cljs.spec.alpha/fn-sym

(defn fn-sym [f-n]
  (when-not (str/blank? f-n)
    (let [xs (map demunge (str/split f-n "$"))]
      (when (c/and (<= 2 (count xs))
                   (every? #(not (str/blank? %)) xs))
        (let [[xs y] ((juxt butlast last) xs)]
          (symbol (str (str/join "." xs) "/" y)))))))