test.ml

let test n list =
  let cons = ref list in
  for i = 0 to n - 1 do
    match !cons with
    | [] -> ()
    | _::xs -> cons := xs
  done;
  !cons

let test2 observe n list =
  let cons = ref list in
  for i = 0 to n - 1 do
    observe cons;
    match !cons with
    | [] -> ()
    | _::xs -> cons := xs
  done;
  !cons