Though I agree that immutability and functional programming are very useful, and I like writing that style of code, you can always come across a situation where a certain amount of performance is necessary so that creating a lot of new data structures or very big ones (like map does) is not an option.
For further actions, you may consider blocking this person and/or reporting abuse
We're a place where coders share, stay up-to-date and grow their careers.
Though I agree that immutability and functional programming are very useful, and I like writing that style of code, you can always come across a situation where a certain amount of performance is necessary so that creating a lot of new data structures or very big ones (like map does) is not an option.