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<!doctype html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no">
<title>Rust Primer</title>
<link rel="stylesheet" href="reveal.js-4.1.2/dist/reveal.css">
<link rel="stylesheet" href="reveal.js-4.1.2/dist/theme/black.css">
<!-- Theme used for syntax highlighting of code -->
<link rel="stylesheet" href="reveal.js-4.1.2/plugin/highlight/zenburn.css">
<style type="text/css">
.reveal span>code, .inline-code code {
line-height: 1.2em;
font-size: 0.55em;
padding: 5px;
width: 100%;
display: inline;
}
</style>
</head>
<body>
<div class="reveal">
<div class="slides">
<section>
<h2>Rust Primer</h2>
<h3></h3>
</section>
<section>
<h2>What is Rust?</h2>
<p>
<ul>
<li>Systems programming language</li>
<li>Strong static typing</li>
<li>Guaranteed memory safety<span style="color: red;">*</span></li>
<li>No undefined behavior<span style="color: red;">*</span></li>
</ul>
</p>
<p style="text-align: right;" class="fragment">
<span style="color: red;">*</span>except when using 👻<code class="rust">unsafe</code>👻
</p>
<img src="rust-logo-white.svg" style="border: 0; background: 0; box-shadow: unset; margin: auto 0;">
<aside class="notes" data-markdown>
* No dynamic memory management, run-time
* Namespacing, sane file inclusion, lambdas
* Package manager
</aside>
</section>
<section>
<h2>More information</h2>
<p>
<ul>
<li>Installing: <a href="https://www.rust-lang.org/tools/install">rust-lang.org/tools/install</a></li>
<li>Learn: <a href="https://www.rust-lang.org/learn">rust-lang.org/learn</a>
<ul>
<li>Rust book: <a href="https://doc.rust-lang.org/book/">doc.rust-lang.org/book</a></li>
<li>Standard library: <a href="https://doc.rust-lang.org/std"/>doc.rust-lang.org/std</a></li>
</ul>
</li>
<li>Playground: <a href="https://play.rust-lang.org/">play.rust-lang.org</a></li>
<li>These slides: <a href="https://hugwijst.github.io/rust-primer/">hugwijst.github.io/rust-primer</a></li>
</ul>
</p>
</section>
<section>
<h2>Using Cargo</h2>
<p>
<ul>
<li><code>cargo init</code></li>
<li><code>cargo check</code></li>
<li><code>cargo build</code></li>
<li><code>cargo run</code></li>
<li><code>cargo test</code></li>
</ul>
</p>
<aside class="notes" data-markdown>
* `init` is binary by default, `--lib` for library
* Cargo will automatically rebuild if needed (run/test)
* normal build is debug, `--release` for release builds
</aside>
</section>
<section>
<h2>Contents</h2>
<ul>
<li>Primitive types</li>
<li>References & Borrowing</li>
<li>Control flow</li>
<li>Code organization</li>
<li>Custom data types</li>
<li>Error handling</li>
<li>Heap allocated data</li>
</ul>
</section>
<section>
<h2>Primitive types</h2>
<ul class="rust">
<li><span class="rust"><code>bool</code> (<code>true</code>, <code>false</code>)</span></li>
<li><span class="rust">
<code>u8</code>, <code>u16</code>, <code>u32</code>, <code>u64</code>, <code>u128</code>
(<code>12u8</code>, <code>b'a'</code>, <code>65_536u32</code>)
</span></li>
<li><span class="rust">
<code>i8</code>, <code>i16</code>, <code>i32</code>, <code>i64</code>, <code>i128</code>
(<code>0x1EEFi16</code>, <code>-3_000_000_000i64</code>)
</span></li>
<li><span class="rust">
<code>usize</code>, <code>isize</code> (<code>15usize</code>, <code>-12isize</code>)
</span></li>
<li><span class="rust">
<code>f32</code>, <code>f64</code> (<code>1e24f32</code>, <code>0.24f64</code>)
</span></li>
<li><span class="rust">
<code>char</code> (<code>'a'</code>, <code>'💡'</code>)
</span></li>
</ul>
<aside class="notes" data-markdown>
* note suffix
* `b'a'` is an unsigned byte
* `usize`, `isize`: size of a native word on the architecture
* `_` to help readability of numbers
* `char` is a **UTF-8** character, size: 4 bytes!
