reduce-kv-vs-transducers.clj

(defn remove-nil-vals1
  [m]
  (if-let [s (seq m)]
    (persistent! (reduce-kv (fn [acc k v]
                              (if (nil? v)
                                acc
                                (assoc! acc k v)))
                            (transient (empty m))
                            m))))

(defn remove-nil-vals2
  [m]
  (if-let [s (seq m)]
    (into (empty m) (filter (fn [entry]
                              (some? (val entry))))
          s)))
          
(def nilmap (into {} (map vector (range 1000000) (interleave (range 1000000) (repeat nil)))))