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Scala: Type Families, Sealed Traits, and Exhaustive Pattern Matching

By: Matt Barackman

What is a Type Family?

A collection of objects or case classes that share a sealed trait.

In the example below, the type family would be a collection of traffic light colors with Red, Yellow, and Green as member objects.

Applied Functional Programming with Scala - Notes

1. Mastering Functions

A function is a mapping from one set, called a domain, to another set, called the codomain. A function associates every element in the domain with exactly one element in the codomain. In Scala, both domain and codomain are types.

val square : Int => Int = x => x * x

Getting Started in Scala

This is my attempt to give Scala newcomers a quick-and-easy rundown to the prerequisite steps they need to a) try Scala, and b) get a standard project up and running on their machine. I'm not going to talk about the language at all; there are plenty of better resources a google search away. This is just focused on the prerequisite tooling and machine setup. I will not be assuming you have any background in JVM languages. So if you're coming from Python, Ruby, JavaScript, Haskell, or anywhere… I hope to present the information you need without assuming anything.

Disclaimer It has been over a decade since I was new to Scala, and when I was new to Scala, I was coming from a Java and Ruby background. This has probably caused me to unknowingly make some assumptions. Please feel free to call me out in comments/tweets!

One assumption I'm knowingly making is that you're on a Unix-like platform. Sorry, Windows users.

Getting the JVM

Functional Track talks from NDC Oslo 2017

Also, here is the list of all videos from NDC Oslo 2017:

	#![feature(core_intrinsics)]

	struct Something
	{
	data:u32,
	}

	impl Something
	{
	pub fn name(&self)->String

	#!/bin/zsh

	cd /tmp

	wget http://download.springsource.com/release/ECLIPSE/neon/R/eclipse-jee-neon-R-linux-gtk-x86_64.tar.gz

	# eclipse EE
	# http://download.springsource.com/release/ECLIPSE/neon/3/eclipse-jee-neon-3-linux-gtk-x86_64.tar.gz

	tar -zxf eclipse-jee-neon-R-linux-gtk-x86_64.tar.gz -C /opt

	/**************************************
	* Header Counters in TOC
	**************************************/

	/* No link underlines in TOC */
	.md-toc-inner {
	text-decoration: none;
	}

	.md-toc-content {

	# One liner
	wget --recursive --page-requisites --adjust-extension --span-hosts --convert-links --restrict-file-names=windows --domains yoursite.com --no-parent yoursite.com

	# Explained
	wget \
	--recursive \ # Download the whole site.
	--page-requisites \ # Get all assets/elements (CSS/JS/images).
	--adjust-extension \ # Save files with .html on the end.
	--span-hosts \ # Include necessary assets from offsite as well.
	--convert-links \ # Update links to still work in the static version.

	<#
	.SYNOPSIS
	Script to Initialize my custom powershell setup.
	.DESCRIPTION
	Script uses scoop
	.NOTES
	NOTE Will configure the Execution Policy for the "CurrentUser" to Unrestricted.

	Author: Mike Pruett
	Date: October 18th, 2018

	# got to handle both escaped and literal

	df.replace(to_replace=[r"\\t\|\\n\|\\r", "\t\|\n\|\r"], value=["",""], regex=True, inplace=<INPLACE>)