class int_vec dim =
object(self)
    val mutable coords = Array.create dim 0

    method dot (x:int_vec) =
      let rec innerdot sum count =
        if count >= Array.length coords then sum
        else innerdot (sum + coords.(count) * x#coords.(count)) (count + 1)
      in innerdot 0 0

    method len = sqrt(dot self)

    method coords = coords
end
;;