[groestl]

If I look at a thread, I see futures all over the place. They're just implicit, and the OS takes care of concurrency/preemption. Sure, that means that you need concurrency primitives if you access shared resources, but only in the trivial case you can get away without shared state in the promise/future scenario as well (i.e. glue code that ties together the hard stuff). Downside is your code gets convoluted and your stacktraces suck.