3 ms·

I get that part. I want the language/compiler to allow me to use it where it makes sense (as an argument) and prohibit doing things to it that don't (as you dem

• tsimionescu 7y ago
  That would be nice in principle, but where do you expect the error to be thrown in the example above? I don't know of any language which tries to automatically deduce whether a variable is used in a read-only manner or not, and base covariance on this deduction. Even C++, which allows you to explicitly annotate an array to declare that it is read-only (const vector<base*> ) doesn't allow you to pass an array of derived elements instead, so I assume there is some difficulty in implementing these checks and ensuring correctness.