Macros

Macros

Macros provide a facility for extending the base syntax of GOO. The design is based on quasiquote code templates and a simple list pattern matching facility. Macros are currently unhygienic, and users are required to use gensym to avoid name collisions.

QUASIQUOTE	(QUASIQUOTE ,@qq-forms)	S
	QUOTE with selective evaluation using UNQUOTE and SPLICING-UNQUOTE (cf. Lisp and Scheme's QUASIQUOTE), abbreviated "`".
UNQUOTE	(UNQUOTE ,form)	S
	evaluates ,form in the midst of a QUASIQUOTE expression, abbreviated ",".
SPLICING-UNQUOTE	(SPLICING-UNQUOTE ,form)	S
	evaluates ,form in the midst of a QUASIQUOTE expression and splices it in, abbreviated ",@".
MATCH	(MATCH ,exp (,pat ,val) ...)	S
	evaluates ,val corresponding to first ,pat matching ,exp. The pattern is much the same as QUASIQUOTE and can contain either UNQUOTE'd variables or UNQUOTE-SPLICING variables. For example, (MATCH '(1 2) ((,a ,b) (lst a b))) $ --> $ (1 2) (MATCH '(1 2) ((,a ,@b) (lst a b))) $ --> $ (1 (2))
DS	(DS ,pattern ,@body)	S
	defines a macro matching pattern ,pattern and expanding according to ,@body. The pattern matching occurs as in MIF and makes available pattern variables during the evaluation of (SEQ ,@body). For example, (DS (when ,test ,@body) `(if (not ,test) (seq ,@body))) defines the when macro in GOO.

where

pattern	== (,@qq-forms)	L

CT	(CT ,@body)	S
	evaluates (SEQ ,@body) at compile-time allowing a user to make available computations for the purpose of macro-expansion.
CT-ALSO	(CT-ALSO ,@body)	S
	equivalent to CT, but also includes a copy of ,@body in compiled images. Similar to (eval-when (:compile-toplevel :execute) ...) in Common LISP. The return value of CT-ALSO is undefined.
MACRO-EXPAND	(MACRO-EXPAND ,form)	S
	recursively expands macros in expression ,form.

Macros