let compt = 
  let next =
    let c = ref 0 in
      (fun () -> c := !c + 1; !c)
  in
  register_new_service 
    ~url:["compt"]
    ~get_params:unit
    (fun _ () () ->  return
      (html
       (head (title (pcdata "counter")) [])
       (body [p [pcdata (string_of_int (next ()))]])))