type 'a exp =
  | C1 : int -> int exp
  | C2 : int -> int exp
  | C3 : string -> string exp
;;

(* Can I do something like this *)
let inc x = match x with | 'A(y) -> 'A(y+1);;

(* as opposed to having to write out this *)
let inc x = match x with | C1(y) -> C1(y+1) | C2(y) -> C2(y+1);;