</aside>
</section>
<section>
<h2>Assignment</h2>
<pre><code class="rust" data-line-numbers data-trim>
fn main() {
let x: u32 = 24u32; // fully explicit
let x = 16u8; // infered type of `x`
let x: f32 = 12.; // infered type of `12.`
let x = 42; // defaults to isize
let x = 42u; // or usize when unsigned
let x = 42.; // or f64 when float
let x;
x = 15; // deferred assignment
}
</code></pre>
<aside class="notes" data-markdown>
* Note: shadowing of local variables
</aside>
</section>
<section>
<h2>Casting</h2>
<pre><code class="rust" data-line-numbers data-trim>
fn main() {
let x: u32 = 12u8; //< fails to compile!
// ^^^^ expected u32, found u8
let x: u32 = 12u64; //< fails to compile!
// ^^^^^ expected u32, found u64
let x: u32 = 12u64 as u32; // x == 12
let x = 400u16 as u8; // x == 144
let x = -3i8 as u8; // x == 253
}
</code></pre>
<aside class="notes" data-markdown>
* No implicit conversions or promotions
* Negative numbers are interpreted as 2s-complement when converted
</aside>
</section>
<section>
<h2>Mutability</h2>
<pre><code class="rust" data-line-numbers data-trim>
fn main() {
let x = 41;
x = 42; //< fails to compile!
// ^^^^^^ cannot assign twice to immutable variable
let x = 42;
let mut x = 41;
x = 42;
}
</code></pre>
<aside class="notes" data-markdown>
* Shadowing preferred for non-mutable data
</aside>
</section>
<section>
<h2>References</h2>
<ul>
<li>References and mutability</li>
<li>References & Borrowing</li>
</ul>
</section>
<section>
<h2>References</h2>
<pre style="position:absolute; width: 100%"><code class="rust" data-noescape data-line-numbers data-trim style="max-height: 600px;">
fn main() {
let x = 41u32;
let r: &u32 = &x;
assert!(x == 41);
assert!(*r == 41);
}
</code></pre>
<aside class="notes" data-markdown>
* First use of `assert!`
</aside>
</section>
<section>
<h2>Uninitialized References</h2>
<pre><code class="rust" data-line-numbers data-trim>
fn main() {
let r: &u32;
assert!(*r == 4); //< fails to compile!
// ^^ use of possibly uninitialized `*r`
}
</code></pre>
<aside class="notes" data-markdown>
</aside>
</section>
<section>
<h2>Mutable References</h2>
<pre style="position:absolute; width: 100%"><code class="rust" data-line-numbers data-noescape data-trim style="max-height: 600px;">
fn main() {
let x = 41u32;
let r: &u32 = &x;
assert!(*r == 41);
<span class="fragment" data-fragment-index="2">let y = 42;</span>
<span class="fragment" data-fragment-index="2"> r = &y;</span><span class="fragment" data-fragment-index="3"> //< fails to compile!</span>
<span class="fragment" data-fragment-index="3">// ^^^^^^ cannot assign twice to immutable variable</span>
<span class="fragment" data-fragment-index="4"> let mut s = &y; assert!(*s == 42);</span>
<span class="fragment" data-fragment-index="4"> s = &x; assert!(*s == 41);</span>
<span class="fragment" data-fragment-index="5"> *s = 4;</span><span class="fragment" data-fragment-index="6"> //< fails to compile!</span>
<span class="fragment" data-fragment-index="6">// ^^^^^^ `s` is a `&` reference, so the data it refers to</span>
<span class="fragment" data-fragment-index="6">// cannot be written</span>
}
</code></pre>
<aside class="notes" data-markdown>
</aside>
</section>
<section>
<h2>Reference To Mutable</h2>
<pre><code class="rust" data-line-numbers data-noescape data-trim>
fn main() {
let mut x = 41;
let r: &mut u32 = &mut x;
assert!(*r == 41);
*r = 42;
assert!(*r == 42);
assert!(x == 42);
<span class="fragment" data-fragment-index="2">let x = 41u32;</span>
<span class="fragment" data-fragment-index="2">let r: &mut u32 = &mut x; //< fails to compile!</span>
<span class="fragment" data-fragment-index="2">// ^^^^^^ cannot borrow as mutable</span>
}
</code></pre>
<aside class="notes" data-markdown>
</aside>
</section>
<section>
<h2>The Borrowing Rule</h2>
<div style="display: table; margin: 0 auto;">
<div style="display: table-cell; padding-right: 1em;">
Either:
</div>
<ul style="display: table-cell;">
<li>Many immutable borrows</li>
<li>One mutable borrow</li>
</ul>
</div>
<aside class="notes" data-markdown>
Whiteboard analogy
</aside>
</section>
<section>
<h2>Borrowing 1</h2>
<pre><code class="rust" data-line-numbers data-noescape data-trim>
fn main() {
let mut x = 41;
let r = &x;
<span class="fragment" data-fragment-index="3">// -- immutable borrow occurs here</span>
let r_mut = &mut x;
<span class="fragment" data-fragment-index="3">// ^^^^^^ mutable borrow occurs here</span>
assert!(*r == *r_mut);<span class="fragment" data-fragment-index="2"> //< fails to compile!</span>
<span class="fragment" data-fragment-index="3">// -- immutable borrow later used here</span>
}
</code></pre>
<aside class="notes" data-markdown>
Either many immutable borrows *OR* one mutable borrow.
