;Macro study
(defun range-helper(x)
	(if (= x 0)
		(list x)
		(cons x (range-helper (- x 1)))
	)
)

(defun range (x)
	(reverse (range-helper (- x 1)))
)

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;stupid way
(defvar ans nil)
(loop for x in (range 10) if (= 0 (mod x 2)) do
	(setq ans (append ans (list x)))
)
(print ans)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;wise way
(defmacro lcomp (expression for var in list conditional condition-test)
	(let ((result (gensym)))
		`(let ((,result nil))
			(loop for ,var in ,list
				,conditional
				,condition-test
				do (setq ,result (append ,result (list ,expression))))
			,result)))

(setq ans2 (lcomp (+ (* x x) 10) for x in (range 10) if (= 0 (mod x 2))))
(print ans2)