A less baity title might be "Rust pitfalls: Runtime correctness beyond memory safety."
This regularly drives C++ programmers mad: the statement "C++ is all unsafe" is taken as some kind of hyperbole, attack or dogma, while the intent may well be to factually point out the lack of statically checked guarantees.
It is subtle but not inconsistent that strong static checks ("safe Rust") may still leave the possibility of runtime errors. So there is a legitimate, useful broader notion of "safety" where Rust's static checking is not enough. That's a bit hard to express in a title - "correctness" is not bad, but maybe a bit too strong.
You might be talking about "correct", and that's true, Rust generally favors correctness more than most other languages (e.g. Rust being obstinate about turning a byte array into a file path, because not all file paths are made of byte arrays, or e.g. the myriad string types to denote their semantics).
[1] https://doc.rust-lang.org/nomicon/meet-safe-and-unsafe.html
However while speaking about Rust language in general, all half-decent Rust developers specify that it's about memory safety. Even the Rust language homepage has only two instances of the word - 'memory-safety' and 'thread-safety'. The accusations of sleaziness and false accusations is disingenuous at best.
But this can be used with other enums too, and in those cases, having a zero NonZero would essentially transmute the enum into an unexpected variant, which may cause an invariant to break, thus potentially causing memory unsafety in whatever required that invariant.
By that standard anything and everything might be tainted as "unsafe", which is precisely GP's point. Whether the unsafety should be blamed on the outside code that's allowed to create a 0-valued NonZero<…> or on the code that requires this purported invariant in the first place is ultimately a matter of judgment, that people may freely disagree about.
The issue is that this could potentially allow creating a struct whose invariants are broken in safe rust. This breaks encapsulation, which means modules which use unsafe code (like `std::vec`) have no way to stop safe code from calling them with the invariants they rely on for safety broken. Let me give an example starting with an enum definition:
// Assume std::vec has this definition
struct Vec<T> {
capacity: usize,
length: usize,
arena: * T
}
enum Example {
First {
capacity: usize,
length: usize,
arena: usize,
discriminator: NonZero<u8>
},
Second {
vec: Vec<u8>
}
}
fn main() {
let evil = NonZero::new_unchecked(0);
// We write as an Example::First,
// but this is read as an Example::Second
// because discriminator == 0 and niche optimization
let first = Example::First {
capacity: 9001, length: 9001,
arena: 0x20202020,
discriminator: evil
}
if let Example::Second{ vec: bad_vec } = first {
// If the layout of Example is as I described,
// and no optimizations occur, we should end up in here.
// This writes 255 to address 0x20202020
bad_vec[0] = 255;
}
}
It's not, though. NonZero<T> has an invariant that a zero value is undefined behavior. Therefore, any API which allows for the ability to create one must be unsafe. This is a very straightforward case.
I feel people took the comparison of rust to c and extrapolated to c++ which is blatantly disingenuous.
The Rust developers I meet are more interested in showing off their creations than in evangelizing the language. Even those on dedicated Rust forums are generally very receptive to other languages - you can see that in action on topics like goreleaser or Zig's comptime.
And while you have already dismissed the other commenter's experience of finding Rust nicer than C++ to program in, I would like to add that I share their experience. I have nothing against C++, and I would like to relearn it so that I can contribute to some projects I like. But the reason why I started with Rust in 2013 was because of the memory-saftey issues I was facing with C++. There are features in Rust that I find surprisingly pleasant, even with 6 additional years of experience in Python. Your opinion that Rust is unpleasant to the programmer is not universal and its detractions are not nonsense.
I appreciate the difficulty in learning Rust - especially getting past the stage of fighting the borrow checker. That's the reason why I don't promote Rust for immediate projects. However, I feel that the knowledge required to get past that stage is essential even for correct C and C++. Rust was easy for me to get started in, because of my background in digital electronics, C and C++. But once you get past that peak, Rust is full of very elegant abstractions that are similar to what's seen in Python. I know it works because I have trained js and python developers in Rust. And their feedback corroborates those assumptions about learning Rust.
Most often, the comments come from people who don’t even write much Rust. They either know just enough to be dangerous or they write other languages and feel like it’s a “gotcha” they can use against Rust.
So I agree with the above comment that the title could be better, but I also understand why the author gave it this title
> ... with all the other features that create the "if it compiles it probably works" experience
While it's true that Rust's core safety feature is almost exclusively about memory safety, I think it contributes more to the overall safety of the program.