</aside>
</section>
<section>
<h2>Borrowing 2</h2>
<pre><code class="rust" data-line-numbers data-noescape data-trim>
fn main() {
let mut x = 41;
let r_mut = &mut x;
<span class="fragment" data-fragment-index="2">// ------ borrow of `x` occurs here</span>
assert!(x == *r_mut); //< fails to compile!
<span class="fragment" data-fragment-index="2">// ^ ------ borrow later used here</span>
<span class="fragment" data-fragment-index="2">// |</span>
<span class="fragment" data-fragment-index="2">// use of borrowed `x`</span>
}
</code></pre>
<aside class="notes" data-markdown>
No access to borrowed variables.
</aside>
</section>
<section>
<h2>Borrowing 3</h2>
<pre><code class="rust" data-line-numbers data-noescape data-trim>
fn main() {
let mut x = 41;
let r = &x;
<span class="fragment" data-fragment-index="2">// -- borrow of `x` occurs here</span>
assert!(x == *r);
x = 42;
<span class="fragment" data-fragment-index="2">// ^^^^^^ assignment to borrowed `x` occurs here</span>
assert!(x == *r); //< fails to compile!
<span class="fragment" data-fragment-index="2">// -- borrow later used here</span>
}
</code></pre>
<aside class="notes" data-markdown>
No access to borrowed variables.
</aside>
</section>
<section>
<h2>Sequences</h2>
<ul>
<li>Arrays</li>
<li>Slices</li>
<li>Strings</li>
</ul>
</section>
<section>
<h2>Arrays</h2>
<pre><code class="rust" data-line-numbers data-trim>
fn main() {
let array: [i32; 3] = [1, 4, -3];
assert!(array[0] == 1);
assert!(array[3] == 4); //< Fails to compile!
let n = 3;
assert!(array[n] == 4); //< Panics!
let all_5s = [5u8; 5];
assert!(all_5s == [5, 5, 5, 5, 5]);
assert!(all_5s.len() == 5);
}
</code></pre>
<aside class="notes" data-markdown>
* Array is fixed size.
* In example array stored on stack.
* Needs to be fully initialized!
* Panics on out-of-bounds index access.
</aside>
</section>
<section>
<h2>Slices</h2>
<pre><code class="rust" data-line-numbers data-trim style="max-height: 100%">
fn main() {
let arr1: [i32; 3] = [1, 4, -3];
let mut arr_ref: &[i32] = &arr1;
assert!(arr_ref[0] == 1);
assert!(arr_ref[3] == 4); //< Panics!
let arr2 = [1, 2, 3, 4, 5];
arr_ref = &arr2;
assert!(*arr_ref == [1, 2, 3, 4, 5]);
arr_ref = &arr_ref[2..];
assert!(arr_ref == [3, 4, 5]);
assert!(arr_ref.len() == 3);
}
</code></pre>
<aside class="notes" data-markdown>
* Slice: reference to contiguous data **and** length
* Panics on out-of-bounds index access.
* Can create and store subslice with range.
* `*` can often be elided.
