Re: [Haskell-cafe] How can I pass IOUArrays to FFI functions?

20 Aug 2007


      On Monday 20 August 2007 07:27:04 Ryan Ingram wrote:
...
I have a C function of type
   void f ( HsWord32* p0, HsWord32* p1, HsWord32 size );
along with the FFI declaration:
   foreign import ccall unsafe f :: Ptr Word32 -> Ptr Word32 -> Word32 ->
IO ()
In my Haskell code I have an unboxed IO array of Word32; IOUArray Int
Word32.
I want to pass the pointer to this array to f().  How can I get the pointer
out of the array?  Or, is there a better way to declare f() to do this?
I'm open to using GHC hackery; using v6.6.1 right now.
-- ryan
Perhaps you'd like to use Data.Array.Storable?  It supports the MArray
interface, and has the additional operation:

    withStorableArray :: StorableArray i e -> (Ptr e -> IO a) -> IO a


Cheers,
Spencer Janssen