In some languages, there are also (non/)threadsafe variants of mutable classes. As you say, this approach blows up quickly. If I saw that, I would ask what 'p

In some languages, there are also (non/)threadsafe variants of mutable classes. As you say, this approach blows up quickly. If I saw that, I would ask what 'problem' it's trying to solve. Is mutation actually the goal, or simply the means? In languages which don't support general mutation (I'm writing Clojure right now), I really don't miss it at all.