typescript-talk/index.html at master · Errorific/typescript-talk · GitHub

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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>Typescript</title>

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	<body>
		<div class="reveal">
			<div class="slides">
        <section>
          <h1>Typescript</h1>
          <h2>JS for squares</h2>
          <p>Chris Mckay</p>
        </section>

        <section>
          <img data-src="/img/javascripthomer.jpg" />
          <aside class="notes">
            Talking js languages a lot of late. Thought we'd look at some typescript.
          </aside>
        </section>

        <section>
          <p>Typescript is...</p>
          <ul>
            <li class="fragment">Release by Microsoft in 2012, 1.0 in 2014</li>
            <li class="fragment">Designed to deal with large-scale application development</li>
            <li class="fragment">Strictly typed superset of JS</li>
            <li class="fragment">That thing Angular 2 is written in</li>
          </ul>
          <aside class="notes">
            <span>v2.0 late last year</span>
            <br/>
            <span>Deals with the javascript issues faced in large applications</span>
            <br/>
            <span>Superset so js is valid ts</span>
            <br/>
            <span>Flow started in 2014</span>
          </aside>
        </section>
        <section data-background="/img/showmewhatyougot.gif">
        </section>
        <section>
          <table>
            <tbody>
              <tr>
                <td>Algebraic Data Types</td>
                <td>Got it</td>
              </tr>
              <tr>
                <td>Higher Kinded Types</td>
                <td>Don't got it</td>
              </tr>
              <tr>
                <td>Generics</td>
                <td>Got it</td>
              </tr>
              <tr>
                <td>Classes</td>
                <td>Got it</td>
              </tr>
              <tr>
                <td>Type classes</td>
                <td>Don't got it</td>
              </tr>

              <tr>
                <td>Pattern Matching</td>
                <td>Don't got it</td>
              </tr>
              <tr>
                <td>Currying</td>
                <td>Don't got it</td>
              </tr>
              <tr>
                <td>First class functions</td>
                <td>Got it</td>
              </tr>
              <tr>
                <td>Type inference</td>
                <td>Got it</td>
              </tr>
            </tbody>
          </table>
        </section>
        <section data-background="/img/disqualified.gif">
          <aside class="notes">
            <span>we're not getting all the cool functional stuff</span>
          </aside>
        </section>
        <section>
          Lets look at the language
        </section>
        <section>
          <pre><code class="typescript" data-trim>
var a = 'a';

let b = 'b';

const c = 'c';
          </code></pre>
          <aside class="notes">
            3 variable types. Var is a leaky variable. Let is lexically sealed. Const is lexically sealed
            and assignable once, not really immutable though.
          </aside>
        </section>
        <section>
          <pre><code class="typescript" data-trim>
const num: number = 3;

const bool: boolean = true;

const str: string = "a string";
          </code></pre>
          <aside class="notes">
            Basic primitives.
            <br/>
            One type of number, no refinement for floats etc
            <br/>
            2 strings, you want the lower case one
          </aside>
        </section>
        <section>
          <pre><code class="typescript" data-trim>
const nothing: undefined = undefined;

const nada: null = null;
          </code></pre>
          <aside class="notes">
            undef = uninitialised
            null = unavailable
            they're both basically the same except when they're not.
            Just don't use null
          </aside>
        </section>
        <section>
          <pre><code class="typescript" data-trim>
const artistFormerlyKnownAs: symbol = Symbol('Prince');
          </code></pre>
          <aside class="notes">
            Symbol, it makes completely unique values. es6, you probably won't need it, it's metaprogramming magic
          </aside>
        </section>
        <section>
          <pre><code class="typescript" data-trim>
const yolo: any = 42;

const slightlyLessYolo: object = new Date();
          </code></pre>
          <aside class="notes">
            any is anything
            <br/>
            Things used to default to any, not commonly seen since 2.0, now recommended to be turned off
            <br/>
            object is anything not a primitive
          </aside>
        </section>
        <section>
          <pre><code class="typescript" data-trim>
const voldemort: never = `boom`;
          </code></pre>
          <aside class="notes">
            never is the bottom type. No equivilence. New with 2.0. Implemented to support control flow analysis.
          </aside>
        </section>
        <section>
          <pre><code class="typescript" data-trim>
const youGetNothing: void = undefined;
          </code></pre>
          <aside class="notes">
            Void = return of nothing from a function. In assignment it can only receive undef or null.
          </aside>
        </section>
        <section>
          <pre><code class="typescript" data-trim>
function logHello (name: string): void {
  console.log('Hello ' + name);
}

