(** The function is undefined *)
exception Undefined of UTF8.t * string list

exception TypeError

exception Cycle

let printf formatter = function
  | Undefined (name, args) -> Format.fprintf formatter
      "There is no function '%s' with signature %a"
      (UTF8.to_utf8string name)
      (Format.pp_print_list Format.pp_print_text) args
  | _ -> Format.fprintf formatter "#Error"