Juan Manuel Méndez Rey vejeta

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

Category theory jargon cheat sheet

A primer/refresher on the category theory concepts that most commonly crop up in conversations about Scala or FP. (Because it's embarassing when I forget this stuff!)

I'll be assuming Scalaz imports in code samples, and some of the code may be pseudo-Scala.

Functor

A functor is something that supports map.

Install Folding@home FAHClient on Linux as a systemd service unit

Republished on my website, keeping this version here for historical reasons.

Install FAHClient as documented in the official guide. Stop the traditional init script service that was created and automatically started.

	#!/bin/zsh
	# WARNING! The script is meant to show how and what can be disabled. Don’t use it as it is, adapt it to your needs.
	# Credit: Original idea and script disable.sh by pwnsdx https://gist.github.com/pwnsdx/d87b034c4c0210b988040ad2f85a68d3
	# Disabling unwanted services on macOS Big Sur (11), macOS Monterey (12), macOS Ventura (13) and macOS Sonoma (14)
	# Disabling SIP is required ("csrutil disable" from Terminal in Recovery)
	# Modifications are written in /private/var/db/com.apple.xpc.launchd/ disabled.plist, disabled.501.plist
	# To revert, delete /private/var/db/com.apple.xpc.launchd/ disabled.plist and disabled.501.plist and reboot; sudo rm -r /private/var/db/com.apple.xpc.launchd/*


	# user

	package arrow.refined

	import arrow.Kind
	import arrow.core.*
	import arrow.data.*
	import arrow.effects.validated.positiveInt.plus
	import arrow.effects.validated.positiveInt.positive
	import arrow.extension
	import arrow.instances.either.applicativeError.applicativeError
	import arrow.instances.listk.traverse.traverse

	import scala.concurrent._
	import scala.concurrent.duration._
	import ExecutionContext.Implicits.global

	object MyApp {
	def processA(f: Int, b: Int, c: Int) = {
	Thread.sleep(2000)
	f + b + c
	}
	def processB(g: Int) = {

	import scala.util._
	import java.security.SecureRandom
	import java.security.MessageDigest

	/*
	* Generates a Bearer Token with a length of
	* 32 characters (MD5) or 64 characters (SHA-256) according to the
	* specification RFC6750 (http://tools.ietf.org/html/rfc6750)
	*
	* Uniqueness obtained by hashing system time combined with a

	# How Akka maps to EAI Patterns

	Might be up for debate or just plain wrong. Just some notes I scribbled down some time ago.

	-----------------------------------------------------------------------------------------------------------------
	EAI PATTERN AKKA PATTERN REFERENCE
	-----------------------------------------------------------------------------------------------------------------
	Point to Point Channel Regular Actor Communication http://www.eaipatterns.com/PointToPointChannel.html
	Event-Driven Consumer Regular Actor Receive http://www.eaipatterns.com/EventDrivenConsumer.html
	Message Selector Actor with Stash http://www.eaipatterns.com/MessageSelector.html

	import java.net.URL
	import scala.xml.XML
	import org.xml.sax.InputSource
	import scala.xml.parsing.NoBindingFactoryAdapter
	import org.ccil.cowan.tagsoup.jaxp.SAXFactoryImpl
	import java.net.HttpURLConnection
	import scala.xml.Node

	object HTML {
	lazy val adapter = new NoBindingFactoryAdapter