sig
type t = int array
val create : int -> Istring.t
val sub : Istring.t -> int -> int -> Istring.t
val length : Istring.t -> int
val blit : Istring.t -> int -> Istring.t -> int -> int -> unit
val get : Istring.t -> int -> char
val set : Istring.t -> int -> char -> unit
val make : int -> char -> Istring.t
end