create_update_params.rb

CURRENCY_PARAMS = {
  name: { desc: -> { API::V2::Admin::Entities::Currency.documentation[:name][:desc] } },
  deposit_fee: {
    type: { value: BigDecimal, message: 'admin.currency.non_decimal_deposit_fee' },
    values: { value: -> (p){ p >= 0 }, message: 'admin.currency.invalid_deposit_fee' },
    desc: -> { API::V2::Admin::Entities::Currency.documentation[:deposit_fee][:desc] },
    default: 0.0
  }
  #...
}

params :create_currency_params do
  CURRENCY_PARAMS.each do
    # Use values from CURRENCY_PARAMS with default values
  end
end

params :update_currency_params do
  CURRENCY_PARAMS.each do
    # Use values from CURRENCY_PARAMS without default values
  end
end