</aside>
</section>
<section>
<h2>String slices</h2>
<pre style="width: initial;"><code class="rust" data-line-numbers data-trim>
fn main() {
let hello_world: &str = "Hello World 👋!";
assert!(hello_world.len() == 17); // in bytes!
assert!(hello_world.chars().count() == 14);
assert!(&hello_world[..5] == "Hello");
assert!(&hello_world[..12] == "Hello World ");
assert!(&hello_world[..13] == "Hello World "); //< Panics!
assert!("".len() == 0);
assert!("\0".len() == 1);
}
</code></pre>
<aside class="notes" data-markdown>
* Strings are complicated
* `&str` points to a UTF-8 string
* No null-termination
</aside>
</section>
<section>
<h2>Contents</h2>
<ul>
<li style="color: grey;">Primitive types</li>
<li style="color: grey;">References & Borrowing</li>
<li>Control flow</li>
<li>Code organization</li>
<li>Custom data types</li>
<li>Error handling</li>
<li>Heap allocated data</li>
</ul>
</section>
<section data-markdown class="inline-code">
<textarea data-template>
## Operators
* numeric (`+`, `-`, `*`, `/`, `%`)
* bitwise (`|`, `&`, `^`, `<<`, `>>`)
* comparison (`==`, `!=`, `>`, `<`, `>=`, `<=`)
* logical (`||`, `&&`)
* number negation (`-`)
* boolean negation (`!`)
* number bitwise negation (`!`) <span class="fragment" data-fragment-index="1">🚨</span>
* compound assignment (`+=`, `|=`, etc.)
* **NO**: increment/decrement (`++`, `--`)
notes:
* overflow and underflow well defined, 2s-complement in release
* logical operations only on `bool`
* bitwise negation is non-C
</textarea>
</section>
<section>
<h2>Control Flow</h2>
<ul>
<li>If</li>
<li>Loops</li>
<li>Lambdas and Closures</li>
<li>Iterators</li>
</ul>
</section>
<section>
<h2>Control flow: if</h2>
<div class="fragment fade-out" data-fragment-index="1"><pre style="position:absolute;width:100%"><code class="rust" data-line-numbers data-trim>
fn min(a: usize, b: usize) -> usize {
let ret;
if a < b {
ret = a;
} else {
ret = b;
}
return ret;
}
fn main() {
assert!(min(5,8) == 5);
}
</code></pre></div>
<div class="fragment current-visible" data-fragment-index="1"><pre style="position:absolute;width:100%"><code class="rust" data-line-numbers data-trim>
fn min(a: usize, b: usize) -> usize {
let ret;
if a < b {
ret = a;
} else {
ret = b;
}
ret
}
fn main() {
assert!(min(5,8) == 5);
}
</code></pre></div>
<div class="fragment current-visible" data-fragment-index="2"><pre style="position:absolute;width:100%"><code class="rust" data-line-numbers data-trim data-noescape>
fn min(a: usize, b: usize) -> usize {
let ret <mark>=</mark> if a < b { a } else { b }<mark>;</mark>
ret
}
fn main() {
assert!(min(5,8) == 5);
}
</code></pre></div>
<div class="fragment fade-in" data-fragment-index="3"><pre style="position:absolute;width:100%"><code class="rust" data-line-numbers data-trim data-noescape>
fn min(a: usize, b: usize) -> usize {
if a < b { a } else { b }
}
fn main() {
assert!(min(5,8) == 5);
}
</code></pre></div>
<aside class="notes" data-markdown>
* first non-`main` function!
