I thought it was going to be a program for helping me draw Ascii art diagrams. I was disappointed. It's a program for converting Ascii art into graphical diagrams.
(setq ditaa-cmd "java -jar ~/.emacs.d/ditaa0_9.jar")
(defun ditaa-generate ()
(interactive)
(shell-command
(concat ditaa-cmd " -o -r " buffer-file-name))
(find-file (concat (file-name-sans-extension buffer-file-name) ".png")))