before_filter :set_locale

def set_locale
  I18n.locale = extract_locale_from_tld
end

def extract_locale_from_tld
  parsed_locale = request.host.split('.').last
  I18n.available_locales.include?(parsed_locale.to_sym) ? parsed_locale  : nil
end

# Get locale from top-level domain or return nil if such locale is not available
# You have to put something like:
#   127.0.0.1 example.com
#   127.0.0.1 example.it
#   127.0.0.1 example.pl
# in your /etc/hosts file to try this out locally