function hello (name: string): string {
  return 'Hello ' + name;
}

const hello = (name: string): string => {
  return 'Hello ' + name;
}

// Infers string => string
const hello = (name: string) => 'Hello ' + name;
          </code></pre>
          <aside class="notes">
            Functions. You've got arrow functions, lambdas. Inference is pretty good but its one directional, forward or down depending on your perspective.
          </aside>
        </section>
        <section>
          <pre><code class="typescript" data-trim>
const stringArray: Array&lt;string&gt; = [ 'a', 'b', 'c' ];

const numberArray: number[] = [ 1, 2, 3 ];
          </code></pre>
          <aside class="notes">
            arrays. Community leans towards the square brackets trailing. Matches c# and doesn't confuse jsx
          </aside>
        </section>
        <section>
          <pre><code class="typescript" data-trim>
interface Point {
  x: number;
  y: number;
  label?: string;
}

interface Point3D extends Point {
  z: number;
}
          </code></pre>
          <aside class="notes">
            Interfaces are data types. Inheritence and multiple inheritence.
            ? is optional key.
          </aside>
        </section>
        <section>
          <pre><code class="typescript" data-trim>
interface BirthdayCard {
  message: string;
}

interface TerminationLetter {
  message: string;
}

const badNews: TerminationLetter = {
  message: "you're fired"
};

const happyBirthday: BirthdayCard = badNews;
          </code></pre>
          <aside class="notes">
            Structural typing. The type names mean nothing. So long as the structure of the types are the same its equivelent. So long as the structure contains at least what is required then it can fulfil it.
          </aside>
        </section>
        <section>
          <pre><code class="typescript" data-trim>
class Queue {
  private data: string[] = [];

  constructor(seed: string[] = []) {
    this.data = seed;
  }

  push = (item: string) => this.data.push(item);
  pop = () => this.data.shift();
}

const queue = new Queue(['seed', 'values']);
          </code></pre>
          <aside class="notes">
            Classes are es6 classes. Compile down fine. Types here are realish and can be referred to at run time. Can extend interfaces.
          </aside>
        </section>
        <section>
          <pre><code class="typescript" data-trim>
class Queue&lt;T&gt; {
  private data: T[];

  constructor(seed: T[] = []) {
    this.data = seed;
  }

  push = (item: T) => this.data.push(item);
  pop = () => this.data.shift();
}

const queueNumbers = new Queue&lt;number&gt;([1, 2]);

// Inferred as Queue&lt;number&gt;
const numbersQueue = new Queue([1,2]);
          </code></pre>
          <aside class="notes">
            Generics. Classes, interfaces and functions can be paramaterized across types allowing for parametric code.
            <br/>
            Can explicitly define the type params
            <br/>
            Can be inferred, but only forwards/down
          </aside>
        </section>
        <section>
          <pre><code class="typescript" data-trim>
interface Payload {
  id: string;
}

interface MessagePayload extends Payload {
  message: string;
}

class Action&lt;P extends Payload&gt; {
  private payload: P;
  constructor(payload: P) {
    this.payload= payload;
  }
  payloadId = () => this.payload.id;
}
          </code></pre>
          <aside class="notes">
            Can constrain the generic parameters. Can also constrain in terms of other parameters.
          </aside>
        </section>
        <section>
          <pre><code class="typescript" data-trim>
interface Cat {
  smiling: boolean,
  teeth: number
}

interface Bus {
  speed: number,
  capacity: number
}

type CatOrBus = Cat | Bus;

type CatBus = Cat & Bus;
          </code></pre>
          <aside class="notes">
            ADT's, | is a type union. The variable assigned to it must fulfil at least 1 of its member types requirements. & is an intersection type. values must fulfil all of its member types requirements
          </aside>
        </section>
        <section>
          <img height="200" alt="" src="/img/kona.jpg"/>
          <pre><code class="typescript" data-trim>
type CutePuppy = 'Kona';

const cutePuppy: CutePuppy = 'Kona';
          </code></pre>
          <aside class="notes">
            Last type, type literals. Type can be a value. Restricts assignment to just that value.
          </aside>
        </section>
        <section>
          <img height="200" alt="" src="/img/kona.jpg"/>
          <img height="200" alt="" src="/img/monty.jpg"/>
          <pre><code class="typescript" data-trim>
type CutePuppy = 'Kona' | 'Monty';

