test for t0716

git-svn-id: http://lampsvn.epfl.ch/svn-repos/scala/scala/trunk@14495 5e8d7ff9-d8ef-0310-90f0-a4852d11357a
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rytz 2008-04-04 10:03:03 +00:00
parent 21fab568a0
commit 7f889e862d
1 changed files with 24 additions and 0 deletions

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trait Functor[F[_]] {
def fmap[A,B](fun: A=>B, arg:F[A]): F[B]
}
object Functor{
implicit val ListFunctor = new Functor[List] {
def fmap[A, B](f: A => B, arg: List[A]):List[B] = arg map f
}
final class OOFunctor[F[_],A](arg:F[A])(implicit ftr: Functor[F]) {
def fmap[B](fun: A=>B):F[B] = ftr.fmap(fun,arg)
}
//breaks if uncommented
implicit def lifttoOO[F[_],A](arg:F[A])(implicit ftr: Functor[F]) = new OOFunctor[F,A](arg)(ftr)
//works if uncommented
//implicit def liftListtoOO[A](arg:List[A]):OOFunctor[List,A] = new OOFunctor[List,A](arg)
}
object GeneralLiftingDemo extends Application {
import Functor._
val l = List(1,2,3)
println("OO : " + l.fmap( 1+) )
}