1 {-# OPTIONS -fno-implicit-prelude #-}
2 -----------------------------------------------------------------------------
4 -- Module : Foreign.StablePtr
5 -- Copyright : (c) The University of Glasgow 2001
6 -- License : BSD-style (see the file libraries/base/LICENSE)
8 -- Maintainer : ffi@haskell.org
9 -- Stability : provisional
10 -- Portability : portable
12 -- This module is part of the Foreign Function Interface (FFI) and will usually
13 -- be imported via the module "Foreign".
15 -----------------------------------------------------------------------------
18 module Foreign.StablePtr
19 ( -- * Stable references to Haskell values
21 , newStablePtr -- :: a -> IO (StablePtr a)
22 , deRefStablePtr -- :: StablePtr a -> IO a
23 , freeStablePtr -- :: StablePtr a -> IO ()
24 , castStablePtrToPtr -- :: StablePtr a -> Ptr ()
25 , castPtrToStablePtr -- :: Ptr () -> StablePtr a
26 , -- ** The C-side interface
31 #ifdef __GLASGOW_HASKELL__
53 -- The following definition is available to C programs inter-operating with
54 -- Haskell code when including the header @HsFFI.h@.
56 -- > typedef void *HsStablePtr; /* C representation of a StablePtr */
58 -- Note that no assumptions may be made about the values representing stable
59 -- pointers. In fact, they need not even be valid memory addresses. The only
60 -- guarantee provided is that if they are passed back to Haskell land, the
61 -- function 'deRefStablePtr' will be able to reconstruct the
62 -- Haskell value referred to by the stable pointer.