; quicksort
(defun quick-sort (l)
    (if (<= (len l) 1)
        l
        (do
            (define pivot (first l))
            (+
                (quick-sort (filter (lambda (n) (> pivot n)) l))
                (list pivot)
                (quick-sort (tail (filter (lambda (n) (<= pivot n)) l)))
            ))
    ))

; decrement a number
(defun dec (n) (- n 1))

; increment a number
(defun inc (n) (+ n 1))

; not a bool
(defun not (x) (if x 0 1))

; negate a number
(defun neg (n) (- 0 n))

; is a number positive?
(defun is-pos? (n) (> n 0))

; is a number negative?
(defun is-neg? (n) (< n 0))

; return second element of list
(defun second (l) (index l 1))

; return third element of list
(defun third (l) (index l 2))

; return fourth element of list
(defun fourth (l) (index l 3))

; return fifth element of list
(defun fifth (l) (index l 4))



; from list of lists creates csv string
; (print (make-csv '(("r1c1" "r1c2") ("r2c1" "r2c2"))))
(defun make-csv (csv_list)
    (do
        (define rows_str "")
        (define r 0)
        (for row csv_list
            (define cols_str "")
            (define c 0)
            (for col row
                (if (= c 0)
                    (define cols_str col)
                    (define cols_str (+ cols_str "," (display col)))) 
                (define c (inc c)))
            (if (= r 0)
                (define rows_str cols_str)
                (define rows_str (+ rows_str "\n" cols_str))) 
            (define r (inc r)))

        rows_str
    ))


(defun setq (var val) (define var val))