Mapping a function on the values of a map in Clojure

Question

I want to transform one map of values to another map with the same keys but with a function applied to the values. I would think there was a function for doing this in the c

Answer 1

I like your reduce version. With a very slight variation, it can also retain the type of records structures:

(defn map-function-on-map-vals [m f]
  (reduce (fn [altered-map [k v]] (assoc altered-map k (f v))) m m))

The {} was replaced by m. With that change, records remain records:

(defrecord Person [firstname lastname])

(def p (map->Person {}))
(class p) '=> Person

(class (map-function-on-map-vals p
  (fn [v] (str v)))) '=> Person

By starting with {}, the record loses its recordiness, which one might want to retain, if you desire the record capabilities (compact memory representation for instance).