If your data is immutable or not is significant for program analysis and correctness, so I would say the distinction makes absolutely sense. > Sometimes I just

If your data is immutable or not is significant for program analysis and correctness, so I would say the distinction makes absolutely sense. > Sometimes I just want to create a map and mutate its structure, and the language saying "no" is constraining me in an unpleasant way. Languages that provide immutable data structures have often 2 variants, an immutable and mutable. Why can't you just take the mutable in that case? I think it's more about making immutability or mutability explicit.