Feedback request for #9628 AST Annotations

[Richard Eisenberg]

I'm only speaking up because Alan is specifically requesting feedback: I'm really ambivalent about this. I agree with Edward that this is a big change and adds permanent noise in a lot of places. But, I also really respect the goal here -- better tool support. Is it worthwhile to do this using a dynamically typed bit (using Typeable and such), which would avoid the noise? Maybe.

What do other languages do? Do we know what, say, Agda does to get such tight coupling with an editor? Does, say, Eclipse have such a chummy relationship with a Java compiler to do its refactoring, or is that separately implemented? Haskell/GHC is not the first project to have this problem, and there's plenty of solutions out there. And, unlike most other times, I don't think Haskell is exceptional in this regard (there's nothing very special about Haskell's AST, maybe beyond indentation-awareness), so we can probably adopt other solutions nicely.

Richard

On Sep 29, 2014, at 8:58 PM, "Edward Z. Yang" <ezyang at mit.edu> wrote:

> Excerpts from Alan & Kim Zimmerman's message of 2014-09-29 13:38:45 -0700:
>> 1. Is this change too big, should I scale it back to just update the
>>   HsSyn structures and then lock it down to Located SrcSpan for all
>>   the rest?
> 
> I don't claim to speak for the rest of the GHC developers, but I think
> this change is too big.  I am almost tempted to say that we shouldn't
> add the type parameter at all, and do something else (maybe Backpack
> can let us extend SrcSpan in a modular way, or even use a dynamically
> typed map for annotations.)
> 
> Edward
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