Helper to allow passing locales to :coffeescript filters and javascript filters if you wrap your javascript in (function() { ... without having to use interpolation, saving you against slow rendering on Windows servers.

haml_helper.rb

module HamlHelper

  def coffee_with_locals locals={}, &block
    # This helper will set locals as values inside of the :coffeescript filter that follows.
    # Doing this instead of using regular interpolation allows haml to keep a compiled version of the CoffeeScript
    # instead of having to compile on every render after the interpolation is applied. On Linux, the impact is
    # negligible because V8 is fast, but Windows environments don't have this chance and page rendering can be slowed
    # heavily from having to compile CoffeeScript.

    block_content = capture_haml do
      block.call
    end

    return block_content if locals.blank?

    javascript_locals = "\nvar "
    javascript_locals << locals.map{ |key, value| j(key.to_s) + ' = ' + value.to_json.gsub('</', '<\/') }.join(",\n    ")
    javascript_locals << ";\n"

    content_node = Nokogiri::HTML::DocumentFragment.parse(block_content)
    content_node.search('script').each do |script_tag|
      # This will match the '(function() {' at the start of coffeescript's compiled code
      split_coffee = script_tag.content.partition(/\(\s*function\s*\(\s*\)\s*\{/)
      script_tag.content = split_coffee[0] + split_coffee[1] +  javascript_locals + split_coffee[2]
    end

    content_node.to_s.html_safe
  end
end

your_view.html.haml

= coffee_with_locals "test" => "hello ", :something => ["monde", "mundo", "world"], :signs => {:interogation => "?", :exclamation => "!"} do
  :coffeescript
    alert(test + something[2] + signs['exclamation'])