> except throwing OOP into something that doesn't need it I feel like you're jumping to wild conclusions. All I'm suggesting is to change your code to priva

> except throwing OOP into something that doesn't need it I feel like you're jumping to wild conclusions. All I'm suggesting is to change your code to private object EUR : Currency private object USD : Currency data class Money<C : Currency>(...) { ... } That's just an empty tag interface and that's not particularly hardcore OOP, you can do the same thing with Haskell typeclasses.