Tail recursive function to find depth of a tree in Ocaml

Question

I have a type tree defined as follows

type \'a tree = Leaf of \'a | Node of \'a * \'a tree * \'a tree ;;

I have a function to

Answer 1

There's a neat and generic solution using fold_tree and CPS - continuous passing style:

let fold_tree tree f acc =
  let loop t cont =
    match tree with
    | Leaf -> cont acc
    | Node (x, left, right) ->
      loop left (fun lacc ->
        loop right (fun racc ->
          cont @@ f x lacc racc))
  in loop tree (fun x -> x)

let depth tree = fold_tree tree (fun x dl dr -> 1 + (max dl dr)) 0