val map : ('a -> 'b) -> 'a option -> 'b option
  (** Apply f to the Some value *)

val apply : ('a -> 'b option) -> 'a option -> 'b option
  (** Like map, for use when f returns an option.  With this
      you can turn Some's to None's. *)

val get : 'a option -> 'a
  (** Return the Some value, or raise an exception *)

val set : 'a -> 'a option -> 'a
  (** Like get, but provide a default value for None instead
      of raising an exception. *)

val setmap : 'a -> ('b -> 'a) -> 'b option -> 'a
  (** Commonly used combination of set and map *)

val zap : ('a -> bool) -> 'a option -> 'a option
  (** Turn selected Somes into Nones *)

val compare : ('a -> 'b -> int) -> 'a option -> 'b option -> int
  (** Wrap up a compare function so that None values sort later *)

val pred : 'a option -> bool
  (** Map None to false, Some x to true *)

val filter : 'a option list -> 'a list
  (** Filter the Nones out of an option list and return the Some values. *)

val to_string : ('a -> string) -> 'a option -> string
  (** Debugging function *)