[Haskell-cafe] Downsides to disabling unticked-promoted-constructor warning?

[Markus Läll]

Hi and thank you both!

For disambiguation the tick may be required for syntactically empty and one
element lists, right? As only these can be ambiguous at locations where a
type is expected.


On Wed, Oct 20, 2021 at 3:29 PM Adam Gundry <adam at well-typed.com> wrote:

> I've created a ticket to request disabling this warning by default:
> https://gitlab.haskell.org/ghc/ghc/-/issues/20531
>
> I'm not sure if this needs a full ghc-proposal.
>
> Cheers,
>
> Adam
>
>
>
> On 18/10/2021 03:19, Richard Eisenberg wrote:
> > As its author, I think -Wunticked-promoted-constructors is a misfeature.
> It was motivated by the fact that writing [True] when you mean '[True]
> produces a cascade of obscure kind errors, and so I thought it was good to
> encourage people to always write the ticks. But the feature does not
> achieve its goal: because errors squelch warnings, we do not see the
> warnings if there are any errors. Furthermore, I agree with Adam's post
> that I've come to prefer a style where we leave off the ticks (where
> possible).
> >
> > Bottom line: feel free to turn this warning off.
> >
> > Richard
> >
> >> On Oct 16, 2021, at 5:55 AM, Markus Läll <markus.l2ll at gmail.com> wrote:
> >>
> >> Hi!
> >>
> >> Is there any consensus on unticked promoted constructors -- are they
> generally safe to use?
> >>
> >> Currently the warning is part of -Wall, but having promoted
> constructors unticked is just aesthetically nicer.
> >>
> >>
> >> Thanks,
> >>
> >> --
> >> Markus Läll
>
>
> --
> Adam Gundry, Haskell Consultant
> Well-Typed LLP, https://www.well-typed.com/
>
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> 118 Wymering Mansions, Wymering Road, London W9 2NF, England
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-- 
Markus Läll
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