In Scala, there is scala.Option class. This is a great class with some drawbacks. They are:

1. No null safety. Values null and Some(null) are valid for type Option[String]
2. Additional runtime overhead.

I've tried to overcome these drawbacks by this experiment.

However, some other limitations have appeared.

First, SafeNone is not SafeOption[Nothing]. It has a generic function that creates instance for any T. That is better than having ugly hack SafeOption[Null], but it makes ugly pattern matching. (I.e. using SafeNone() instead of SafeNone.)

Note that SafeNone[Nothing] seems to be buggy.

Second, only AnyRefs are supported. This is a design limitation.

Last but not least, SafeNone.hashCode throws NullPointerException. This problem is caused by Scala bug I've no workaround for. See https://issues.scala-lang.org/browse/SI-7401 and https://issues.scala-lang.org/browse/SI-7396 .

If you have some ideas how to overcome some of these problems, your ideas are welcome.