middleware.clj

(deftest middlewares
  (testing "chain"
    (let [add (fn [f v]
                (fn [input]
                  (+ (f input) v)))
          sub (fn [f v]
                (fn [input]
                  (- (f input) v)))

          chain (-> identity
                    (add 1)
                    (add 42)
                    (sub 1))

          _ (println (chain 0))]))

  (testing "other"
    (let [add (fn [v]
                (fn [input]
                  (+ input v)))

          sub (fn [v]
                (fn [input]
                  (- input v)))

          invoke (fn [chain seed]
                   (reduce (fn [a f] (f a)) seed chain))

          chain [(add 1) (add 42) (sub 1)]

          _ (println (invoke chain 0))])))