2 % (c) The AQUA Project, Glasgow University, 1998
5 \section[PrelWeak]{Module @PrelWeak@}
8 {-# OPTIONS -fno-implicit-prelude #-}
18 data Weak v = Weak (Weak# v)
22 -> Maybe (IO ()) -- finalizer
23 -> IO (Weak v) -- weak pointer
25 mkWeak key val (Just finalizer) = IO $ \s ->
26 case mkWeak# key val finalizer s of { (# s1, w #) -> (# s1, Weak w #) }
27 mkWeak key val Nothing = IO $ \s ->
28 case mkWeak# key val (unsafeCoerce# 0#) s of { (# s1, w #) -> (# s1, Weak w #) }
30 mkWeakPtr :: k -> Maybe (IO ()) -> IO (Weak k)
31 mkWeakPtr key finalizer = mkWeak key key finalizer
33 addFinalizer :: key -> IO () -> IO ()
34 addFinalizer key finalizer = do
35 mkWeakPtr key (Just finalizer) -- throw it away
38 addForeignFinalizer :: ForeignObj -> IO () -> IO ()
39 addForeignFinalizer (ForeignObj fo) finalizer = addFinalizer fo finalizer
42 instance Eq (Weak v) where
43 (Weak w1) == (Weak w2) = w1 `sameWeak#` w2