Type Inference Question

I haven't worked through the full semantics of the type inference in
my following scenario, but can someone let me know why the type
variable T in class B is not bound to String and requires the type
definition in class B? Can't this be inferred from the return type of
doDerivedInit in class B?


abstract class A {
type T
val generigvar : T = init

def init = {
doDerivedInit
}

def doDerivedInit : T
}

class B extends A {
type T = String
override def doDerivedInit = {
"Some String"
}
}

Declan Conlon