Flash Messages with Bootstrap 2 and Rails 3.2.3

flash_messages.rb

# in application_helper
def flash_class(level)
  case level
  when :notice then "alert alert-info"
  when :success then "alert alert-success"
  when :error then "alert alert-error"
  when :alert then "alert alert-error"
  end
end

# app/views/layouts/application.html.haml
= render "layouts/flash_messages"

# layouts/_flash_messages.haml
- flash.each do |type, message|
  %div{:class => "fade in #{twitterized_type(type)}" }
    %button{:class => 'close', 'data-dismiss' => 'alert'} ×
    = message