Yeah seems so. It’s a shame that they can only be shallowly cast from mutable to immutable (and will even throw errors if non-primitive values are present). See

Yeah seems so. It’s a shame that they can only be shallowly cast from mutable to immutable (and will even throw errors if non-primitive values are present). Seems like quite the limitation. And yeah, I’m all for immutability as a default, but breaking so pervasive an existing API is a lot of damage.