This is only a small piece of the story for what people say when they want tagged unions. Without all of the ancillary support in the language, like exhaustive pattern matching, it really doesn't count.
replyYou can also add support for exhaustive switches on tags.
replyJust as a linter config though?
replyThe C++ committee said the same thing, and gave us std::variant. They are painful to work with and do not really deliver most of the benefits people want.
replyThat is a LOT of code (very ugly code, I would add) that could be replaced by `type Float = float32 | float64` in a language with actual support for union types.
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replyTagged unions are not union types. A union type is a supertype for any arbitrary collection of types, but a tagged union aka sum type is a single type with multiple data constructors, and does not require subtyping to be implemented.
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