(defn apply-map-fn [f ks]
  (let [params (->> (-> f meta :arglists first)
                    (map keyword)
                    (reduce #(conj %1 (ks %2)) [])
                    (remove nil?))
        f-args-count (-> f meta :arglists first count)
        params-count (count params)]
    (if (= f-args-count params-count)
      (apply f params)
      (throw (str "You passed " params-count " param(s) to " (-> f meta :name) " when it takes " f-args-count)))))