I think the use of an enum (in the Rust example) makes this a sum type situation: https://tonyarcieri.com/a-quick-tour-of-rusts-type-system-part-1-sum-types-a-k

I think the use of an enum (in the Rust example) makes this a sum type situation: https://tonyarcieri.com/a-quick-tour-of-rusts-type-system-part-1-sum-types-a-k-a-tagged-unions https://tonyarcieri.com/a-quick-tour-of-rusts-type-system-pa...