A half-hour to learn Rust (2020)(fasterthanli.me) |
A half-hour to learn Rust (2020)(fasterthanli.me) |
When I was first getting started I learned so much from Amos and his INSANE deep-dives over at fasterthanli.me, basically he taught me Rust. For my 3rd video I messaged him and asked if I could base it on his article and he said 'go for it' - since then we've both found ways to go full-time in our respective worlds, and we shitpost in a private discord together :-D
This video isn't really a good intro to either my channel or the WHYs of Rust, just the syntax.
If I may signpost my own intro to Rust playlist https://www.youtube.com/watch?v=oY0XwMOSzq4&list=PLZaoyhMXgB...
And an example of one of Amos's deep-dive videos "C++ vs Rust: which is faster?" https://www.youtube.com/watch?v=VMpSYJ_7aYM
[1]: https://fasterthanli.me/articles/recursive-iterators-rust
However, 8 years later I did eventually come to love rust after learning the One Weird Trick of using indices instead of pointers.
IMvHO, Rust Ownership and Lifetime rules aren't really that hard to learn. The only trick is that a programmer cannot learn Rust exclusively by trial-and-error (which programmers love to do), trying dozens of syntax combinations to see what works. A programmer is forced to learn Rust by RTFM (which programmers hate to do), in order to understand how Rust works. That's all there's to it. It's like trying to learn to play the guitar without reading a book on guitar cords, pulling guitar strings individually at random - the music just won't happen for quite a long time, unless you're Mozart. At any rate, one can always forget Rust references (i.e., raw pointers) and use Rust reference-counted smart pointers[1], effectively writing Rust analogously to Swift.
Having seen that kind of opinion stated elsewhere, it seems what most people would like is rust minus borrowing, and I feel I would get behind that too.
It's already possible. Use Rust reference-counted smart pointers[1] for shareable immutable references and internal mutability[2] for non-shareable mutable references checked at runtime instead of compile time.
[1] https://doc.rust-lang.org/book/ch15-04-rc.html
[2] https://doc.rust-lang.org/book/ch15-05-interior-mutability.h...
I have never written a game before, so Catherine West[1] might have very good reasons for choosing ECS, but I... am not so crazy about it. ECS seems to replace Rust references (raw pointers) and/or Rust smart pointers with indexes into one, large "registry" (a container: e.g., a `Vec<T>`) of entities (e.g., `struct` instances). In other words, instead of allowing a Rust pointer (a managed memory address) to keep a piece of memory alive, ECS chooses to have a "registry" keep a piece of memory alive under a particular index, managing allocation and deallocation manually.
In a sense, ECS dumps Rust memory management in favor of... writing the good, ol', data-and-function -oriented C. Quite needlessly (?), since the same (?) can probably be accomplished with Rust reference counted pointers[2], weak pointers[3] and interior mutability[4].
----- CUT HERE -----
use std::rc::{Rc, Weak};
use std::cell::RefCell;
type WeakMutEntity = Weak<RefCell<Entity>>;
struct Entity {
related: WeakMutEntity,
}
impl Entity {
fn new(related: WeakMutEntity) -> Self {
Self { related }
}
fn use_related(&mut self) {
let Some(related) = self.related.upgrade() else { return; };
related.borrow_mut().use_related();
}
}
let entity1 = Rc::new(RefCell::new(
Entity::new(/* null */ Weak::new())));
let entity2 = Rc::new(RefCell::new(
Entity::new(Rc::downgrade(&entity1))));
entity2.borrow_mut().use_related();
If the above does not get the job done, the solution shouldn't be to just abandon the Rust borrow checker; the solution should be to get the Rust Gods to optimize the available pointer types syntax-wise and/or performance-wise.
[1] https://www.youtube.com/watch?v=aKLntZcp27M
[2] https://doc.rust-lang.org/book/ch15-04-rc.html
[3] https://doc.rust-lang.org/book/ch15-06-reference-cycles.html
[4] https://doc.rust-lang.org/book/ch15-05-interior-mutability.h...
A half-hour to learn Rust - https://news.ycombinator.com/item?id=25610741 - Jan 2021 (330 comments)
A half-hour to learn Rust - https://news.ycombinator.com/item?id=22448933 - Feb 2020 (148 comments)
I've been using other languages longer than 10 years too but not continuously enough to ever consider myself expert.
I'd say there are definitely rust experts out there, but I'd posit it's unlikely for the average dev to have gotten that far yet.
I think TFA is a great resource in terms of presenting syntax and idioms. My biggest problem with learning Rust though has been understanding how to do things when the borrow checker prohibits the solution that would be 'obvious' in C#, C++, etc. I started to make progress when I bought the O'Reilly Programming in Rust book, and then thoroughly read and re-read the chapter on memory management.
