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import language.higherKinds
object hk0 {
trait Lambda[type Elem]
abstract class Functor[F <: Lambda] {
def map[A, B](f: A => B): F[Elem = A] => F[Elem = B]
}
object test1 {
class ListT[T] extends Lambda[T]
val ml: Functor[ListT] = ???
val mx = ml
var xs: ListT[Int] = ???
var ys: ListT { type Elem = Int } = xs
xs = ys
val mm: (Int => Boolean) => ListT[Int] => ListT[Boolean] = mx.map[Int, Boolean]
val mm2: (Int => Boolean) => ListT[Int] => ListT[Boolean] = mx.map
}
}
object higherKinded {
type Untyped = Null
class Tree[type -Attr >: Untyped] {
type ThisType <: Tree
def withString(s: String): ThisType[Attr = String] = withString(s)
}
/*
class Ident[-Attr >: Untyped] extends Tree[Attr] {
type ThisType = Ident
}
val id = new Ident[Integer]
val y = id.withString("abc")
val z: Ident[String] = y
val zz: tpd.Tree = y
abstract class Instance[T >: Untyped] {g
type Tree = higherKinded.Tree[T]
}
object tpd extends Instance[String]
def transform(tree: Tree[String]) = {
val tree1 = tree.withString("")
tree1: Tree[String]
}
*/
}
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