I’m trying to see if I can gain more performance by turning alias-map transformation into a transducer alias-map-xf:

(defn alias-map []
  (->> emojis
       (map (juxt identity :aliases))
       (mapcat (fn [[emoji aliases]] (map (fn [alias] [(keyword alias) emoji]) aliases)))
       (into {})))

(defn alias-map-xf []
  (into {} (comp
            (map (juxt :aliases identity))
            (mapcat (fn [[aliases emoji]]
                      (map (fn [alias] [(keyword alias) emoji]) aliases))))
        emojis))

{:emojiChar "string"
 :aliases ["alias1" "alias2" ...]
 ...}

'(
[:alias1 {:emojiChar "string"
              :aliases ["alias1" "alias2" ...]
              ...}]
[:alias2 {:emojiChar "string"
              :aliases ["alias1" "alias2" ...]
              ...}]
)