Lambda the Ultimate

This is probably one of those naive I should first finish the Pierce book kind of questions, but here goes anyway:

Are there languages where a constant value, such as 42, can act is its own type?

So putting this in real-world terms, in the Cat language I can write the following function with a type annotation:

define the_answer : ()->(int) 
{ 
  42 
}

However, it seems that I am being too general by saying it returns an int in the type annotation because it always returns 42 (edit: which we could say is a subtype of int). So ... shouldn't the type annotation be:

define the_answer : ()->(42) 
{
  42
}

So the more general question is: what is good / bad about this?