I like Michael Krämer’s idea to use implicits, but I think it can be applied more directly:
case class IntList(list: List[Int])
case class StringList(list: List[String])
implicit def il(list: List[Int]) = IntList(list)
implicit def sl(list: List[String]) = StringList(list)
def foo(i: IntList) { println("Int: " + i.list)}
def foo(s: StringList) { println("String: " + s.list)}
I think this is quite readable and straightforward.
[Update]
There is another easy way which seems to work:
def foo(p: List[String]) { println("Strings") }
def foo[X: ClassTag](p: List[Int]) { println("Ints") }
def foo[X: ClassTag, Y: ClassTag](p: List[Double]) { println("Doubles") }
For every version you need an additional type parameter, so this doesn’t scale, but I think for three or four versions it’s fine.
[Update 2]
For exactly two methods I found another nice trick:
def foo(list: => List[Int]) = { println("Int-List " + list)}
def foo(list: List[String]) = { println("String-List " + list)}