const cutePuppies: CutePuppy[] = ['Kona', 'Monty'];
          </code></pre>
          <aside class="notes">
            Lets you build things like enums
          </aside>
        </section>
        <section>
          <pre><code class="typescript" data-trim>
interface Blossom {
  colour: 'Pink';
  freeze(): void;
}

interface Bubbles {
  colour: 'Blue';
  scream(): void;
}

type PowerpuffGirl = Blossom | Bubbles;
          </code></pre>
          <aside class="notes">
            Also use them for type information. You can have a member variable thatas reliably a certain value.
          </aside>
        </section>
        <section>
          <pre><code class="typescript" data-trim>
const doSuperPower = (girl: PowerpuffGirl) => {
  // colour is available on both
  if (girl.colour === 'Pink') {
    // The girl is Blossom in here
    girl.freeze();
  } else {
    // The girl is Bubbles here
    p.scream();
  }
}
          </code></pre>
          <aside class="notes">
            control flow analysis figures out what the value possibly could be at each point
          </aside>
        </section>
        <section>
          <pre><code class="typescript" data-trim>
interface Buttercup {
  colour: 'Green';
  fight(): void;
}

type PowerpuffGirl = Blossom | Bubbles | Buttercup;
          </code></pre>
          <aside class="notes">
            There's 3 powerpuff girls though
          </aside>
        </section>
        <section>
          <pre><code class="typescript" data-trim>
const doSuperPower = (girl: PowerpuffGirl) => {
  // colour is available on both
  if (girl.colour === 'Pink') {
    // The girl is Blossom in here
    girl.freeze();
  } else {
    // Error here The girl could be Bubbles or Buttercup
    p.scream();
  }
}
          </code></pre>
          <aside class="notes">
            The controll flow analysis figures out we haven't been discriminatory enough
          </aside>
        </section>
        <section>
          <pre><code class="typescript" data-trim>
const whatsHerName = (girl: PowerpuffGirl): string {
  switch (girl.colour) {
    case 'Pink': return 'Blossom';
    case 'Blue': return 'Bubbles';
    case 'Green': return 'Buttercup';
  }
}
          </code></pre>
          <aside class="notes">
            Great for switches
            Not great, doesn't work properly for if-else. Side effect of how control flow analysis done, they're trying to fix it.
          </aside>
        </section>
        <section>
          <pre><code class="typescript" data-trim>
// Module.ts
export const myExport = "Export Me";

// Index.ts
import { myExport } from './Module';
          </code></pre>
          <aside class="notes">
            Module system is exactly like in es6. All the same behaviours and  You export things and import them.
            Nothing interesting to go into except for how typing gets involved.
          </aside>
        </section>
        <section>
          <pre><code class="typescript" data-trim>
declare function moment(...): moment.Moment;

declare namespace moment {
  type RelativeTimeKey = 's' | ... ;

  interface Moment extends Object{
    format(format?: string): string;
    ...
  }
}

