Why the @ in @safe? & UDAs

[Adam D. Ruppe]

On Thursday, 7 November 2013 at 00:13:49 UTC, Shammah Chancellor 
wrote:
> My understanding is that @ attributes were for used-defined 
> behavior only.

It is all a historical thing... at first, all new things were 
done as keywords. Then around the time @safe came around, they 
were changing their minds and new things became @keywords. Then, 
some time after that, UDAs came around and used the @ syntax.

But the reason it is pure and @safe instead of @pure @safe or 
pure and safe is just historical accident - they were introduced 
in that particular phase, and now the worry is changing it will 
annoyingly break too much code for very little real benefit.