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mwotton/gist:ffa6dfb73fe3b0a8ef9b

Created May 28, 2014 08:14
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gistfile1.hs
mvarEnumerator :: (MonadIO m, ToJSON a1) => (Async a, MVar a1) -> Step Builder m b -> Iteratee Builder m b
mvarEnumerator (task,mvar) step = case step of
Yield a b -> Iteratee . return . Yield a $ b
Continue s -> do
r' <- liftIO $ race (wait task) (takeMVar mvar)
s $ case r' of
Left _ -> EOF
Right r -> Chunks [fromLazyByteString $ encode r]
Error s -> error (show s)
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