In a functional language like Haskell or O'Caml, it feels like half of what you write involves enums (sum types). They're fantastic in those contexts and I real

In a functional language like Haskell or O'Caml, it feels like half of what you write involves enums (sum types). They're fantastic in those contexts and I really miss them in python. But OO is a different approach to data and I suspect the "code smell" advice comes from not wanting to mix the two paradigms. For example Functional: data Switch = On | Off function flip: Switch -> Switch flip s = case s of On -> Off Off -> On Object Oriented: abstract class Switch { Switch flip(Switch); } class On : Switch { flip(s) { return new Off(); } class Off : Switch { flip(s) { return new On(); } Weird mixture: enum State {On, Off}; class Switch { State myState; Switch flip(Switch s) { if (s.myState == Off) { s.myState = On; return s ; } if (s.myState == On) { s.myState = Off; return s; }