* No braces around condition expression
* `if` is an expression, not a statement
</aside>
</section>
<section>
<h2>Control flow: loop</h2>
<pre><code class="rust" data-line-numbers data-trim style="max-height: 475px;">
fn main() {
let start = 3;
let mut x = start;
while x > 0 {
println!("down = {}", x);
x -= 1;
}
let end = loop {
println!("up = {}", x);
x += 1;
if x >= start { break x; }
};
assert!(end == start);
}
</code></pre>
<aside class="notes" data-markdown>
* First `println!`
* No do-while
* Loops are expressions too
</aside>
</section>
<section>
<h2>Control flow: for-loop</h2>
<pre><code class="rust" data-line-numbers data-trim style="max-height: 450px;">
fn main() {
let mut x = 0;
for i in 1..5 {
x += i;
}
assert!(x == 10);
}
</code></pre>
<aside class="notes" data-markdown>
* `1..5` is a range, 1-inclusive and 5-exclusive
* `for` iterates over an iterator, a range is an iterator
</aside>
</section>
<section>
<h2>Lambdas & Closures</h2>
<pre><code class="rust" data-line-numbers data-trim style="max-height: 500px;">
fn min(a: usize, b: usize) -> usize {
if a < b { a } else { b }
}
fn main() {
fn local_min(a: usize, b: usize) -> usize {
if a < b { a } else { b }
}
assert!(min(1, 2) == 1);
assert!(local_min(1, 2) == 1);
let lambda_min = |a, b| if a < b { a } else { b };
assert!(lambda_min(5, 8) == 5);
let a = 4;
let min_of_a_and = |b| if a < b { a } else { b };
assert!(min_of_a_and(8) == 4);
}
</code></pre>
<aside class="notes" data-markdown>
* Contrived :)
* Local functions
* Closure captures environment
* Closure useful when passed to function, see later
</aside>
</section>
<section>
<h2>Iterator: filter + map</h2>
<pre><code class="rust" data-line-numbers data-trim style="max-height: 450px;">
fn main() {
let mut s = 0;
for i in (1..10).filter(|x| x % 2 == 0) {
s += i; // i <- [2, 4, 6, 8]
}
assert!(s == 20);
s = 0;
for i in (1..5).map(|x| x * 3 + 1) {
s += i; // i <- [4, 7, 10, 13]
}
assert!(s == 34);
}
</code></pre>
<aside class="notes" data-markdown>
* explain `filter` and `map` methods
* would be better without the `mut s`
</aside>
</section>
<section>
<h2>Iterator: sum</h2>
<pre><code class="rust" data-line-numbers data-trim style="max-height: 450px;">
fn main() {
let s: isize = (1..10)
.filter(|x| x % 2 == 0)
.sum();
assert!(s == 20);
let s: u32 = (1..5)
.map(|x| x * 3 + 1)
.sum();
assert!(s == 34);
}
</code></pre>
<aside class="notes" data-markdown>
* explain `sum` method
* methods often on separate lines if long
* requires typing because inference has limits
</aside>
</section>
<section>
<h2>Contents</h2>
<ul>
<li style="color: grey;">Primitive types</li>
<li style="color: grey;">References & Borrowing</li>
<li style="color: grey;">Control flow</li>
<li>Code organization</li>
<li>Custom data types</li>
<li>Error handling</li>
<li>Heap allocated data</li>
</ul>
</section>
<section>
<h2>Code organization</h2>
<ul>
<li>Modules</li>
<li>Visibility</li>
<li>Multi-file crate</li>
</ul>
</section>
<section>
<h2>Modules</h2>
<pre><code class="rust" data-line-numbers data-trim style="max-height: 450px;">
mod math {
pub fn sum_u32(a: u32, b: u32) -> u32 {
a + b
}
pub fn sum_f32(a: f32, b: f32) -> f32 {
a + b
}
}
fn main() {
assert!(math::sum_u32(15, 5) == 20);
use math::sum_f32;
assert!(sum_f32(1.5, 20.5) == 22.0);
}
</code></pre>
<aside class="notes" data-markdown>
* `mod` used for organizing code in different name spaces
* import into current name space using `use`
</aside>
</section>
<section>
<h2>Visibility</h2>
<pre style="width: initial"><code class="rust" data-line-numbers data-trim style="max-height: 560px;">
mod math {
pub mod u32 {
pub fn sum(a: u32, b: u32) -> u32 { helper(a, b) }
fn helper(a: u32, b: u32) -> u32 { a + b }
}
pub mod f32 {
pub fn sum(a: f32, b: f32) -> f32 { a + b }
}
}
fn main() {
assert!(math::u32::sum(15, 5) == 20);
use math::f32::sum as sum_f32;
assert!(sum_f32(1.5, 20.5) == 22.0);
math::u32::helper(1, 2); //< fails to compile!
// ^^^^^^ function `helper` is private
}
</code></pre>
<aside class="notes" data-markdown>
* `helper` called before it is defined!
</aside>
</section>
<section>
<h2>Exporting</h2>
<pre style="width: initial"><code class="rust" data-line-numbers data-trim style="max-height: 550px;">
mod math {
mod u32 {
pub fn sum(a: u32, b: u32) -> u32 { helper(a, b) }
fn helper(a: u32, b: u32) -> u32 { a + b }
}
pub use self::u32::sum as sum_u32;
use self::u32::sum as sum_u32_priv;
}
fn main() {
assert!(math::sum_u32(15, 5) == 20);
math::sum_u32_priv(1, 2); //< fails to compile!
