recursive-descent2.clj

(declare read-term)

;; accumulate terms from an input sequence until \)
(defn read-terms [[c & more :as input] acc]
  (if (= c \)) [(reverse acc) more]
               (let [[term input] (read-term input)]
                 (recur input (cons term acc)))))

;; read one term from an input param
(defn read-term [[c & more]]
  (if (not= c \() [c more]
                  (read-terms more ())))

(println (first (read-term (vec "(ABC(DE(FGH)I)J)"))))