Nick Name
As the result of a conversation on haskell-gui, I have tried to implement the disallocation of resources when a stream is garbage collected.
To explain myself:
I have a function
f :: IO [a]
which returns a lazy stream after allocating some resource to feed it (say installing a callback).
I wish that the resource could be disallocated when it's no longer used. I did the obvious implementation with Weak.addFinalizer; results are encouraging but not completely satisfying; the scheme I used is:
f = do allocateResource l <- makeTheStream addFinalizer l (disallocateResource) return l
The problem is that if no memory is allocated, no garbage collection happens; of course finalization is not guaranteed, as the manual states.
You may want to have a look at how ports are closed by finalizers in the Haskell Ports Library: http://www.cse.unsw.edu.au/~chak/haskell/ports/ It seems that the set up there is similar to yours. Cheers, Manuel