taisukeoe

import cats.
import cats.implicits._

case class MyError(errorMsg: String)

object MyError {
  implicit val s: Semigroup[MyError] = new cats.kernel.Semigroup[MyError] {
    override def combine(t1: MyError, t2: MyError): MyError = MyError(t1.errorMsg + "\n" + t2.errorMsg)
  }
}

taisukeoe

import cats._
import cats.data.{Kleisli, Reader, ReaderT}
import cats.implicits._

import scala.concurrent.{ExecutionContext, Future}

object ReaderStyle extends App {
  def someCalc(i: Int): Int = ???

  import ExecutionContext.Implicits.global

taisukeoe

Welcome to Scala 2.12.8 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_201).
Type in expressions for evaluation. Or try :help.

scala> trait A {val x:AnyRef = null;type X = x.type}
defined trait A

scala> val a = new A{}
a: A = $anon$1@36417a54

scala> val ax:a.type#X = a.x

taisukeoe

#多相な関数の定義から学ぶ、型クラスデザインパターン

　　　　　　　　　twitter: @OE_uia github: taisukeoe

##多相な関数

• 複数の異なる型に対して適用可能な関数
• どの型に対して定義されているか、静的に決定できる(定義されてない型の値を渡すとコンパイルエラーになる)

taisukeoe

```scala
implicit def cofreeEqual[A, F[_]](implicit A: Equal[A], F: Equal[F[Cofree[F, A]]]): Equal[Cofree[F, A]] =
  Equal.equal{ (a, b) =>
    A.equal(a.head, b.head) && F.equal(a.tail, b.tail)
  }
  
scala> import scalaz._,Scalaz._
import scalaz._
import Scalaz._

taisukeoe

01-13 02:59:43.556 21402-21402/com.example.android.displayingbitmaps E/AndroidRuntime: FATAL EXCEPTION: main
01-13 02:59:43.556 21402-21402/com.example.android.displayingbitmaps E/AndroidRuntime: Process: com.example.android.displayingbitmaps, PID: 21402
01-13 02:59:43.556 21402-21402/com.example.android.displayingbitmaps E/AndroidRuntime: java.lang.NoClassDefFoundError: Failed resolution of: Ljavax/imageio/ImageIO;
01-13 02:59:43.556 21402-21402/com.example.android.displayingbitmaps E/AndroidRuntime:     at org.canova.image.recordreader.BaseImageRecordReader.<clinit>(BaseImageRecordReader.java:72)
01-13 02:59:43.556 21402-21402/com.example.android.displayingbitmaps E/AndroidRuntime:     at com.example.android.displayingbitmaps.ui.ImageGridActivity.trainMLP(ImageGridActivity.java:99)
01-13 02:59:43.556 21402-21402/com.example.android.displayingbitmaps E/AndroidRuntime:     at com.example.android.displayingbitmaps.ui.ImageGridActivity.onCreate(ImageGridActivity.java:72)
01-13 02:59:43.556 21402-21402/com.examp

taisukeoe

scala> val ndArray = (1d to 8d by 1).mkNDArray(Array(2,2,2),NDOrdering.C)
ndArray: org.nd4j.linalg.api.ndarray.INDArray =
[[[1.00,2.00]
 [3.00,4.00]]
  [[5.00,6.00]
 [7.00,8.00]]]

scala> ndArray.sliceP.map(s => s.rowP.map(r => r*r))
res12: org.nd4j.linalg.api.ndarray.INDArray =
[[[1.00,2.00]

taisukeoe

import streams._
import util._
implicit val s = Strategy.fromExecutionContext(scala.concurrent.ExecutionContext.Implicits.global)
val t = Task(println(Thread.currentThread.getName))

// Exiting paste mode, now interpreting.

import streams._
import util._
s: streams.util.Strategy = streams.util.Strategy$$anon$1@60d8175

taisukeoe

trait Callback{
	 def onSet(s:Set[String]):Unit
   def onList(l:List[String]):Unit
}
def funcWithCallback(s:String,callback:Callback):Unit = ???

def funcAsFuture(s:String):Future[Traversable[String]] = {
    val p = Promise[Traversable[String]]() 
    val f = p.future
	funcWithCallback(s,new Callback{

taisukeoe

jmhSettings