SystemFw

cats-effect

The cats-effect project defines a purely functional effect type (IO[A]), and associated typeclasses defining its behaviour. The ones we care about for this example are:

trait Sync[F[_]] extends MonadError[F, Throwable] {
   def delay[A](a: => A): F[A]
   ...
}

notxcain

import cats.Applicative
import cats.effect.Sync
import com.evotor.common.logging.Logger.Level
import org.slf4j.LoggerFactory

import scala.reflect.ClassTag

trait Logger[F[_]] {

  def log(level: Level.Value, msg: => String, throwable: Throwable): F[Unit]

gvolpe

Shared State in pure Functional Programming

Newcomers to Functional Programming are often very confused about the proper way to share state without breaking purity and end up having a mix of pure and impure code that defeats the purpose of having pure FP code in the first place.

Reason why I decided to write up a beginner friendly guide :)

Use Case

We have a program that runs three computations at the same time and updates the internal state to keep track of the

travisbrown

import cats.data.StateT
import cats.implicits._
import scala.collection.JavaConverters._
import scala.concurrent.{Await, Future}
import scala.concurrent.ExecutionContext.Implicits.global
import scala.concurrent.duration.Duration
import twitter4j._, twitter4j.conf.ConfigurationBuilder

object YourTweetsAreTooLong {
  private type PagingState = (Long, Option[Long])

djspiewak

Thread Pools

Thread pools on the JVM should usually be divided into the following three categories:

1. CPU-bound
2. Blocking IO
3. Non-blocking IO polling

Each of these categories has a different optimal configuration and usage pattern.

d1egoaz

If you want to learn Scala, I’d suggest:

• Install IntelliJ + Scala Plugin
• Don’t do the Coursera courses yet.
• Don’t do the “red book” Functional Programming in Scala yet.
• Do: http://underscore.io/books/
  • Essential Scala
  • Essential Play
  • Essential Slick
• Do Scala for the Impatient: https://www.amazon.com/Scala-Impatient-Cay-S-Horstmann/dp/0321774094
• The Neophyte’s Guide to Scala http://danielwestheide.com/scala/neophytes.html

shinnya

import scala.concurrent.Await
import scala.concurrent.Future
import scala.concurrent.duration._
import scala.concurrent.ExecutionContext.Implicits.global
import scala.language.higherKinds
import scalaz.ContT
import scalaz.std.scalaFuture.futureInstance

object Main {

fdietze

Jitpack

https://jitpack.io

For testing purposes, the easiest way to go is jitpack:

resolvers += "jitpack" at "https://jitpack.io"
libraryDependencies += "com.github.User" % "Repo" % "Tag"

jawadatgithub

Note for community:

A. IdentityServer3 docs, samples and source code use OIDC & OAuth2 terms interchangeably to refer to same thing in many areas. I think that's make sense because OIDC introduced as complement & extension for OAuth2.

B. IdentityServer3, STS, OP, OIDC server, OAuth2 server, CSP, IDP and others: means same thing (software that provide/issue tokens to clients) as explained in [Terminology] (http://identityserver.github.io/Documentation/docs/overview/terminology.html).

C. Grants and flows mean same thing, grant was the common term in OAuth2 specs and flow is the common term in OIDC specs.

D. This document will not focus on custom flow/grant.

E. [Important] Choosing wrong flow leads to security threat.

denisshevchenko

{-
   Денис Шевченко, 2015
-}

module Main where

import Control.Monad.Writer.Lazy
import Data.Functor ((<$>))
import Data.List (dropWhileEnd)
import Data.Char (isSpace)