type Tree =
     | Empty
     | Node of Tree * int * Tree

// printTree : Tree -> int
let rec printTree t =
    match t with
    | Empty -> printf "nul"; 0
    | Node (l, v, r) -> printf "%A (" v
                        let lc = printTree l
                        printf ", "
                        let rc = printTree r
                        printf ")"
                        lc + rc + 1

printTree (Node (Empty, 1, Empty)) |> ignore

// printTree'cps : Tree -> (int -> 'a) -> 'a
let rec printTree'cps t k =
    match t with
    | Empty -> k (printf "nul"; 0)
    | Node (l, v, r) -> printf "%A (" v
                        printTree'cps l
                          (fun lc ->
                             printf ", "
                             printTree'cps r
                                (fun rc ->
                                   printf ")"
                                   k (lc + rc + 1)
                                )
                          )

printTree'cps (Node (Node (Empty, 2, Empty), 1, (Node (Empty, 3, Empty)))) (fun cnt -> printfn "\ncount = %A" cnt)