New templating system idea

index(production).html

<!-- Some JS loading JSON from /users/index.json and put it to #users via jTemplates -->

<div id="users">
</div>

<script type="text/javascript" id="Templates">
{#template USERS}
  <div class="user">
    <p>{$T.name}</p>
    <p>{$T.email}</p>
    <ul>
      {#foreach $T.comments as comment}
        {#include comment root=$T.comment}
      {#/for}
    </ul>
  </div>
{/#template USERS}

{#template COMMENT}
  <li>{$T.content}</li>
{/#template COMMENT}
</script>

index(test or robot).html

<!-- No JS used -->

<div id="users">
  <div class="user">
    <p>First</p>
    <p>first@example.org</p>
    <ul>
      <li>first comment</li>
      <li>second comment</li>
    </ul>
  </div>
  <div class="user">
    <p>Second</p>
    <p>seconf@example.org</p>
    <ul>
      <li>third comment</li>
      <li>fourtn comment</li>
    </ul>
  </div>
</div>

index.html.haml

// This could be also used in ERB or anything else...

#users
  = @source.users.each do |user|
    .user
      %p
        = user.name
      %p
        = user.email
      %ul
        - user.comments.each do |comment|
          %li
            = comment.content

users_controller.rb

class UsersController < ApplicationController

  def index
    respond_to do |format|
      format.html
      format.json { render :json => User.all }
    end
  end

end