_____ _____ __
 / ___// ___// /
/ /__ / /__ / /__
\___/ \___//____/

sjl at ouroboros in ~
><((°> ccl
Clozure Common Lisp Version 1.12-dev (v1.12-dev.5-11-gbfcb7f0e) LinuxX8664

For more information about CCL, please see http://ccl.clozure.com.

CCL is free software.  It is distributed under the terms of the Apache
Licence, Version 2.0.

[ClozureCL] COMMON-LISP-USER>
(defun foo (&rest args)
  (destructuring-bind (&key (a (values :foo 'what) a?)) args
    (list args a a?)))
FOO

[ClozureCL] COMMON-LISP-USER> (foo :a 10)
((:A 10) 10 T)

[ClozureCL] COMMON-LISP-USER> (foo)
(NIL :FOO NIL)


==================================================================================================

   ____ ___   _____ __
  / __// _ ) / ___// /
 _\ \ / _  |/ /__ / /__
/___//____/ \___//____/

sjl at ouroboros in ~
><((°> sbcl

[SBCL] CL-USER>
(defun foo (&rest args)
  (destructuring-bind (&key (a (values :foo 'what) a?)) args
    (list args a a?)))
FOO

[SBCL] CL-USER> (foo :a 10)
((:A 10) 10 T)

[SBCL] CL-USER> (foo)
(NIL :FOO WHAT)

[SBCL] CL-USER>