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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=0' />
<title>Big</title>
<link href='big.css' rel='stylesheet' type='text/css' />
<link href='styles/vs2015.css' rel='stylesheet' type='text/css' />
<style>
.new-shiny { background: #aaaaaa; }
:-webkit-full-screen {
width: 100%;
height: 100%;
}
.light {
background: #f8f8f8;
color: #4C5859;
}
.light em {
color: #26CC8F;
}
.light a {
color: #05A8AA;
}
.light a:hover {
color: #058A8C;
}
code {
padding: 20px 100px 30px 50px !important;
font-family: "hermit", monospace;
}
/* .inline-block {
display: inline-block;
} */
</style>
<script>BIG_ASPECT_RATIO=1.6;</script>
<script src='big.js'></script>
<script src='highlight.pack.js'></script>
<script>hljs.initHighlightingOnLoad();</script>
<script>
// document.addEventListener('keydown', ({ key }) => {
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//
// if (document.fullscreenElement) {
// document.exitFullscreen()
// } else {
// document.documentElement.requestFullscreen()
// }
// })
</script>
</head>
<body id='body' class='light'>
<div>
<center><em>Practical Rust:</em> <br/>Absence of Data</center>
<notes>Data absence is a continual challenge of interfacing with the real world.</notes>
</div>
<div>
Two forms of <em>data absence</em>:
<br/>
<br/>
<ul>
<li>Data does not exist</li>
<li>Processing result was unexpected</em></li>
</ul>
<notes></notes>
</div>
<div>
"Data does not exist"
<br/>
<br/>
<ul>
<li>Nullable references</li>
<li><em>Optional</em> types</li>
</ul>
<notes>In some languages this means that all references may be nullable, or that raw pointers may be nullable.</notes>
BILLION DOLLAR MISTAKE
</div>
<div>
"Processing result was unexpected"
<br/>
<br/>
<ul>
<li>Error behavior</li>
<li>Exceptional control flow</li>
<li><em>Result</em> types</li>
</ul>
<notes>Mostly C++ -style exceptional control flow</notes>
</div>
Rust: you must handle these things, "the compiler doesn't add complexity but the compiler ensures you handles these cases" - CJ
<div>
Rust:
<br/>
<br/>
<li><em>Option<T></em></li>
<li><em>Result<T, Err></em></li>
<notes>These types are not really magic! Rust enums EXCEPT THAT WEIRD NON IMPORT Some() None THING</notes>
</div>
briefly touch on generics
<div>
Rust Enums
<br/>
<br/>
<em>Value-Holding</em>
<br/>
Similar to <i>"Algebraic Data Types"</i>
<notes>Can hold values for each different enum variation</notes>
</div>
<div>
<pre><code class="rust">
pub enum Option<T> {
/// No value
None,
/// Some value of type `T`
Some(T),
}
</code></pre>
</div>
<div>
<pre><code class="rust">
let a = Some("a");
a; // Option<&str>
a.unwrap(); // &str OR panic
</code></pre>
<notes>This is very efficient! This compiles to a null reference check!</notes>
</div>
<div>
<pre><code class="rust">
let a = Some("a");
match a {
Some(a) => a,
None => panic!("Oh No"),
}
</code></pre>
</div>
<div>
<pre><code class="rust">
let a = Some("a");
if let Some(a) = a {
// Do something with `a`
}
</code></pre>
</div>
<div>
<pre><code class="rust">
let a = Some("a");
a.is_some(); // true
a.is_none(); // false
</code></pre>
</div>
talk about option chaining here
<div>
<pre><code class="rust">
pub enum Result<T, E> {
/// Contains the success value
Ok(T),
/// Contains the error value
Err(E),
}
</code></pre>
</div>
<div>
<pre><code class="rust">
let a = Ok("a");
a.is_ok(); // true
a.is_err(); // false
match a {
Ok(a) => a,
Err(error) => panic!("Oh No, error: {}", error),
}
</code></pre>
</div>
<div>
<pre><code class="rust">
fn parse_json(input: &str) -> serde_json::Value {
let result = serde_json::from_str(input);
match result {
Ok(val) => val,
Err(error) => panic!("Oh No, serde_json error: {}", error),
}
}
</code></pre>
</div>
<div>
<pre><code class="rust">
use serde_json::{Value, Error};
fn parse_json(input: &str) -> Result<Value, Error> {
let result = serde_json::from_str(input);
//
//
result // implicit return
}
</code></pre>
</div>
<div>
<pre><code class="rust">
use serde_json::Value;
fn parse_json(input: &str) -> eyre::Result<Value> {
let val = serde_json::from_str(input)?;
// ---^---
//
val // implicit return
}
</code></pre>
</div>
<div>
<pre><code class="rust">
use serde_json::Value;
fn parse_json(input: &str) -> eyre::Result<Value> {
let val = serde_json::from_str(input)?;
// ^ ---^---
// | Result<T, serde_json::Error>
val // implicit return
}
</code></pre>
</div>
<div>
<pre><code class="rust">
use serde_json::Value;
fn parse_json(input: &str) -> eyre::Result<Value> {
let val = serde_json::from_str(input)?;
// ---^---
// Converts if an `Into<ReturnErrorType>` exists.
val // implicit return
}
</code></pre>
</div>
TRY OPERATOR SIMILAR TO JavaScript new ?
<div>
Cool, but this is a bit <em>verbose</em>.
<br/>
<br/>
What are the benefits?
</div>
<div>
<em>Benefits</em> of Option<T>
<br/>
<br/>
<ul>
<li></li>
<li></li>
<li></li>
<li></li>
</ul>
<notes></notes>
</div>
<div>
<em>Benefits</em> of Option<T>
<br/>
<br/>
<ul>
<li>No null errors!</li>
<li></li>
<li></li>
<li></li>
</ul>
<notes></notes>
</div>
<div>
<em>Benefits</em> of Option<T>
<br/>
<br/>
<ul>
<li>No null errors!</li>
<li>Developer visibility</li>
<li></li>
<li></li>
</ul>
<notes></notes>
</div>
<div>
<em>Benefits</em> of Option<T>
<br/>
<br/>
<ul>
<li>No null errors!</li>
<li>Developer visibility</li>
<li>Explicit propagation</li>
<li></li>
</ul>
<notes></notes>
</div>
<div>
<em>Benefits</em> of Result<T, Err>
<br/>
<br/>
<ul>
<li></li>
<li></li>
<li></li>
<li></li>
</ul>
<notes></notes>
</div>
<div>
<em>Benefits</em> of Result<T, Err>
<br/>
<br/>
<ul>
<li>Explicit propagation</li>
<li></li>
<li></li>
<li></li>
</ul>
<notes></notes>
</div>
<div>
<em>Benefits</em> of Result<T, Err>
<br/>
<br/>
<ul>
<li>Explicit propagation</li>
<li>No out-of-band control flow</li>
<li></li>
<li></li>
</ul>
<notes></notes>
</div>
<div>
<em>Benefits</em> of Result<T, Err>
<br/>
<br/>
<ul>
<li>Explicit propagation</li>
<li>No out-of-band control flow</li>
<li>Known typing at handlers</li>
<li></li>
</ul>
<notes></notes>
</div>
<div>
Real world examples
<notes>Real internal examples of Option and Result to follow outside of slides</notes>
</div>
<div>
<div><center><em>Practical Rust:</em> <br/>Absence of Data</center></div>
<br/>
<ul>
<li><em>Option<T></em></li>
<li><em>Result<T, Err></em></li>
</ul>
</div>
</body>
</html>