(in-package :araneida) #| (mapcar (l xml-for-function foo bar _ baz) (my-list-of-stuff)) => (mapcar (lambda (_) (xml-for-function foo bar _ baz)) (my-list-of-stuff)) |# (defmacro l ((name &rest args))   "Expands to an anonynmous function with one argument _ that calls NAME with whatever arguments are supplied - which may include _.  For example, (mapcar (l xml-for-function foo bar _ baz) (my-list-of-stuff)) => (mapcar (lambda (_) (xml-for-function foo bar _ baz)) (my-list-of-stuff))"   `(lambda (_) (,name ,@args))) ;;; we don't want to evaluate the user-supplied form unless we have to. ;;; we don't know until page access time whether we have to.  So, we ;;; compile the supplied forms into a function: at runtime we choose ;;; whether or not to evaluate that function (defun maybe-output-func (request last-modified headers output-form)   (let ((if-mod-since (request-if-modified-since request 0)))     (cond ((< if-mod-since last-modified)            (let ((o (funcall output-form)))              (apply #'request-send-headers                     request :last-modified last-modified headers)              (html-stream (request-stream request) o)))           (t            (request-send-headers             request :response-code 304 :response-text "Not modified"))))) (defmacro define-page ((url                         &key patterns variable-lookup-fn changed-time headers)                        &rest forms)   (let* ((page-compile-time (get-universal-time))          (mod-time-form           (if changed-time               `(max ,page-compile-time ,changed-time)             page-compile-time)))     `(progn        (export-handler         ,url         (lambda (request rest-of-url)           (declare (ignorable request rest-of-url))           (labels ((page ()                      (rewrite-tree (progn ,@forms) ,patterns                                    :variable-lookup-fn ,variable-lookup-fn)))             (maybe-output-func request ,mod-time-form ,headers #'page)))))))