Writerモナドの使い道 [実行回数]
def hoge(): Writer[Int, String] = for { _ <- Writer.tell(1) r <- Writer.value[Int, String]("hoge") } yield r val w: Writer[Int, List[String]] = List.range(0, 100).map(_ => hoge()).sequence println(w.run) // (hoge()実行回数, 結果のリスト)
def hoge(): Writer[Int, String] = for { _ <- Writer.tell(1) r <- Writer.value[Int, String]("hoge") } yield r val w: Writer[Int, List[String]] = List.range(0, 100).map(_ => hoge()).sequence println(w.run) // (hoge()実行回数, 結果のリスト)