Which is madness that completely misses the point of proper immutable collections (Clojure style) - that you can "modify" them, by creating a new copy with the

Which is madness that completely misses the point of proper immutable collections (Clojure style) - that you can "modify" them, by creating a new copy with the thing added, and it shares storage with the original and the copying isn't as slow as a copy-by-clone. The first thing people are going to do with these half assed immutable collections is pour the contents out into a mutable container. Which completely obviates all the thread safety and whatnot. I slap my forehead. Do these people have no sense?