The ':white-space' keyword is an entry that is used in the *readtable* system variable that contains XLISP's data structures relating to the processing of characters from the user [or files] and read-macro expansions. The existance of the ':white-space' keyword means that the specified character may be skipped over. The system defines that 'tab', 'space', 'return' and 'line-feed' are ':white-space' characters.
;; define a function to look in a table
;; and print out any white-space characters
(defun look-at (table)
(dotimes (ch 127)
(prog ((entry (aref table ch)))
(case entry
(nil nil)
(:constituent nil)
(:white-space (print ch))
(t nil))))
(terpri))
(look-at *readtable*) ; prints 9 - tab
; 10 - newline
; 12 - formfeed
; 13 - return
; 32 - space
Caution: If you experiment with
See the
:white-space
keyword in the