SymbolicWeb: 用Lisp写AJAX和Comet程序

Lisp 长久以来一直被视为伟大的编程语言之一。其漫长的发展过程（接近五十年）中引发的追随狂潮表明：这是一门非同凡响的语言。但是用Lisp写的web应用很少，现在出现了SymbolicWeb，希望改变这种情况。SymbolicWeb目标是用Lisp来创建一个GUI框架，类似GTK+ 和 QT，不同点是SymbolicWeb使用浏览器来渲染UI元素。

下面是一个简单的Echo Chat例子：

;;;; http://nostdal.org/ ;;;;
	(in-package #:sw)
	(defparameter *max-chat-pane-size* 100)
	(defapp chat-app (empty-page-app)
  ((input (mk-text-input))
   (chat-pane :allocation :class (mk-container nil))))
	(defuri chat-app "chat")
	(defmethod main ((chat-app chat-app))
  (with-slots (input chat-pane) chat-app
    (setf (on-enterpress-of input
                          :callback-data `((:input-value . ,(js-code-of (value-of input)))) ;; Include some data when the event fires.
                          :js-after (js-code-of (setf (value-of input) "")))                ;; Clear the input field after the event has been fired and sent.
          (lambda (&key input-value)
            (prepend (mk-span (escape-for-html input-value) :display "block")
                     chat-pane)
            ;; Don't let it grow too big; delete some chat history.
            (when (> (length (children-of chat-pane)) *max-chat-pane-size*)
              (dolist (span (subseq (children-of chat-pane) *max-chat-pane-size*))
                (remove span)))))
    (add-to *root*
            (mk-span (who (:p "Type something in and press enter. New content is added at the top.")))
            input
            chat-pane)))