Major Section: MISCELLANEOUS
Examples: (x y z) (x y z &optional max (base '10 basep)) (x y &rest rst) (x y &key max base) (&whole sexpr x y)
The ``lambda-list'' of a macro definition may include simple formal
parameter names as well as appropriate uses of the following
lambda-list keywords from CLTL (pp. 60 and 145), respecting the
&whole, &optional, &rest, &body, &key, and &allow-other-keys.ACL2 does not support
&environment. In addition, we make the following restrictions:
You are encouraged to experiment with the macro facility. One way to do so is to define a macro that does nothing but return the quotation of its arguments, e.g.,
(1) initialization forms in
&keyspecifiers must be quoted values;
&allow-other-keysmay only be used once, as the last specifier; and
(3) destructuring is not allowed.
(defmacro demo (x y &optional opt &key key1 key2) (list 'quote (list x y opt key1 key2)))You may then execute the macro on some sample forms, e.g.,
term value (demo 1 2) (1 2 NIL NIL NIL) (demo 1 2 3) (1 2 3 NIL NIL) (demo 1 2 :key1 3) error: non-even key/value arglist (because :key1 is used as opt) (demo 1 2 3 :key2 5) (1 2 3 NIL 5)In particular, Common Lisp specifies that if you use both
&key, then both will be bound using the same list of arguments. The following example should serve to illustrate how this works.
ACL2 !>(defmacro foo (&rest args &key k1 k2 k3) (list 'quote (list args k1 k2 k3)))
Summary Form: ( DEFMACRO FOO ...) Rules: NIL Warnings: None Time: 0.00 seconds (prove: 0.00, print: 0.00, other: 0.00) FOO ACL2 !>(foo :k1 3 :k2 4 :k3 5) ((:K1 3 :K2 4 :K3 5) 3 4 5) ACL2 !>(foo :k1 3 :k2 4) ((:K1 3 :K2 4) 3 4 NIL) ACL2 !>
Also see trans.