let x =

  match y with

  | A z -> z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z z

  | B l ->

      (match l with

       | [] -> ()

       | x::xs -> p x; self xs)

  | C -> ()

in x