gistfile1.rkt

#lang typed/racket

(define-type Tree (U leaf node))
(struct: leaf ([val : Number]))
(struct: node ([left : Tree] [right : Tree]))

(: tree-height (-> Tree Integer))
(define (tree-height t)
  (match t
    [(leaf v) 1]
    [(node l r) (max (tree-height l) (tree-height r))]))