I spent some time thinking about how a data stream would work with feedback, and determined that it would need to be clock driven (at least for now). When data flows between units (I/O, processing, bifurcation, etc.), the timing would have to be determined so that everything is at the right place at the right time. A unit would have to be timed as well, and could be made out of subunits that take a determined amount of time.
In Flow programming, the timing of the data would be just as, and probably more important as where the data is flowing to and from.