- in distrib: cargo, analyzer, clippy
- others: Aquascope godbolt intellij flowistry
__________________________
https://www.infoworld.com/article/3267624/whats-new-in-the-r...
I also chuckled at the "20 minute read".
fn tail<'a>(s: &'a [u8]) -> &'a [u8] {
&s[1..]
}
...
fn main() -> Result<(), std::str::Utf8Error> {
let s = std::str::from_utf8(&[240, 159, 141, 137])?;
println!("{}", s);
Ok(())
}
It does take a little while to get accustomed to, but the investment is more than worth it.
Can't comment on my sanity though.
One example:
> `let` patterns can be used as conditions in `if`:
Anyway, this tutorial looks great, I'll give Rust another go when I have a good project for it, but to me it seems there is a great need for a simpler language with similar memory management. Rust is just too complex, imho.
As an utter newbie to Rust, I can't guess whether or not the tutorial has become dated.
You can code without that, it's just that you are going to wish you had it after your first few programs.
> but the language itself seems needlessly complex to me
A lot of the complexity is around making the explicitness of the language bearable. If you had to be explicit without all the syntax sugar and type / lifetime inference it would be insufferable to program in.
See example from code I wrote this week: https://github.com/trane-project/trane/blob/master/src/data/...
Without the let, I'd have to do a match statement followed by an unwrap just to check if a field in an enum is set.
You... would not?
An `if let` trivially desugars to a `match`.
if let <pat> = <expr> {
...
}
match <expr> {
<pat> => {
...
}
_ => {}
}Well, I have to agree Rust isn't one of the simplest PL-s on the planet. This is due to the fact that it is quite a modern PL and quite a versatile PL, supporting elements of functional programming, trait-oriented (conditional generics) programming, asynchronous programming, etc. and a capable standard library on top of it all. It takes, indeed, quite some time to take all of that Rust in. As a reward, you get a lot of expressiveness and the capability to discover a significant percentage (if not an overwhelming majority) of your programming mistakes at compile time as opposed to runtime (unit/integration tests or Q/A), which to me is priceless.
Nevertheless, from my experience, Rust is, at the same time, one of the most... "consistent", "predictable", "internally symmetric" PL-s I have ever seen. I consider Rust to be way easier to learn than, say, Swift.
> `let` patterns can be used as conditions in `if`
I somewhat cannot help it but feel that such an example should not be used in an introductory tutorial. `if let` is usually used to pattern-match a simple `enum`[1], not a complex `struct` that looks "dense" unless you're used to it.
Yes, exactly! Now can I have just a safe C without all the other stuff, pretty please? :) I understand Rust is not it, but I hope someone comes up with a simple PL which is also compile-time memory safe. I think it would be an instant hit.
> when I have a good project for it
... is a bad idea. I've heard this from several programmers who now use Rust professionally, but don't have first-hand experience about it. Their take can be boiled down to:
Rust has a learning curve that will mean that the first version will invariably be throw-away. Developing a mental model for how to change memory management structures to please the borrow checker and properly encode ownership seems like the biggest hurdle to writing good Rust.
I believe this is the main reason Rust adoption isn't skyrocketing, but still growing. The "onboarding" for Rust is more labor intensive and therefore disincentivizes its use.
Your example is a minor but quite useful piece of syntactic sugar, which was introduced a few years in following a similar construct being successful in Swift. You can read the entire reasoning at https://rust-lang.github.io/rfcs/0160-if-let.html
No construction made up of any kind of pointers can achieve that, unless there's a Sufficiently Smart compiler that can magically fully eliminate these pointers.
Not sure how much we could remove from Rust while keeping the problem tractable. The borrow checker is needed for compile time memory safety sans garbage collection. For borrow checking to be tractable, one needs shared references, exclusive references, owned values, the possibility for reference counting, and the possibility for interior mutability. This mandates smart pointers, that pretty much mandate generics. These various abstractions also mandate a capable standard library, unless the language would hardcode all these abstractions, which would endanger the low-levelness of the language (since you wouldn't be able to implement your own abstractions for e.g. embedded contexts)
For the demarcation between unsafe Rust and safe Rust to work, one needs encapsulation, so field privacy.
For concurrency, the language requires a way to mark types as thread safe, which requires a way to say things about structures, so a least a weak version of traits.
