1structure UniversalType :> UniversalType = 2struct 3 4 (* stolen from MLton webpage: http://mlton.org/UniversalType *) 5type t = exn 6 7fun 'a embed () = let 8 exception E of 'a 9 fun project (e: t): 'a option = 10 case e of 11 E a => SOME a 12 | _ => NONE 13in 14 (E, project) 15end 16end (* struct *) 17