DIP 1027---String Interpolation---Format Assessment

[Adam D. Ruppe]

On Sunday, 23 February 2020 at 18:57:55 UTC, Adam D. Ruppe wrote:
>> As the DIP author, Walter also rejected the suggestion to go 
>> with an implementation that resolves to a library template. He 
>> sees that as equivalent to AST macros, a feature which he has 
>> previously rejected.
>
> How is `foo!str, args...` a macro when `str, args...` is not?


The one thing that MIGHT motivate this mistaken belief is if you 
think `foo` is defined in and looked up from random libraries.

That is NOT the case. `foo` here is a placeholder name for a 
template defined once and only once, in druntime. It is a normal 
lowering, just like is done very successfully in several places 
throughout the D language.