2024/05/16

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2024-05-16 22:42:21 +0200 <talismanick> fair enough
2024-05-16 22:42:15 +0200 <glguy> If I'm using transformers it's behind a newtype
2024-05-16 22:42:09 +0200 <talismanick> I mean, say what you will about transformer stacks with tons of parameters, lens signatures, etc, but I feel like Except is universally understood
2024-05-16 22:42:07 +0200califax_califax
2024-05-16 22:41:03 +0200califax_(~califax@user/califx)
2024-05-16 22:41:01 +0200 <talismanick> if anything, that's all the stronger an argument for getting rid of (Either String) and using the transformers package, given that a homegrown error type is liable to be a source of problems itself
2024-05-16 22:40:50 +0200ChaiTRex(~ChaiTRex@user/chaitrex) (Ping timeout: 260 seconds)
2024-05-16 22:40:50 +0200califax(~califax@user/califx) (Ping timeout: 260 seconds)
2024-05-16 22:38:53 +0200 <glguy> The nice solution is to make a new datatype with documented behaviors you rely on. Piecing together behaviors from generic types can be nice in a pinch but it's challenging for the future reader to know what properties of the generic thing are being relied upon later
2024-05-16 22:38:43 +0200 <talismanick> err, Except
2024-05-16 22:37:24 +0200 <talismanick> I mean, I guess that's a win for convenient typeclass polymorphism anyways
2024-05-16 22:36:53 +0200 <talismanick> so, the right solution is probably to tear out Either altogether and use Error from transformers?
2024-05-16 22:35:53 +0200waleee(~waleee@h-176-10-144-38.NA.cust.bahnhof.se)
2024-05-16 22:35:34 +0200EvanR_EvanR
2024-05-16 22:33:56 +0200 <glguy> I think there are just too many options for there to be a sensible implementation. Picking one arbitrarily will just lead to surprise bugs
2024-05-16 22:32:00 +0200 <ncf> https://gitlab.haskell.org/ghc/ghc/-/issues/9588
2024-05-16 22:31:45 +0200 <talismanick> (if we get Bialternative and it lets us do what we wanted from Alternative/MonadPlus)
2024-05-16 22:31:00 +0200 <talismanick> there is https://github.com/ekmett/bifunctors/issues/126 in the works, which might be enough
2024-05-16 22:30:44 +0200pavonia(~user@user/siracusa)
2024-05-16 22:28:41 +0200 <talismanick> glguy: yeah, that looks right... am I missing something obvious about why this is wrong?
2024-05-16 22:27:51 +0200 <talismanick> ski: do you think I maybe need to add some newtype wrappers using Ap to lift Monoid to Alternative?
2024-05-16 22:27:50 +0200 <glguy> so this? instance Monoid e => Alternative (Either e) where empty = Left mempty; Right x <|> _ = Right x; _ <|> Right x = Right x; Left x <|> Left y = Left (x <> y)
2024-05-16 22:27:04 +0200 <talismanick> (deriving these instances for the reversible Printer type, that is)
2024-05-16 22:26:12 +0200 <talismanick> relaxing the <4.13 constraint went smoothly, except that newtype-deriving the all-important Alternative and MonadPlus failed with the error "no instance for MonadPlus (Either String)"
2024-05-16 22:25:39 +0200 <ski> (doesn't seem to be one for `Alternative', though)
2024-05-16 22:25:29 +0200 <ski> hmm .. i see `Monoid e => Monoid (Validation e a)'
2024-05-16 22:24:35 +0200 <talismanick> for context, I'm playing around with a package promising bidirectional parsing <-> prettyprinting on the basis of monadic profunctoriality, but it's bitrotted as GHC has evolved
2024-05-16 22:22:31 +0200 <talismanick> Is it something to do with kind, as in biasing a choice so it then acts "as if" it were `* -> *` like `Maybe` breaks some law I haven't thought of yet?
2024-05-16 22:22:28 +0200 <talismanick> Why is there no `Monoid e -> Alternative (Either e)` instance?
2024-05-16 22:13:45 +0200sord937(~sord937@gateway/tor-sasl/sord937) (Quit: sord937)
2024-05-16 22:10:44 +0200kadir(~kadir@88.251.51.100)
2024-05-16 22:10:15 +0200talismanick(~user@2601:644:937c:ed10::ae5)
2024-05-16 22:09:06 +0200danse-nr3(~danse-nr3@rm-19-5-133.service.infuturo.it)
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2024-05-16 22:02:23 +0200L29Ah(~L29Ah@wikipedia/L29Ah)
2024-05-16 22:00:54 +0200L29Ah(~L29Ah@wikipedia/L29Ah) ()
2024-05-16 21:58:57 +0200L29Ah(~L29Ah@wikipedia/L29Ah)
2024-05-16 21:57:47 +0200raehik(~raehik@rdng-25-b2-v4wan-169990-cust1344.vm39.cable.virginm.net) (Ping timeout: 256 seconds)
2024-05-16 21:56:36 +0200wootehfoot(~wootehfoo@user/wootehfoot) (Read error: Connection reset by peer)
2024-05-16 21:52:22 +0200philopsos(~caecilius@user/philopsos) (Ping timeout: 246 seconds)
2024-05-16 21:51:58 +0200immae(~immae@2a01:4f8:141:53e7::)
2024-05-16 21:51:04 +0200sudden(~cat@user/sudden)
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2024-05-16 21:39:25 +0200sudden(~cat@user/sudden) (Ping timeout: 272 seconds)
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2024-05-16 21:32:34 +0200bsima(~bsima@2604:a880:400:d0::19f1:7001)
2024-05-16 21:32:01 +0200remmie(ianremsen@tilde.team)
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