mapmap.clj

(defn mapmap [f m]
  "Map over an associative array using a function on the values.  Returns a
  new map where the keys are the same as in the original but the values are
  the result of applying f to the original values."
  (reduce (fn [acc-map [k v]] (assoc acc-map k (f v))) {} m))

(mapmap inc {:a 1 :b 2 :c 3}) => {:a 2 :b 3 :c 4}