export = moment;
          </code></pre>
          <aside class="notes">
            ambient declarations. Namespaces are modules of interface descriptions and functional descriptions. Can export top level stuff too.
            Can declare globally available variables, attach things to window, etc.
          </aside>
        </section>
        <section>
          <img alt="" src="/img/definitelytypedrepo.png" />
          <aside class="notes">
            definitely typed module count, dates?
          </aside>
        </section>
        <section>
          <img alt="" src="/img/npmjstypes.png"/>
          <aside class="notes">
            As of typescript 2.0. Types managed by npm rather than 'typings' tool. Exported from definitelytyped
          </aside>
        </section>
        <section>
          <ul>
            <li>/node_modules/moment/index.d.ts</li>
            <li>/node_modules/@types/moment/index.d.ts</li>
            <li>/types/moment/index.d.ts</li>
          </ul>
          <aside class="notes">
            Looks first for ambient declaration in your source, then in shipped npm package, then in @types packages
          </aside>
        </section>
        <section>
          <img alt="" src="/img/tsc.png"/>
          <aside class="notes">
            Theres a compiler, Lots of options, not that interesting, but the JS it outputs is
          </aside>
        </section>
        <section>
          <img alt="" src="/img/tsjsemit.png"/>
          <aside class="notes">
            outputs es6 or es5 or es3.
            <br/>
            Most language features compile to es3.
            <br/>
            ts is close to JS to emitted code is close to what you wrote
            <br/>
            No chunky prelude etc to compile in, just the same esX polyfills you'd be using anyway.
          </aside>
        </section>
        <section>
          <img width=200 alt="" src="/img/tslint.jpg"/>
          <br/>
          <img alt="" src="/img/tslinteg.jpg"/>
          <aside class="notes">
            tslint is powerful.
            <br/>
            Regular linting very good
            <br/>
            Semantic linting uses type & control flow analysis
            <br/>
            e.g. JqueryDeferred must have reject or resolve called on it in all branches
          </aside>
        </section>
        <section>
          But Why?
          <aside class="notes">
            Nothing presented so far is that different from flow. Significantly worse than purescript or ghcjs or elm.
            So why use this one
          </aside>
        </section>
        <section>
          <blockquote cite="Tony Morris">
            <p>
              &ldquo;I can't write correct javascript and I haven't met anyone else who can either.&rdquo;
            </p>
            <div style="text-align:right">
            - Tony Morris
            </div>
          </blockquote>
          <aside class="notes">
            I don't think I have to convince anyone here that coding in JS isn't a great idea
          </aside>
        </section>
        <section>
          <img src="/img/javascripteverywhere.jpeg" alt="" />
          <aside class="notes">
            But its still everywhere, browsers, servers
          </aside>
        </section>
        <section>
          <img alt="" src="/img/dynamic-languages-godfather.jpg"/>
          <aside class="notes">
            Most problems are runtime errors
          </aside>
        </section>
        <section>
          <img alt="" src="/img/type-error-jesus.jpg"/>
          <aside class="notes">
            We can fix those types of errors
          </aside>
        </section>
        <section>
          <img src="/img/purescriptwindow.jpg" alt="" />
          <aside class="notes">
            It's a hard sell to reskill existing teams and beligerant managers
          </aside>
        </section>
        <section>
          <img src="/img/canttelltypescript.jpg" alt="" />
          <aside class="notes">
            Typescript is close enough that you don't need to reskill
            <br/>
            existing devs can read/write it
          </aside>
        </section>
        <section>
          <img alt="" src="/img/vscode.png"/>
          <aside class="notes">
            Awesome tools. vs code is Awesome. Fast, clean. Intellisense & documentation mapping. Great plugin support. Constant updates.
          </aside>
        </section>
        <section>
          <table>
            <tr>
              <td>vim</td>
              <td>Tsuquyomi</td>
            </tr>
            <tr>
              <td>emacs</td>
              <td>Tide</td>
            </tr>
          </table>
          <aside class="notes">
            Both do intellisense omnicompletion. Tide has been excellent for me.
          </aside>
        </section>
        <section>
          <ul>
            <li>Angular 2</li>
            <li>RxJS</li>
            <li>VS Code</li>
            <li>ionic</li>
            <li>Sodium</li>
            <li>CycleJS</li>
          </ul>
          <aside class="notes">
            Community adoption. Some big projects are driving it
          </aside>
        </section>
        <section>
          <h3>Stack Overflow</h3>
          <table>
            <tr>
              <td>Javascript</td>
              <td>1,444,140</td>
            </tr>
            <tr>
              <td>Typescript</td>
              <td>34,355</td>
            </tr>
            <tr>
              <td>Elm</td>
              <td>997</td>
            </tr>
            <tr>
              <td>Flow</td>
              <td>474</td>
            </tr>
            <tr>
              <td>Purescript</td>
              <td>252</td>
            </tr>
            <tr>
              <td>GHCJs</td>
              <td>74</td>
            </tr>
          </table>
          <aside class="notes">
            Enough people using it to catch the problems before you do and fix it
            <br/>
            Great getting on irc and asking bodil about purescript or Luite about ghcjs
          </aside>
        </section>
        <section>
          3385 packages in Definitely Typed
          <aside class="notes">
            No point gradual typing, and you don't want to do the work typing the world. You want it typed for you.
          </aside>
        </section>
        <section>
          <ul>
            <li>Video courses</li>
            <li>Books by every major publisher</li>
            <li>Community guides</li>
          </ul>
          <aside class="notes">
            Educational resources being developed
          </aside>
        </section>
        <section>
          <pre><code class="typescript" data-trim>
const some = Option(33) // some === Some(33)
const none = Option(null) // none === None

const some = Option.all(
  Option(10),
  Option(5)
)
// some === Some([10, 5])

const none = Option.all(
  Option(10),
  None,
  Option(5),
)
// none === None
          </code></pre>
        </section>
        <section>
          It's just enough
          <aside class="notes">
            More has been invested in typescript than any of its competitors. It aims a lot lower, but you know where you need to go if you want to stretch higher
          </aside>
        </section>
        <section>
          Questions?
        </section>
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