RingとかのMiddlewareのしくみ解説にFizzBuzzを使ってみるサンプル

fizzbuzz-middleware.clj

;;; fizzbuzzで渡される一つ一つの数値はひとつのリクエストとみなすことができる

(defn wrap-request
  [x]
  {:request x
   :result x})

(defn wrap-result
  [map]
  (:result map))

(defn wrap-fizz
  [map]
  (let [x (:request map)]
    (if (= (mod x 3) 0)
      (assoc map :result "fizz")
      map)))

(defn wrap-buzz
  [map]
  (let [x (:request map)]
    (if (= (mod x 5) 0)
      (assoc map :result "buzz")
      map)))

(defn wrap-fizzbuzz
  [map]
  (let [x (:request map)]
    (if (and (= (mod x 3) 0) (= (mod x 5) 0))
      (assoc map :result "fizzbuzz")
      map)))

(defn fizzbuzz-server
  "fizz buzz サーバー本体"
  [vec]
  (map (fn [in] (-> in
                    wrap-request
                    wrap-fizz
                    wrap-buzz
                    wrap-fizzbuzz
                    wrap-result)) vec))


;; -> (fizzbuzz-server (range 1 20))
;; (1 2 "fizz" 4 "buzz" "fizz" 7 8 "fizz" "buzz" 11 "fizz" 13 14 "fizzbuzz" 16 17 "fizz" 19)