// ^^^^^^^^^^^^ function `sum_u32_priv` is private
math::u32::sum(1, 2); //< fails to compile!
// ^^^ module `u32` is private
}
</code></pre>
<aside class="notes" data-markdown>
* `self` in path context needed to disambiguate from the `u32` builtin type
* `pub use` exports publicly
</aside>
</section>
<section>
<h2>Multi-file crate</h2>
<pre style="width: initial">bin.rs<code class="rust" data-line-numbers data-trim style="max-height: 550px;">
mod math {
mod u32 {
pub fn sum(a: u32, b: u32) -> u32 { helper(a, b) }
fn helper(a: u32, b: u32) -> u32 { a + b }
}
pub use self::u32::sum as sum_u32;
pub fn sum_f32(a: f32, b: f32) -> f32 { a + b }
}
fn main() {
assert!(math::sum_u32(15, 5) == 20);
assert!(math::sum_f32(1.5, 20.5) == 22.0);
}
</code></pre>
<aside class="notes" data-markdown>
* `bin.rs` is crate entry point for binaries, `lib.rs` for libraries
* can think of this file as the "root module"
</aside>
</section>
<section>
<h2>Multi-file crate</h2>
<pre style="width: initial">math.rs:<code class="rust" data-line-numbers data-trim style="max-height: 550px;">
mod u32 {
pub fn sum(a: u32, b: u32) -> u32 { helper(a, b) }
fn helper(a: u32, b: u32) -> u32 { a + b }
}
pub use self::u32::sum as sum_u32;
pub fn sum_f32(a: f32, b: f32) -> f32 { a + b }
</code></pre>
<pre style="width: initial">bin.rs:<code class="rust" data-line-numbers data-trim style="max-height: 550px;">
mod math;
fn main() {
assert!(math::sum_u32(15, 5) == 20);
assert!(math::sum_f32(1.5, 20.5) == 22.0);
}
</code></pre>
<aside class="notes" data-markdown>
* `mod` without body loads from external file
</aside>
</section>
<section>
<h2>Multi-file crate</h2>
<pre style="width: initial">math/u32.rs:<code class="rust" data-line-numbers data-trim style="max-height: 550px;">
pub fn sum(a: u32, b: u32) -> u32 { helper(a, b) }
fn helper(a: u32, b: u32) -> u32 { a + b }
</code></pre>
<pre style="width: initial">math.rs:<code class="rust" data-line-numbers data-trim style="max-height: 550px;">
mod u32;
pub use self::u32::sum as sum_u32;
pub fn sum_f32(a: f32, b: f32) -> f32 { a + b }
</code></pre>
<pre style="width: initial">bin.rs:<code class="rust" data-line-numbers data-trim style="max-height: 550px;">
mod math;
fn main() {
assert!(math::sum_u32(15, 5) == 20);
assert!(math::sum_f32(1.5, 20.5) == 22.0);
}
</code></pre>
<aside class="notes" data-markdown>
C/C++ differences:
* no duplicate symbols during linking
* no `-I` or include files
* discoverable file and item locations
* no duplicate definition/declaration
</aside>
</section>
<section>
<h2>Contents</h2>
<ul>
<li style="color: grey;">Primitive types</li>
<li style="color: grey;">References & Borrowing</li>
<li style="color: grey;">Control flow</li>
<li style="color: grey;">Code organization</li>
<li>Custom data types</li>
<li>Error handling</li>
<li>Heap allocated data</li>
</ul>
</section>
<section>
<h2>Custom data types</h2>
<ul>
<li>Data type definitions: Struct and Enum</li>
<li>Pattern matching</li>
<li>Method definitions</li>
<li>Traits</li>
<li>Generics</li>
</ul>
</section>
<section>
<h2>Struct initialization</h2>
<pre><code class="rust" data-line-numbers data-trim style="max-height: 450px;">
struct S {
field1: i32,
field2: f32,
}
fn main() {
let s1: S = S { field1: 42, field2: 12.0 };
let s2 = S { field2: 18.0, ..s1 };
assert!(s2.field1 == 42 && s2.field2 == 18.0);
let s3 = S { field1: 15 }; //< fails to compile!
