Модуль? который инклудится в нужный нам класс, например ApplicationController.rb

access_helper.rb

module AccessHelper
  # ...
  def acl
    YaAcl::Acl.instance
  end

  def can?(route_method, action = nil, options = {})
    url_options = send "hash_for_#{route_method}_path"
    resource = "#{url_options[:controller].to_s.camelize}Controller"

    privilege = action || url_options[:action]
    acl.allow? resource, privilege, current_roles, options
  end
  # ...
end

any_view.html.haml

= link_to 'title', 'edit_user_path' if can?('edit_user')

ya_acl_builder.rb

YaAcl::Builder.build do
  roles do
    role :site_admin
  end

  resources :site_admin do
    resource 'Web::UsersController' do
      privilege :index
      privilege :show
      privilege :edit
      # ...
    end
  end
end