Move IntPair and PosSet into Aoc library.

These are obviously generic enough and useful for the future that they
can be moved to a shared library.

lib/aoc.mli

@@ -15,3 +15,62 @@ val main : (string -> 'a) -> (('b -> string) * ('a -> 'b)) list -> unit
     pair of functions. The first converts the output to a string (for example
     [string_of_int]). The second executes the given part. Output is given as if
     done by: [print_string ( prep fname |> snd |> fst )] *)
+
+(** Module representing a pair of integers, useful for Set.Make *)
+module IntPair : sig
+  type t = int * int
+  (** [t] is a pair of integers *)
+
+  val compare : t -> t -> int
+  (** Standard comparion operation. *)
+end
+
+(** IntPairSet represents a Set of integers, see standard docs for info. *)
+module IntPairSet : sig
+  type elt = IntPair.t
+  type t = Set.Make(IntPair).t
+
+  val empty : t
+  val add : elt -> t -> t
+  val singleton : elt -> t
+  val remove : elt -> t -> t
+  val union : t -> t -> t
+  val inter : t -> t -> t
+  val disjoint : t -> t -> bool
+  val diff : t -> t -> t
+  val cardinal : t -> int
+  val elements : t -> elt list
+  val min_elt : t -> elt
+  val min_elt_opt : t -> elt option
+  val max_elt : t -> elt
+  val max_elt_opt : t -> elt option
+  val choose : t -> elt
+  val choose_opt : t -> elt option
+  val find : elt -> t -> elt
+  val find_opt : elt -> t -> elt option
+  val find_first : (elt -> bool) -> t -> elt
+  val find_first_opt : (elt -> bool) -> t -> elt option
+  val find_last : (elt -> bool) -> t -> elt
+  val find_last_opt : (elt -> bool) -> t -> elt option
+  val iter : (elt -> unit) -> t -> unit
+  val fold : (elt -> 'acc -> 'acc) -> t -> 'acc -> 'acc
+  val map : (elt -> elt) -> t -> t
+  val filter : (elt -> bool) -> t -> t
+  val filter_map : (elt -> elt option) -> t -> t
+  val partition : (elt -> bool) -> t -> t * t
+  val split : elt -> t -> t * bool * t
+  val is_empty : t -> bool
+  val mem : elt -> t -> bool
+  val equal : t -> t -> bool
+  val compare : t -> t -> int
+  val subset : t -> t -> bool
+  val for_all : (elt -> bool) -> t -> bool
+  val exists : (elt -> bool) -> t -> bool
+  val to_list : t -> elt list
+  val of_list : elt list -> t
+  val to_seq_from : elt -> t -> elt Seq.t
+  val to_seq : t -> elt Seq.t
+  val to_rev_seq : t -> elt Seq.t
+  val add_seq : elt Seq.t -> t -> t
+  val of_seq : elt Seq.t -> t
+end