Hi Vladimir,
I think this is ok. The kind of _ in _[X, Y <: X] is (X: *) -> *(Nothing, X) -> *
The kind of _ in _[X, Y] is * -> * -> *
Now, * -> * -> * is a subkind of (X: *) -> *(Nothing, X) -> * , just like Any -> Any -> Any is a subtype of Any -> String -> Any.
Or am I missing something?
cheers,
adriaan
On Tue, Jun 16, 2009 at 2:31 PM, Vladimir Reshetnikov
<v.reshetnikov@...> wrote:
Hi,
Consider these definitions:
///////////////////////////////////////
trait A[B[_[X, Y <: X]]] {
def f() : B[P]
}
trait C[_[X, Y]]
trait P[X, Y <: X]
///////////////////////////////////////
Type application C[P] is (correctly) rejected by the Scala 2.7.5
compiler. But A[C] is (incorrectly) accepted, which results in
incorrect type of member f(). It looks like unsoundness.
Thanks,
Vladimir
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