I'm not sure exclusive access is enough in all cases though. That's why immutability is still a strong default in Rust and Swift. The classic example is calling

I'm not sure exclusive access is enough in all cases though. That's why immutability is still a strong default in Rust and Swift. The classic example is calling a method on an object which will mutate its content without the caller knowing. That's why I'd still favor immutability if performance doesn't preclude it.