aoiroaoino

trait Either3Optics {

  final def pLeft3[A, B, C, D]: PPrism[Either3[A, B, C], Either3[D, B, C], A, D] =
    PPrism[Either3[A, B, C], Either3[D, B, C], A, D] {
      case Left3(a)   => \/-(a)
      case Middle3(b) => -\/(Middle3(b))
      case Right3(c)  => -\/(Right3(c))
    }(Left3.apply)

  final def left3[A, B, C]: Prism[Either3[A, B, C], A] =

aoiroaoino

Welcome to Scala version 2.11.7 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_25).
Type in expressions to have them evaluated.
Type :help for more information.

scala> import akka.actor.ActorSystem
import akka.actor.ActorSystem

scala> import akka.stream.ActorMaterializer
import akka.stream.ActorMaterializer

aoiroaoino

sealed abstract class Season
case class Spring() extends Season
case class Summer() extends Season
case class Fall() extends Season
case class Winter() extends Season

// FallとWinterを忘れたパターンマッチ
scala> def checkSeason(s: Season) = s match {
     | case Spring() => "Spring!"
     | case Summer() => "Summer!"

aoiroaoino

import scala.util.parsing.combinator._

abstract class AST
case class Add(left: AST, right: AST) extends AST
case class Sub(left: AST, right: AST) extends AST
case class Multi(left: AST, right: AST) extends AST
case class Div(left: AST, right: AST) extends AST
case class Num(num: Int) extends AST

class OperationParsers extends RegexParsers {

aoiroaoino

//
// ちょっと冗長なクラスとメソッドの宣言
//
class Human(name: string) {
  def say(partner: String): String = {
    return "Hello " + partner
  }
}

//

aoiroaoino

//
// Scalaの変数宣言は二種類あります。
//
val name: String = "Aoino"
var num: Int = 5
 
//
// valは再代入不可な変数です。(value)
//
scala> val name = "Aoino"

aoiroaoino

!SLIDE
# test

aoiroaoino

!SLIDE
## 第三回社内Scala勉強会

!SLIDE
（個人的には第一回ですけど...）

!SLIDE
## 第一回社内Scala勉強会

!SLIDE

aoiroaoino

def splitN[A](list: List[A], index: Int): List[List[A]] = if(list.length == 0) List() else if(index < 1) List(list) else List(list.take(index)) ::: splitN[A](list.drop(index), index)
    
scala> splitN(List(1,2,3,4,5,6,7,8,9,0), 3)
rest0: List[List[Int]] = List(List(1, 2, 3), List(4, 5, 6), List(7, 8, 9), List(0))

scala> splitN(List("Red", "Green", "Yellow", "Blue"), 1)
res1: List[List[java.lang.String]] = List(List(Red), List(Green), List(Yellow), List(Blue))

aoiroaoino

trait Monoid[A] {
  def mzero: A
  def mappend(a: A, b: A): A
}

trait FoldLeft[F[_]] {
  def foldLeft[A, B](xs: F[A], b: B, f: (B, A) => B): B
}

object Monoid {