johnynek

package example    
    
object RecMap {                                            
                                                                                   
  object Record {                               
    // use this scope to bound who can see inside the opaque type
    opaque type Rec[A <: Tuple] = Map[String, Any]
                                                   
    object Rec {                          
      type HasKey[A <: Tuple, K] =

tpolecat

import java.io.ByteArrayInputStream
import java.security.PrivateKey
import java.security.PublicKey
import org.bouncycastle.jce.provider.BouncyCastleProvider
import org.bouncycastle.openpgp.operator.jcajce._
import org.bouncycastle.openpgp._
import scala.util.control.NonFatal

/**
 * Methods to turn GPG ASCII-amored exported text into JCA keys. Many thanks to Twitter friends, 

olafurpg

import sbt._, Keys._

object DownloadSources extends AutoPlugin {
  override def trigger = allRequirements
  override def requires = sbt.plugins.JvmPlugin
  override def projectSettings = 
    List(Compile, Test).flatMap { config =>
      inConfig(config)(
        TaskKey[Seq[File]]("downloadSources") := Def.task[Seq[File]] {
          val out = baseDirectory.in(ThisBuild).value / "target" / "sources"

Daenyth

package teikametrics

import scala.collection.SortedMap

/**
  * Immutable implementation of an LRU cache.
  *
  * @author Twitter
  *
  *  Copy pasted from the version previously in twitter-util v19.1.0 at

mpilquist

/*
scalaVersion := "2.12.7"

resolvers += Resolver.sonatypeRepo("snapshots")

libraryDependencies += "co.fs2" %% "fs2-core" % "1.0.1-SNAPSHOT"
 */
import cats._
import cats.implicits._
import cats.effect._

SystemFw

// This is the traditional encoding, using abstract type members
// to encode existentials
object AbstractExistentials {
  trait E {
    type X
    val x: X
    def f(p: X): String
  }
   

SystemFw

import shapeless._

@annotation.implicitNotFound("Make sure all cases of ${C} have an instance of ${TC}")
trait CopTCs[C <: Coproduct, TC[_]] {
  type Out <: HList
  def result: Out
}
object CopTCs {
  type Aux[C <: Coproduct, TC[_], O <: HList] = CopTCs[C, TC] { type Out = O }
  def apply[C <: Coproduct, TC[_]](implicit ev: CopTCs[C, TC]) = ev

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

mrkgnao

{-# LANGUAGE Arrows                 #-}
{-# LANGUAGE ConstraintKinds        #-}
{-# LANGUAGE FlexibleContexts       #-}
{-# LANGUAGE FlexibleInstances      #-}
{-# LANGUAGE GADTs                  #-}
{-# LANGUAGE InstanceSigs           #-}
{-# LANGUAGE LambdaCase             #-}
{-# LANGUAGE MultiParamTypeClasses  #-}
{-# LANGUAGE RankNTypes             #-}
{-# LANGUAGE ScopedTypeVariables    #-}

jkachmar

All actions should be performed in the root directory of a Haskell project that uses stack. The following lines should be present in the project's stack.yaml file:

docker:
  enable: true

Additionally, the BaseImage and Dockerfile files from this gist should also be present in the project's root directory.