Syntax:

macro-function symbol &optional environment => function

(setf (macro-function symbol &optional environment) new-function)

Arguments and Values:

symbol---a symbol.

environment---an environment object.

function---a macro function or nil.

new-function---a macro function.

Description:

Determines whether symbol has a function definition as a macro in the specified environment.

If so, the macro expansion function, a function of two arguments, is returned. If symbol has no function definition in the lexical environment environment, or its definition is not a macro, macro-function returns nil.

It is possible for both macro-function and special-operator-p to return true of symbol. The macro definition must be available for use by programs that understand only the standard Common Lisp special forms.

Examples:

 (defmacro macfun (x) '(macro-function 'macfun)) =>  MACFUN 
 (not (macro-function 'macfun)) =>  false 

 (macrolet ((foo (&environment env)
               (if (macro-function 'bar env)
                  ''yes
                  ''no)))
    (list (foo)
          (macrolet ((bar () :beep))
             (foo))))
 
=>  (NO YES)

Affected By:

(setf macro-function), defmacro, and macrolet.

Exceptional Situations:

The consequences are undefined if environment is non-nil in a use of setf of macro-function.

See Also:

defmacro, Section 3.1 (Evaluation)

Notes:

setf can be used with macro-function to install a macro as a symbol's global function definition:

 (setf (macro-function symbol) fn)

• SPECIAL-FORM-P-MISNOMER:RENAME
• MACRO-FUNCTION-ENVIRONMENT