symbol-function symbol contents

    (setf (symbol-function symbol) new-contents)

    Arguments and Values

    symbol — a symbol.

    contents — If the symbol is globally defined as a macro or a special operator, an object of implementation-dependent nature and identity is returned. If the symbol is not globally defined as either a macro or a special operator, and if the symbol is fbound, a function object is returned.

    new-contents — a function.


    Accesses the symbol’s function cell.

     (symbol-function 'car)  #<FUNCTION CAR> 
     (symbol-function 'twice) is an error   ;because TWICE isn't defined. 
     (defun twice (n) (* n 2))  TWICE 
     (symbol-function 'twice)  #<FUNCTION TWICE> 
     (list (twice 3) 
           (funcall (function twice) 3) 
           (funcall (symbol-function 'twice) 3)) 
     (6 6 6) 
     (flet ((twice (x) (list x x))) 
       (list (twice 3) 
             (funcall (function twice) 3) 
             (funcall (symbol-function 'twice) 3))) 
     ((3 3) (3 3) 6) 
     (setf (symbol-function 'twice) #'(lambda (x) (list x x))) 
     #<FUNCTION anonymous> 
     (list (twice 3) 
           (funcall (function twice) 3) 
           (funcall (symbol-function 'twice) 3)) 
     ((3 3) (3 3) (3 3)) 
     (fboundp 'defun)  true 
     (symbol-function 'defun) 
     (functionp (symbol-function 'defun)) 
     (defun symbol-function-or-nil (symbol) 
       (if (and (fboundp symbol) 
                (not (macro-function symbol)) 
                (not (special-operator-p symbol))) 
           (symbol-function symbol) 
           nil))  SYMBOL-FUNCTION-OR-NIL 
     (symbol-function-or-nil 'car)  #<FUNCTION CAR> 
     (symbol-function-or-nil 'defun)  NIL
    Affected By


    Exceptional Situations

    Should signal an error of type type-error if symbol is not a symbol.

    Should signal undefined-function if symbol is not fbound and an attempt is made to read its definition. (No such error is signaled on an attempt to write its definition.)

    See Also

    fboundp, fmakunbound, macro-function, special-operator-p


    symbol-function cannot access the value of a lexical function name produced by flet or labels; it can access only the global function value.

    setf may be used with symbol-function to replace a global function definition when the symbol’s function definition does not represent a special operator.

    (symbol-function symbol)  (fdefinition symbol)

    However, fdefinition accepts arguments other than just symbols.