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scala

• Function value signature for generics, context functions

  scala/scala3 2024. 3. 22. 01:01

  import scala.concurrent.duration.* import scala.concurrent.{Await, ExecutionContext, Future} def processOption[A](opt: Option[A]): String = opt match { case Some(v) => s"[$v]" case None => "[]" } @main def main(): Unit = { /** Generics in functions */ val processOptionFunction: [A] => Option[A] => String = { [A] => (opt: Option[A]) => processOption(opt) } processOptionFunction(Some(1)) /** Conte..

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• typeclass

  scala/scala3 2024. 3. 22. 00:21

  OLD but Good 방법trait Shape[A] { def area(a: A): Double}object Shape { def area[A](a: A)(using x: Shape[A]): Double = x.area(a) given Shape[Rect] = new Shape[Rect]{ override def area(a: Rect): Double = a.width * a.height } given Shape[Circle] = new Shape[Circle] { override def area(a: Circle): Double = 3.14 * a.radius * a.radius }}object ShapeSyntax { extension [A](a: A) { def are..

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• method 이름은 같은데 param, return 타입을 다르게 구현하기

  scala/basic 2024. 3. 7. 17:06

  case class GoogleRaw(content: String, crawlId: String) case class NaverRaw(content: String) case class GoogleParsed(sections: Seq[String], crawlId: String) case class NaverParsed(sections: Seq[String]) trait Cralwer { type Raw type Parsed def fetch(url: String): Raw def parse(raw: Raw): Parsed def save(raw: Raw, parsed: Parsed): Int } object GoogleCrawler extends Cralwer { type Raw = GoogleRaw t..

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• 기본 사용법

  scala/scala-cli 2024. 1. 27. 20:29

  https://scala-cli.virtuslab.org/ 사용법 소개 (scala 2.13 을 사용 중인데, scala 3 survey 에 scala-cli 를 활용해 보았다.) Run scripts hello.sc def helloMessage(names: Seq[String]) = names match case Nil => "Hello!" case names => names.mkString("Hello: ", ", ", "!") println(helloMessage(args.toSeq)) println(os.pwd) 실행 scala-cli \ --jvm 21 \ --dep com.lihaoyi::os-lib:0.9.0 \ hello.sc -- James Candy Run scala code Test..

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• Eval and Trampolining

  scala/cats2 2023. 7. 29. 11:43

  scala with cats 에 나오는 Eval.defer 를 이용한 factorial 구현 def factorial(n: BigInt): Eval[BigInt] = if(n == 1) { Eval.now(n) } else { Eval.defer(factorial(n - 1).map(_ * n)) } factorial(50000).value 내가 생각해본 Eval.defer 를 사용하지 않고 factorial 구현 def factorial(n: BigInt): Eval[BigInt] = { if (n == 1) Eval.now(n) else { for { x

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• Request & URI

  scala/sttp 2023. 7. 18. 15:09

  sttp 사용법 소개한다. 공식 메뉴얼 대신에 scala toolkit 에 나오는 간단한 예제를 옮겨봤다. libraryDependencies += "com.softwaremill.sttp.client4" %% "core" % "4.0.0-M2" object SttpMain { def main(args: Array[String]): Unit = { import sttp.client4.Response import sttp.client4.quick._ val response: Response[String] = quickRequest .get(uri"https://httpbin.org/get") .send() println(response.code) println(response.body) //////////..

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• airframe-control: Retry

  scala/airframe 2023. 7. 6. 17:11

  https://wvlet.org/airframe/docs/airframe-control#retry 의 코드를 참고한다.

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• airframe-control: Parallel

  scala/airframe 2023. 7. 6. 16:39

  airframe-control 의 Parallel 을 테스트 해 본다. 코드 import wvlet.airframe.control.Parallel import java.text.SimpleDateFormat import java.util.Date object AirframeParallel { def now(): String = { val pattern = "HH:mm:ss.SSSZ" val simpleDateFormat = new SimpleDateFormat(pattern) simpleDateFormat.format(new Date()) } def main(args: Array[String]): Unit = { val source: Seq[Int] = Seq(1, 2, 3, 4, 5) println(s..

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