> Strangely a lot of the functional programming advocates are fine with closures, which are guilty of all the same issues -- private state, hidden state, combin

> Strangely a lot of the functional programming advocates are fine with closures, which are guilty of all the same issues -- private state, hidden state, combining data with functions. In functional programming closures (like other functions) only hold immutable data and cannot have side effects, so there is no private/hidden state involved. Code which can mutate state or produce side effects is procedural, not functional.