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

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 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

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As its author, I think -Wunticked-promoted-constructors is a misfeature. It was motivated by the fact that writing [True] when you mean '[True]

On 18/10/2021 03:19, Richard Eisenberg wrote: 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).

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Bottom line: feel free to turn this warning off.

Richard

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On Oct 16, 2021, at 5:55 AM, Markus Läll wrote:

Hi!

Is there any consensus on unticked promoted constructors -- are they

generally safe to use?

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Currently the warning is part of -Wall, but having promoted

constructors unticked is just aesthetically nicer.

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Thanks,

-- Markus Läll

-- Adam Gundry, Haskell Consultant Well-Typed LLP, https://www.well-typed.com/

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-- Markus Läll