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constantly (Function)

Syntax:
— 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:

identity

Notes:

constantly could be defined by:

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