[pflanze]

> explicitly start a fiber

Fair point.

BTW what's interesting about yield based versus lazy evaluation (functional stream) based sequence generation? Advantages of the latter are that they can easily be understood as sequences and thus further processed by lazy versions of the known sequence processing functions (map etc.), also they can be re-read multiple times, which you just made impossible for yield by not basing it on call/cc :).

[jcoglan]

I've been thinking about this. I might try out making all the primitive functions understand promises. So not lazy evaluation per se, but having the core library transparently deal with asynchronous values. Maybe monads would help but that really requires a decent type system.