slugify.rb

# Adapted from ActiveSupport's parameterize
# http://github.com/rails/rails/blob/ea0e41d8fa5a132a2d2771e9785833b7663203ac/activesupport/lib/active_support/inflector.rb#L259

def slugify(str, sep = '-')
  str.gsub!(/[^a-z0-9\-_\+]+/i, sep)
  unless sep.nil? || sep == ''
    re_sep = Regexp.escape(sep)
    str.gsub!(/#{re_sep}{2,}/, sep)
    str.gsub!(/^#{re_sep}|#{re_sep}$/i, '')
  end
  str.downcase
end

puts slugify("Hello    World!")