Typeclass instance = Adaptor/Decorator in OOP terms, automatically derived (and wrapped in) for you by the compiler. You want to fold over Options? Make a Fold

Typeclass instance = Adaptor/Decorator in OOP terms, automatically derived (and wrapped in) for you by the compiler. You want to fold over Options? Make a FoldableOption class implementing Foldable<Option> and pass "new FoldableOption(myOptionValue)" to whatever places you need. Haskell does pretty much the same (unless they moved away from dictionary passing).