type: keyword location: built-in source file: xlread.c Common LISP compatible: no supported on: all machines
:WHITE-SPACE is an entry that is used in the *READTABLE*. *READTABLE* is a 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.
(defun look-at (table) ; define a function to (dotimes (ch 127) ; look in a table (prog ( (entry (aref table ch)) ) ; and print out any (case entry ; entries with a function (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 *READTABLE*, it is useful to save the old value in a variable, so that you can restore the system state.