Clojure Рекурсивное вычисление суммы четных

(defun sum-even (n)
  (cond ((= n 1) 0)
        ((evenp n) (+ n (sum-even (1- n))))
        (t (sum-even (1- n)))))
 
> (sum-even 10)
30

(defun sum-even (n)
  (cond ((zerop n) 0)
        ((evenp n) (+ n (sum-even (1- n))))
        ((sum-even (1- n)))))
 
> (sum-even 10)
30

(defun sum-even (n)
  (if (plusp n)
      (if  (evenp n)
           (+ n (sum-even (1- n)))
           (sum-even (1- n)))
      0))
 
> (sum-even 10)
30

(defun sum-even (n)
  (if (plusp n)
      (+ (if (evenp n) n 0) (sum-even (1- n)))
      0))
 
> (sum-even 10)
30

(defn task [n]
  (loop [n n acc 0]
    (cond (zero? n) acc
          (even? n) (recur (dec n) (+ acc n))
          :else (recur (dec n) acc))))
;; => #'user/task
 
(task 10)
;; => 30

;;racket
(define (foo1 n)
  (foldl + 0 (range 0 (+ n 1) 2)))
 
(define (foo2 n)
  (let sum-rec ((start 0) (end n) (acc 0))
    (if (> start end) acc (sum-rec (+ start 2) end (+ acc start)))))
 
(define n 15)
 
(define (main)
  (displayln (foo1 n))
  (displayln (foo1 n))
  (displayln "Have fun!"))
 
(main)
 
>
56
56
Have fun!
>

(defun sum-even (n)
  (cond ((oddp n) (sum-even (- n 1)))
        ((zerop n) 0)
        (t (+ n (sum-even (- n 2))))))
 
==> sum-even
 
(sum-even 10)
 
==> 30
 
(sum-even 9)
 
==> 20
 
(sum-even 3)
 
==> 2