Helper for HTML5 Boilerplate-style IE conditionals in Middleman with HAML. Thanks to http://ricostacruz.com/2010/haml_and_ie_compatibility.html

config.rb

helpers do
  def conditional_html(opts={}, &blk)
    attrs = opts.map { |(k, v)| " #{h k}='#{h v}'" }.join('')
    [ "<!--[if lt IE 7 ]>    <html#{attrs} class='ie6 no-js oldie'> <![endif]-->",
      "<!--[if IEMobile 7 ]> <html#{attrs} class='iemob7 no-js oldie'> <![endif]-->",    
      "<!--[if IE 7 ]>       <html#{attrs} class='ie7 no-js oldie'> <![endif]-->",
      "<!--[if IE 8 ]>       <html#{attrs} class='ie8 no-js oldie'> <![endif]-->",
      "<!--[if IE 9 ]>       <html#{attrs} class='ie9 no-js oldie'> <![endif]-->",
      "<!--[if (gt IE 9)|!(IE)]><!--> <html#{attrs} class='no-js'> <!--<![endif]-->",
      capture_haml(&blk).strip,
      "</html>"
    ].join("\n")
  end
end

layout.haml

!!! 5
!= conditional_html(:lang => 'no-NB') do
  %head