I think the parent meant only a sum type, not a concrete example of it such as Either of Haskell, which would surely not suffice here. In Haskell you would prob

I think the parent meant only a sum type, not a concrete example of it such as Either of Haskell, which would surely not suffice here. In Haskell you would probably define a new sum type for this occasion, e.g.: data ForkResult = Failure | Parent Int | Child