constantly (ANSI and GNU Common Lisp Document)

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#### 5.3.39 constantly [Function]

`constantly` value ⇒ function

#### Arguments and Values::

value—an object.

function—a function.

#### Description::

constantly returns a function that accepts any number of arguments, that has no side-effects, and that always returns value.

#### Examples::

     (mapcar (constantly 3) '(a b c d)) ⇒  (3 3 3 3)
     (defmacro with-vars (vars &body forms)
       `((lambda ,vars ,@forms) ,@(mapcar (constantly nil) vars)))
    ⇒  WITH-VARS
     (macroexpand '(with-vars (a b) (setq a 3 b (* a a)) (list a b)))
    ⇒  ((LAMBDA (A B) (SETQ A 3 B (* A A)) (LIST A B)) NIL NIL), true

#### See Also::

not

#### Notes::

constantly could be defined by:

     (defun constantly (object)
       #'(lambda (&rest arguments) object))