Anand George anandgeorge

Elixir Supervision Trees Made Easy

I started with Elixir just a couple weeks after the switch from 1.4 to 1.5, so the bulk of online resources were out of date (or at least resulted in deprecation warnings). This guide is for defining Elixir 1.5 supervised modules.

It's not actually terribly complicated. It's just sometimes unclear from examples what's implemented by the language and what you actually have to implement yourself.

Say we want a supervision tree like this (where each atom is a process):

:a

/ \

My Elixir Study Notes

Important Links

Writing Assertive Code With Elixir

Notes

Get some help:

iex> i 'hello'
Term

Some exercises from the Falsy Values workshops.

The good parts:

HTTP server and client in same script
Express cookies example
Express routing example
Express error handling
Express middlewares example
Simple HTTP proxy

	Access help functions for a module using the h command; so

	h String

	will give you help related to the String function

	#### Data types

	iex> 2 # integer
	iex> 2.0 # floating point

	defmodule Game do
	use GenServer

	def init(game_id) do
	{:ok, %{game_id: game_id}}
	end

	def start_link(game_id) do
	GenServer.start_link(__MODULE__, game_id, name: {:global, "game:#{game_id}"})
	end

	population = for _ <- 1..100, do: for _ <- 1..1000, do: Enum.random(0..1)

	# evaluate, selection, crossover and algorithm are anonymous functions.

	evaluate =
	fn population ->
	# population is a list of lists [[1,1,0,0,1...1,1,0],[1,1,1,0,0...0,1,1]] 100 lists, 1000 bits each
	Enum.sort_by(population, &Enum.sum/1, &>=/2)
	# sort the list of lists by sum of bits so lists with higher number of one's are at the top. Mapper sums each row. Sorter is descending &>=/2
	# note the use of anonymous functions defined by &.

	// The code is based on a MongoDB database myhome with a typical record as below:
	// {
	// "rec_time" : ISODate("2013-11-25T16:53:43.808Z"),
	// "rec_data" : {
	// "power" : 372.201,
	// "current" : 1.73,
	// "voltage" : 221.678,
	// },
	// "rec_asset" : {
	// "name" : "Airconditioner",

	var io = require('socket.io').listen(8000),
	nicknames = {};

	io.sockets.on('connection', function (socket) {
	socket.on('user message', function (msg) {
	socket.broadcast.emit('user message', socket.nickname, msg);
	});

	socket.on('nickname', function (nick, fn) {
	if (nicknames[nick]) {

	/**
	* Read Linux mouse(s) in node.js
	* Author: Marc Loehe ([email protected])
	*
	* Adapted from Tim Caswell's nice solution to read a linux joystick
	* http://nodebits.org/linux-joystick
	* https://github.com/nodebits/linux-joystick
	*/

	var fs = require('fs'),

	#!/usr/bin/env node

	CHANNEL = '#bozler'
	MINIMUM_HUMAN_REACTION = 2

	DIALOGUE =
	ACTIONS_IN_REPLY: [
	"I vote for pizza",
	"Disregard that, I vote for pizza",
	"Another vote for pizza!"