+ (defmacro unless (condition &rest body)
+ `(if ,condition nil (progn ,@body)))
+
+ (defmacro dolist (iter &rest body)
+ (let ((var (first iter))
+ (g!list (make-symbol "LIST")))
+ `(let ((,g!list ,(second iter))
+ (,var nil))
+ (while ,g!list
+ (setq ,var (car ,g!list))
+ ,@body
+ (setq ,g!list (cdr ,g!list))))))
+
+ (defmacro cond (&rest clausules)
+ (if (null clausules)
+ nil
+ (if (eq (caar clausules) t)
+ `(progn ,@(cdar clausules))
+ `(if ,(caar clausules)
+ (progn ,@(cdar clausules))
+ (cond ,@(cdr clausules))))))
+
+ (defmacro case (form &rest clausules)
+ (let ((!form (make-symbol "FORM")))
+ `(let ((,!form ,form))
+ (cond
+ ,@(mapcar (lambda (clausule)
+ (if (eq (car clausule) t)
+ clausule
+ `((eql ,!form ,(car clausule))
+ ,@(cdr clausule))))
+ clausules)))))
+
+ (defmacro ecase (form &rest clausules)
+ `(case ,form
+ ,@(append
+ clausules
+ `((t
+ (error "ECASE expression failed."))))))
+
+ (defmacro and (&rest forms)
+ (cond
+ ((null forms)
+ t)
+ ((null (cdr forms))
+ (car forms))
+ (t
+ `(if ,(car forms)
+ (and ,@(cdr forms))
+ nil))))
+
+ (defmacro or (&rest forms)
+ (cond
+ ((null forms)
+ nil)
+ ((null (cdr forms))
+ (car forms))
+ (t
+ (let ((g (make-symbol "VAR")))
+ `(let ((,g ,(car forms)))
+ (if ,g ,g (or ,@(cdr forms))))))))
+
+ (defmacro prog1 (form &rest body)
+ (let ((value (make-symbol "VALUE")))
+ `(let ((,value ,form))
+ ,@body
+ ,value))))
+
+;;; This couple of helper functions will be defined in both Common
+;;; Lisp and in Lispstrack.