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class: center, middle, ferris
Introduction to Rust
====================
Wesley Moore
------------
![Ferris the Rustacean animation](images/ferris.gif)
---
# Agenda
1. Features
2. Tooling
3. Concepts
4. Demo
5. Questions
---
# Introduction
```rust
fn main() {
println!("Rust Introduction");
}
```
> **Rust** is a systems programming language that runs blazingly fast, prevents
> segfaults, and guarantees thread safety.
— [rust-lang.org](https://www.rust-lang.org/)
---
# Systems Programming Language
* Compiles to native code.
--
* Aims to solve the same sorts of problems that C and C++ are used to solve but
with improved safety.
--
* Also seeing use in:
--
* Web (front and backend)
--
* Operating systems ([Redox OS][redox])
--
* Embedded systems (microcontrollers)
---
# Runs Blazingly Fast
![Benchmarks Chart](images/benchmarks.png)
---
# Runs Blazingly Fast
* No interpreter, no runtime.
--
* Memory safety without garbage collection.
--
* Zero cost abstractions.
---
class: segfaults
# Prevents Segfaults
* No `nil`, `NULL` or other [billion dollar mistakes][billion-dollar-mistake].
![undefined method for nil:NilClass](images/undefined-method-nil.png)
This is not a thing. At all. Ever.
.center[[billion-dollar-mistake]: https://www.infoq.com/presentations/Null-References-The-Billion-Dollar-Mistake-Tony-Hoare]
---
# Guarantees Thread Safety
* Strongly, statically typed with an emphasis on safety and correctness.
--
* Ownership model tracks owner and lifetime of memory.
--
* No data races: Compiler knows which thread owns what data.
--
* This leads to, "[Fearless Concurrency][fearless-concurrency]".
> Mozilla made two previous attempts to parallelize its style system in C++,
> and both of them failed. But Rusts fearless concurrency has made parallelism
> practical!
— [Fearless Concurrency in Firefox Quantum](https://blog.rust-lang.org/2017/11/14/Fearless-Concurrency-In-Firefox-Quantum.html) (Nov 2017)
---
# Strong Static Type System
* Do more at compile time so fewer tests and runtime checks are required.
--
* Concepts mostly familiar. No need to learn an entirely new paradigm.
--
* Traits and generics instead of objects and inheritance.
--
* Type inference reduces the need to provide type annotations.
--
* Refactor with impunity — even in large code bases.
---
# Tooling
Official distribution includes: `cargo`
--
:
* Build tool (no Makefiles)
--
* Package manager (like bundler)
--
* Test runner
--
* Documentation generator
---
## Releases
Generally managed with `rustup`
--
:
* Official toolchain manager (like rbenv)
--
* New releases every 6 weeks
* Committed to backwards compatibility in every release.
---
class: crates
# Crates
* Rust favours a small, stable standard library.
* Crates are the equivalent of Ruby gems. They are published to
[crates.io](https://crates.io/).
![screenshot of crates.io](images/crates-io.png)
---
# Community and Direction
* RFC process.
--
* Systematic improvement.
--
* Emphasis on inclusion and building a friendly community.
---
class: center, middle, bigger
Concepts
========
---
# Functions
```rust
fn add(left: i32, right: i32) -> i32 {
left + right
}
fn main() {
let sum = add(2, 3);
}
```
---
# Conditionals: if
```rust
let temperature: i32 = 29;
if temperature > 25 {
println!("Wesley is happy");
}
else {
println!("Too cold");
}
```
---
# Conditionals: match
Can match structure and values:
```rust
let month = "jan";
match month {
"jan" => 1, "feb" => 2,
"mar" => 3, "apr" => 4,
"may" => 5, "jun" => 6,
"jul" => 7, "aug" => 8,
"sep" => 9, "oct" => 10,
"nov" => 11, "dec" => 12,
_ => panic!("invalid month"),
};
```
---
# Loops
```rust
let numbers = [1, 2, 3];
for i in numbers.iter() {
// do something
}
for i in 0..10 {
// do something
}
```
Also less frequently used commonly used `loop` and `while`.
---
# Functional or Imperative
```rust
fn variance_mean(data: &[f64], mean: f64) -> f64 {
let mut sum = 0.;
for d in data {
sum += (d - mean).powf(2.0);
}
sum / data.len() as f64
}
```
Code from [hydromath] crate by Andrew MacDonald.
---
# Functional or Imperative
```rust
fn variance_mean(data: &[f64], mean: f64) -> f64 {
data.into_iter()
.map(|d| (d - mean).powf(2.0))
.sum::<f64>() / data.len() as f64
}
```
--
You pay _no cost_ for using the higher level style, it compiles to identical
machine code (I checked).
---
# enums
Type that represents one possibility of several variants. Variants may optionally
carry data.
```rust
enum SerialProtocol {
Usb,
Rs485,
Rs232,
I2C,
Spi,
}
```
---
# structs
Type that carries structured data.
```rust
struct Person {
name: String,
age: i32,
favourite_serial_protocol: SerialProtocol,
}
impl Person {
fn name_and_age(&self) -> String {
format!("{} is {} years old", self.name, self.age)
}
}
```
---
# Option
Instead of `nil` and `NULL` there is `Option`.
* Used to represent something that may be absent.
```rust
enum Option<T> {
Some(T),
None
}
```
---
# Result
When something can succeed or fail with an error.
* There are no exceptions in Rust, `Result` is how you handle errors.
```rust
enum Result<T, E> {
Ok(T),
Err(E)
}
```
---
Demo
====
Small tool that will determine a file's type from its extension:
```shell
filetype src/main.rs somefile.rb
```
Should give output like:
```
Rust: src/main.rs
Ruby: src/somefile.rb
```
---
class: center, middle, bigger
Demo
====
---
class: center, middle, invert, bigger
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Questions?
==========
---
Credits
=======
* [Animated Ferris][animated-ferris] by A. L. Palmer, via [rustacean.net][rustacean].
* Portions of this talk were derived from [A Very Brief Intro to Rust][rust-intro]
Copyright © 2016 Ashley Williams.
* Benchmarks chart generated from data on [The Computer Language
Benchmarks Game][benchmarks] on 10 Jan 2018.
[rust-intro]: https://github.com/rustbridge/a-very-brief-intro-to-rust
[animated-ferris]: https://www.behance.net/gallery/42774743/Rustacean
[rustacean]: http://rustacean.net/
[fearless-concurrency]: https://doc.rust-lang.org/book/second-edition/ch16-00-concurrency.html
[redox]: https://www.redox-os.org/
[hydromath]: https://github.com/amacd31/hydromath_rs
[benchmarks]: https://benchmarksgame.alioth.debian.org/