wezm.net/v1/output/technical/2018/01/introduction-to-rust-talk/slides/slides.md

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Introduction to Rust

Wesley Moore

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Agenda

1. Features
2. Tooling
3. Concepts
4. Demo
5. Questions

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Introduction

fn main() {
  println!("Rust Introduction");
}

Rust is a systems programming language that runs blazingly fast, prevents segfaults, and guarantees thread safety.

— rust-lang.org

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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)

--

• Embedded systems (microcontrollers)

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Runs Blazingly Fast

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Runs Blazingly Fast

• No interpreter, no runtime.

--

• Memory safety without garbage collection.

--

• Zero cost abstractions.

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Prevents Segfaults

• No nil, NULL or other [billion dollar mistakes][billion-dollar-mistake].

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]

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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".

Mozilla made two previous attempts to parallelize its style system in C++, and both of them failed. But Rust’s fearless concurrency has made parallelism practical!

— Fearless Concurrency in Firefox Quantum (Nov 2017)

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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.

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Tooling

Official distribution includes: cargo

:

• Build tool (no Makefiles)

--

• Package manager (like bundler)

--

• Test runner

--

• Documentation generator

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Releases

Generally managed with rustup

:

• Official toolchain manager (like rbenv)

--

• New releases every 6 weeks
  • Committed to backwards compatibility in every release.

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Crates

• Rust favours a small, stable standard library.
• Crates are the equivalent of Ruby gems. They are published to crates.io.

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Community and Direction

• RFC process.

--

• Systematic improvement.

--

• Emphasis on inclusion and building a friendly community.

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Concepts

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Functions

fn add(left: i32, right: i32) -> i32 {
    left + right
}

fn main() {
    let sum = add(2, 3);
}

---

Conditionals: if

let temperature: i32 = 29;

if temperature > 25 {
    println!("Wesley is happy");
}
else {
    println!("Too cold");
}

---

Conditionals: match

Can match structure and values:

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

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

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.

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Functional or Imperative

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).

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enums

Type that represents one possibility of several variants. Variants may optionally carry data.

enum SerialProtocol {
    Usb,
    Rs485,
    Rs232,
    I2C,
    Spi,
}

---

structs

Type that carries structured data.

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.

enum Option<T> {
    Some(T),
    None
}

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Result

When something can succeed or fail with an error.

• There are no exceptions in Rust, Result is how you handle errors.

enum Result<T, E> {
    Ok(T),
    Err(E)
}

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Demo

Small tool that will determine a file's type from its extension:

filetype src/main.rs somefile.rb

Should give output like:

Rust: src/main.rs
Ruby: src/somefile.rb

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Demo

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Questions?

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Credits

• Animated Ferris by A. L. Palmer, via rustacean.net.
• Portions of this talk were derived from A Very Brief Intro to Rust
  Copyright © 2016 Ashley Williams.
• Benchmarks chart generated from data on The Computer Language Benchmarks Game on 10 Jan 2018.