[web-devel] A light-weight web framework

Thu Apr 5 10:30:53 EDT 2007

On Apr 5, 2007, at 2:51 PM, David House wrote:

> Why add another dependency, force your coders to learn another
> language, restrict yourself to a language which isn't as expressive as
> Haskell, reduce your ability to reuse code from different areas of the
> project and decrease project-wide consistency when you could just
> write your templates in Haskell to begin with?

Embedding code in web templates doesn't work well when you have  
designers on board.

Let me elaborate on my approach as it doesn't reduce or restrict  
anything!

I'm suggesting that you make your templates look like this, which is  
parseable as XML. Note the "tal:" tags. Please scroll through to the  
bottom for more thoughts.

<?xml version="1.0" encoding="ISO-8859-1"?>
<html>
   <head>
     <title tal:content="page/title">Page title</title>
   </head>
   <body>
     <h1 tal:content="page/title">Heading</h1>
     <p>
       Hello <b tal:omit-tag="visitor/humble"><span  
tal:replace="visitor/name">wo
rld</span></b>
     </p>
     <p tal:condition="msg page/message" tal:content="msg">Message</p>
     <ul>
       <li>Hard-coded</li>
       <li tal:define="users page/users" tal:repeat="item users"  
tal:content="ite
m/name">Dummy</li>
     </ul>
     <p tal:condition="page/renderfooter">
       Back to
       <a href="#" tal:define="up page/up" tal:attributes="href up/ 
href;title up/
title">index</a>
     </p>
   </body>
</html>

The above expands into this:

<html>
   <head>
     <title>Demo page</title>
   </head>
   <body>
     <h1>Demo page</h1>
     <p>
       Hello
       <b>Bruno</b>
     </p>
     <p>(c) 2006</p>
     <ul>
       <li>Hard-coded</li>
       <li>Xavier</li>
       <li>Damien</li>
       <li>Jacques</li>
       <li>Didier</li>
       <li>Jerome</li>
     </ul>
     <p>
       Back to
       <a title="Caml Home" href="http://caml.inria.fr/">index</a>
     </p>
   </body>
</html>

Note how

     <ul>
       <li>Hard-coded</li>
       <li tal:define="users page/users" tal:repeat="item users"  
tal:content="ite
m/name">Dummy</li>
     </ul>

is expanded to

     <ul>
       <li>Hard-coded</li>
       <li>Xavier</li>
       <li>Damien</li>
       <li>Jacques</li>
       <li>Didier</li>
       <li>Jerome</li>
     </ul>

This is nice and _very_ clean and allows you to use any Haskell code  
you want to _process_ the template. You can, in fact, make template  
processing recursive and have tags produce more tags, i.e. make your  
components produce HTML instead of data for tags in the template.

What do you think?

--
http://wagerlabs.com/