call/cc

Is it worth the implementation cost, or are native coroutines good enough for most usecases?

>>1

Continuations eliminate stack, so
1. No stack-trace, complicating debugging order of magnitude.
2. Object destructors depends on stack being linear. No with-open-file or using(var memory = malloc(size)).
3. GC is a must, because you can't depend on stack pop-ing anymore.
4. CPS-transformation requires optimizing compiler eliminating useless closures.