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Index
fdefinition Data and Control Flow Dictionary fmakunbound
Function

fboundp

fboundp name ⇒ generalized-boolean

Pronunciation

pronounced ,ef ’baund p\=e

Arguments and Values

namea function name.
generalized-booleana generalized boolean.

Description

Returns true if name is fbound; otherwise, returns false.

Examples

 (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

Exceptional Situations

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

See Also

symbol-function, fmakunbound, fdefinition

Notes

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.

Backlinks

Constraints on the COMMON-LISP Package for Conforming Implementations, Data and Control Flow Dictionary, fdefinition, fmakunbound, Function Forms, Naming of Compiler Macros, symbol-function, symbol, Symbols in the COMMON-LISP Package