Ocaml also has open variants where one can add cases to an existing sum type (essentially this is like exceptions but less special) and it’s objects are like a

Ocaml also has open variants where one can add cases to an existing sum type (essentially this is like exceptions but less special) and it’s objects are like a dual of polymorphic variants where you get a record which you may add fields to. Neither of these features is as commonly used as polymorphic variants however.