view conditional with yield

00-helper.rb

class MyPresenter
  def initialize(user)
    @user = user
  end

  def admin_only(&block)
    yield if user.admin?
  end
end

# or

module MyHelper
  def admin_only(&block)
    yield if current_user.admin?
  end
end

01-view.html.haml

- admin_only do
  %p secret admin stuff