(* !!take care!!, this is not a pure data structure *)

class ['a] oarray : int -> 'a ->
object ('o)
  inherit ['a] Osequence.osequence

  (* ocollection concrete instantiation of virtual methods *)
  method empty : 'o
  method add : (int * 'a) -> 'o

  method iter : (int * 'a -> unit) -> unit
  method view : (int * 'a, 'o) Ocollection.view

  method del : (int * 'a) -> 'o
  method mem : int * 'a -> bool
  method null : bool


  (* oassoc concrete instantiation of virtual methods *)
  method assoc : int -> 'a
  method delkey : int -> 'o

  method keys: int list

  (* osequence concrete instantiation of virtual methods *)
  method first : 'a
  method last : 'a
  method nth : int -> 'a

end