DIP 50 - AST macros

[Walter Bright]

On 11/17/2013 9:10 PM, deadalnix wrote:
> On Monday, 18 November 2013 at 05:05:02 UTC, Walter Bright wrote:
>> On 11/17/2013 7:14 PM, deadalnix wrote:
>>> As I understand it, Timon choosed that syntax simply to demonstrate the
>>> limitation of your proposal using a similar syntax. Not to propose a syntax.
>>
>> Ok, then I'm not seeing what AST macros do that lazy parameters / template
>> overloading / mixin templates do not?
>
> 2 things. First, they can act on statement or declaration. Simply not with the
> proposed syntax.

If they can insert a statement or a declaration uplevel, then they are doing 
what I suggested with the return statement.

> Second they can reflect what is passed as argument and act
> accordingly, when the lazy expression solution cannot.

Expression templates can.