hack the future

Hack the FutureJason McCreary "JMac" @gonedark

Hack the Future - Jason McCreary - php[world] 2015

Talk the Talk

1. What is Hack?2. Key Features of Hack3. Unsupported PHP features in Hack4. How can I use Hack?5. Why Hack?6. The Future

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But first…A quick disclaimer.

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"Some things are going to be said."

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"This is not a talk to push Hack."

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"This is not a talk to shit on PHP."

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"This is a talk about the evolution of a language."

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What is Hack?A very brief history.

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Brief History

• In 2009, Facebook released HipHop - a PHP compiler• In 2010, Facebook introduced new features into PHP• In 2012, Facebook began working on Hack• In 2013, Facebook released HHVM - a HipHop VM• In 2014, Facebook released Hack

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So what is Hack?

"Hack is a programming language for HHVM that interoperates seamlessly with PHP."

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So what is Hack, really?

"Hack is a superset of PHP that runs on HHVM which provides type checking."

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WTF Facebook?Just use PHP.

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"Well, they do."

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"Facebook has millions of lines of PHP."

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"Instead of a rewrite or waiting or influencing the PHP community, they made Hack."

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"The goal being to write cleaner, safer, andrefactorable code."

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Key FeaturesA deeper look at some of the features of Hack.

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Key Features in Hack

• Type Annotations• Additional types• Generics and Nullable• Asynchronous programming• Syntactic sugar

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Type Annotations<?hh // parameter type annotations

function output(string $str) {

echo 'Hello, ' . $str;

}

// return type annotations

function get_output(string $str): string {

return 'Hello, ' . $str;

}

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"Hack is not a statically typed language."

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"Hack allows more type hinting than PHP."

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"HHVM performs type checking before runtime which ensures your code is type safe."

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Additional Types

• Collections• Enums• Shapes• Tuples• Custom Types

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The problem with array

"In PHP, arrays are used for all the things!"

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The problem with array<?php

// indexed, starting at 0

$arr1 = array(1, 2, 3);

// indexed, starting at 1

$arr2 = array(1 => 1, 2, 3);

// keyed, mix of integer keys and string keys

$arr3 = array("foo" => 1, 73 => 2, "bar" => 3);

// all array values are the same

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"Primitive obsession is a code smell!"

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"In PHP, arrays are primitives (i.e. non-objects)."

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$ php -r 'var_dump(is_object(array()));'

bool(false)

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Collections

• Vector - an ordered, index collection

• Map - a key-based collection

• Set - an unordered, uniquely value collection

• Pair - an immutable, indexed, 2 element collection

• Both immutable and mutable versions

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Collections

<?hh

$vector = Vector {5, 10, 15};

$map = Map {"A" => 1, "B" => 2, "C" => 3};

$set = Set {"A", "B"};

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Enums<?hh

enum DayOfWeek: int {

Sunday = 0;

Monday = 1;

Tuesday = 2;

Wednesday = 3;

Thursday = 4;

Friday = 5;

Saturday = 6;

}

echo DayOfWeek::Wednesday; // outputs 3

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Shapes

<?hh

// fixed size and type

// keyed collection of mixed values

$sh = shape('x' => 3, 'y' => 5);

echo $sh['x'] . ',' . $sh['y']; // outputs 3,5

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Tuples

<?hh

// fixed size and type, index array of mixed values

$tup = tuple('3', 2, 3, 4, 'hi');

echo $tup[1]; // outputs 2

unset($tup[0]); // error

$tup[5] = 'new value'; // error

$tup[4] = 'change value'; // ok, string to string

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Custom Types

<?hh // define your own types

type MyInt = int;

type Point = (int, int);

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Generics and Nullable

• Generics - ability to parameterize the type of a class or method and declare it upon instantiation

• Nullable - ability to declare a type allows null

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Generics<?hh

class Box<T> {

protected T $data;

public function __construct(T $data) {

$this->data = $data;

}

public function getData(): T {

return $this->data;

}

}

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Nullable

<?hh

function check_not_null(?int $x): int {

if ($x === null) {

return -1;

} else {

return $x;

}

}

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Asynchronous Programming<?hh

async function helloAfter($name, $timeout): Awaitable<string> {

await SleepWaitHandle::create($timeout * 1000000);

echo sprintf("hello %s\n", $name);

}

async function run() {

$joe = helloAfter('Joe', 3);

$mike = helloAfter('Mike', 1);

await GenArrayWaitHandle::create(array($joe, $mike));

}

run()->join();

// prints:

// hello Mike

// hello Joe

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Syntactic Sugar

• Constructor Argument Promotion• Lambdas

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Constructor Argument Promotion

<?php

class Person {

private string $name;

private int $age;

public function __construct(string $name, int $age) {

$this->name = $name;

$this->age = $age;

}

}

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Constructor Argument Promotion

<?hh

class Person {

public function __construct(public string $name,

protected int $age) {}

}

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Lambdas<?php

$foo = function($x) {

return $x + 1;

}

$foo(12); // returns 13

$squared = array_map(function($x) {

return $x * $x;

}, array(1,2,3));

var_dump($squared); // $squared is array(1,4,9)

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Lambdas

<?hh

$foo = $x ==> $x + 1;

$foo(12); // returns 13

$squared = array_map($x ==> $x * $x, array(1,2,3));

var_dump($squared); // $squared is array(1,4,9)

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Unsupported PHP FeaturesThe things Hack no likey.

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Unsupported PHP Features• Alternative syntaxes: AND, OR, XOR, endif, etc.

• Dynamic features: eval, continue n, break n, $$var, $obj->{$var}

• Top Level Code• References• Globals• Case insensitive function calls• Explicitly named constructors

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How can I use Hack?What you need to do to start Hack’in.

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"Change <?php to <?hh"

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"You’re right, first install HHVM."

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"Then change <?php to <?hh!"

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Hack Modes• Hack has three modes: strict, partial, and decl

• strict - type checker will catch every type error

• partial - type checker checks code that uses types

• decl - allows strict code to call separate, legacy code

• The default is partial

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Hack Modes

<?hh // strict

function example(int $x) {

echo "I'm so strict!";

}

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Why Hack?Some reasons for using Hack.

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Reasons to Hack

• Code clarity• Performance• Language features, like Asynchronous Programming• Evolution

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The FutureSo bright, I gotta wear shades.

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Some things in PHP

• Variadic functions (PHP 5.6)• Scalar type declarations (PHP 7)• Return type declarations (PHP 7)• Null coalesce operator (PHP 7)• Deprecations: alternative syntax and named

constructors (PHP 7)

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Look familiar?

<?php

function add(int $x, int $y): int {

return $x + $y;

}

$nil = null;

$foo = $nil ?? add(2, 3);

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"Yeah, Hack had it first."

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"Hack, coming soon in PHP 7+."

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"This is evolution."

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Questions…Ask now or tweet me @gonedark.

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