The story of #"

story-of-hash-dquote.txt

   It is #*100101 nowadays, but used to be #"100101" according to a
   Kent M. Pitman message in cl-su-ai.

   Pitman suggested the new sub-char so that he could use #" for
   strings passed through FORMAT:

   (defun read-sharpsign-doublequote (stream char n)
     (declare (ignore n))
     (unread-char char stream)
     (format nil (read stream t nil t)))

   Then one can use, say, #"Hello~%World" to have a string composed of
   two lines, or

   (defun f (x)
     #"This function takes X~@
       and returns it, as-is."
     x)

   To have the text in the docstring indented in source but appearing
   unindented in DOCUMENTATION output.