web-monad.asd

Web Monad

This is the reason I implemented monads on common lisp. The web-monad allows composition of functions in a monad which provides:-

1. Output of HTML onto a page
2. Handling of input from the web page (either via AJAX or not).
3. Tracking of events assigned to elements on the page
4. Nesting of HTML content

Quickstart

The following will get a web-monad web page running.

(asdf:operate 'asdf:load-op :web-monad)
(asdf:operate 'asdf:load-op :configuration)

(in-package :cl-user)

(defpackage :web-monad-demo
  (:use :cl :monads :web-monad :net.aserve :configuration))

(in-package :web-monad-demo)


(defun demo-web-page ()
  (with-web-monad
    - (mweb-page)
    quit <- (msubmit "quit" "quit")
    (when quit
      (ccl:process-run-function "bye" (lambda () (sleep 1) (ccl:quit))))
    - (if quit
          (mhtml (:h2 "(quitting...)"))
          (unit nil))
    (mhtml (:h1 "This is a web page served up using the Web Monad!!!"))))

;; First we need to publish a prefix to dispatch to the web monad
;; I ought to implement this more straightforwardly in the web monad package
;; clim does its own thing anyway
(publish-prefix :prefix "/web-monad-demo/"
                :function (lambda (request entity)
                            (let ((*m-entity* entity)
                                  (monad (demo-web-page)))

                              ;; NOT SHOWN: register-monadic-handler and dispatch tables (which you don't have to use)
                              
                              (let ((result
                                     (handler-case
                                         (web-monad-handle-request monad request)
                                       (t (c)
                                         (web-monad-handle-request
                                          (error-page c)
                                          request)))))

                                ;; !!! Need to handle display errors too
                                (render-web-thunk result (web-thunk-event-handlers result)
                                                  ;; ajax-id
                                                  :renderer (if (testable-query-value "__AJAX" request)
                                                                #'web-thunk-ajax-render
                                                                #'web-thunk-render))))))

(defparameter *port* (configuration-parameter :http/port :type 'integer :default 12000))

;; then fire up the web server
(start :port *port*)
  

Overview of Features

Binding of event handlers to elements

(with-web-monad
  - (mbutton "b1" "Click Me!")

  (event-handler "b1" :onclick '(alert "You clicked it!")))

Handling of events via AJAX

(in-package :web-monad)

(with-web-monad
  - (mbutton "b2" "Click Me!")

  clicked <- (ajax-event "b2" :onclick)

  - (draw-context "foo"
                  (if clicked
                      (mhtml (:h1 "Try clicking the button"))
                      (mhtml (:h1 "You clicked it!")))
                  ;; passing redraw t means this element will be redrawn every time an AJAX event is triggered
                  :redraw t))

to be continued…