GHC.Stable (original) (raw)
Description
Stable pointers.
Synopsis
- data StablePtr a = StablePtr (StablePtr# a)
- newStablePtr :: a -> IO (StablePtr a)
- deRefStablePtr :: StablePtr a -> IO a
- freeStablePtr :: StablePtr a -> IO ()
- castStablePtrToPtr :: StablePtr a -> Ptr ()
- castPtrToStablePtr :: Ptr () -> StablePtr a
Documentation
A stable pointer is a reference to a Haskell expression that is guaranteed not to be affected by garbage collection, i.e., it will neither be deallocated nor will the value of the stable pointer itself change during garbage collection (ordinary references may be relocated during garbage collection). Consequently, stable pointers can be passed to foreign code, which can treat it as an opaque reference to a Haskell value.
A value of type StablePtr a is a stable pointer to a Haskell expression of type a.
Instances
Instances details
castStablePtrToPtr :: StablePtr a -> Ptr () Source #
Coerce a stable pointer to an address. No guarantees are made about the resulting value, except that the original stable pointer can be recovered by [castPtrToStablePtr](GHC-Stable.html#v:castPtrToStablePtr "GHC.Stable"). In particular, the address may not refer to an accessible memory location and any attempt to pass it to the member functions of the class [Storable](Foreign-Storable.html#v:Storable "Foreign.Storable") leads to undefined behaviour.