pico_case.rb

module PicoCase
  class Result
    attr_reader :type, :data

    def self.Success(**data)
      new(:success, data)
    end

    def self.Failure(**data)
      new(:failure, data)
    end

    def initialize(type, data)
      @type = type
      @data = data
    end

    def success?
      type == :success
    end

    def failure?
      !success?
    end

    def then(&block)
      return self if failure?
      raise LocalJumpError if block.nil?

      block_result = ResultBlockContext.module_exec(**data, &block)
      raise ArgumentError unless block_result.is_a?(Result)

      block_result
    end

    private

    def respond_to_missing?(name, include_private = false)
      @data.respond_to?(name, include_private)
    end

    def method_missing(method, *args, &block)
      @data.send(method, *args, &block)
    end
  end

  module ResultBlockContext
    def self.Success(**data)
      Result.new(:success, data)
    end

    def self.Failure(**data)
      Result.new(:failure, data)
    end
  end

  def self.new(**data)
    Result::Success(data)
  end
end

pcase = PicoCase.new(number: 4)

puts 'no sucesso, a execução continua'
p pcase
  .then { |number:| Success(number: number * 2) }
  .then { |number:| Success(number: number + 2) }

puts 'na falha, a execução é cancelada'
p pcase
  .then { |**| Failure() }
  .then { |asdasdad| asdadadsa }

puts 'erro se o retorno não for outro Result'
begin
  pcase.then { |**| 6 }
rescue => e
  puts e.message
end

puts 'erro ao não usar colocar outro bloco'
begin
  pcase.then
rescue => e
  puts e.message
end