Flatten nested maps using clojure / clojurescript using compound keys

flatten-maps.clj

(defn get-key
    [prefix key]
    (if (nil? prefix)
        key
        (str prefix "-" key)))
(defn flatten-map-kvs
    ([map] (flatten-map-kvs map nil))
    ([map prefix]
     (reduce
         (fn [memo [k v]]
             (if (map? v)
                (concat memo (flatten-map-kvs v (get-key prefix (name k))))
                (conj memo [(get-key prefix (name k)) v])))
         [] map)))

(defn flatten-map
    [m]
    (into {} (flatten-map-kvs m)))

(flatten-map {:a 12 :fromUser { :id 12 :url "something"}})
; {"a" 12, "fromUser-id" 12, "fromUser-url" "something"}

jsonify-values.clj

(defn jsonify-values
  "Recursively transforms all map values from json string to clj."
  [m]
  (let [f (fn [[k v]] (try [k (json/read-str v)] (catch Exception e [k v])))]
    ;; only apply to maps
    (walk/postwalk (fn [x] (if (map? x) (into {} (map f x)) x)) m)))

I need to flatten the vector also.
ex. {r: 6, a: [{b:6},{b:4}]} ---> {r:6 , {[a_b: 6] [a_b: 4]}}