DIP 50 - AST macros

[John Colvin]

On Tuesday, 12 November 2013 at 13:50:49 UTC, Jacob Carlborg 
wrote:
> auto person = Person.where(e => e.name == "John");
>
> Translates to:
>
> select * from person where name = 'John'
>

for those of us entirely unfamiliar with linq, what is this 
supposed to do? Select people with name "John" from a collection 
of people, like in sql? It seems trivial to do this using filter, 
or am I missing something...?