// ^ missing `field2`
let s4 = S { }; //< fails to compile!
// ^ missing `field1`, `field2`
}
</code></pre>
</section>
<section>
<h2>Struct nesting</h2>
<pre><code class="rust" data-line-numbers data-trim style="max-height: 450px;">
pub struct S {
pub field1: i32,
field2: f32,
}
struct STuple {
s1: S,
s2: S,
}
fn foo(s_tup: STuple) {
if s_tup.s1.field1 == s_tup.s2.field1 {
println!("field1 matches!");
}
}
</code></pre>
<aside class="notes" data-markdown>
field visibility rules same as other data:
* visible for own module and sub-modules
* only visible higher if marked as `pub`
Very different from C++!
</aside>
</section>
<section>
<h2>Tuples</h2>
<pre><code class="rust" data-line-numbers data-trim style="max-height: 600px;">
// Tuple Struct
struct Fraction(isize, isize);
fn main() {
let f = Fraction(1, 2);
assert!(f.0 == 1);
let tup = (5, true, 42.); // type: (isize, bool, f64)
assert!(tup.1);
}
fn div_rem(a: isize, b: isize) -> (isize, isize) {
(a / b, a % b)
}
fn get_quotient(f: Fraction) -> isize {
let Fraction(a, b) = f;
let (quot, _) = div_rem(a, b);
quot
}
</code></pre>
<aside class="notes" data-markdown>
* Return tuple: type: `(a, b)`
* Note: pattern matching in `get_quotient`
* Note: `.` access in `main`
</aside>
</section>
<section>
<h2>New Type</h2>
<pre><code class="rust" data-line-numbers data-trim style="max-height: 600px;">
// Single element tuple structs (new types)
struct Time(f32); // in seconds
struct Distance(f32); // in meters
struct Speed(f32); // in km/h
fn avg_speed(d: Distance, t: Time) -> Speed {
Speed(d.0 / t.0 * 3.6)
}
fn main() {
let d = Distance(402.3);
let t = Time(11.8);
assert!(avg_speed(d, t).0 > 122.5);
}
</code></pre>
<aside class="notes" data-markdown>
* Encode quantity in types.
</aside>
</section>
<section>
<h2>Enums</h2>
<pre><code class="rust" data-line-numbers data-trim style="max-height: 600px;">
enum Color {
Red,
Blue,
White,
Black,
}
fn rgb(c: Color) -> u32 {
match c {
Color::Red => 0xFF0000,
Color::Blue => 0x0000FF,
Color::White => 0xFFFFFF,
Color::Black => 0x000000,
}
}
fn main() {
assert!(rgb(Color::Red) == 0xFF0000);
}
</code></pre>
<aside class="notes" data-markdown>
* `match` is not yet discussed
* `match` is complete, cannot add more clauses
* enum variants in the namespace of the enum type
</aside>
</section>
<section>
<h2>Enums with data</h2>
<pre><code class="rust" data-line-numbers data-trim style="max-height: 600px;">
enum Color {
Black,
White,
Other(u32),
}
fn rgb(c: Color) -> u32 {
use Color::*;
match c {
White => 0xFFFFFF,
Black => 0x000000,
Other(other_col) => other_col,
}
}
fn main() {
assert!(rgb(Color::Black) == 0x000000);
assert!(rgb(Color::Other(0x123456)) == 0x123456);
}
</code></pre>
<aside class="notes" data-markdown>
* use `use` to bring enum names in name space
* pattern matching in `match`
</aside>
</section>
<section>
<h2>Pattern matching</h2>
<pre><code class="rust" data-line-numbers data-trim style="max-height: 600px;">
enum Color { Black, White, Other(Rgba) }
struct Rgba { rgb: u32, a: u8 }
use Color::*;
fn opaque(c: Color) -> bool {
match c {
White | Black
| Other(Rgba { a: 0xFF, .. }) => true,
_ => false,
}
}
fn main() {
assert!(opaque(Black) == true);
assert!( opaque(Other(Rgba{a:0xFF, rgb:0})) );
assert!( !opaque(Other(Rgba{a:0x42, rgb:0})) );
}
</code></pre>
<aside class="notes" data-markdown>
* Rgba *after* Color