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import scala.language.higherKinds
trait Bound[B]
package p1 {
case class Sub[B <: Bound[B]](p: B)
object Test {
def g[A](x: Bound[A]) = ()
def f(x: Any) = x match { case Sub(p) => g(p) }
}
}
package p2 {
trait Traversable[+A] { def head: A = ??? }
trait Seq[+A] extends Traversable[A] { def length: Int = ??? }
case class SubHK[B <: Bound[B], CC[X] <: Traversable[X]](xs: CC[B])
class MyBound extends Bound[MyBound]
class MySeq extends Seq[MyBound]
object Test {
def g[B](x: Bound[B]) = ()
def f1(x: Any) = x match { case SubHK(xs) => xs }
def f2[B <: Bound[B], CC[X] <: Traversable[X]](sub: SubHK[B, CC]): CC[B] = sub match { case SubHK(xs) => xs }
def f3 = g(f1(SubHK(new MySeq)).head)
def f4 = g(f2(SubHK(new MySeq)).head)
}
}
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