Im folgenden Code (von Functional Programming in Scala):"Higher Kinded Typ aktiviert werden soll" Warnung
trait Functor[F[_]] {
def map[A,B](fa: F[A])(f: A => B): F[B]
}
trait Monad[F[_]] {
def unit[A](a: => A): F[A]
def flatMap[A,B](ma: F[A])(f: A => F[B]): F[B]
def apply[A](a: => A): F[A]
}
ich die folgende Warnung sehen:
[warn] C:\...\Monad.scala:3: higher-kinded type should be enabled
[warn] by making the implicit value scala.language.higherKinds visible.
[warn] This can be achieved by adding the import clause 'import scala.language.higherKinds'
[warn] or by setting the compiler option -language:higherKinds.
[warn] See the Scala docs for value scala.language.higherKinds for a discussion
[warn] why the feature should be explicitly enabled.
[warn] trait Functor[F[_]] {
[warn] ^
[warn] C:\...\Monad.scala:7: higher-kinded type should be enabled
[warn] by making the implicit value scala.language.higherKinds visible.
[warn] trait Monad[F[_]] {
Was ist hier los? Beachten Sie, dass ich diese post gelesen habe, aber nicht verstanden habe.
See [SIP-18 - Modularisierung Sprache Features] (http://docs.scala-lang.org/sips/ completed/modularizing-language-features.html). – senia