Trying dry-monads

monads.rb

# #fmap - bypass Failure object, or return Success(result)
# #bind - bypass Failure object, or return result

require 'dry/monads'
require 'dry/monads/do'

class SequenceExecutor
  include Dry::Monads[:result]

  # This will prepend the class with a module, bypassinf a block to #call
  include Dry::Monads::Do.for(:call)

  def call
    # Each yield will short-circuits the execution unless result is Success
    content = yield load_content('FEED')
    puts "content == #{content}"
    entities = yield process(content)
    puts "entities == #{entities}"
    normalize(entities)
  end

  def load_content(feed)
    puts "-----> load #{feed}"
    Success('CONTENT')
    # Failure('loading error')
  end

  def process(content)
    puts "-----> process #{content}"
    Success([
      %i[uid1 entity1],
      %i[uid2 entity2],
      %i[uid3 entity3]
    ])
    # Failure('processing error')
  end

  def normalize(entities)
    puts "-----> normalize #{entities}"
    result = entities.map { |entity| Success(entity) }
    Success(result)
    # Failure('normalization error')
  end
end

result = SequenceExecutor.new.call
puts "result = #{result}"