How about macro == symbol for mixin statement? [was Re: Member functions C to D]

Don nospam at
Sat Oct 10 01:50:02 PDT 2009

Yigal Chripun wrote:
> On 10/10/2009 00:36, Christopher Wright wrote:
>> Yigal Chripun wrote:
>>> On 09/10/2009 00:38, Christopher Wright wrote:
>>>> It makes macros highly compiler-specific, or requires the compiler's 
>>>> AST
>>>> to be part of the language.
>>>> Nemerle took the nuclear option, and its macros are all-powerful. 
>>>> That's
>>>> a reasonable way of doing things. I'd be happy with a more restricted
>>>> system that's easier to standardize, especially if it got rid of all 
>>>> the
>>>> hacky string manipulation in current D metaprogramming. (Seriously, 
>>>> even
>>>> __traits returns string arrays for a lot of stuff. It's ridiculous.)
>>> It doesn't have to be compiler specific. all is needed is a
>>> standardized API to the compiler.
>> Right. It adds something huge that's normally compiler-specific to the
>> language. This makes me uncomfortable. It greatly increases the
>> difficulty of implementation.
> I disagree - a properly designed compiler will have such an API anyway. 

Not if you have compilers from different vendors. And that's one of the 
key problems with making such an API part of language -- the potential 
for vendor lock-in.

>>> What's so hackish about that?
>> Reread. Current D metaprogramming is hackish. Nemerle's isn't.
> I was referring to what Don said that providing a hook into the compiler 
> is hackish.

I stand by that.
Look, I was Forth guy back in the day. Forth and Lisp both have 
hack-free macros. Particularly in the case of Forth, the language is 
largely defined in the library; you can even make the case that the 
compiler is part of the library. So there's no problem with the library 
extending the language.
But in the case of Nemerle, it's a conventional compiler with hooks for 
library code.

I just feel that Nermele's approach is diametrically opposed to Forth/Lisp.
It's personal opinion. To me, that looks like a hack.

To make one thing clear:
D's compile-time reflection is a hack. And that makes most current 'D 
macros' hackish. I just feel that most of the problems lie on the 
reflection side.

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