ref: db34187dc25f6b3f1a85b85c4dcf9a69b1cb4d54
dir: /test/genericret.myr/
use std
type t(@a) = union
	`Val @a
	`None
;;
const f = {-> t(int)
	-> `None
}
const main = {
	match f()
	| `None:	std.exit(42)
	| _:		std.die("Impossible match failure\n");
	;;
	std.exit(0)
}