type param in method name in scala

Type parameters can be specified with methods also like in the example below...
scala> def A[a](b:a){ println(b) }
A: [a](a)Unit

scala> A[String]("hi")
hi
scala> A[String](2)
:6: error: type mismatch;
found : Int(2)
required: String
A[String](2)
^
They're being used in receive method in Actor class, lets take a look at the signature of receive
def receive[R](f: PartialFunction[Any, R]):R
The advantage is that we automatically get the type checking done to be sure that return type of receive is gonna be same as the second type parameter of the PartialFunction.