type Tree<'a> = 

  | Empty

  | Node of 'a * Tree<'a> * Tree<'a>

​

let traverse (tree : Tree<'a>) =

  let rec loop (tree : Tree<'a>) = seq {

    match tree with

    | Empty -> ()

    | Node (value, left, right) ->

      yield value

​

      yield! loop left

      yield! loop right

  }

  loop tree

​

let tree = 

  Node (1, 

    Node (2, 

      Node (4, Empty, Empty), 

      Node (5, Empty, Empty)), 

    Node (3, 

      Node (6, 

        Node (7, Empty, Empty),

        Empty), 

      Node (8, Empty, Empty)))

​

//       1

//    /     \

//   2       3

//  / \     / \

// 4   5   6   8

//        /

//       7

traverse tree |> Seq.iter (printfn "%d") // 1 2 4 5 3 6 7 8