djspiewak

Quick Tips for Fast Code on the JVM

I was talking to a coworker recently about general techniques that almost always form the core of any effort to write very fast, down-to-the-metal hot path code on the JVM, and they pointed out that there really isn't a particularly good place to go for this information. It occurred to me that, really, I had more or less picked up all of it by word of mouth and experience, and there just aren't any good reference sources on the topic. So… here's my word of mouth.

This is by no means a comprehensive gist. It's also important to understand that the techniques that I outline in here are not 100% absolute either. Performance on the JVM is an incredibly complicated subject, and while there are rules that almost always hold true, the "almost" remains very salient. Also, for many or even most applications, there will be other techniques that I'm not mentioning which will have a greater impact. JMH, Java Flight Recorder, and a good profiler are your very best friend! Mea

sir-wabbit

Scalanomicon

the most asInstanceOf per line in Scalazzi-compliant code (efficient Nat and Fin types)

nonEmpty without boolean blindness and older version and another one

Dank Cord

Scala having too many features resulting in unsoundness

rudogma

import scala.language.higherKinds
import scala.language.implicitConversions

object TestNewtypes extends App {
  
  /**
  Changed lines:
  type NewType = Newtype[T, Tag0] with superduper.Tag[T, this.type]

    def apply[TagIn, Sub, C](c: C)(implicit tagger: Tagger[TagIn, Type, Tag, Sub, C]): NewType = c.asInstanceOf[T with NewType]

jdegoes

package fpmax

import scala.util.Try
import scala.io.StdIn.readLine

object App0 {
  def main: Unit = {
    println("What is your name?")

    val name = readLine()

zenglian

Cisco AnyConnect: auto login in silent mode

This gist is for Linux. For windows is the same thing.

Connect

create a file .login_info as below:

connect your.server.url    
usernanme 

francoism90

Disclaimer

Following instructions are provided without any warranty, and may even get you in trouble legally. The instructions are provided for testing, learning, preventing e-waste, and should be use with care. We (including contributers + commentators) are not responsible for any damage to your device(s) or any legal issues.

Getting Started

Instructions have been moved to https://github.com/francoism90/asus-router. :)

fcamblor

Starting from February 2019, Oracle JDK updates will require Commercial license if you make any business using Java (eg, you're a Java Developper not spending only your spare time developping with Java).

It includes Java not only on your server, but on your laptop as well.

Source | Source

What's nasty is Java versions will remains free to download since if you use it as an individual/personal use, you won't be concerned by the commercial aspects of the license.

non

package demo

import cats.{Applicative, Functor, Id, Semigroupal, Traverse}
import cats.arrow.FunctionK

/**
 * Type-lifting operation to replace the wildcard type (i.e. _).
 *
 * In some cases we end up with code like: List[Option[_]]. This is
 * fine unless you later need to write code in terms of a particular

iravid

import akka.actor.ActorSystem
import akka.kafka.ConsumerMessage.CommittableMessage
import akka.kafka.scaladsl.Consumer
import akka.kafka.{ ConsumerSettings, Subscriptions }
import akka.stream.ActorMaterializer
import akka.stream.scaladsl.{ Keep, Sink => AkkaSink }
import org.apache.kafka.common.serialization.StringDeserializer
import scalaz.zio._
import scalaz.zio.stream.Sink
import scalaz.zio.interop.reactiveStreams._

BrychanOdlum

[
	{
		"name": "Algeria",
		"code": "DZ",
		"storefrontId": 143563
	},
	{
		"name": "Angola",
		"code": "AO",
		"storefrontId": 143564