Re: DIP78 - macros without syntax extensions

[Idan Arye via Digitalmars-d]

On Wednesday, 27 May 2015 at 08:14:36 UTC, Kagamin wrote:
On Tuesday, 26 May 2015 at 23:47:41 UTC, Dennis Ritchie wrote:
If this proposal is considered, it is required to propose to 
look
at the implementation of macros in Nemerle. Many believe that 
it
is in Nemerle macros implemented the most successful compared 
to
other modern languages. Of course, the most successful macros 
are
implemented in Lisp, but the syntax of the language is poor :)

The problem with declarative macro system is that you would 
need to learn yet another language. Possibly turing-complete. 
And a declarative turing-complete language is an overkill both 
for usage and implementation. Imperative macros get it done in 
an intuitive way in the existing language.

But D already has such a declarative language - the one used in 
template metaprogramming. I think a macro system that plays well 
with that template metaprogramming sub-language will be really 
nice. For example, CTFE that works like a macro and returns 
types/aliases:

    Auto deduceType(Auto args) {
        // some complex imperative code to deduce the type from 
the args
        return DeducedType;
    }

    struct Foo(T...) {
        deduceType(T) value;
    }