Same Fringe with core.async

same_fringe.clj

(defn same-fringe
  "http://c2.com/cgi/wiki?SameFringeProblem"
  [t1 t2]
  (letfn [(walk [t c]
            (go (if (seq? t)
                  (doseq [t' t]
                    (<! (walk t' c)))
                  (>! c t))))]
    (let [c1 (chan)
          c2 (chan)]
      (go (<! (walk t1 c1)) (close! c1))
      (go (<! (walk t2 c2)) (close! c2))
      (<!!
       (go (loop [x1 (<! c1)
                  x2 (<! c2)]
             (cond
               (and (nil? x1) (nil? x2)) true
               (= x1 x2) (recur (<! c1) (<! c2))
               :else false)))))))

(comment
 
  (same-fringe '((0 1) 2 (3 (4 (5)))) '(0 (1 2) 3 4 ((((5))))))

  (same-fringe '((0 1) 2 (3 (4 (5)))) '(0 (1 2) 3 :foo ((((5))))))
 
  )