(defmacro bad-idea-double [x] `(+ ~x ~x))
 
(println (bad-idea-double 5))
 
(println "Let's see what happens when we use bad-idea-double with side-effects")
 
(println (bad-idea-double (do (println "A) doing side effects") 3)))
; How many times will "A) doing side effects" print?
 
(defmacro right-way-double [x] `(let [x-val# ~x] (+ x-val# x-val#)))
 
(println (right-way-double (do (println "B) doing side effects") 4)))
; How many times will "B) doing side effects" print?
 

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