AST Macros?

[foobar]

On Tuesday, 5 June 2012 at 07:08:19 UTC, Don Clugston wrote:
> On 04/06/12 20:46, Jacob Carlborg wrote:
>> On 2012-06-04 10:03, Don Clugston wrote:
>>
>>> AST macros were discussed informally on the day after the 
>>> conference,
>>> and it quickly became clear that the proposed ones were 
>>> nowhere near
>>> powerful enough. Since that time nobody has come up with 
>>> another
>>> proposal, as far as I know.
>>
>> I think others have suggested doing something similar like 
>> Nemerle,
>> Scala or Nimrod.
>>
>
> Yes but only in very vague terms -- not in any more words than 
> that. When I look at the Nimrod docs, it basically seems to be 
> nothing more than "expose the compiler internal data 
> structures". Which is extremely easy to do but causes a heap of 
> problems in the long term.

This argument was raised before. That "heap of problems" is as 
vague as the proposed AST system(s).
As far as I can tell, that heap of problems is mainly about 
making it harder to make internal breaking changes since the 
compiler is no longer a black box.

Now, I'd argue that having a stable API for those compiler 
internals in needed anyway. Besides the obvious benefits of a 
more modular design that better encapsulates the different layers 
of the compilation process, it allows us to implement a compiler 
as a set of libraries which benefits the tool ecosystem, IDEs, 
text-editors, lint tools, etc. Thools which could reuse subsets 
of these libraries (e.g. think of Clang's design and how it 
allowed for the vim auto-complete plugin).

Even _without_ the AST macros I think it's a worthy goal to 
pursuit, AST macros simply make the outcome that much sweeter.