The author should look into Koka. As I see it, Koka is at the bleeding edge of effect handling, which is why the async Rust team has taken some nibbles of inspiration from it. Alas, Rust as a whole is far too cemented to overhaul everything for generic effect support, but at least it’s been beneficial for async.
Teams does actually have a sound cue when people join calls: high-pitched repeated beeps that most people can’t hear due to presbycusis, and the few who do hear it think they’re going crazy.
Related reddit thread.