an Objective-C implementation of asynchronous inter-thread message passing

"a language that builds upon the architecture of the Web and principles of isolation, actors, and message-passing to increase application safety, responsiveness, scalability, and developer productivity"

...as a state machine. Bet it's more readable but performs worse than the current Actor implementation.

Nice use of annotations.

"an Objective-C implementation of asynchronous inter-thread message passing"

Note the handy comment from Julian Morrison.

Basically, because there are complicated use cases for Actors.

"Actors rule. You really should use them in your programs. Especially if your programs do a lot of stuff at once. Seriously, whatever you’re doing besides Actors, it probably sucks."