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<div onmouseover="hoverslick()" onmouseout="nonhoverslick()">
  <p class="Noanimation">I can</p>
  <p class="Noanimation">also do</p>
  <p class="Noanimation">slick animations</p>
  <script>
    function hoverslick() {
      document
        .querySelectorAll(".Noanimation")
        .forEach(function(animationtxt) {
          animationtxt.classList.add("Animation");

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let storeA = createStore({ a: 1 })
let storeB = createStore({ b: 2 })
let withStoreA = connect(storeA)
let withStoreB = connect(storeB)

type StateA = {
  a: number
}
type StateB = {
  b: number

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// hyperscript and React-inspired DSL
// "react in 50 lines"

void function() {

  /////////// tags

  type Tagish = string | Tag

  type Attrs = {

bcherny

void function() {

  class ChessError extends Error { }
  class InvalidMoveError extends ChessError { }
  class NoLineOfSightError extends ChessError { }
  class NotYourTurnError extends ChessError { }

  // Represents a chess game
  class Game {
    private board = new Board

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Problem

Code changes that cause program behavior to change can be dangerous if the behavior change was unintentional. Unit tests help mitigate this, but in practice a lot of code is not covered by unit tests.

Solution

Property based snapshot testing.

For example, say our program is a single function:

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hackle

1. Parsing Hack ASTs

Top level functions

function a()

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<?hh

async function seq(vec<(function(): Awaitable<T>)> $as): Awaitable<vec<T>> {
  $result = vec[];
  foreach ($as as $a) {
    $r = await $a();
    $result[] = $r;
  }
  return $result;
}

bcherny

Some notes while reading through the Hack Lang spec.

4. Basic Concepts

VSlot -> VStore -> value: scalar | null
                \_ type tag: Null, Bool, Int, Float, Str, Arr, Arr-D, Obj, or Res

  eg. `$a = true;`

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// Type definitions for babel-types 7.0
// Project: https://github.com/babel/babel/tree/master/packages/babel-types
// Definitions by: Troy Gerwien <https://github.com/yortus>
//                 Sam Baxter <https://github.com/baxtersa>
//                 Marvin Hagemeister <https://github.com/marvinhagemeister>
//                 Boris Cherny <https://github.com/bcherny>
// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
// TypeScript Version: 2.3

export interface Comment {

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// Shadows built-in $Keys
type $Keys<A> = number

type A<B> = $Keys<B>