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在Scalaz,有一個簡單的方法來轉換的Writer[W, A]
一個實例(這是WriterT[Id, W, A])
到WriterT[F, W, A]
?創建WriterT [F,W,A]從文學家[W,A]
我的別名在找類似optionT
功能與point
相結合的東西,但對於作家,而不是:
如
// Similar situation, but using OptionT
val opt: Option[String] = Some("log")
val optT: OptionT[IO, String] = optionT(opt.point[IO])
// Case in hand, using WriterT
val w: Writer[String, Unit] = "log".tell
val wt: WriterT[IO, String, Unit] = ???
// Similar scenario
val w: Writer[String, Int] = 3.set("log")
val wt: WriterT[IO, String, Int] = ???
輝煌,謝謝!是的,monad變形金剛會是一種痛苦... – dcastro