That could be much better solved through coeffects, but unfortunately most languages don’t support that. Doesn’t mean using async functions is a good way for this either
It's possible, but I can't thoroughly evaluate coeffects until they land in a mainstream language with production usage. What I do know from experience is that you can't quietly block the entire thread on a network request in some innocuous looking function in JS. You have to return a promise and then the calling function has the option to await that promise, but I'm sure the academics in their ivory towers have theorized about something better.
If there was a way for users to define their own coeffects then you could sidestep this issue, but I saw this quote in one of the design documents: "Runtime will have a native knowledge of each co-effect. We will not allow co-effects to be defined in user-land code [...] An important aspect to note here is that certain co-effects that need deep support from runtime such as io and pure will need to be implemented in the runtime" [2].
[1] https://docs.hhvm.com/hack/contexts-and-capabilities/availab...
[2] https://github.com/facebook/hhvm/blob/master/hphp/hack/doc/H...