They are located in scalaz.stream.tcp and scalaz.stream.nio.
tcp version treats the Connection as Process[Task, A]nio version treats the Connection as Process[Task, Exchange[I, W]]Why do these two versions exist? Which situation are they intended for?
There are currently two versions because truly the tcp version is more like the experimental and future API. The one living in nio, has likely more complicated API, but is the one which shall be eventually used for now.