The Clojure ethos is quite anti-encapsulation. Generally, you maintain complex invariants by defining the functions that manage your data and not updating it ex

The Clojure ethos is quite anti-encapsulation. Generally, you maintain complex invariants by defining the functions that manage your data and not updating it except through them. (This is easier than it sounds, because when all data structures are immutable, drive-by-mutation just doesn't happen.)