My professional background is more in electronics than in software. So when the Rust borrow checker complains, I tend to map them to nuances of the hardware and seek work-arounds for those problems. Those work-arounds often tend to be better restructuring of the code, with proper data isolation. While that may seem like hard work in the beginning, it's often better towards the end because of clarity and modularity it contributes to the code.
Rust won't eliminate logical bugs or runtime bugs from careless coding. But it does encourage better coding practices. In addition, the strict, but expressive type system eliminates more bugs by encoding some extra constraints that are verified at compile time. (Yes, there are other languages that do this better).
And while it is not guaranteed, I find Rust programs to just work if it compiles, more often than in the other languages I know. And the memory-safety system has a huge role in that experience.
Containers like std::vector and smart pointers like std::unique_ptr seem to offer all of the same statically checked guarantees that Rust does.
I just do not see how Rust is a superior language compared to modern C++
This results in an ecosystem where safety is opt-in, which means in practice most implementations are largely unsafe. Even if an individual developer wants to proactive about safety, the ecosystem isn't there to support them to the same extent as in rust. By contrast, safety is the defining feature of the rust ecosystem. You can write code and the language and ecosystem support you in doing so rather than being a barrier you have to fight back against.
In C++ (and C#, Java, Go and many other “memory safe languages”), it’s very easy to mess up multithreaded code. Bugs from multithreading are often insanely difficult to reproduce and debug. Rust’s safety guardrails make many of these bugs impossible.
This is also great for performance. C++ libraries have to decide whether it’s better to be thread safe (at a cost of performance) or to be thread-unsafe but faster. Lots of libraries are thread safe “just in case”. And you pay for this even when your program / variable is single threaded. In rust, because the compiler prevents these bugs, libraries are free to be non-threadsafe for better performance if they want - without worrying about downstream bugs.
You can still create a mess from logical race conditions, deadlocks and similar bugs, but you won’t get segfaults because you after the tenth iteration forgot to diligently manage the mutex.
Personally I feel that in rust I can mostly reason locally, compared to say Go when I need to understand a global context whenever I touch multithreaded code.
I think rust delivers on its safety promise.
Make those threads access external resources simultaneously, or memory mapped to external writers, and there is no support from Rust type system.
I don’t think that’s true.
External thread-unsafe resources like that are similar in a way to external C libraries: they’re sort of unsafe by default. It’s possible to misuse them to violate rust’s safe memory guarantees. But it’s usually also possible to create safe struct / API wrappers around them which prevent misuse from safe code. If you model an external, thread-unsafe resource as a struct that isn’t Send / Sync then you’re forced to use the appropriate threading primitives to interact with the resource from multiple threads. When you use it like that, the type system can be a great help. I think the same trick can often be done for memory mapped resources - but it might come down to the specifics.
If you disagree, I’d love to see an example.
You can control safety as much as you feel like from Rust side, there is no way to validate that the data coming into the process memory doesn't get corrupted by the other side, while it is being read from Rust side.
Unless access is built in a way that all parties accessing the resource have to play by the same validation rules before writting into it, OS IPC resources like shared mutexes, semaphores, critical section.
The kind of typical readers-writers algorithms in distributed computing.
Managing something like that is a design decision of the software being implemented not a responsibility of the language itself.
The problem, rather, is that there's no implementation of checked iterators that's fast enough for release build. That's largely a culture issue in C++ land; it could totally be done.
There’s a great talk by Louis Brandy called “Curiously Recurring C++ Bugs at Facebook” [0] that covers this really well, along with std::map’s operator[] and some more tricky bugs. An interesting question to ask if you try to watch that talk is: How does Rust design around those bugs, and what trade offs does it make?
It seems the bug you are flagging here is a null reference bug - I know Rust has Optional as a workaround for “null”
Are there any pitfalls in Rust when Optional does not return anything? Or does Optional close this bug altogether? I saw Optional pop up in Java to quiet down complaints on null pointer bugs but remained skeptical whether or not it was better to design around the fact that there could be the absence of “something” coming into existence when it should have been initialized
For example if I write a C# function which takes a Goose, specifically a Goose, not a Goose? or similar - well, too bad the CLR says my C# function can be called by this obsolete BASIC code which has no idea what a Goose is, but it's OK because it passed null. If my code can't cope with a null? Too bad, runtime exception.
