Another ducktrap I use to assert hand written .yml files are not fucked up.

ducktrap.rb

date_parser = Ducktrap.build do
  primitive(String)
  extern do
    forward do |input|
      Date.parse(input) || raise
    end

    inverse do |date|
      raise
    end
  end
end

DUCKTRAP = Ducktrap.build do
  collection do
    attributes_hash_from_params_hash_extraction do
      attribute_from_params_hash(:name) 
      attribute_from_params_hash(:start) do
        add(date_parser)
      end
      attribute_from_params_hash(:end) do
        add(date_parser)
      end
      attribute_from_params_hash(:location)
    end
    anima_from_attributes_hash(Event)
  end
end