get-macro-character char &optional readtable → function, non-terminating-p

set-macro-character char new-function &optional non-terminating-p readtable → t

char — a character.

non-terminating-p — a generalized boolean. The default is false.

readtable — a readtable designator. The default is the current readtable.

function — nil, or a designator for a function of two arguments.

new-function — a function designator.

get-macro-character returns as its primary value, function, the reader macro function associated with char in readtable (if any), or else nil if char is not a macro character in readtable. The secondary value, non-terminating-p, is true if char is a non-terminating macro character; otherwise, it is false.

set-macro-character causes char to be a macro character associated with the reader macro function new-function (or the designator for new-function) in readtable. If non-terminating-p is true, char becomes a non-terminating macro character; otherwise it becomes a terminating macro character.

(get-macro-character #\{) → NIL, false 
(not (get-macro-character #\;)) → false

The following is a possible definition for the single-quote reader macro in standard syntax:

(defun single-quote-reader (stream char) 
  (declare (ignore char)) 
  (list 'quote (read stream t nil t))) → SINGLE-QUOTE-READER 
(set-macro-character #\' #'single-quote-reader) → T

Here single-quote-reader reads an object following the single-quote and returns a list of quote and that object. The char argument is ignored.

The following is a possible definition for the semicolon reader macro in standard syntax:

(defun semicolon-reader (stream char) 
  (declare (ignore char)) 
  ;; First swallow the rest of the current input line. 
  ;; End-of-file is acceptable for terminating the comment. 
  (do () ((char= (read-char stream nil #\Newline t) #\Newline))) 
  ;; Return zero values. 
  (values)) → SEMICOLON-READER 
(set-macro-character #\; #'semicolon-reader) → T

The readtable is modified.

*readtable*