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;; macro_based_decorator.clj

;; 3. Macro-based Decorator (More Python-like Syntax)

(defmacro decorate [decorator & body]
(let [form (first body)]
(if (and (list? form) (= 'fn (first form)))
;; Anonymous function: (decorate decorator (fn [x y] (+ x y)))
`(~decorator ~form)
;; Named function: (decorate decorator (add [x y] (+ x y)))
(let [[fname args & fbody] form]
`(def ~fname (~decorator (fn ~args ~@fbody)))))))

;; Define decorators
(defn log-calls [f]
(fn [& args]
(println (str "Calling function with args: " args))
(let [result (apply f args)]
(println (str "Result: " result))
result)))

(defn timer-decorator [f]
(fn [& args]
(let [start (System/nanoTime)
result (apply f args)
end (System/nanoTime)]
(println (str "Execution time: " (/ (- end start) 1000000.0) " ms"))
result)))

;; Usage examples:

;; Named function with decorator
(decorate log-calls
(add [x y]
(+ x y)))

(macroexpand '(decorate log-calls (add [x y] (+ x y))))
;;=> (def add (log-calls (clojure.core/fn [x y] (+ x y))))

;; Test the decorated function
(add 5 3)

;; Or with anonymous function
(def my-add (decorate timer-decorator
(fn [x y] (+ x y))))

(macroexpand '(decorate timer-decorator
(fn [x y] (+ x y))))
;;=> (timer-decorator (fn [x y] (+ x y)))

;; Test the anonymous decorated function
(my-add 10 20)