[ghc-steering-committee] Proposal #400: COMPLETE set signatures; rec: accept

[Alejandro Serrano Mena]

 Hi,
I am also happy with the proposal. The only thing I could not figure out is
whether changing the COMPLETE sets to the new syntax works also in the old
one. I mean, would a way to ensure compatibility with both current GHC, and
GHC+this proposal to write:

{-# COMPLETE … :: Either l r #-}

Regards,
Alejandro

El 16 sept 2021 18:55:46, Joachim Breitner <mail at joachim-breitner.de>
escribió:

> Hi,
>
> very convincing proposal, so I am happy with it.
>
> I’ll ask a minor question about  breaking existing COMPLETE pragmas on
> Github.
>
> Cheers,
> Joachim
>
> Am Donnerstag, dem 16.09.2021 um 19:07 +0300 schrieb Vladislav Zavialov
> (int-index):
>
> Dear Committee,
>
>
> Proposal #400 "COMPLETE set signatures” by Sebastian Graf has been
> submitted for our consideration.
>
>
> Read it here:
> https://github.com/sgraf812/ghc-proposals/blob/constrained-complete-sigs/proposals/0000-complete-set-signatures.rst
>
> Discussion here: https://github.com/ghc-proposals/ghc-proposals/pull/400
>
>
> The proposal presents an alternative treatment for type annotations on
> COMPLETE pragmas. Today one could write
>
>
>    {-# COMPLETE P, Q :: Either #-}
>
>
> where P and Q are some pattern synonyms. But this isn’t even well-kinded.
>
>
> Instead, the author proposes that we ask our users to write
>
>
>   {-# COMPLETE P, Q :: Either l r #-}
>
>
> By requiring a proper type on the RHS, we also gain the ability to talk
> about more advanced use cases (described in the proposal).
>
>
> I recommend acceptance. In fact, I learned about the way these annotations
> are treated today only from reading the proposal, and it came as a surprise
> to me. Using proper, well-kinded types there, seems like the right thing to
> do even if we ignore the new use cases it enables.
>
>
> Let me know what you think.
>
>
> - Vlad
>
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>
> --
> Joachim Breitner
>  mail at joachim-breitner.de
>  http://www.joachim-breitner.de/
>
>
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