blob: 47784f22979208b43de0bfe74c9d294228a6c4d5 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
|
-- The simplifier changes the shapes of closures that we expect.
{-# OPTIONS_GHC -O0 #-}
{-# LANGUAGE MagicHash, UnboxedTuples, LambdaCase #-}
import GHC.Exts.Heap
import GHC.IORef
import GHC.Weak
import System.Mem
main :: IO ()
main = do
key <- newIORef "key"
let val = "val"
wk@(Weak w) <- mkWeak key val Nothing
getClosureData w >>= \case
WeakClosure{} -> putStrLn "OK"
_ -> error "Weak is not a WeakClosure"
deRefWeak wk >>= \case
Nothing -> error "Weak dead when key alive"
Just _ -> pure ()
readIORef key >>= putStrLn
performMajorGC
deRefWeak wk >>= \case
Nothing -> pure ()
Just _ -> error "Weak alive when key dead"
getClosureData w >>= \case
ConstrClosure{} -> putStrLn "OK"
_ -> error "dead Weak should be a ConstrClosure"
|
