I finding it challenging learning about all these things and combining them at the same time. I've attached the complete source to what I have so far in a zip file. Thanks -John On 2/6/07, Stefan O'Rear wrote:

On Tue, Feb 06, 2007 at 12:40:38PM +1100, John Ky wrote:

...

Hi Stefan,

In that case, how do I marshall [String] to Ptr (Ptr CChar)?

look at Foreign.C.String and Foreign.Ptr