> On Jul 21, 2016, at 2:25 PM, Yuras Shumovich <shumovi...@gmail.com> wrote:
> 
> It is hopeless. Haskell2020 will not include TemplateHaskell, GADTs,
> etc.

Why do you say this? I don't think this is a forgone conclusion. I'd love to 
see these standardized.

My own 2ยข on these are that we can standardize some subset of TemplateHaskell 
quite easily. GADTs are harder because (to my knowledge) no one has ever 
written a specification of type inference for GADTs. (Note that the OutsideIn 
paper admits to failing at this.) Perhaps we can nail it, but perhaps not. Even 
so, we can perhaps standardize much of the behavior around GADTs (but with 
pattern matches requiring lots of type annotations) and say that an 
implementation is free to do better. Maybe we can do even better than this, but 
I doubt we'll totally ignore this issue.

> Haskell Prime committee will never catch up if GHC will continue
> adding new extensions.

Of course not. But I believe some libraries also refrain from using new 
extensions for precisely the same reason -- that the new extensions have yet to 
fully gel.

> In 2020 everybody will use pattern synonyms,
> overloaded record fields and TypeInType, so the standard will be as far
> from practice as it is now.

Pattern synonyms, now with a published paper behind them, may actually be in 
good enough shape to standardize by 2020. I don't know anything about 
overloaded record fields. I'd be shocked if TypeInType is ready to standardize 
by 2020. But hopefully we'll get to it.

> 
> The whole idea of language extensions, as it is right now, works
> against Haskell Prime.

I heartily disagree here. Ideas that are now standard had to have started 
somewhere, and I really like (in theory) the way GHC/Haskell does this.

The (in theory) parenthetical is because the standardization process has been 
too, well, dead to be useful. Is that changing? Perhaps. I'd love to see more 
action on that front. I'm hoping to take on a more active role in the committee 
after my dissertation is out the door (2 more weeks!).
> 
> I see only one real way to change the situation -- standardize all
> widely used extensions and declare anything new as experimental unless
> accepted by the Haskell Prime Committee.

Agreed here. I think that's what we're trying to do. If you have a good 
specification for GADT type inference, that would help us. :)

Richard
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