45 lines
832 B
OCaml
45 lines
832 B
OCaml
type bstree = L | N of int * bstree * bstree
|
|
|
|
let rec insert x t =
|
|
match t with
|
|
| L -> N (x, L, L)
|
|
| N (x', l, r) ->
|
|
if x < x' then N (x', insert x l, r)
|
|
else if x > x' then N (x', l, insert x r)
|
|
else t
|
|
|
|
let of_list l = List.fold_left (Fun.flip insert) L l
|
|
|
|
(* val right : bstree -> bstree option *)
|
|
let right t =
|
|
match t with
|
|
| L -> None
|
|
| N (_, _, r) -> Some r
|
|
|
|
(* val left : bstree -> bstree option *)
|
|
let left t =
|
|
match t with
|
|
| L -> None
|
|
| N (_, l, _) -> Some l
|
|
|
|
let right_left t =
|
|
match right t with
|
|
| None -> None
|
|
| Some r -> left r
|
|
|
|
(* maybe monad *)
|
|
let bind mt f =
|
|
match mt with
|
|
| None -> None
|
|
| Some t -> f t
|
|
|
|
let ( >>= ) = bind
|
|
|
|
let t = of_list [3;2;7;6;8];;
|
|
t |> right >>= left;;
|
|
t |> right >>= left >>= right >>= left;;
|
|
|
|
let return t = Some t;;
|
|
|
|
return t >>= right >>= left;;
|