Name

missing-value

Usage

constant

Syntax

missing-value

Description

Alternative for null default arguments.

make-html > (defmacro some-return (&optional (a missing-value))
                (if (missing-value? a)
                      `(return)
                    `(return ,a)))
it: some-return
make-html > (macroexpand '(some-return))
it: (return)
make-html > (macroexpand '(some-return null))
it: (return null)

See also

missing-value?