Tagged union type seems a defining feature of Hare to me. It is not exactly "tagged" in the sense that it internally has tags but users don't explicitly see the

Tagged union type seems a defining feature of Hare to me. It is not exactly "tagged" in the sense that it internally has tags but users don't explicitly see them [1]. This kind of types are normally headaches for language designers (cf. polymorphic variants in OCaml), but the Hare type system is simple enough that it doesn't pose a significant problem. In turn it gives an intuitive model of conversion; you don't have to convert from, say, one type of error to another type of error. Zig error type is also similar in this aspect, but it is not as general as Hare's tagged union type. [1] I really want to refer this as to "untagged" union type, but of course this will cause a confusion with C-style unsafe unions.