That's a good point. A sum type/disjoint union (by my understanding) means the type is in the union of subsets and that the subsets are pairwise disjoint, but i

That's a good point. A sum type/disjoint union (by my understanding) means the type is in the union of subsets and that the subsets are pairwise disjoint, but it doesn't say that the subsets have to be finite. Since this post is really aimed at Haskell beginners, I was trying to avoid going down the rabbit hole as regards type system or set theory and I might have oversimplified in the process.