framework 'Foundation'
class String
  def language
    CFStringTokenizerCopyBestStringLanguage(self, CFRangeMake(0, self.size))
  end
end

puts "Happy new year!".language
# => "en"
puts "С новым годом!".language
# => "ru"
puts "Bonne année!".language
# => "fr"
puts "明けましておめでとうございます。".language
# => "ja"