Question

I don’t understand why the following case doesn’t match. Null should be an instance of Any, but it doesn’t match. Can someone explain what is going on?

val x = (2, null)
x match {
    case (i:Int, v:Any) => println("got tuple %s: %s".format(i, v))
    case _ => println("catch all")
}

prints catch all

Thanks.

Answer 1

This is exactly as specified.

Type patterns consist of types, type variables, and wildcards.
A type pattern T is of one of the following forms:

* A reference to a class C, p.C, or T#C.
This type pattern matches any non-null instance of the given class.

It’s interesting that so much relevance has been attributed to null being a member of Any. It’s a member of every type but AnyVal and Nothing.