[gameswithgo]

> the compiler will statically guarantee the impossibility of null dereference exceptions,

almost every language that gets rid of nulls with something like the Option type will let you still bypass it and get a null reference exception. Rust lets you unwrap, F# lets you bypass it. You could at least enforce a lint that doesn't allow the bypasses in projects where that is desired though.

[electrograv]

Yes, but there’s a big difference between the default member access operator crashing conditionally based on null-ness — vs — the same operator guaranteeing deterministic success (thanks to static type checks), with the option to circumvent those safe defaults if the programmer really wants to (in which case they usually must be very explicit about using this discouraged, unsafe behavior).

It may seem to be just semantics, but it’s really quite important that the default (and most concise) way in these languages to read optional values is to check if they’re null/None first in an if statement, after which you can call “object.method()” all you like. It’s important that you can’t just forget this check; it’s essential to using the content of the optional, unless you explicitly type something like “.unwrap()” — in which case there’s almost no chance the programmer won’t know and think about the possibility a crash. Take this in contrast to the chance of crash literally every time you type “->” or “.” in C++, for example.

[imtringued]

Perfect is the enemy of good. By reducing the possibility of null dereference exceptions from 100% to 10% you have reduced the cognitive burden by 90%. Removing the bypass would result in a 100% reduction in cognitive burden, only 10% more than the second best solution. However handling null cases correctly isn't free either. Especially when you know that a value cannot be "null" under certain conditions which those 10% fall under. In those cases handling the error "correctly" is actually an additional cognitive burden that can ruin the meager 10% gain you have obtained by choosing the perfect solution.

[electrograv]

> However handling null cases correctly isn't free either. Especially when you know that a value cannot be "null" under certain conditions which those 10% fall under.

While I agree there are rare cases where .unwrap() is the right thing to do, I actually disagree here that it’s anywhere close to 10%: If you want to write a function that accepts only non-null values in Rust, you simply write it as such! In fact, this is the default, and no cognitive burden is necessary: non-nullable T is written simply as “T”. If you have an Option<T> and want to convert it into a T in Rust, you simply use “if let” or “match” control flow statements.

I actually think using .unwrap() in Rust anywhere but in test code or top-level error handling is almost always a mistake, with perhaps 0.001% of exceptions to this rule. I write code that never uses it, except those cases mentioned; while I’ve run into situations where I felt at first .unwrap() was appropriate, I took a step back to think of the bigger picture and so far always find safer solutions to yield a better overall design.

The cognitive burden from Rust comes not from this, but almost entirely from the borrow checker (a completely different toptic), and in some cases, arguably inferior “ergonomics” vs how Zig or Kotlin handle optionals.

For example, in some null-safe languages, you can write:

  if (myObject) { myObject.mehod(); }

And the compiler will understand this is safe. Whereas, in Rust, you must write:

  if let Some(x) = myObject { x.method(); }

This is not even to mention that Rust has no built-in shorthand for Option<T> (some languages write “T?” for example), but I understand why they chose not to build this into the language; rather, Option<T> in Rust is actually a component of the stranded library! In a way, that’s actually quite cool and certainly is by-design; however, it doesn’t change the fact that it’s slightly more verbose.

IMO it’s not a huge deal, but certainly Rust could benefit from some syntax sugar here at least. Either way, both examples here are safe and statically checked by the compiler.

[gameswithgo]

Yeah I think unwrap is best used when experimenting/prototyping, but it can be very very useful there. Imagine trying to get started using Vulkan or Opengl without it. Big mess. But in production code you might want to lint it as a strong warning or error.

[majewsky]

> but certainly Rust could benefit from some syntax sugar here at least

It's a tough balance. Rust could benefit from more sugaring, but on the other hand, Rust already has quite a lot of syntax at this point.