David Sankel wrote:
> Hello FFI experts,
>
> Say I have a function somewhere in c land with the following declaration:
>
> void doStuff( int &a, int &b);
That isn't C. Are you referring to C++ references, or did you mean:
void doStuff(int *a, int *b);
?
> What would the appropriate Haskell wrapper for this function look like?
> I'm looking to construct a haskell function of the type:
>
> doStuff :: Int -> Int -> IO( (Int,Int) )
The direct translation would be:
Ptr CInt -> Ptr CInt -> IO ()
Higher level interfaces, such as the one which you suggest, could be
built upon that, e.g.:
import Foreign.C(CInt)
import Foreign.Ptr(Ptr)
import Foreign.Marshal.Utils(with)
import Foreign.Storable(peek)
foreign import ccall doStuff :: Ptr CInt -> Ptr CInt -> IO ()
doStuff' :: Int -> Int -> IO (Int,Int)
doStuff' x y = do
with (fromIntegral x) $ \px ->
with (fromIntegral y) $ \py -> do
doStuff px py
x' <- peek px
y' <- peek py
return (fromIntegral x', fromIntegral y')
--
Glynn Clements <[EMAIL PROTECTED]>
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