In local.glasgow-haskell-users, you wrote:
That makes isEmptyChan essentially useless. Either it should be removed, or the implementation of Chan needs to be elaborated to support isEmptyChan.
I have a new implementation here which should track the number of elements in a channel, taking also into account unGetChan & dupChan. It seems to work, but lacks thorough testing. In any case, as it bloats the data structure data Chan a = Chan (MVar ([MVar Integer],Stream a)) (MVar ([MVar Integer],Stream a)) (MVar Integer) type Stream a = MVar ([MVar Integer],ChItem a) it should probably be something like Control.Concurrent.CountChan. http://www.foldr.org/~stolz/Chan2.hs Without documentation it's quite useless, I'll leave it over the weekend... If nobody comes up with a more sensible solution, I'd say remove isEmptyChan from the regular module. [although I consider mapM_ (uncurry putMVar) (zip counts (map (+1) vs)) rather neat :)] -- http://www-i2.informatik.rwth-aachen.de/stolz/ *** PGP *** S/MIME rage against the finite state machine