In real C# apps written by an in-house team this isn't an issue, Ollie may not be the world's best programmer but he's not going to figure out how to explicity call this API with a null, he's going to be stopped by the C# compiler diagnostic saying it needs a Goose, and worst case he says "Hey tialaramex, why do I need a Goose?". But if you make stuff that's used by people you've never met it can be an issue.
That's actually no different to Rust still; if you try, you can pass a 0 value to a function that only accepts a reference (i.e. a non-zero pointer), be it by unsafe, or by assembly, or whatever.
Disagreeing with another comment on this thread, this isn't a matter of judgement around "who's bug is it? Should the callee check for null, or the caller?". Rust's win is by clearly articulating that the API takes non-zero, so the caller is buggy.
As you mention it can still be an issue, but there should be no uncertainty around who's mistake it is.
OTOH with Rust you'd have to violate its safety guarantees, which if I understand correctly triggers UB.
Yes, your parent's example would be UB, and require unsafe.
This is an issue with the C++ standardization process as much as with the language itself. AIUI when std::optional (and std::variant, which has similar issues) were defined, there was a push to get new syntax into the language itself that would’ve been similar to Rust’s match statement.
However, that never made it through the standardization process, so we ended up with “library variants” that are not safe in all circumstances.
Here’s one of the papers from that time, though there are many others arguing different sides: https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/p00...
So this is actually why "no null, but optional types" is such a nice spot in the programming language design space. Because by default, you are making sure it "should have been initialized," that is, in Rust:
struct Point {
x: i32,
y: i32,
}
By contrast, here's a point where they could be:
struct Point {
x: Option<i32>,
y: Option<i32>,
}
> Are there any pitfalls in Rust when Optional does not return anything?
So, Rust will require you to handle both cases. For example:
let x: Option<i32> = Some(5); // adding the type for clarity
dbg!(x + 7); // try to debug print the result
error[E0369]: cannot add `{integer}` to `Option<i32>`
--> src/main.rs:4:12
|
4 | dbg!(x + 7); // try to debug print the result
| - ^ - {integer}
| |
| Option<i32>
|
note: the foreign item type `Option<i32>` doesn't implement `Add<{integer}>`
let x: Option<i32> = Some(5); // adding the type for clarity
let result = match x {
Some(num) => num + 7,
None => panic!("we don't have a number"),
};
dbg!(result); // try to debug print the result
Because this pattern is useful, there's a method on Option called `unwrap()` that does this:
let result = x.unwrap();
let result = match x {
Some(num) => num + 7,
None => 0,
};
let result = x.unwrap_or(0);
--------------
But to go back to the type thing for a bit, knowing statically you don't have any nulls allows you to do what some dynamic language fans call "confident coding," that is, you don't always need to be checking if something is null: you already know it isn't! This makes code more clear, and more robust.
If you take this strategy to its logical end, you arrive at "parse, don't validate," which uses Haskell examples but applies here too: https://lexi-lambda.github.io/blog/2019/11/05/parse-don-t-va...
(Basically, the 'newer' C++ features do help a little with memory safety, but it's still fairly easy to trip up even if you restrict your own code from 'dangerous' operations. It's not at all obvious that a useful memory-safe subset of C++ exists. Even if you were to re-write the standard library to correct previous mistakes, it seems likely you would still need something like the borrow checker once you step beyond the surface level).
#include<iostream>
#include<memory>
int main() {
std::unique_ptr<int> null_ptr;
std::cout << *null_ptr << std::endl; // Undefined behavior
}
==1==ERROR: UndefinedBehaviorSanitizer: SEGV on unknown address 0x000000000000 (pc 0x55589736d8ea bp 0x7ffe04a94920 sp 0x7ffe04a948d0 T1)
Vec1[0];
Vec1.at(0);
At least that's my understanding of the situation. Happy to be corrected though.
It's like if I wrote an article "pitfalls of Kevlar vests" which talked about how they don't protect you from being shot in the head. It's technically correct, but misleading.
I thought the C++ language did that.
That said, I still prefer to use it only where necessary.
Notably the log4shell[1] vulnerability wasn't due to buffer overruns, and happened in a memory safe language.
This sort of bug is still possible in rust. (Although this particular bug is probably impossible - since safe rust checks UTF8 string validity at the point of creation).
