http://wiki.dlang.org/DIP25

[Dominikus Dittes Scherkl via Digitalmars-d]

On Tuesday, 6 January 2015 at 09:11:10 UTC, bearophile wrote:
> Dominikus Dittes Scherkl:
>
>> Yeah. I wish it would be possilbe to do something like:
>>
>> alias @smooth = @save pure nothrow @nogc;
>>
>> and then use this instead.
>
> You most probably want something more principled instead, as 
> the algebra of effects of Koka language 
> (http://rise4fun.com/Koka/tutorial/guide ) or something even 
> better.
>
> Bye,
> bearophile

Sounds interesting, but would be hard to cover other attributes 
(or effects) like @save and @nogc within this system.
And I think using alias for creating combined attributes by hand 
would be easy to implement, not breaking any existing code and 
handy enough for most common combinations.
And by the way, this would also allow to define ore remove the @ 
as one wiches:
alias nogc = @nogc;
or vice versa:
alias @pure = pure;