class Result

# File lib/result.rb, line 57
def self.combine_map(list)
  list.reduce(self.ok []) do |acc, item|
    break acc if acc.error?

    result = yield item

    map2(acc, result) do |acc_list, result_item|
      acc_list + [result_item]
    end
  end
end

# File lib/result.rb, line 10
def self.error(errored_thing)
  new(Err.new(errored_thing))
end

# File lib/result.rb, line 69
def self.map2(first_result, second_result)
  first_result.then do |first|
    second_result.then do |second|
      self.ok yield first, second
    end
  end
end

# File lib/result.rb, line 2
def initialize(result)
  @result = result
end

# File lib/result.rb, line 6
def self.ok(successful_thing)
  new(Ok.new(successful_thing))
end

# File lib/result.rb, line 49
def error?
  @result.is_a?(Err)
end

# File lib/result.rb, line 14
def map
  case @result
  when Ok
    self.class.ok(yield @result.extract)
  when Err
    self
  end
end

# File lib/result.rb, line 36
def map_error
  case @result
  when Err
    self.class.error(yield @result.extract)
  when Ok
    self
  end
end

# File lib/result.rb, line 45
def ok?
  @result.is_a?(Ok)
end

# File lib/result.rb, line 23
def then
  case @result
  when Ok
    yield(@result.extract).tap do |returned_result|
      unless returned_result.is_a?(self.class)
        raise InvalidReturn, 'then handler must return a Result'
      end
    end
  when Err
    self
  end
end

# File lib/result.rb, line 53
def when_ok(&block)
  Case.when_ok(self, &block)
end

# File lib/result.rb, line 79
def _result
  @result
end