This is one article about it - there was a better write up somewhere but I can’t find it now: https://www.rapid7.com/blog/post/2025/02/13/cve-2025-1094-po...
Rust’s static memory protection does still protect you against most RCE bugs. Most is not all. But that’s still a massive reduction in security vulnerabilities compared to C or C++.
If you think back to the big breaches over the last five years, though -- SolarWinds, Colonial Pipeline, Uber, Okta (and through them Cloudflare), Change Healthcare, etc. -- all of these were basic account takeovers.
To the extent that anyone has to choose between investing in "safe" code and investing in IT hygiene, the correct answer today is IT hygiene.
As an example of a bad data set for this conversation, the vast majority of published CVEs have never been used by an attacker. CISA's KEVs give a rough gauge of this, with a little north of 1300 since 2021, and that includes older CVEs that are still in use, like EternalBlue. Some people point to the cardinality of CVE databases as evidence of something, but that doesn't hold up to scrutiny of actual attacks. And this is all before filtering down to memory safety RCE CVEs.
Probably the closest thing to a usable data set here would be reports from incident response teams like Verizon's, but their data is of course heavily biased towards the kinds of incidents that require calling in incident response teams. Last year they tagged something like 15% of breaches as using exploits, and even that is a wild overestimate.
> Memory safety is definitely a worthwhile investment.
In a vacuum, sure, but Python, Java, Go, C#, and most other popular languages are already memory safe. How much software is actively being written in unsafe languages? Back in atmosphere, there's way more value in first making sure all of your VPNs have MFA enabled, nobody's using weak or pwned passwords, employee accounts are deactivated when they leave the company, your help desk has processes to prevent being social engineered, and so on.
Well, let's see. Most major operating system kernels for starters. Web browsers. OpenSSL. Web servers/proxies like Apache, Nginx, HAProxy, IIS, etc. GUI frameworks like Gtk, Qt, parts of Flutter. And so on.
[0] For some reason I'm having trouble finding primary sources, but it's at least referenced in ex. https://security.googleblog.com/2024/09/eliminating-memory-s...
https://github.com/flux-rs/flux
I haven't actually used it but I do have experience of refinement types / liquid types (don't ask me about the nomenclature) and IMO they occupy a very nice space just before you get to "proper" formal verification and having to deal with loop invariants and all of that complexity.
There's a nice FOSDEM presentation "Understanding liquid types, contracts and formal verification with Ada/SPARK" by Fernando Oleo Blanco (Irvise): https://fosdem.org/2025/schedule/event/fosdem-2025-4879-unde.... One of the slides says:
Liquid types!
Logically Qualified Types, aka, Types with Logic! Aka dependent types, etc...Regarding `as` casting, I completely agree. I am trying to use safe `From::from` instead. However, this is a bit noisy: `usize::from(n)` vs `n as usize`.
[0] https://doc.rust-lang.org/std/num/struct.Wrapping.html [1] https://doc.rust-lang.org/std/num/struct.Saturating.html
If there's enough information in the surrounding code for type inference to do its thing, you can shorten it to `n.into()`.
If you wrap a Future in Arc, you won't be able to use it. Polling requires exclusive access, which Arc disables. Most combinators and spawn() require exclusive ownership of the bare Future type. This is verified at compile time.
Making a cycle with `Arc` is impossible unless two other criteria are met:
1. You have to have a recursive type. `Arc<Data>` can't be recursive unless `Data` already contains `Arc<Data>` inside it, or some abstract type that could contain `Arc<Data>` in it. Rust doesn't use dynamic types by default, and most data types can be easily shown to never allow such cycle.
It's difficult to make a cycle with a closure too, because you need to have an instance of the closure before you can create an Arc, but your closure can't capture the Arc before it's created. It's a catch-22 that needs extra tricks to work around, which is not something that you can just do by accident.
2. Even if a type can be recursive, it's still not enough, because the default immutability of Arc allows only trees. To make a cycle you need the recursive part of the type to also be in a wrapper type allowing interior mutability, so you can modify it later to form a cycle (or use `Arc::new_cycle` helper, which is an obvious red flag, but you still need to upgrade the reference to a strong one after construction).
It's common to have Arc-wrapped Mutex. It's possible to have recursive types, but having both together at the same time are less common, and then still you need to make a cycle yourself, and dodge all the ownership and borrow checking issues required to poll a future in such type.
