layout.haml

!!!
%html
  %head
    %title Web App Example
    %link{:rel => "stylesheet", :type => "text/css", :href => "/stylesheet.css"}
    %script{:type => "text/javascript", :src => "/application.js"}
  %body
    #Header
      != haml :"header"
    #contents
      = yield
    #footer
      != haml :"footer"

WebAppExample.rb

require 'sinatra/base'
require 'haml'
require 'coffee-script'
require 'sass'

class WebAppExample < Sinatra::Base

    set :root, File.dirname(__FILE__)

    #Needed for CoffeeScript and SCSS
    get '/application.js' do
          coffee :application
    end

    get '/stylesheet.css' do
        scss :stylesheet
    end

    #Starting actual application
    get '/' do
        haml :index
    end

end

why it dont work?

Thanks for help

Files into repository

../WebAppExample
|-- Gemfile
|-- Gemfile.lock
|-- README.md
|-- Rakefile
|-- WebAppExample.rb
|-- config.ru
|-- public
`-- views
    |-- about.haml
    |-- coffee
    |   `-- application.coffee
    |-- footer.haml
    |-- header.haml
    |-- index.haml
    |-- layout.haml
    `-- scss
        `-- stylesheet.scss