sunset.lisp

(defun sunset (color &key (shift-list '(1 4/3 4/3)))
  "Redshifts the #RRGGBB color."
  (format nil
          "#~{~X~}"
          (loop for start in '(1 3 5) and shift in shift-list
                collect (truncate (parse-integer color
                                                 :start start
                                                 :end   (+ start 2)
                                                 :radix 16)
                                  shift))))

(defun sunset (color &key (shift-list '(1 4/3 4/3)))
  "Redshifts the #RRGGBB color."
  (format nil
          "#~{~X~}"
          (mapcar (lambda (start shift)
                    (truncate (parse-integer color :start start :end (+ start 2) :radix 16)
                              shift))
                  '(1 3 5)
                  shift-list)))

; (sunset "#AABBCC" :shift-list '(1 3/2 4/3))