Simple decorator in Clojure

Code

;; simple_function_decorator.clj

;; 1. Simple Function Decorator (Higher-Order Function)

;; Define a decorator function
(defn timer-decorator [f]
  (fn [& args]
    (println "Starting execution...")
    (let [start (System/currentTimeMillis)
          result (apply f args)
          end (System/currentTimeMillis)]
      (println (str "Execution time: " (- end start) "ms"))
      result)))

;; Define a function
(defn slow-add [x y]
  (Thread/sleep 1000)
  (+ x y))

;; Apply the decorator
(def timed-add (timer-decorator slow-add))

;; Use it
(timed-add 5 3)  ; prints timing info and returns 8