And this, in turn, is one of the beauties of the Futures approach -- it isn't nearly as susceptible to those bugs as traditional lock-based approaches.

But the complexity still has to go *somewhere*, right? It moves away from the programmer, it looks like, but that presumably increases the burden on the compiler or execution engine or whatever to get it right. *Somebody* has to unravel all the multi-threaded async crud, right? I mean, it's great that it's not me, but it's not free either, right?

Granted, concentrating the bug exposure in the compiler instead of distributing it among all programmers means that when a bug is found it's more likely to get fixed and benefit everyone. I'm not sure I'd want to be on the team that has to make that work, though. :-)