'State' design pattern in Clojure

dp_state.clj

(def user (atom {:name "John Doe"
                 :user-state :not-subscribed}))

(println user)          ;; print the memory address
(println (deref user))  ;; dereference the memory address, and print the value 
(println @user)         ;; short-hand form of dereferencing

(defn subscribe [user]
  (when (= :not-subscribed (:user-state @user))
    (swap! user assoc :user-state :subscribed)))

(defmulti greet :user-state)

(defmethod greet :subscribed [user]
  (println (str "Greetings, " (:name user) "!!!")))

(defmethod greet :not-subscribed [user]
  (println (str "Greetings, " (:name user) ".")))

(greet @user)
(subscribe user)
(greet @user)

As discussed here:
https://www.mpj-analytics.co.uk/2019/09/18/design-patterns-r-state/

Inspired by:
http://mishadoff.com/blog/clojure-design-patterns/#episode-3-state