So what does (inout int = 0) do?

[ixid via Digitalmars-d]

On Friday, 15 April 2016 at 03:10:12 UTC, Andrei Alexandrescu 
wrote:
> We want Phobos to be beautiful, a prime example of good D code. 
> Admittedly, it also needs to be very general and efficient, 
> which sometimes gets in the way. But we cannot afford an 
> accumulation of mad tricks to obscure the large design.
>
>
> Andrei

Why didn't we go with all functions being able to infer const, 
pure etc rather than just templates?