Important aspect is performance. HPC code needs to be able to opt out of math checks.
Also Results and Options are very costly, as they introduce lot of branching. Panic is just faster. Hopefully one day rust will use something like IEX by default https://docs.rs/iex/latest/iex/ It has the same benefits as Results, but if error is returned in less than 15% of function calls, then IEX is much faster.
Btw. allocation failure in std returning Result anytime soon?
> I was not the only one who was confused by this behavior. Here’s a thread on the topic, which also includes an answer by Johannes Dahlström:
> > The behavior is useful because a caller […] can choose whether it wants to use a relative or absolute path, and the callee can then simply absolutize it by adding its own prefix and the absolute path is unaffected which is probably what the caller wanted. The callee doesn’t have to separately check whether the path is absolute or not.
> And yet, I still think it’s a footgun. It’s easy to overlook this behavior when you use user-provided paths. Perhaps join should return a Result instead? In any case, be aware of this behavior.
Oh, hey, that's me! I agree that it's a footgun, for what it's worth, and there should probably get a dedicated "absolutize" method for getting the "prefix this if relative, leave as is if already absolute" semantics.
(link to the thread: https://users.rust-lang.org/t/rationale-behind-replacing-pat...)
nope, I won't do that. I'd rather waste away at a bank using early 2000s oracle forms . Make it a compiler flag, detect it statically or gtfo.
“as” is a good example. Floats are pretty much the only reason PartialEq exists, so why can’t we have a guaranteed-not-NaN-nor-inf type in std and use that everywhere? Why not make wrapping integers a panic even in release mode? Why not have proper dependent types (e.g. to remove bound checks), and proper linear types (to enforce that object destructors always run)?
It’s easy to forget that Rust is not an ideal language, but rather a very pragmatic one, and sometimes correctness loses in favour of some other goals.
As Rust is both evolving and spreading wide, we; the programmers, users of Rust; are also leveling up in how we approach correctness and design with it.
Maybe the next evolution will be something like Haskell but fast like Rust is fast like C without the pain of C++.
But it takes a while for the world to catch up, and for everybody to explore and find ways to work with or around the abstractions that helps with correctness.
It's a bit like the evolution from a pointer to some malloc memory, then the shared/unique pointer of C++, to the fully safe box/(a)rc of Rust.
It might be obvious today how much more efficient it is programming with those abstractions.
I see some similarities with functional programming that still seems so niche. Even though the enlighteneds swears by it. And now we actually seem to be slowly merging the best parts of functional and imperative together somehow.
So maybe we are actually evolving programming as a species. And Rust happens to be one of the best scaffold at this point in history.
Thank you for reading my essay.
I do agree that the evolution is most likely a language that combines automatic resource management with affine/linear/effects/dependent/proofs.
Or AIs improve to the point to render all existing programming languages a thing from the past, replaced by regular natural languages and regular math.
I don't remember every argument in there but it seemed that there are good reasons not to add it unlike a NonZero integer type which seems to have no real downsides.
https://doc.rust-lang.org/std/primitive.f64.html#method.tota...
Did you read the article? Rust includes overflow checks in debug builds, and then about a dozen methods (checked_mul, checked_add, etc.) which explicitly provide for checks in release builds.
Pragmatism, for me, is this help when you need it approach.
TBF Rust forces certain choices on one in other instances, like SipHash as the default Hasher for HashMap. But again opting out, like opting in, isn't hard.
You can turn those checks on, in release mode, of course: https://doc.rust-lang.org/rustc/codegen-options/index.html#o...
But I think the behavior on overflow is to "panic!()" (terminate immediately)? So -- I guess from my POV I wouldn't in release mode. I just think that tradeoff isn't generally worth it, but again, you can turn that behavior on.
I don't disagree though this point is a little pedantic. I suppose the docs also need an update? See: https://doc.rust-lang.org/std/macro.panic.html
"This allows a *program to terminate immediately* and provide feedback to the caller of the program."
And my point remains, without more, this probably isn't the behavior one wants in release mode. But, yes, also perhaps an even better behavior is turning on checks, catching the panic, and logging it with others.
