Rust Review Redux

It was aaaages ago that I first reviewed Rust. For those not in the know, Rust is a next-generation compiled language (similar to Go, but this is where they diverge) developed by Mozilla - out of a need to have a safer alternative to C++ for writing key components of Firefox in.

Since then, I've obtained both a degree and a masters in computer science. I've also learnt a number of programming languages since then. I have been searching for a better alternative to C++ that's easier to use and doesn't fight you at every step - and I decided to give Rust another go.

After a few false starts, I managed to get going with starting to build a little web app (which will probably take a while until I can really show it off here). The tooling for the compiler is pretty good once you actually get it installed - although the installer itself is truly shocking (ly bad):

• rustup - Manages multiple versions of Rust installed (I haven't used it much yet; apparently it's like nvm the Node Version Manager, but I don't use that either)
• cargo - Orchestrates the building of your project and the installation of dependencies, which are known as crates.
• rustc - The compiler itself. You probably won't interact with it directly much - instead going through cargo most of the time.

Together (and with the right Atom packages installed), they make for a relatively pleasant development experience. I mention the installer in particular though, because it's awful. I noted a number of issues with it:

• The official website forces you to download an installation script that pipes to sh
• It will only install on a per-user basis (goodbye disk space, hello extra system config complexity)
• It doesn't even tell you how much disk space it's going to use (which wouldn't be an issue if they just setup an apt repository....)

These issues aside, other aspects of the experience were also worthy of note. First, the error messages the Rust compiler generates are actually useful. Much better than they were the last time I really dove into Rust, they provide you with much moree detail as to what's gone wrong, and there's even a special rustc --explain ERROR_CODE command you can execute to get more detail about what went wrong, why, and how to fix it.

This as a feature is certainly helpful for me as a beginner Rust programmer, but I think it's also a pretty essential feature given Rust's weirdness as a language.

I'm seriously not kidding - Rust is a nutty language. For one, classes exist.... sort of - but only as structs. Which are passed by reference (again, sort of) by default and may not contain methods - that's the job of an impl, which is short for an implementation. Implementations are a strange mix between C♯'s interfaces and multiple inheritance (in C++ I think it is?). And there are traits, which I haven't really looked into fully yet, but are a mix between interfaces and abstract classes..... you get the picture.

Point is, all this funky strangeness that goes on in Rust makes it a very challenging language to learn. A challenge that I feel is worth persevering with, but a challenge nonetheless. Rust does have a number of very powerful features that make it worth the effort, in my opinion.

For example, it catches entire classes of critically nasty bugs that plague other low-level systems languages such as C and C++ like use-after-free and the really awful concurrency race conditions at compile time - which is incredible, if you ask me. Such bugs have been a serious bother to many high-profile software projects that exist today and have caused a number of security issues. Rust is a testament to what can be achieved when you start from scratch and fix these issues by designing them out of the language.

For the curious, it does this by a complex system of variable lifetime, ownership, moving, and borrowing. I don't yet understand all the details, but the system enables the Rust compiler to be able to trace the lifetime of a variable at compile time, so you get the benefit of having a garbage collector without any of the overhead, since it's all been done at compile-time and built into your program that way.

This deep understanding of how data is passed around also yields performance and efficiency benefits too. C and C++ do not have such an understanding, so there are a number of performance optimisations the Rust compiler can make that would be considered far too dangerous for gcc to do. The net result of this is that sometimes code written in Rust will actually be faster than C and C++. This is a significant accomplishment, as the speed of C and C++ has been held as the gold standard for a long time (see exhibits A and B just for starters).

These are just some of the reasons that I'm persisting with learning Rust. So far, it seems like a "slow and steady wins the race" kinda deal - in that I'm taking it one concept at a time. There's a huge amount to take in, so I can't recommend that you try and do it all at once - time to consolidate what I've learnt so far is quite important I've found.

Rust is absolutely one of the hardest languages I've tried to learn, as it reinvents a lot of concepts which have been a staple of programming languages for a long time. However, it also comes with key benefits ease-of-use (once learnt, compared to C and C++), performance, and program execution safety at runtime (it was originally invented by Mozilla specifically to make Firefox a safer and faster browser, IIRC). To this end, I'm going to try my best to keep learning the language - and report back here at some point with cool stuff I've created (at the moment it's still in a state of flux and I'm refactoring heavily at each successive stage) :D

Edit: I've just remembered. I do currently have 2 big issues with rust: compilation time and disk space usage. When you install a dependency, it not only builds it from source,e but also recursively builds all of it's dependencies from source too. Not only does this take forever, but it also eats huge volumes of disk space for breakfast!

Found this interesting? Got some helpful advice or a question about Rust? Comment below!

Rust: First Impressions

You may have heard of Mozilla's Rust - a fairly new language developed by Mozilla for their new rendering engine, Servo. Recently, I took a look at Rust, and this post contains my thoughts.

Please note that I am looking at Rust (a compiled language) from the prespective of an interpreted language programmer, since I have not actually learnt any other compiled languages yet.

To start off with, Rust code appears fairly easy to read, and is loosely based on other languages that I already know, such as Javascript. You can quickly get the gist of a piece of Rust code just by reading it through, even without the comments.

The compiler is easy to use for beginners, and also quite helpful when you make mistakes, although some of the error messages are definitely not friendly to a new Rust programmer. I personally got totally confused by the finer points of Rust's type system, and the compiler was most certainly not helpful when it came to sorting the problems out.

The ability to set a variable equal to the output of a complex expression is also nice - allowing you to do this:

fn main() {
    let x = 2u;

    let y = match x {
        0 => "x is zero!",
        1 => "x is one!",
        2 => "x is two!",
        3 => "x is three!",
        4 => "x is four!",
        5 => "x is five!",
        _ => "x is larger than five!"
    };

    println!("{}", y);
}

Rust has some nice language constructs too - the match statement above is an example is this. It looks so much better than the traditional switch statement, and is more flexable as well.

The problem with Rust, though, is that it doesn't really have very many different tutorials and guides out there for new programmers, especially those coming from an interpreted language background, like me. This will sort itself out though, in time. The language itself is also changing frequently, which makes keeping a tutorial updated a considerable amount of work. This also make the language more difficult to learn, since you can't be sure whether the tutorial you are reading is up to date or not. This problem will also gradually disappear on it's own as the language stabilises though.

To conclude, Rust looks like a promising new language that I will resume learning at some point in the future, perhaps when I have more experience with compiled languages (and type systems!), and when rust has stabilised a little more. At the moment Rust does not feel stable enough and mature enough for me to easily learn it.