[amluto]

Ah, so you want both sum and union types, and you probably want those unions to be genuinely unordered, so that A | B is the same as B | A. And maybe even with inferred subtype relationships or automatic conversions so that A | B can be used where A | B | C is expected. This could be useful.

I can also imagine it resulting in horrible compilation times and/or generated code bloat in a language+toolchain like Rust that insists on monomorphizing everything.