async libraries will be. In the community meeting, it was mentioned that async and coroutines would be areas of focus in Mojo's design for the next few months, so I think this is the right time to discuss their design. async libraries were built was initially chosen to be coroutines, but there's work going on right now to introduce a better alternative:In a suite of generic async algorithms that are expected to be callable from hot code paths, the extra allocations and indirections are a deal-breaker. It is for these reasons that we consider coroutines a poor choice for a basis of all standard async.