(assert (= 3
  ((fn [a b] a) 3 2)))

(defn add4 [a] (+ a 4))

(assert (= 7 (add4 3)))

; testing recursion
(defn fact [n]
  (cond (= n 0) 1 (* n (fact (- n 1)))))

(assert (= 120 (fact 5)))
(assert (= 3628800 (fact 10)))

(defn sum [l]
  (cond (empty? l)
    0 (+ (first l) (sum (rest l)))))

(assert (= 0 (sum [])))
(assert (= 6 (sum [1 2 3])))

; testing tail recursion
(defn fact-tc [n accum]
  (cond (= n 0) accum
    (let [newn (- n 1)
          newaccum (* accum n)]
      (fact-tc newn newaccum))))

(assert (= 120 (fact-tc 5 1)))
(assert (= 3628800 (fact-tc 10 1)))

(defn sum-tc [l a]
  (cond (empty? l)
    a (sum-tc (rest l) (+ a (first l)))))

(assert (= 0 (sum-tc [] 0)))
(assert (= 6 (sum-tc [1 2 3] 0)))

; testing anonymous dispatch
((fn [a] (assert (= a 0))) 0)