[wruza]

>Mutable state is always a problem, but it's a bigger problem when there are less constraints on when it can mutate.

A very long-time project I’m idly working on with my life-long colleague addresses this issue. It is real, as are all race conditions and threading issues. But it doesn’t have to be solved at the language level.

One of solutions we proposed to ourselves was that an object storage should manage shared access conflicts. You may see it in Redux and other stores that serve a “frontend framework backend layer” duty today. Even with explicit async, you will always have some high-level races that must be dealt with. And these do exactly that.

The basic idea is that local state is strictly local and not a subject of parallel mutation, and shared state is shared via internally locking/serializing controller who knows better how to mutate, merge or throw. It doesn’t push the problem down the code or execution model, since it’s what’s it for.

[kragen]

Sounds like you'd benefit from reading Mark's dissertation. Not that he solved the problem but he did try a lot of candidate approaches, discuss them with others, and comprehensively review the existing literature; and he reports on several years of trying things similar to what you're thinking of.