James Drew jdrew1303

Fundamentals: why state machines?

States. The final frontier. These are the voyages of an enterprising developer. Her eternal mission: to explore strange new techniques, to seek out better ways to engineer for mental models and new design patterns. To boldly go where a few awesome devs have gone before.

So you’ve found our poignant guide to SCXML and surely you’re wondering “Why should I want to go out of my way to use formal state machines?” or something like that. Hopefully this introduction addresses that kind of question.

An example: Nancy’s RPG

The problem

Enable SSH

To enable SSH, first navigate to the boot directory:

cd /Volumes/boot Now create an empty file called "ssh":

touch ssh This will enable SSH when the Pi is booted.

Primitive Types & Reference Types in JavaScript

An explanation of JavaScript's pass-by-value, which is unlike pass-by-reference from other languages.

Facts

JavaScript has 2 kinds of variable types: primitive and reference.
A fixed amount of memory is reserved after creation of every variable.
When a variable is copied, it's in-memory value is copied.
Passing a variable to a function via a call also creates a copy of that variable.

Primitive Types

Visual Studio Code: My setup (macOS)

Global settings

git clone [email protected]:branneman/dotfiles.git ~/.dotfiles
ln -s ~/.dotfiles/vscode-settings.json "~/Library/Application Support/Code/User/settings.json"

Run from terminal

Open the Command Palette (⌘ + ⇧ + P)

Better local require() paths for Node.js

Problem

When the directory structure of your Node.js application (not library!) has some depth, you end up with a lot of annoying relative paths in your require calls like:

const Article = require('../../../../app/models/article');

Those suck for maintenance and they're ugly.

	[
	{
	"date": "02/01/2019",
	"rate": -0.31
	},
	{
	"date": "03/01/2019",
	"rate": -0.309
	},
	{

	const mimir = require('mimir');
	const brain = require('brain.js');

	/* few utils for the example */

	// our output is recorded as a vector, where the index in the vector
	// is the enum (we create it with a zero index). We fill the index in
	// the array with a 1 and the rest of the items as a 0 (true and false).
	const vectorise = (category, numberOfCategories) => {
	const vector = new Array(numberOfCategories).fill(0);

	require('text-encoding');
	const fs = require("fs");
	const {NES} = require("jsnes");
	const sinon = require("sinon");


	const SCREEN_WIDTH = 256;
	const SCREEN_HEIGHT = 240;

	/**
	* Globals
	*/
	var Carrousel = function(elem) { this.init() };
	Carrousel.prototype = { init: function() {} };
	new Carrousel();

	/**
	* Namespacing
	* - No globals (only the namespace variable itself is global)

	// FP Lenses
	const lens = get => set => ({ get, set });
	const view = lens => obj => lens.get(obj);
	const set = lens => val => obj => lens.set(val)(obj);
	const over = lens => fn => obj => set(lens)(fn(view(lens)(obj)))(obj);
	const lensProp = key => lens(prop(key))(assoc(key));