Paul Young paulyoung

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

Proposal for this year's Reactive lightning talks @ReactiveConf - If you want to see my talk, star this gist please :-) [Reactive Blogpost][reactive-conference-blogpost]

A life on a Commandline

As a JavaScript developer, could you imagine using something else than Atom, Sublime or other IDE-like text-editors? During their daily work, people wrangle a lot with different applications, editors, windows, browsers and loose a lot of time because of their tools getting in their way.

GPG and git on macOS

Setup

No need for homebrew or anything like that. Works with https://www.git-tower.com and the command line.

Install https://gpgtools.org -- I'd suggest to do a customized install and deselect GPGMail.
Create or import a key -- see below for https://keybase.io
Run gpg --list-secret-keys and look for sec, use the key ID for the next step
Configure git to use GPG -- replace the key with the one from gpg --list-secret-keys

Processing JSON using jq

jq is useful to slice, filter, map and transform structured json data.

Installing jq

On Mac OS

brew install jq

	{ nixpkgs ? import <nixpkgs> {}, compiler ? "default" }:

	let

	inherit (nixpkgs) pkgs;

	# Build a default.nix file from our .cabal file:
	here = ./.;
	project = pkgs.stdenv.mkDerivation ({
	name = "default.nix";

	module.exports = {
	config: {
	// default font size in pixels for all tabs
	fontSize: 13,

	// font family with optional fallbacks
	fontFamily: '"Droid Sans Mono", Menlo, monospace',

	// terminal cursor background color (hex)
	cursorColor: '#cccccc',

	class Option<A> {
	protected Option() { }
	}
	interface App<F, A> {
	F proof();
	}
	class OptionF {
	private OptionF() {}

	private static class AppOption<A> implements App<OptionF, A> {

	import { mountWithIntl } from 'helpers/intl-enzyme-test-helper.js';

	const wrapper = mountWithIntl(
	<CustomComponent />
	);

	expect(wrapper.state('foo')).to.equal('bar'); // OK
	expect(wrapper.text()).to.equal('Hello World!'); // OK


	A really simple interpreter to use while learning about monads. Based on
	the paper "Monads for Functional Programming" by Phil Wadler.

	the type of terms:

	> data Term = Con Int
	> \| Div Term Term
	> deriving Show

	import React from 'react'

	const provideContext = (contextKey, contextType) => (
	React.createClass({
	childContextTypes: {
	[contextKey]: contextType
	},

	getChildContext() {
	const { children, ...props } = this.props