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fboundp name ⇒ generalized-boolean
pronounced ,ef ’baund p\=e
name—a function name.
generalized-boolean—a generalized boolean.
Returns true if name is fbound; otherwise, returns false.
(fboundp 'car) ⇒ true
(fboundp 'nth-value) ⇒ false
(fboundp 'with-open-file) ⇒ true
(fboundp 'unwind-protect) ⇒ true
(defun my-function (x) x) ⇒ MY-FUNCTION
(fboundp 'my-function) ⇒ true
(let ((saved-definition (symbol-function 'my-function)))
(unwind-protect (progn (fmakunbound 'my-function)
(fboundp 'my-function))
(setf (symbol-function 'my-function) saved-definition)))
⇒ false
(fboundp 'my-function) ⇒ true
(defmacro my-macro (x) `',x) ⇒ MY-MACRO
(fboundp 'my-macro) ⇒ true
(fmakunbound 'my-function) ⇒ MY-FUNCTION
(fboundp 'my-function) ⇒ false
(flet ((my-function (x) x))
(fboundp 'my-function)) ⇒ false
Should signal an error of type type-error if name is not a function name.
symbol-function , fmakunbound , fdefinition
It is permissible to call symbol-function on any symbol that is fbound.
fboundp is sometimes used to “guard” an access to the function cell, as in:
(if (fboundp x) (symbol-function x))
Defining a setf expander F does not cause the setf function (setf F) to become defined.