A smaller version of Rust probably exists, but I don't think we could remove as much of the language as we could imagine at first without compromising safety. It also wouldn't be "just a safe C", because C itself has heaps of accidental complexity (e.g. the way function pointers are declared, integer promotions, implicit conversions, the antiquated textual inclusion compilation model that is prone to ODR violations and complicates build systems, array decay, and so on...) that would need to be removed.
Hmmmmm, if you are not being forced by others into any particular Rust feature set (standard) and you are not being forced into any preexisting Rust codebase, then perhaps just forget the entire standard library, traits, async, etc. and go Bare Metal Rust[1], using only the Rust language features that you need and interfacing with external C APIs through Foreign Function Interface[2].
[1] https://google.github.io/comprehensive-rust/bare-metal.html
let lock = Arc::new(RwLock::new(1));
This plus a few unwrapping things is enough to get you almost std::shared_ptr and then you can fight the borrow checker some other day.
This is probably because using internal mutability not to achieve a valid design goal (such as a controlled side-effect on an otherwise immutable entity), but to side-step the borrow checker for ease of programming, is not considered idiomatic Rust and even though it makes a good educational tool, it should rather not end up in production codebases.
Firstly, when using regular references, you cannot create multiple mutable references. This rule prevents subtle bugs such as data races. When using internal mutability, you still keep that protection, but it is (undesirably) delayed from compile time to runtime, potentially causing an unavoidable crash/panic.
Secondly, when using regular references, you cannot create even a single mutable reference when an immutable reference already exists. This rule prevents subtle bugs such as unexpected mutation ("from under you") of data that was passed-in as immutable. When using internal mutability, you throw away that protection, since multiple immutable reference owners can request a mutable reference (even if only one at a time).
use std::rc::Rc;
use std::cell::RefCell;
let entity1 = Rc::new(RefCell::new(42));
let /* immutable */ entity2 = entity1.clone();
*entity1.borrow_mut() += 27;
assert_ne!(*entity2.borrow_mut(), 42);The snippet you link to should be replaceable by something along the lines of
match &passages.asset {
TranscriptionAsset::Track {
artist_name: Some(artist_name),
..
} => {
metadata
.entry(ARTIST_METADATA.to_string())
.or_default()
.push(artist_name.clone());
}
_ => {}
}
If you keep removing redundant constructs from languages, you will end up with something pure and minimal like the lambda calculus or turing machine. But these aren't easy to program in!
Languages are an interface for humans. If the code density is too low or too high, it becomes difficult to for people reason about the programs. Concepts like readability and expressiveness are important, but end up requiring some level of complexity.
You could learn lambda calculus in an afternoon, but then spend a month writing a single complex algorithm. You could spend 5 years learning Haskell, and then write the most powerful system in a couple minutes.
There's a sweet spot somewhere between those two, and Rust is definitely near it.
Which, while it might arguably hurt adoption, is a good value proposition, since you spend a lot more time knowing the language than not knowing it.
Now, not everything is always perfect, and I agree that the `if let` is not the most useful part of the language, as it drives pointless discussions about when to use it vs match (some people prefer the esthetics of match even when an if let can be used, others prefer to use a if let whenever possible). This redundancy apart, the construct doesn't eat any mental energy once you know it. The same can't be said of many of C++ quirks (initialization rules, member-initializer list in constructors, the rule of five)
Are there are good workarounds when breaking changes to occur? No idea if/how well breaking language changes can be isolated to stay within individual crates.
[0] https://subscription.packtpub.com/book/programming/978178934...
I don't think that matters at all. If I try to build a new project with an older version of Rust, the compiler will still throw errors when stumbling upon newer features.
I don't think so.
Both C and C++ are specified in international standards. That's the gold standard.
Java has very concrete versioning and specification process.
Python is also exemplary in its release and versioning process.
C# even breaks down versioning in terms of both CLR and fundamental frameworks.
Exactly which widely used language do you think is missing from that list?
You're now listing languages, such as Python, that don't have a specification, so it is unclear what your criticism actually is.
By python's standards, Rust is very good: a lot fewer breaking changes (changes are tested against the entire, huge, open source ecosystem to check if they are breaking, I think this level of testing is unparalleled), the release and versioning process is extremely clear (one minor release every six weeks, patch releases to address unexpected regressions + security issues), and it also have a really well specified evolution process through the RFC process.
Usually when people worry about language evolution, the concern is that a newer compiler can't handle older code.
If the concern is that projects are using "too new a rustc version", then your beef is with those projects, but be advised that demanding open source projects not use newer versions of their toolchains can be a big ask that increases their workloads and they might not be amenable to cater to your usecase.
Finally, because every Rust version is backwards compatibility, there's no reason for builders and developers to not use the latest stable release as quickly as feasible, all existing projects will continue compiling.