rakefile.rb

namespace :haml do
  # Monitor the current directory looking for changes to Haml source files and
  # compile on updates. Defaults to watching the current directory. You can
  # override by specifying another directory in square brackets immediately
  # after the watch target, e.g.
  #
  # rake haml:watch[/tmp]
  #
  # Note, you need the FSSM gem installing, i.e. gem install fssm. Of course,
  # you also need Haml itself.
  desc "Look for changes to Haml source files and compile on update"
  task :watch, [:directory] do |t, args|
    args.with_defaults(:directory => Dir.getwd)
    puts "Watching #{args.directory}"
    require 'fssm'
    FSSM.monitor do
      path args.directory do
        glob '**/*.haml'
        update do |base, relative|
          relative_base = Pathname.new(base).relative_path_from(Pathname.new(Dir.getwd)).to_s
          sh "haml \"#{File.join(relative_base, relative)}\" \"#{File.join(relative_base, relative.chomp(File.extname(relative)))}\""
        end
      end
    end
  end
end