I find Result[] and Optional[] somewhat overrated, but nil does bother me. However, nil isn't going to go away (what else is going to be the default value for pointers and interfaces, and not break existing code?). I think something like a non-nilable type annotation/declaration would be all Go needs.
Typescript has another way of dealing with null/undefined: it's in the type definition, and you can't use a value that's potentially null/undefined. Using Optional<T> in Typescript is, IMO, weird. Typescript also has exceptions...
I think they only work if the language is built around it. In Rust, it works, because you just can't deref an Optional type without matching it, and the matching mechanism is much more general than that. But in other languages, it just becomes a wart.
As I said, some kind of type annotation would be most go-like, e.g.
func f(ptr PtrToData?) int { ... }
Yeah default values are one of Go's original sins, and it's far too late to roll those back. I don't think there are even many benefits—`int i;` is not meaningfully better than `int i = 0;`. If it's struct initialization they were worried about, well, just write a constructor.
Go has chosen explicit over implicit everywhere except initialization—the one place where I really needed "explicit."
It makes types very predictable though: a var int is always a valid int no matter what, where or how. How would you design the type system and semantics around initialization and declarations without defaults? Just allow uninitialized values like in C? That’s basically default values with extra steps and bonus security holes. An expansion of the type system to account for PossiblyUndefined<t>? That feels like a significant complication, but maybe someone made it work…
Yeah maybe they're overrated, but they seem like the agreed-upon set of types to avoid null and to standardize error handling (with some support for nice sugars like Rust's ? operator).
I quite often see devs introducing them in other languages like TypeScript, but it just doesn't work as well when it's introduced in userland (usually you just end up with a small island of the codebase following this standard).