I suspected as much. It is a pretty good guarantee. Have you found any use for it yet in programs? That is, a program where the causal message ordering is preferred and removes code from the program?
That's just what I was thinking about: Where would this be useful?
On the other hand I could imagine that this could also cause problems: If you have a large program, could then this causality cause some messages to be delayed for a (too) long and not directly visible time in order to achieve the causality guarantee? But the claim was that there is no runtime overhead.
You have an actor A13 that communicates with actor A2. The guarantee allows you to break up A13 into the two actors A1 and A3 that now both communicate with A2 and be done with it.
In erlang, you might not've done so, because you know nothing about message ordering in non-tree-shaped topologies.
