insert-typewrite.el

;;  I would like a function that inserts a phrase or paragraph into a
;;  buffer, but that it is looks like it is being typed. This means to
;;  have a slight, but random time delay between each letter. Calling
;;  `sit-for' is sufficient for short sentences (around 140
;;  characters), but anything longer makes the display look like it
;;  hangs until some event, and then the entire results are displayed.
;;
;;  Ideas or thoughts on what to look for?

(defun insert-typewriter (str)
  "Insert STR into the current buffer as if you were typing it by hand."
  (interactive "s")
  (dolist (ch (string-to-list str))
    (insert ch)
    (sit-for (/ 1.0 (+ 10 (random 80))) nil)))

;; This works well:
(insert-typewriter "Hello, how the hell are you doing today?")

;; But this is really fun to watch:
(insert-typewriter "Lorem ipsum dolor sit amet, consectetur
adipiscing elit, sed do eiusmod tempor incididunt ut labore et
dolore magna aliqua. Ut enim ad minim veniam, quis nostrud
exercitation ullamco laboris nisi ut aliquip ex ea commodo
consequat. Duis aute irure dolor in reprehenderit in voluptate
velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint
occaecat cupidatat non proident, sunt in culpa qui officia
deserunt mollit anim id est laborum.

Sed ut perspiciatis unde omnis iste natus error sit voluptatem
accusantium doloremque laudantium, totam rem aperiam, eaque ipsa
quae ab illo inventore veritatis et quasi architecto beatae vitae
dicta sunt explicabo. Nemo enim ipsam voluptatem quia voluptas
sit aspernatur aut odit aut fugit, sed quia consequuntur magni
dolores eos qui ratione voluptatem sequi nesciunt. Neque porro
quisquam est, qui dolorem ipsum quia dolor sit amet, consectetur,
adipisci velit, sed quia non numquam eius modi tempora incidunt
ut labore et dolore magnam aliquam quaerat voluptatem. Ut enim ad
minima veniam, quis nostrum exercitationem ullam corporis
suscipit laboriosam, nisi ut aliquid ex ea commodi consequatur?
Quis autem vel eum iure reprehenderit qui in ea voluptate velit
esse quam nihil molestiae consequatur, vel illum qui dolorem eum
fugiat quo voluptas nulla pariatur?")

cool! the string-empty-p wasn't defined for me. maybe fix.

Ah! But of course! The sit-for function, when given a 0 was the culprit! I will edit the gist in case anyone else comes along looking for something similarly silly. Thanks for the help!