Walter's second axiom

[Jason House]

Walter Bright wrote:

> Jason House wrote:
>> Walter Bright wrote:
>>> That axiom didn't really exist until Andrei started pointing out to me
>>> all the advantages of being able to wrap types in a struct. So we can
>>> expect some historical problems with it.
>> 
>> Can you please share with us all the advantages of "Any type T can be
>> wrapped inside a struct S, and that S can be made to behave as a typedef
>> for type T."
> 
> You might, for example, want to create an associative array that behaved
> slightly differently, but use it just like an AA.

... so even without the const issues, this type of functionality does not
yet work in D?  As far as I know, AA's are the only thing that support the
in operator.