Re: Proposal: deprecate Prelude.read

readEither is kind of a lie. The Read parsing system has no real error handling, so readEither just confuses people into thinking they're getting a useful message when they're not. On Fri, Oct 15, 2021 at 12:28 AM Fumiaki Kinoshita wrote:

I'm not proposing to *remove* it; my suggestion is to attach a warning perpetually (or like 20 years). Without warnings, I think just adding readMaybe would have little incentive to the ecosystem; we can't expect people to eyeball the uses of read (highly generic name) in their codebase. We've broken a lot of code using fail simply because there was no warning enabled by default.

To be clear I'm all for bringing readMaybe and readEither (I prefer the either variant because of the Nothing blindness) into Prelude. Once that happens, IMO DEPRECATE pragma should be added to encourage switching to safer variants.

2021年10月15日(金) 12:53 Carter Schonwald :

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I agree with emily david and ed

Bringing readMaybe into prelude plus adding call stack info to read are the Sane path forward to improving Haskell.

Deprecating read, insofar as how ghc deprecation works, is a lotta pain for no real hao.

On Thu, Oct 14, 2021 at 11:47 PM Edward Kmett wrote:

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A variant of this that I would support would be to bring readMaybe into Prelude from Text.Read for a good long time, and *then* to deprecate read. As it stands, read and the almost equally ugly readIO are the only Prelude facing ways for a user to really consume a Read instance, so losing read there is a heck of a blow to usability without a replacement being in place with an established pattern of usage.

-Edward

On Thu, Oct 14, 2021 at 11:16 PM Emily Pillmore wrote:

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NOPE.

On Thu, Oct 14, 2021 at 8:31 PM, Fumiaki Kinoshita

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wrote:

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It is a partial function that does not provide a call stack, and it's very slow too.

I propose deprecating Prelude.read http://prelude.read/. Adding deprecation should not break anything substantial because Hackage rejects -Werror (application code using -Werror is likely to experience a lot more breakage anyway, and I'd say it's their fault if it fails to build due to a use of read along with -Werror).

Of course those who still want to use Prelude.read http://prelude.read/ can totally ignore warnings. I believe this proposal is not that controversial.

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