Could mkWeakPair do what you want? http://haskell.org/ghc/docs/latest/html/libraries/base/System-Mem-Weak.html#... No, it's just a convenience function that doesn't help much, because the value already refers to the IORef anyway.
Or are you trying to do something else? The goal is to create mutable objects whose update codes are tracked by
Here's a minimal example to illustrate the problem: import Data.IORef import Data.Maybe import System.Mem import System.Mem.Weak main = do ref <- newIORef 42 ptr <- mkWeak ref 21 Nothing performGC print . isNothing =<< deRefWeak ptr print =<< readIORef ref Depending on whether you compile with optimisations, the weak reference might be reported dead, even though the IORef is alive and kicking. Switching to mkWeakPair (or just mentioning ref in the value somehow) doesn't affect that. the main program, but they can be thrown out when all the other references to the objects are lost. Creating weak pointers with MutVar#s seems to do the trick, but I'm not confident if it is a solution I can trust... Gergely -- http://www.fastmail.fm - A fast, anti-spam email service.