That would be unsound
with Jazz <: Music
, Classical <: Music
, but no relation between Jazz
and Classical
,
meow[K <: T]
means that a Cat[Music]
can meow in Jazz
, Classical
, or any choice of genre.
On the other hand, a Cat[Classical]
meow cannot be Jazz
.
But if you have covariant Cat[+T]
, then a Cat[Classical] <: Cat[Music]
, so a Cat[Classical]
, being an eclectic Cat[Music]
too, should be able to meow Jazz
.
Contradiction.