Foreign/StablePtr.hs

    {-# LANGUAGE CPP, PackageImports #-}
    #if __GLASGOW_HASKELL__ >= 701
    {-# LANGUAGE Safe #-}
    #endif

    module Foreign.StablePtr
            ( -- * Stable references to Haskell values
              StablePtr          -- abstract
            , newStablePtr       -- :: a -> IO (StablePtr a)
            , deRefStablePtr     -- :: StablePtr a -> IO a
            , freeStablePtr      -- :: StablePtr a -> IO ()
            , castStablePtrToPtr -- :: StablePtr a -> Ptr ()
            , castPtrToStablePtr -- :: Ptr () -> StablePtr a
            , -- ** The C-side interface

              -- $cinterface
      ) where
    import "base" Foreign.StablePtr as This___

    -- $cinterface
    --
    -- The following definition is available to C programs inter-operating with
    -- Haskell code when including the header @HsFFI.h@.
    --
    -- > typedef void *HsStablePtr;  /* C representation of a StablePtr */
    --
    -- Note that no assumptions may be made about the values representing stable
    -- pointers.  In fact, they need not even be valid memory addresses.  The only
    -- guarantee provided is that if they are passed back to Haskell land, the
    -- function 'deRefStablePtr' will be able to reconstruct the
    -- Haskell value referred to by the stable pointer.