For what it’s worth it sounds no worse than Java: you have immutable strings but you have no way to enforce that you can’t modify something that you have recieved, which is why the underlying char array for a string has to be defensively copied if the user asks for `asArray()` or whatever it is.

Strings being immutable doesn’t seem like a special case, though. The underlying mutable array is just encapsulated, which is something that you can implement yourself. (But reflection… maybe you can break the rules with reflection.)