; A simple binary tree with numbers:
(import scheme (chicken base) (chicken format) (chicken string) datatype test)

(define-datatype tree tree?
  (leaf (n number?))
  (branch (left tree?) (right tree?)) )

(define t (branch (branch (leaf 33) (leaf 44)) (leaf 55)))

(define (listify t)
  (cases tree t
    (leaf (n) n)
    (branch (left right) (cons (listify left) (listify right))) ) )

(test "listify" '((33 . 44) . 55) (listify t))


(define-record-printer (tree x out)
  (cases tree x
    (leaf (n) 
          (fprintf out "~A" n))
    (branch (left right) 
            (fprintf out "(~A . ~A)" left right))))

(test "to string" "((33 . 44) . 55)" (->string t))


(test-exit)