Could mkWeakPair do what you want?
http://haskell.org/ghc/docs/latest/html/libraries/base/System-Mem-Weak.html#...
Or are you trying to do something else?
- Job
2009/11/2 Patai Gergely
Hello all,
I wanted to create a weak pointer with an IORef as the key and something else as the value, but I saw no way to do it through the API provided. After some experimentation I came up with the following abomination for a solution:
myWeakRef (IORef (STRef r)) v f = IO $ \s -> case mkWeak# r v f s of (# s', w #) -> (# s', Weak w #)
This works perfectly when the code is compiled both with and without optimisations, but ghci chokes on it with an internal error. So my question is if I can expect this to work at least this much in the long run, or is it a hopelessly fragile hack?
Gergely
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