test.ml

open Base
open With_return

type node = { value: int; left: node option; right: node option }

let is_bst tree=
  with_return (fun r ->
      let rec tick = function
        | { value; left = None; right = None} -> value
        | { value; left = Some l; right = None} ->
          if tick l <= value then value else r.return false
        | { value; left = None; right = Some ri} ->
          let a = tick ri in
          if a > value then a else r.return false
        | { value; left = Some l; right = Some ri;} ->
          let a = tick ri in
          if tick l <= value && a > value then a else r.return false in
      tick tree |> ignore;
      true)