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%
% (c) The AQUA Project, Glasgow University, 1998
%
\section[PrelWeak]{Module @PrelWeak@}
\begin{code}
{-# OPTIONS -fno-implicit-prelude #-}
module PrelWeak where
import PrelGHC
import PrelBase
import PrelMaybe
import PrelIOBase
import PrelForeign
data Weak v = Weak (Weak# v)
mkWeak :: k -- key
-> v -- value
-> Maybe (IO ()) -- finalizer
-> IO (Weak v) -- weak pointer
mkWeak key val (Just finalizer) = IO $ \s ->
case mkWeak# key val finalizer s of { (# s1, w #) -> (# s1, Weak w #) }
mkWeak key val Nothing = IO $ \s ->
case mkWeak# key val (unsafeCoerce# 0#) s of { (# s1, w #) -> (# s1, Weak w #) }
mkWeakPtr :: k -> Maybe (IO ()) -> IO (Weak k)
mkWeakPtr key finalizer = mkWeak key key finalizer
addFinalizer :: key -> IO () -> IO ()
addFinalizer key finalizer = do
mkWeakPtr key (Just finalizer) -- throw it away
return ()
addForeignFinalizer :: ForeignObj -> IO () -> IO ()
addForeignFinalizer (ForeignObj fo) finalizer = addFinalizer fo finalizer
{-
instance Eq (Weak v) where
(Weak w1) == (Weak w2) = w1 `sameWeak#` w2
-}
\end{code}
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