jdjkelly

// A collection Orders contains the following documents:
{ "_id" : 1, "item" : "abc", "price" : 12, "quantity" : 2 }
{ "_id" : 2, "item" : "jkl", "price" : 20, "quantity" : 1 }
{ "_id" : 3  }

// Another collection Inventory contains the following documents:
{ "_id" : 1, "sku" : "abc", description: "product 1", "instock" : 120 }
{ "_id" : 2, "sku" : "def", description: "product 2", "instock" : 80 }
{ "_id" : 3, "sku" : "ijk", description: "product 3", "instock" : 60 }
{ "_id" : 4, "sku" : "jkl", description: "product 4", "instock" : 70 }

jdjkelly

db.articles.aggregate(
    [{ $match: { 
          $or: [{ 
            score: { $gt: 90 } 
          }, { 
            author: "dave" 
          }}] 
    }}]
);

jdjkelly

// Given these documents in a collection
{ "_id" : ObjectId("512bc95fe835e68f199c8686"), "author" : "dave", "score" : 80 }
{ "_id" : ObjectId("512bc962e835e68f199c8687"), "author" : "dave", "score" : 85  }
{ "_id" : ObjectId("55f5a192d4bede9ac365b257"), "author" : "ahn", "score" : 60 }
{ "_id" : ObjectId("55f5a192d4bede9ac365b258"), "author" : "li", "score" : 55 }
{ "_id" : ObjectId("55f5a1d3d4bede9ac365b259"), "author" : "annT", "score" : 60 }
{ "_id" : ObjectId("55f5a1d3d4bede9ac365b25a"), "author" : "li", "score" : 94 }
{ "_id" : ObjectId("55f5a1d3d4bede9ac365b25b"), "author" : "ty", "score" : 95 }

// Apply this aggregation

jdjkelly

Elixir-flavored Redux:

defmodule Store do
 def start_link(reducer, preloadedState) do
   Agent.start_link(fn -> { reducer, preloadedState } end)
 end

 def start_link(reducer) do
   Agent.start_link(fn -> { reducer, nil } end)

jdjkelly

import { createStore } from 'redux'

function counter(state = 0, action) {
  switch (action.type) {
  case 'INCREMENT':
    return state + 1
  case 'DECREMENT':
    return state - 1
  default:
    return state

jdjkelly

let currentListeners = []
let nextListeners = currentListeners

...

function subscribe(listener) {
  if (typeof listener !== 'function') {
    throw new Error('Expected listener to be a function.')
  }

jdjkelly

declare type Dispatch<A: { type: $Subtype<string> }> = (action: A) => A;

jdjkelly

function dispatch(action) {
  if (!isPlainObject(action)) {
    throw new Error(
      'Actions must be plain objects. ' +
      'Use custom middleware for async actions.'
    )
  }

  if (typeof action.type === 'undefined') {
    throw new Error(

jdjkelly

...

let currentState = preloadedState  

...

function getState() {
  return currentState
}

jdjkelly

export default function createStore(reducer, preloadedState) {
  let state = preloadedState
  let listeners = []
  let dispatching = false

  function getState() {
    return state
  }
  
  function dispatch(action) {