Trim imports, remove a cycle
[packages/base.git] / Foreign / StablePtr.hs
1 {-# OPTIONS_GHC -fno-implicit-prelude #-}
2 -----------------------------------------------------------------------------
3 -- |
4 -- Module : Foreign.StablePtr
5 -- Copyright : (c) The University of Glasgow 2001
6 -- License : BSD-style (see the file libraries/base/LICENSE)
7 --
8 -- Maintainer : ffi@haskell.org
9 -- Stability : provisional
10 -- Portability : portable
11 --
12 -- This module is part of the Foreign Function Interface (FFI) and will usually
13 -- be imported via the module "Foreign".
14 --
15 -----------------------------------------------------------------------------
16
17
18 module Foreign.StablePtr
19 ( -- * Stable references to Haskell values
20 StablePtr -- abstract
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
27
28 -- $cinterface
29 ) where
30
31 #ifdef __GLASGOW_HASKELL__
32 import GHC.Stable
33 #endif
34
35 #ifdef __HUGS__
36 import Hugs.StablePtr
37 #endif
38
39 #ifdef __NHC__
40 import NHC.FFI
41 ( StablePtr
42 , newStablePtr
43 , deRefStablePtr
44 , freeStablePtr
45 , castStablePtrToPtr
46 , castPtrToStablePtr
47 )
48 #endif
49
50 -- $cinterface
51 --
52 -- The following definition is available to C programs inter-operating with
53 -- Haskell code when including the header @HsFFI.h@.
54 --
55 -- > typedef void *HsStablePtr; /* C representation of a StablePtr */
56 --
57 -- Note that no assumptions may be made about the values representing stable
58 -- pointers. In fact, they need not even be valid memory addresses. The only
59 -- guarantee provided is that if they are passed back to Haskell land, the
60 -- function 'deRefStablePtr' will be able to reconstruct the
61 -- Haskell value referred to by the stable pointer.