Nor negative zero
Most of the time I want the behavior of ".try_into().unwrap()" (with the compiler optimizing the checks away if it's always safe) or would even prefer a version that only works if the conversion is safe and lossless (something I can reason about right now, but want to ensure even after refactorings). The latter is really hard to achieve, and ".try_into.unwrap()" is 20 characters where "as" is 2. Not a big deal to type with autocomplete, but a lot of visual clutter.
No they can’t. Overflows aren’t a real problem. Do not add checked_mul to all your maths.
Thankfully Rust changed overflow behavior from “undefined” to “well defined twos-complement”.
Having done a bunch of formal verification I can say that overflows are probably the most common type of bug by far.
Arithmetic overflows have become the punchline of video game exploits.
Unsigned underflow is also one of the most dangerous types. You go from one of the smallest values to one of the biggest values.
Don’t do arithmetic with u8 or probably even u16.
If I play "Appeal to Authority" you can read some thoughts on this from Alexandrescu, Stroustrup, and Carruth here: https://stackoverflow.com/questions/18795453/why-prefer-sign...
Unsigned integers are appealing because they make a range of invalid values impossible to represent. That's good! Indices can't be negative so simply do not allow negative values.
The issues are numerous, and benefits are marginal. First and foremost it is extremely common to do offset math on indices whereby negative values are perfectly valid. Given two indices idxA and idxB if you have unsigned indices then one of (idxB - idxA) or (idxA - idxB) will underflow and cause catastrophe. (Unless they're the same, of course).
The benefits are marginal because even though unsigned cannot represent a value below the valid range it can represent a value above container.size() so you still need to bounds check the upper range. If you can't go branchless then who cares about eliminating one branch that can always be treated as cold.
On a modern 64-bit machine doing math on smaller integers isn't any faster and may in fact be slower!
Now it can be valuable to store smaller integers. Especially for things like index lists. But in this case you're probably not doing any math so the overflow/underflow issue is somewhat moot.
Anyhow. Use unsigned when doing bitmasking or bitmanipulation. Otherwise default to signed integer. And default to i64/int64_t. You can use smaller integer types and even unsigned. Just use i64 by default and only use something else if you have a particular reason.
I'm kinda rambling and those thoughts are scattered. Hope it was helpful.
But at the same time in real code in the real world you just do the maths, throw caution to the wind, and if it overflows and produces a bug you just fix it there. It's not worth the performance hit and your fellow developers will call you mad if you try to have a whole codebase with only checked maths.
Similarly in this case, it's not like we don't have languages that do checked arithmetic throughout by default. VB.NET, for example, does exactly that. Higher-level languages have other strategies to deal with the problem; e.g. unbounded integer types as in Python, which simply never overflow. And, like you say, this sort of thing is considered unacceptable for low-level code on perf grounds, but, given the history with nulls and OOB checking, I think there is a lesson here.
Overflow bugs are a real pain, and so easy to prevent in Rust with just a function call. It's pretty high on my list of favorite improvements over C/C++
Of course don't use saturating_add to calculate account balance, there you should use checked_add.
That's also not the only choice in the design space for correct array accesses. Instead of indices being raw integers, you can use tagged types (in Rust, probably using lifetimes as the mechanism if you had to piggy back on existing features, but that's an implementation detail) and generate safe, tagged indices which allow safe access without having to bounds check on access.
However you do it, the point is to not lie about what you're actually doing and invoke a panic-handler-something as a cludgy way of working around the language.
The coolest one I've heard is that Fuchsia's network stack managed to eliminate deadlocks.
But even on a basic level Rust has that "if it compiles it works" experience which Go definitely doesn't.
Is there a write up on this? That's very cool
There are some crates which implement lock ordering as well (e.g., [2, 3]). lock-ordering states it's inspired by the technique discussed in the talk as well, for what it's worth.
[0]: https://youtu.be/qd3x5MCUrhw?t=1001 (~16:41 in case the timestamp link doesn't work)
[1]: https://joshlf.com/files/talks/Safety%20in%20an%20Unsafe%20W... (deadlock prevention example starting slide 50)
That way you can never lock lock B if you have not received a guard aka lock from lock A prior. Ensured on the type level.
I suppose doing this at scale is a real challenge.
slice := []int{1, 2, 3}
i := slice[3]
fmt.Println(i)My biggest critisim of Rust (in comparison to Go) is the lack of a powerful standard library while Go's standard library is outstanding. I would also like to see standardized interfaces in Rust (like AsyncWrite) and in general the async story could be better - though I appreciate the versatility.