Name

missing-value

Usage

constant

Syntax

missing-value

Description

Alternative for null default arguments.

user 1 > (defmacro some-return (&optional (a missing-value))
             (if (missing-value? a)
                   `(return)
                 `(return ,a)))
it: some-return
user 2 > (macroexpand '(some-return))
it: (return null)
user 3 > (macroexpand '(some-return null))
it: (return null)

See also

missing-value?