[di4na]

Well the first question you have to answer is simple : what is the type of self(), your own pid. This is a really hard problem and what stopped SPJ in the late 90s/early 2000s

Then the second problem is that at any given time you can receive a message from another node/process 10 years in the future compared to you, that you know nothing about his code or types. How do you type check it?

Finally, the actor model in general allows unbounded nondeterminism. This is not really something you can build into a static type checker.

The "easy" solution is to make messages an opaque black box that can be anything... but at that point you are leaking static typechecking everywhere.