If T[new] is the container for T[], then what is the container for T[U]?

[Christopher Wright]

Andrei Alexandrescu wrote:
> It looks we can't make it with only T[].

Citation needed. If this is a continuation of a previous discussion, a 
link to the previous discussion will suffice.

I grant that appending to an array is expensive. Make Array a 
user-defined type and we can see what's appropriate.