Please review: #515 Relaxing HasField constraints

Hi all, Ollie Charles’ proposal https://github.com/ghc-proposals/ghc-proposals/pull/515 removes the restrictions placed on HasField instances. Close to my heart, this addresses the problem of creating custom `HasField` instances for record types. I’m in favour of this proposal as it would solve some issues I have encountered, but the floor is open for discussion. Thanks, Tom

I don't have much of an opinion on this proposal.
I do believe that, in the current state, it doesn't discuss in sufficient
detail about whether instances should be considered coherent or not by the
compiler. This seems to be the most non-trivial choice in the proposal.
I've asked for an addition to that respect on the Github thread.
On Wed, Aug 10, 2022 at 12:58 PM Tom Harding
Hi all,
Ollie Charles’ proposal https://github.com/ghc-proposals/ghc-proposals/pull/515 removes the restrictions placed on HasField instances. Close to my heart, this addresses the problem of creating custom `HasField` instances for record types. I’m in favour of this proposal as it would solve some issues I have encountered, but the floor is open for discussion.
Thanks, Tom _______________________________________________ ghc-steering-committee mailing list ghc-steering-committee@haskell.org https://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-steering-committee

I have raised what may be an important technical objection: https://github.com/ghc-proposals/ghc-proposals/pull/515#issuecomment-1239289... I like the spirit of this proposal, but it may be out of reach given my linked post. Curious for others' thoughts -- I hope my objection is ill-founded! Richard
On Aug 23, 2022, at 4:54 AM, Spiwack, Arnaud
wrote: I don't have much of an opinion on this proposal.
I do believe that, in the current state, it doesn't discuss in sufficient detail about whether instances should be considered coherent or not by the compiler. This seems to be the most non-trivial choice in the proposal. I've asked for an addition to that respect on the Github thread.
On Wed, Aug 10, 2022 at 12:58 PM Tom Harding
mailto:i.am.tom.harding@gmail.com> wrote: Hi all, Ollie Charles’ proposal https://github.com/ghc-proposals/ghc-proposals/pull/515 removes the restrictions placed on HasField instances. Close to my heart, this addresses the problem of creating custom `HasField` instances for record types. I’m in favour of this proposal as it would solve some issues I have encountered, but the floor is open for discussion.
Thanks, Tom _______________________________________________ ghc-steering-committee mailing list ghc-steering-committee@haskell.org mailto:ghc-steering-committee@haskell.org https://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-steering-committee https://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-steering-committee _______________________________________________ ghc-steering-committee mailing list ghc-steering-committee@haskell.org https://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-steering-committee
participants (3)
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Richard Eisenberg
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Spiwack, Arnaud
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Tom Harding