Use will_paginate with ActiveRecord in Sinatra

will_paginate in Sinatra.md

1. Add gem 'will_paginate', '~> 3.0' to Gemfile
2. Add %w(will_paginate will_paginate/active_record).each {|lib| require lib} to config.ru
3. Assuming modular Sinatra, open Sinatra::Base and add include WillPaginate::Sinatra::Helpers so that all views can use will_paginate
4. In controller, @users = User.paginate(:page => params[:page], :per_page => 30)
5. In view, = will_paginate @users will generate the pagers

If you want to style your pagers

• Include this css in your layout
• Style it

.digg_pagination
  = will_paginate @notifications

Another document even original document does not include instruction to add the following command.
include WillPaginate::Sinatra::Helpers
You save me 2 hours.