"I think there's a sweet spot for a language that accepts mutability inside of actors, but only allows immutable objects to be sent as messages, with an escape hatch available if needed."
That's kind of what akka is on scala or java.
Messages are immutable _BY CONVENTION_ but you can do whatever you want.
Isn't that the basis/point of the actor model? Actors can message each other and processing the message can trigger state mutation of the recipient, but they can't directly mutate each other.
That's kind of what akka is on scala or java. Messages are immutable _BY CONVENTION_ but you can do whatever you want.