module Car = struct type car = { car : string ; age : int ; } let make car_name age = { car = car_name ; age } let print_car_name car = print_endline car . module Car : sig type car = { car : string ; age : int ; } val make : string -> int -> car val print_car_name : car -> unit val print_car_age : car -> unit end One thing to note in the code is that the type is only defined once, as OCaml infers the type within the functions since car is a type within this scope.