Hello,
I'm trying to use a C++ class in Haskell through C exports.
It works all very well, except that when I call the function that deletes the object, it is still valid, I can still call methods on it.

Here is my Haskell code:

{-# LANGUAGE ForeignFunctionInterface #-}

import Foreign
import Foreign.C.Types

newtype PKlass = PKlass (Ptr PKlass)

foreign import ccall unsafe "Klass_Create"
kCreate :: CInt -> CInt -> IO PKlass

foreign import ccall unsafe "Klass_Destroy"
kDestroy :: PKlass -> IO ()

foreign import ccall unsafe "Klass_GetX"
kGetX :: PKlass -> IO CInt
foreign import ccall unsafe "Klass_GetY"
kGetY :: PKlass -> IO CInt

foreign import ccall unsafe "Klass_AddKlass"
kAdd :: PKlass -> PKlass -> IO PKlass

main = do
k <- kCreate 4 5
kDestroy k
kGetY k >>= print -- This shouldn't work
k' <- kCreate 2 8
k'' <- k `kAdd` k'
kDestroy k''
kGetY k'' >>= print -- This neither

So it is very basic, and I can't understand why the supposedly destroyed objects are still here.
Enclosed is all the source code (C++ class, C exportation and the Haskell main hereabove).

I compile it this way:
ghc --make main.hs *.cpp -lstdc++