The documentation for FFI in the GHC user's guide seems to be out of date with regard to passing Ptrs across. 1. My reference is http://www.haskell.org/ghc/docs/latest/set/ffi.html (from http://www.haskell.org/ghc/docs/latest/set/book-users-guide.html) Is this the latest documentation available? 2. My understanding is that you can use any instance of 'Storable a => Ptr a' as an FFI argument and return type for both imported and exported functions? Is this correct? What if the type is polymorphic (e.g. declared as 'Storable a => Ptr a' rather than something like 'Ptr Word8')? 3. What about ForeignPtr? Can instances of 'Storable a => ForeignPtr a' be used in FFI? 4. Does newForeignPtr work safely with null pointers, and will the finalizer get called? For instance: fp <- newForeignPtr nullPtr finalFunc; let {isNull = (foreignPtrToPtr fp) == nullPtr}; r <- withForeign fp (\p -> foo p); Will foo be passed nullPtr? Will finalFunc ever get called? Is my use, above, of foreignPtrToPtr safe, and will isNull be True? -- Ashley Yakeley, Seattle WA