gistfile1.clj

(def brackets (zipmap "([{<" ")]}>"))
(def opening-brackets (set (keys brackets)))
(def closing-brackets (set (vals brackets)))

(defn- check-aux [[x & xs] stack]
  (if x
    (cond (opening-brackets x) (recur xs (conj stack (brackets x)))
          (closing-brackets x) (if (= x (peek stack))
                                 (recur xs (pop stack))
                                 false)
          :else (recur xs stack))
    (empty? stack)))

(defn check-brackets [s]
  (check-aux s []))