I'm watching Zig and Jai closely. We need a better C and C++ isn't it. Good luck!
This is somewhat subjective of course, but from what I’ve seen, Zig has just the right set of features to modernize systems programming, without making the language too complex or difficult to write (which arguably Rust’s “borrow checker” system does), and (like Rust) gets rid of some huge legacy language design mistakes most people agree on today (e.g. nullable-by-default pointer types, or no way to know at compile time or at a glance what range of exceptions a function may throw).
And of course, the “automatic” interoperability with C is an essential part of any C/C++ replacement contender.
Rust, Zig, Kotlin, Swift, and many other modern languages can express the same concept of a null reference, but in a fundamentally superior way. In modern languages like these, the compiler will statically guarantee the impossibility of null dereference exceptions, without negatively impacting performance or code style!
But it goes beyond just static checking. It makes coding easier, too: You will never have to wonder whether a function returning a reference might return null on a common failure, vs throw an exception. You’ll never have to wonder if an object reference parameter is optional or not, because this will be explicit in the data type accepter/returned. You’ll never have to wonder if this variable of type T in fact contains a valid T value, or actually is just “null”, because the possible range of values will be encoded in the type system: If it could be null, you’ll know it and so will the compiler. Not only is this better for safety (the compiler won’t let you do the wrong thing), it’s self-documenting.
It blows my mind that any modern language design would willingly think nullable object references is still a good idea (or perhaps its out of ignorance), when there are truly zero-cost solutions to this — in both runtime performance and ease of writing code, as you can see for example from Zig or Kotlin.
[1] https://www.infoq.com/presentations/Null-References-The-Bill...
In any case I think the modern fashion of trying to eliminate null from PLs won't matter much in the effort to replace C, whereas something like a mandatory GC is an instant no-go (though Java at least was very successful at sparing the world a lot of C++). OTOH a language that makes more kinds of formal verification possible (beyond just type theory proofs) might one day replace C and have null-analysis as a subfeature too.
For example, most older languages with “the billion dollar mistake” have no complaint whatsoever when your write “object.method();” where it’s unknown at this scope whether “object” is null or not.
The fact that such code compiles is the billion dollar mistake; not the fact that the pointer is nullable.
I don’t care if you want to write nullable references everywhere, or whatever else you prefer or your application demands. That’s fine, so long as:
1. Non-nullable reference types must exist.
2. Nullable references types must exist as statically distinct from #1.
3. The compiler must not let you write code that assumes a nullable reference is not null, unless you check via a control flow statement first.
Now to take a step back, the principle behind this certainly applies beyond just nullability (if that was the point you were trying to make): Generally, dynamic, untyped invalidation states are dangerous/bad, while statically typed invalidation states are ideal. And yes, this does include bad states internal to a non-null reference, just as much as to a null reference.
Sum types are the key to being able to statically declare what range of values a function may return (or accept), and ensure at compile time that these different cases are all accounted for. If you aren’t aware of how elegantly sum types solve this, you should look into it — and I suspect it will be quickly clear why nullable references are useless, outdated, and harmful.
But at the very least, we’ve solved the pain of null dereference — and virtually without compromise. So, it’s irresponsible or ignorant IMO to create a new language that doesn’t include this solution in its core.
Well, you're in luck then! You don't even need a 'modern' successor, C++ (even the ancient versions) disallow null references.
For fairly low values of those. Creating a null reference is UB, your program is not legal at all.
The whole point is to NOT have it be accepted.
Which is a textbook example of the null reference problem.
Edit: There may be some terminological confusion here: when programming language folks talk about "references", they include in that definition what C/C++ call "pointers". See for example the Wikipedia article, which gives as the C++ example not C++ references, but C++ pointers.
Since nobody stopped you, the problem is still there.
That's useful, until you realise that all its smart pointers are semantically nullable (they can all be empty with the same result as a null raw pointer) and then nothing's actually fixed.
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.
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.
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(); }
if let Some(x) = myObject { x.method(); }
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.
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.
Yes, a Lisp-like language could do it. Why not Common Lisp? Because PreScheme and ZL were both better if we're aiming at C's niche:
https://en.wikipedia.org/wiki/Scheme_48
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.3.40...
http://www.schemeworkshop.org/2011/papers/Atkinson2011.pdf
I was looking for a way to do metaprogramming, verified programming, LISP-like programming, and low-level programming. Past few years of searching led me to a lot of verification stuff obviously, PreScheme for low-level Lisp, ZL for Scheme/C, and Red/System for a REBOL-like answer. I was eyeballing Nim, too, since the masses usually hate LISP's syntax. Then, I thought a front-end that let one go with various syntax's, esp inspired by famous languages, with the same underlying semantics or just easy integration.
On a practical note, I noticed that strong integration with the dominant language with little to no performance hit is extremely important. Clojure building on Java in enterprise space is an example. It reuses it's ecosystem. For system space, I started recommending using C's data types and calling conventions where possible in new language so calling it would cost nothing. Then, maybe an option to extract to C for its compilers. So, whatever above languages are created need to integrate with C really well.
It could, theoretically, be perfect. Since it's all theoretical at this point I mean.
At first glance, Zig vs Jai reminds me a lot of the Linux vs GNU Hurd thing (or a lot of other "worse is better" examples). A couple of geniuses locking themselves up telling the world "Just wait! It'll be awesome!" seldomly produces something that lasts.
of course, but sometimes it does.