Rakefile - less to sass a.k.a. less2sass or less2scss

Rakefile

# less to scss based on http://stackoverflow.com/a/19167099/2363935
namespace :convert do

  task :less_to_scss do

    source_glob = "assets/less/*.less"
    dest_dir = "converted"

    rm_r dest_dir rescue nil
    mkdir_p(dest_dir)

    file_map = {}

    # copy the files
    Dir.glob(source_glob).each do |source_file|
      # puts "\tWorking on #{source_file}"
      basename = File.basename(source_file, '.less')
      dest_filename = "_#{basename}.scss"
      dest_file = File.join(dest_dir, dest_filename)

      # track the file mapping for a replace later
      file_map["#{basename}.less"] = dest_filename

      cp source_file, dest_file
      # convert_file(source_file, dest_file)
    end

    # do the conversion
    Dir.glob("#{dest_dir}/*.scss").each do |file_name|

      puts "Converting #{file_name}"
      text = File.read(file_name)

      # http://stackoverflow.com/a/19167099/2363935

      # 1. replace @ with $
      text = text.gsub(/@(?!import|media|keyframes|-)/, '$')

      # 2. replace mixins
      text = text.gsub(/\.([\w\-]*)\s*\((.*)\)\s*\{/, '@mixin \1(\2){')

      # 3. replace includes
      text = text.gsub(/\.([\w\-]*\s*;)/, '@include \1')
      # text = text.gsub(/\.([\w\-]*\(.*\)\s*;)/, '@include \1')
      # text = text.gsub(/\.\([a-z0-9-]\+/, '@include \1(/')

      # 3. a) replace no param mixin includes with empty parens
      text = text.gsub(/@include\ ([\w\-]*\s*;)/, '@include \1()')
      # 3. b) I'm terrible with regex, 3a makes a ';()', so fix it
      text = text.gsub(/;\(\)/, '();')

      # 4. replace string literals
      text = text.gsub(/~"(.*)"/, '#{"\1"}')

      # 5. replace spin to adjust-hue (function name diff)
      text = text.gsub(/spin/, 'adjust-hue')

      # 6. replace all the file maps
      file_map.each do |less, scss|
        text = text.gsub(less, scss)
      end


      File.open(file_name, 'w') { |file| file.puts text }
    end

  end
end

3/a/b needs to be rewritten by a more savvy regexer.

Since the ; is a constant(-ish) why not use it in the output (unless you meant to the be optional):

 text = text.gsub(/@include\ ([\w\-]*\s*);/, '@include \1();')

For those of us who aren't Ruby developers, can you please give us a hand running this gist? So far I've ran sudo gem install rake, saved this file as Rakefile and ran rake less_to_css:convert, but I get Don't know how to build task 'less_to_css:convert'

I believe the command would be rake convert:less_to_css. convert is first because that's the namespace that the less_to_css command is in.