wgb

(require '[clojure.string :as str])

;; In this use case, a valid expression won't have an even number of lexemes
(defn valid-length? [lexemes]
  (odd? (count lexemes)))

(defn valid-paren-count? [lexemes]
  (let [opens (filter #(= "(" %) lexemes)
        closes (filter #(= ")" %) lexemes)]
    (= (count opens) (count closes))))