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package test
import scala.language.higherKinds
trait Functor[F[_]] {
def map[A, B](f: A => B, fa: F[A]): F[B]
}
object Functor {
implicit def function[A]: Functor[({ type l[B] = A => B })#l] =
new Functor[({ type l[B] = A => B })#l] {
def map[C, B](cb: C => B, ac: A => C): A => B = cb compose ac
}
}
object FunctorSyntax {
implicit class FunctorOps[F[_], A](fa: F[A])(implicit F: Functor[F]) {
def map[B](f: A => B): F[B] = F.map(f, fa)
}
}
object Test {
val f: Int => String = _.toString
import FunctorSyntax._
f.map((s: String) => s.reverse)
}
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