Trying to get type and name at compile time

[Edwin van Leeuwen via Digitalmars-d-learn]

On Tuesday, 24 May 2016 at 15:09:43 UTC, Adam D. Ruppe wrote:
> On Tuesday, 24 May 2016 at 15:01:33 UTC, Edwin van Leeuwen 
> wrote:
>> // I expected AliasSeq!(double,"x")???
>> pragma(msg,test); // tuple((double), "x")
>
> What Phobos calls AliasSeq is called tuple inside the compiler. 
> They are the same thing, just different names.

That's what I assumed at first.. So why does the following fail 
with: cannot interpret double at compile time? I assumed 
staticMap would automatically flatten the resulting AliasSeqs.

```
import std.meta : AliasSeq, ApplyLeft, staticMap;

struct Point { double x; double y; }

template addType(T,alias name)
{
     alias addType = AliasSeq!( typeof(__traits(getMember, Point, 
name)),
         name );
}

alias test3 = addType!( Point, "x" );

// I expected AliasSeq!(double,"x")???
pragma(msg,test3); // tuple((double), "x")

//static assert(is(test == AliasSeq!(double,"x")));
alias ts = AliasSeq!("x","y");
alias addTypeP = ApplyLeft!(addType,Point);
alias mapped = staticMap!(addTypeP,ts);

pragma(msg,mapped);

void main() {
}
```

Looking at it now, I guess it is because staticMap does not work 
with alias values, only with actual type lists. Is that correct? 
Any ideas on how to do this?

>
>> static assert(is(test == AliasSeq!(double,"x")));
>
> AliasSeq is not comparable as a type. You can test the 
> individual pieces of it (`is(test[0] == double) && test[1] == 
> "x"`) or wrap it in a struct or something.

I thought so, but a lot of the documentation does seem to compare 
it (see the example here):
https://dlang.org/library/std/meta/static_map.html