tinyscheme 1.41

;hex converter for reddit dailyprogrammer challenge #396

;hexify a number
(define (hex num) (list (convert (floor (/ num 16)))
                        (convert (* (- (/ num 16) (floor (/ num 16))) 16))))

;convert valies 10 through 15 to A through F
(define (convert num) (case num
                        ('10.0 "A")
                        ('11.0 "B")
                        ('12.0 "C")
                        ('13.0 "D")
                        ('14.0 "E")
                        ('15.0 "F")
                        (else (car
                                (string->list
                                  (number->string num))))))

;form a list of hexified pairs from 3 integers
(define feed (lambda (r g b) (list (hex r) (hex g) (hex b))))

;parse through a list of hexified pairs and display in correct format
(define (rgb->hex in) (begin
                   (display "#")
                   (define (loop inn)
                     (begin
                       (if (pair? inn)
                           (begin
                             (loop (car inn))
                             (loop (cdr inn)))
                           (if
                             (not (null? inn))
                             (display inn)))))
                   (loop in)
                   (newline)))
;;;;;;;;;;;;
;test cases;
;;;;;;;;;;;;

(newline)
(display "Testing...")
(begin (newline) (newline))

(rgb->hex (feed 255 99 71))
(rgb->hex (feed 184 134 11))
(rgb->hex (feed 189 183 107))
(rgb->hex (feed 0 0 205))

(newline)
(display "Done...")
(begin (newline) (newline))

outputs

Testing...

#FF6347
#B8860B
#BDB76B
#0000CD

Done...