cards_controller.rb

class CardsController
  def create
    render params.inspect
  end
end

# Submitted, this yields:
#       { "cards" => [ { "black" => ["Edit this new black card text..."] } ] }

# I want to yield this:
#       { "cards" => { "black" => ["Edit this new black card text..."] } }

# How can I change the index.html.haml text_area_tag "cards[]black[]" to get it to produce the results I expect?

index.html.haml

= form_tag '/cards' do
  = text_area_tag "cards[]black[]", "Edit this new black card text...", class: 'card hidden'
  = submit_tag