String mixin syntax sugar

[RivenTheMage]

On Wednesday, 21 March 2012 at 12:37:50 UTC, Mantis wrote:
> Builtin annotations' names are not reserved keywords, so this 
> would be possible and ambiguous:
>
> string safe( string s );
> @safe void foo(); // what @safe stands for?

What about "@" for built-in annotations and "@!" for user-defined?

@!license("BSD") @safe @!memoize pure nothrow auto
invertMatrix(T)(T[] elements) if (isArithmetic!T) { ... }