blob: 4d9f1d0dc95f4e66e25c307fbb26f2f9a9f665dd (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
|
object ImplicitProblem {
class M[T]
def nullval[T] = null.asInstanceOf[T];
trait Rep[T] {
def eval: Int
}
implicit def toRep0(n: Int) = new Rep[Int] {
def eval = 0
}
implicit def toRepN[T](n: M[T])(implicit f: T => Rep[T]) = new Rep[M[T]] {
def eval = f(nullval[T]).eval + 1
}
def depth[T <% Rep[T]](n: T) = n.eval
def main(args: Array[String]) {
println(depth(nullval[M[Int]])) // (1) this works
println(nullval[M[Int]].eval) // (2) this works
type m = M[Int]
println(depth(nullval[m])) // (3) this doesn't compile on 2.7.RC1
println(nullval[m].eval) // (4) this works
}
}
|