Earlier quoted context omitted.
One thing I think worth considering for systems languages on this point: if you don't want to solve every expressiveness issue downstream of Result/Option/etc from the outset, look at Swift, which has nullable types. MyObject can't be null. MyObject? can be null. Handling nullability as a special thing might help with the billion-dollar mistake without generating pressure to have a fully fleshed out ADT solution and…
I like to think about how many problems a feature solves to judge whether it's "worth it". I believe that the Sum types solve enough different problems that they're worth it, whereas nullability solves only one problem (the C-style or Java-style null object) the Sum types can solve that with Option and also provide error handling with Result and control flow with ControlFlow among others so that's already a better de…
- `Option` and `Result` at core;
- `?T` and `T!E` as type declaration syntax that desugars to them;
- and `.?` and `.!` operators so chains like `foo()?.bar()!.baz()` can be written and all the relevant possible return branches are inserted without a fuss.
Having `Option` and `Result` be simply normal types (and not special-casing "nullable") has benefits that are... obvious, I'd say. They're just _normal_. Not being special cases is great. Then, having syntactic sugars to make the very, _very_ common cases be easy to describe is just a huge win that makes correct typing more accessible to many more people by simply minimizing keystrokes.
The type declaration sugar is perhaps merely nice to have, but I think it really does change the way the average programmer is willing to write. The chaining operators, though... I would say I borderline can't live without those, anymore.
Chaining operators can change the SLOC count of some functions by as much as... say, 75%, if we consider a language like Go with it's infamous "if err not nil" clause that is mandated to spread across three lines.