map.clj

(defn dissoc-in
  "Associates a value in a nested associative structure, where ks is a sequence of keys and returns
  a new nested structure. If any maps that result are empty, they will be removed from the new
  structure."
  [m [k & ks :as keys]]
  (if ks
    (if-let [old (get m k)]
      (let [new (dissoc-in old ks)]
        (if (seq new)
          (assoc m k new)
          (dissoc m k)))
      m)
    (if (seq keys)      
      (dissoc m k)
      {})))