Transaction.rb

class DoThing
  include Dry::Transaction

  Context = Struct.new(:user, :params, :accumulator)
  Result  = Struct.new(:output)
  Error   = Struct.new(:step, :errors)

  step :build_context
  step :operation_one
  step :operation_two
  failure :recover_one
  step :operation_three
  step :operation_four
  failure :recover_two
  step :prepare_result

  private

  def build_context(input)
    Success(Context.new(input[:user], input[:params], {}))
  end

  def prepare_result(context)
    Success(Result.new(context.accumulator[:output]))
  end

  def operation_one(context)
    # ...
  end

  def operation_two(context)
    # ...
  end

  def operation_three(context)
    # ...
  end

  def operation_four(context)
    # ...
  end

  def recover_one(error)
    # Success() with some recovery
  end
end