(* Dijkstra's Algorithm *)
let
  fun ordering((v1,d1), (v2,d2)) = Int.compare(d1,d2)
  val q: (vertex*int) Heap.heap = Heap.create(ordering)
  val dist: VertexMap.map = VertexMap.create()
  fun expand(v: vertex, d: int) =
    let fun handle_edge(e: edge) =
      let val (_, v', w) = Graph.edgeinfo(e) in
        case get(dist, v') of
          SOME(d') =>
            if d+w < d'
              then (add(dist, v', dist+w);
                    incr_priority(q, v', d+w) )
            else ()
        | NONE => (add(dist, v', d+w);
                   insert(q, v', d+w) )
      end
    in
      app handle_edge (Graph.outgoing(v))
    end
in
  add(visited, v0, 0);
  insert(q, (v0, 0));
  while (not (empty_queue(q))) do expand(extract_min(q))
end