Convert Standard Time (AM/PM) to Militar Time (24h)

std-militar.clj

(defmulti std-to-militar (fn [hour time-info] (keyword time-info)))

(defmethod std-to-militar :AM [hour _]
  (format "%02d" (if (= hour 12) 0 hour)))

(defmethod std-to-militar :PM [hour _]
  (if (= hour 12) hour (+ hour 12)))

(defn convert-time [hour]
  (let [[hour minute seconds time-info] (rest (re-find #"(\d+):(\d+):(\d+)(\w+)" hour))]
    (clojure.string/join ":" [(std-to-militar (Integer/parseInt hour) time-info) minute seconds])))