I didn't say it wasn't useful. It is. But it's checking essentially a sequential property: a sequential actor is using a channel in a consistent way. What e.g.

I didn't say it wasn't useful. It is. But it's checking essentially a sequential property: a sequential actor is using a channel in a consistent way. What e.g. the session type community is aiming at are properties of concurrent computation, such as linear channel usage which depends on the behaviour of multiple processes.