[ghc-steering-committee] [Proposal] #175: Lift.liftTyped (recommendation: accept)

[Joachim Breitner]

Hi,

thanks for the summary!

Am Dienstag, den 18.12.2018, 22:37 -0500 schrieb Eric Seidel:
> 1. We could make violations of MINIMAL pragmas errors instead of
> warnings. This would need its own proposal, but it seems like a good
> idea to me regardless.
>
> 2. We could add a special warning/error for empty Lift instances.
> This is ad-hoc and kludgy, but easily doable since template-haskell
> is bundled with ghc.
>
> 3. We could provide a ghc-fix tool that automatically fixes this
> issue (and maybe others!). A number of other languages do this and it
> seems to work well for them. It also sounds like a very nice
> application of the ghc-exactprint work that Alan has done.

I think 1. is at odds in GHC – we allow partiality in other places as
well (partially initialized records, for example). Disallowing it feels
like a too fundamental change to the language for the problem we need
to solve here.

3. is a neat idea, but again a very big cannon for a niche problem. If
we _had_ ghc-fix, then this might be a good approach, and we can keep
this in mind as additional evidence that ghc-fix would be good (GSOC
anyone), but let's not wait for that here.

2. is good, I think. We have had plenty of such kludges, e.g. around
the Monad refactoring.


Cheers,
Joachim


-- 
Joachim Breitner
  mail at joachim-breitner.de
  http://www.joachim-breitner.de/

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