Every actor in Swift conforms to the Actor protocol, which has one requirement: an instance property named `unownedExecutor`. Swift uses this property implicitly when, for example, the program calls a method on the actor from outside the actor.

https://developer.apple.com/documentation/swift/actor/unowne...

(One could also argue that, because every actor type is a reference type, every actor also has its identity as part of its state.)

So anyone coding anything interesting is almost certainly under or over using their languages' and libraries' abstractions.

Also, for highly composable languages, where null versions of almost anything make sense: Stateless states, operationless operations, destinationless network ports, storage roots not associated with any hardware, just "0 bytes", ... all make practical sense.

  Two processes intend to add two to a number.

  They each read the current value.

  Then they each write back the value which is two bigger then the original.

The exact same thing but with more boilerplate.