Reimplementing the bulk of std.meta iteratively

[Stefan Koch]

On Saturday, 26 September 2020 at 16:18:27 UTC, Andrei 
Alexandrescu wrote:
> 1. Reify the compile-time parameters into values
> 2. Carry processing on these values with the usual algorithms
> 3. If needed, dereify back the results into compile-time 
> parameters

That's the right thought, and that's what type functions were 
designed to do.

How do they compare to the vision you have?

> Commments and ideas for improvements are welcome.

The PR referenced does not give, actually give you the ability to 
dereify types within CTFE.
The PR forces a template and template has to have template 
parameters to take the mangles.
I would think that is against the actual goal.