Yep. If you want to be really broad, even golong's (val, err) is a sum type even tho tuples are more literally product types. Since it's generally one or the ot

Yep. If you want to be really broad, even golong's (val, err) is a sum type even tho tuples are more literally product types. Since it's generally one or the other that has meaningful value, not both. But it sure as hell isn't easy since there is no do syntax or flatMap/selectMany/whatever to handle them nicely.