Hello, I'm somewhat confused about the definition of emptiness for SampleVar: A sample var is /empty/ if it contains no value _and_ if there are no blocked readers[1]. With this definition, the following program prints `False': import Control.Concurrent main = do var <- newEmptySampleVar forkIO $ readSampleVar var threadDelay 1000000 isEmptySampleVar var >>= print Is this intended behavior? And if yes, what is the rational behind this? If this is intended behavior, I'd tend to clarify the documentation? Something like: Returns True if the SampleVar is currently empty and if there are no readers waiting. Any thoughts on that? Cheers, Simon [1] http://hackage.haskell.org/packages/archive/base/4.1.0.0/doc/html/src/Contro...