Manifests

Added in Scala 2.7 as an experimental feature is the manifest class it is a handy class allowing for very limited type reification. Take the following example:
def inspect[T](l:List[T])
If you want to know they type of T in Java you are out of luck because that type information is gone. However, Scala offers help through manifests.

1. def inspect[T](l:List[T])(implicit manifest : scala.reflect.Manifest[T]) = println(manifest.toString)

This code snippet will print out the string representation of type T.

More Examples:

1. scala> def inspect[T](l:List[T])(implicit manifest : scala.reflect.Manifest[T]) = println(manifest.toString)
2. inspect: [T](List[T])(implicit scala.reflect.Manifest[T])Unit
4. scala> inspect(List(1,2,3,4))
5. int
7. scala> inspect(List(List(1,2),List(3,4)))
8. scala.List[int]
10. scala> inspect(List(List(List(1),List(2)),List(List(3),List(4))))
11. scala.List[scala.List[int]]
13. scala> val l:List[Iterable[Int]] = List(List(1,2))  
14. l: List[Iterable[Int]] = List(List(1, 2))
16. scala> inspect(l)                                                                                           
17. scala.collection.Iterable[Int]
19. scala> class MV[T](val v:T)(implicit m:scala.reflect.Manifest[T]) { println(m.toString) }
20. defined class MV
22. scala> new MV(1)
23. Int
24. res1: MV[Int] = MV@180e6899
26. scala> class MV2[T](val v:T)(implicit m:scala.reflect.Manifest[T]) {                     
27.      | def isA[A](implicit testManifest:scala.reflect.Manifest[A]) = m.toString == testManifest.toString
28.      | }
29. defined class MV2
31. scala> val x = new MV2(19)
32. x: MV2[Int] = MV2@41ff8506
34. scala> x.isA[String]
35. res2: Boolean = false
37. scala> x.isA[Int]   
38. res3: Boolean = true
40. scala> def isA[A](o:Object)(implicit m:Manifest[A]) = {
41.      | val `class` = Class.forName(m.toString)         
42.      | `class`.isAssignableFrom(o.getClass)            
43.      | }
44. isA: [A](o: java.lang.Object)(implicit m: scala.reflect.Manifest[A])Boolean
46. scala> isA[java.lang.Integer](java.lang.Integer.valueOf(19))
47. res6: Boolean = true