spark in common lisp

clspark.lisp

#!/usr/bin/clisp

(defconstant ticks (list "▁" "▂" "▃" "▄" "▅" "▆" "▇" "█"))

(defun spark (data-list)
  (let ((max-value (apply #'max data-list))
        (ticks-length (length ticks)))
    (let ((ticks-unit (/ max-value (- ticks-length 1))))
      (map 'list (lambda (x) (elt ticks (ceiling (/ x ticks-unit)))) data-list))))

;; copied from cl-cookbook: http://cl-cookbook.sourceforge.net/strings.html
(defun split (string spliter)
  (loop for i = 0 then (1+ j)
        as j = (position spliter string :start i)
        collect (subseq string i j)
        while j))

(format t
        (apply #'concatenate 'string
                 (spark (map 'list #'read-from-string
                             (if *args*
                                 (split (first *args*) #\,)
                               (split (read-line) #\,))))))

Usage:

chmod u+x clspark

clspark "1,2,3,4,5"

echo "1,2,3,4,5" | clspark

Great implementation. :)