That’s hardly a reason not to include a maybe type. In that particular case, instead of a maybe you can use a combination of sum and product types or just an ad

That’s hardly a reason not to include a maybe type. In that particular case, instead of a maybe you can use a combination of sum and product types or just an additional ShortRead type. NormalRead | ShortRead | Error This case is also an example of why go’s idiom of using error value or return value doesn’t always work. If you had a maybe type and a general sum type it would be clear when a function was going to return either or both.