binding.clj

; the binding macro ought to be handy for implementing something like fakeweb or timecop in Clojure

(def x 9)
(defn printx [] (println x))
(printx)                  ; prints 9
(binding [x 5] (printx))  ; prints 5
(printx)                  ; prints 9

(defn say-hi [] (println "Hi!"))
(defn say-hi-twice [] (dotimes [n 2] (say-hi)))
(say-hi-twice)                                                ; prints "Hi!" twice
(binding [say-hi (fn [] (println "Howdy!"))] (say-hi-twice))  ; prints "Howdy!" twice
(say-hi-twice)                                                ; prints "Hi!" twice