Rust and the Elm Architecture

Rust is a fast, compiled, strongly typed, and memory safe programming language.

Let’s explain what that means:

Compiled languages are “translated” into a lower level machine code that can be directly executed by the computer, before they are run. Languages like C are another example of a compiled language, while languages like Python are typically interpreted languages.

Strongly typed languages usually require you to declare types for parameters and variables, although Rust’s compiler is smart enough that it can often infer types for variables. Strongly typed languages also have strict rules about changing a variable’s type (illegal), etc.

Memory safe: Unlike languages like C, Rust tries to guarantee memory safety through its borrow checker and ownership systems. It’s a bit hard to explain, but you can read the Rust book to learn more.

The basics of Rust is out of scope for this document, but you can check out Rust’s very helpful free online book which can teach you Rust (HIGHLY RECOMMENDED). Up to chapter 10 should be enough. Chapters 13, 15, and 18 are also useful to read. Rust also has amazing documentation for its standard library that you should check out. You can also find documentation for Rust crates by searching in docs.rs. Once you get the basic concepts of Rust, you can probably figure out how to search and read the docs. Of course, as usual, you will learn much better and naturally if you try making some small projects in Rust while you are reading the book. Also, if you encounter any errors, besides searching them up (which can be very helpful), Rust’s compilers is very smart and can help suggest a fix, so make sure to read them! Feel free to ask us if you have some simple Rust questions, eg about unwrap(), Option, references, closures, etc. If you ask me a tricky question about lifetimes though, I will probably just suggest you rewrite your code to avoid them… lifetimes are scary, and unless you’re super sure you need to use them, they can often mean you’re doing something wrong.

The Elm Architecture

Now back on topic. The Elm Architecture has nothing to do with Rust - it’s a way (“architecture”) to make interactive programs like websites and apps. In fact, it originated from a language called Elm. You can think of it as a trait (kinda like the Rust equivalent of classes in other languages) that looks something like this:

trait Component {
  type Message;


  fn new() -> Self;
  fn update(&mut self, message: Self::Message);
  fn view(&self);
}

The new() function creates a new component - of course, you can make the function accept any parameters and do stuff with them, but I just ignored that for simplicity.

update() has &mut self meaning it has a mutable reference of itself - it can change its own state (properties). Message is usually a struct or enum that contains information. Whenever a message is sent, it means the update() function is being called. For example, a message might be sent when a user clicks a button, or the site gets a response from an API call.

The view() function has &self, which is a non-mutable reference of itself - it can read its own state, but cannot modify the state. It just displays what should be shown on screen and sends messages if, say, a button is clicked. If it was a website, that would be HTML, while if it was a desktop app, it would probably be some widgets that came with the library.

I don’t know if that was a good explanation, but no worries, you’ll get it quickly once you try.

Yew

Yew is a frontend framework for websites. It does display html, but instead of Javascript, it uses Rust compiled to Web Assembly (WASM).

Yew has a tutorial, but to be honest, the examples were more helpful for me.

Iced

Iced is a framework for desktop apps on all platforms (Windows, Linux, MacOS, Raspberry Pi…), although it can be compiled into a website also (outputs as code that draws to HTML Canvas, so not really recommended).

You will want to look at the examples, and the documentation on docs.rs.

Conclusion

Rust is really cool. The Elm Architecture is very cool. Yew and Iced are very cool. You should try them, because then you will be cool too (guaranteed and foolproof or your money back).