Why type specialization is defined differently than is expression type specialization ?

[Roman D. Boiko]

On Wednesday, 27 June 2012 at 20:42:39 UTC, Steven Schveighoffer 
wrote:
> Hm... come to think of it, shouldn't TypeSpecialization be Type 
> instead?
>
> Seems weird to say Type : TypeSpecialization, and then say 
> "TypeSpecialization is only allowed to be Type".  Why not Type 
> : Type?

That's what I was trying to explain. It is probably easier to 
implement an IsExpression this way, because it would always 
contain members of the same types.

Also, I made a typo, should be:

> and TypeSpecialization in the `==` case.