Will macros just be syntactic sugar?

[Davidl]

oh noes, why posted so many times.... coz they are too important? :p
forgive my bad network & slow machine , i think the extra posts are
caused by them

> numerle's macro is somewhat worth consideration
> an improved syntax should be something like:
> macro macroname(arg0,arg1,arg2,arg3)
> syntax realname(arg0)[arg1] := arg2 +arg3
> {
>     arg0[arg1] = arg2+arg3;
> }
>
> and calling style would be realname(a)[i] := j + k; // which would call  
> macro macroname(a,i,j,k)
>
>>
>> A couple of weeks ago, I posted an implementation of BLAS1-style vector  
>> expressions, that used tuples and expression templates to generate  
>> near-optimal asm code in many circumstances. Unfortunately, when I've  
>> looked at the code that is generated, there's a *hideous* amount of  
>> stack shuffling -- it is too difficult for the compiler to optimise all  
>> the tuple operations away.
>> So I came up with this alternative, which gives _many_ more  
>> optimisation opportunities, and doesn't require you to wrap arrays of  
>> built-in types.
>>
>> float [] vec1 = [43, 5445, 547, 465];
>> auto vec2 = [1.24, 765, 6756, 23.143];
>>
>> mixin(vectorize("vec2+=vec1*3.3254"));
>>
>> This actually works. There are some awesome side effects -- eg, any  
>> error messages in the library code appear on the line of user code. You  
>> can determine which of the variables are compile-time constants (and  
>> optimise the generated code based on the value of those constants). You  
>> can get the compiler to do _most_ of the heavy lifting (eg, convert  
>> floating point strings <--> const real).
>>
>> As far as I can tell, *all* of the proposed 'macro' functionality can  
>> be done already using mixins and CTFE. It looks as though the power of  
>> macros will be a subset of the power of mixins. This means that macros  
>> can be explored quite thoroughly *before* deciding on the cleanest  
>> syntax for them.
>>
>> Today:
>> ---------
>> char [] magic(char [] args)
>> {
>>     return "stuff-to-mix-in";
>> }
>>
>> :
>>    mixin(magic("a+=b*c"));
>> :
>> -----------
>> With macros:
>>
>> macro magic(args)
>> {
>>    stuff-to-mix-in
>> }
>>
>> :
>> magic(a+=b*c);
>> :
>> ------------
>