type t =
    Pident of Ident.t
  | Pdot of t * string * int

let nopos = -1

let rec same p1 p2 =
  match (p1, p2) with
    (Pident id1, Pident id2) -> Ident.same id1 id2
  | (Pdot(p1, s1, pos1), Pdot(p2, s2, pos2)) -> s1 = s2 & same p1 p2
  | (_, _) -> false

let rec root = function
    Pident id -> id
  | Pdot(p, s, pos) -> root p

let isfree id p = Ident.same id (root p)