Create a look up map with Clojure for faster record access

clojure-look-up-map.clj

(def users [{:id 1
             :email "[email protected]"
             :first_name "Michael"
             :last_name "Lawson"
             :avatar "https://reqres.in/img/faces/1-image.jpg"}
            {:id 2
             :email "[email protected]"
             :first_name "Lindsay"
             :last_name "Ferguson"
             :avatar "https://reqres.in/img/faces/2-image.jpg"}
            {:id 3
             :email "[email protected]"
             :first_name "Tobias"
             :last_name "Funke"
             :avatar "https://reqres.in/img/faces/3-image.jpg"}
            {:id 4
             :email "[email protected]"
             :first_name "Byron"
             :last_name "Fields"
             :avatar "https://reqres.in/img/faces/4-image.jpg"}
            {:id 5
             :email "[email protected]"
             :first_name "George"
             :last_name "Edwards"
             :avatar "https://reqres.in/img/faces/5-image.jpg"}
            {:id 6
             :email "[email protected]"
             :first_name "Rachel"
             :last_name "Howell"
             :avatar "https://reqres.in/img/faces/6-image.jpg"}])


(first (filter #(= (:id %) 3) users))

(def reduce-lookup (reduce (fn [acc {:keys [id] :as user}]
                             (into acc {id user})) {} users))

(get reduce-lookup 3)


(def groupby-lookup (into {} (map (fn [[id user-list]]
                                    {id (first user-list)}) (group-by :id users))))

(get groupby-lookup 3)

(def juxt-lookup (into {} (map (juxt :id identity) users)))

(get juxt-lookup 3)