Michal Bigos teliatko

Install Multiple Java Versions on macOS High Sierra

Install Homebrew Cask

On Mac, Homebrew is the de-facto package manager, and Homebrew Cask is the app manager. I’m going to use Cask to install Java 7 and 8.

Install Homebrew Cask first if you haven’t:

brew update
brew tap caskroom/cask

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

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

References from my QCon London 2016 Keynote

The Morning Paper blog

Thinking Tools

Gitter Desktop App authentication

If you feel uncomfortable signing into GitHub in the node-webkit frame, these instructions will go over a manual way to authorize and set your token.

Note: This guide assumes Gitter is already an authorized app for your GitHub account. To do this, just make sure you can sign in with the web client in your browser.

Get your personal token

Use the login link in the top right of the developer.gitter.im.

	import scala.language.higherKinds

	object Lenses {

	trait Profunctor[P[_, _]] {
	def dimap[A, B, C, D](f: C => A, g: B => D)(p: P[A, B]): P[C, D]
	}

	object Profunctor {

	-- A sequential series of parallel program fragments in `f`:
	type SeqPar f a = Free (FreeAp f) a

	liftFA :: forall f a. f a -> SeqPar f a
	liftFA = pure >>> pure

	liftSeq :: forall f a. Free f a -> SeqPar f a
	liftSeq fa = foldFree fa liftFA

	liftPar :: forall f a. FreeAp f a -> SeqPar f a

	case class IO[A](unsafePerformIO: () => A) {
	def map[B](ab: A => B): IO[B] = IO(() => ab(unsafePerformIO()))
	def flatMap[B](afb: A => IO[B]): IO[B] =IO(() => afb(unsafePerformIO()).unsafePerformIO())
	def tryIO(ta: Throwable => A): IO[A] =
	IO(() => IO.tryIO(unsafePerformIO()).unsafePerformIO() match {
	case Left(t) => ta(t)
	case Right(a) => a
	})
	}
	object IO {

	package com.softwaremill.freemonads

	import cats.free.Free
	import cats.~>
	import cats._, cats.std.all._
	import scala.concurrent.ExecutionContext.Implicits.global
	import scala.concurrent.Future

	sealed trait External[A]
	case class Tickets(count: Int) extends AnyVal

	//
	// Validation[E, A] represents either:
	// - Success[A]
	// - Failure[E]
	//
	// Isomporphic to scala.Either[E, A] and scalaz.\/[E, A]
	//
	// Unlike \/[E, A], Validation is not a Monad, but an Applicative
	// Functor. So if you want to use it as a Monad you can convert back
	// and forth using the `validation` and `disjunction` method