2024/11/08

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2024-11-08 20:17:50 +0100Smiles(uid551636@id-551636.lymington.irccloud.com) (Quit: Connection closed for inactivity)
2024-11-08 20:15:14 +0100merijn(~merijn@128-137-045-062.dynamic.caiway.nl) merijn
2024-11-08 20:14:19 +0100 <tomsmeding> is what I meant
2024-11-08 20:14:17 +0100 <kaol> Are you sure you didn't do it with megaparsec the last time? It has more knobs including type variable for the error type.
2024-11-08 20:14:16 +0100 <tomsmeding> sure, but the Parser monad doesn't support anything more general than String
2024-11-08 20:14:09 +0100 <geekosaur> `fail :: String -> m a`
2024-11-08 20:13:57 +0100 <geekosaur> https://downloads.haskell.org/ghc/latest/docs/libraries/base-4.20.0.0-1f57/Control-Monad-Fail.html…
2024-11-08 20:13:43 +0100 <tomsmeding> "requires"?
2024-11-08 20:13:19 +0100 <geekosaur> afaik `fail` itself requires it?
2024-11-08 20:12:57 +0100 <tomsmeding> and the type that `fail` uses in the parser monad looks pretty monomorphically String
2024-11-08 20:11:50 +0100 <tomsmeding> it has `fail` if you're okay with strings
2024-11-08 20:11:41 +0100 <kqr> Hm. I'd hoped I could hook into the parser monad itself, but maybe it doesn't support failure in the way I think of it?
2024-11-08 20:11:15 +0100 <kaol> ExceptT is one option.
2024-11-08 20:07:43 +0100 <kqr> Hm. I'm looking at doing some validation in an Attoparsec parser and I want to fail the parse if the validation fails – ideally with a value of some custom error type. I feel like I have done this before but I cannot for the life of me figure out how I did it now.
2024-11-08 20:07:03 +0100longlongdouble(~longlongd@169.150.196.101) (Ping timeout: 245 seconds)
2024-11-08 20:06:06 +0100 <ncf> ah, https://en.wikipedia.org/wiki/Natural_transformation#Whiskering
2024-11-08 20:06:05 +0100 <famubu> Okay, looks like I got a few terms to look up. Thanks. Had seen horizonatal composition mentioned in the wikipedia article. Reading nlab now.
2024-11-08 20:05:10 +0100 <ncf> or pure @T @(T a)
2024-11-08 20:04:40 +0100shapr(~user@2601:19c:417e:5434:6d2c:aeb2:81b3:3df4) shapr
2024-11-08 20:04:30 +0100merijn(~merijn@128-137-045-062.dynamic.caiway.nl) (Ping timeout: 252 seconds)
2024-11-08 20:04:06 +0100 <ncf> in haskell, Tη is fmap @T pure, while ηT is pure @(T a)
2024-11-08 20:03:29 +0100 <ncf> also called horizontal compositions: https://en.wikipedia.org/wiki/Natural_transformation#Operations_with_natural_transformations
2024-11-08 20:03:09 +0100 <ncf> famubu: those are whiskerings
2024-11-08 20:00:18 +0100 <tomsmeding> perhaps wait until someone like ncf comes along lol
2024-11-08 20:00:09 +0100 <tomsmeding> I'm not sure what I just said is correct
2024-11-08 19:59:51 +0100merijn(~merijn@128-137-045-062.dynamic.caiway.nl) merijn
2024-11-08 19:58:51 +0100 <tomsmeding> the difference is that the source and target of T(mu_X) have an additional T() around them
2024-11-08 19:58:37 +0100 <tomsmeding> see e.g. the third commutative diagram: you have mu_X on the bottom arrow, and T(mu_X) on the top arrow
2024-11-08 19:58:10 +0100 <tomsmeding> they denote that by applying T to the natural transformation
2024-11-08 19:57:56 +0100 <tomsmeding> if you have a natural transformation between two functors T1 and T2, and a functor T, then you can build a natural transformation from T . T1 to T . T2
2024-11-08 19:57:09 +0100longlongdouble(~longlongd@169.150.196.101)
2024-11-08 19:56:51 +0100 <tomsmeding> famubu: a functor from C to C' consists of a mapping from Ob C to Ob C' and a mapping from the arrows in C to the arrows in C'
2024-11-08 19:51:56 +0100 <famubu> I am not that familiar with category theory.
2024-11-08 19:51:49 +0100 <famubu> * `T` is a functor.
2024-11-08 19:51:35 +0100 <famubu> is a functor. That means it's like a function whose 'argument' is a category, right? And `η` is a natural transformation, not a category.
2024-11-08 19:51:31 +0100 <famubu> I could understand `η T` part. It does the 'opposite' of flattening.
2024-11-08 19:51:19 +0100 <famubu> What is the difference between the two?
2024-11-08 19:51:16 +0100 <famubu> The commutative diagram and properties mention both `T ηand `η T`.
2024-11-08 19:51:13 +0100 <famubu> I was looking at the wikipedia page for monad in category theory: https://en.wikipedia.org/wiki/Monad_(category_theory)#Formal_definition
2024-11-08 19:51:12 +0100user363627(~user@user/user363627) (Quit: Konversation terminated!)
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2024-11-08 19:47:01 +0100longlongdouble(~longlongd@169.150.196.101)
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2024-11-08 19:46:39 +0100merijn(~merijn@128-137-045-062.dynamic.caiway.nl) (Ping timeout: 260 seconds)
2024-11-08 19:45:53 +0100 <kqr> merijn, Numeric looks good for what I need. Thanks!
2024-11-08 19:42:58 +0100noctux(~noctux@user/noctux) noctux
2024-11-08 19:42:33 +0100Tuplanolla(~Tuplanoll@91-159-69-59.elisa-laajakaista.fi) Tuplanolla
2024-11-08 19:42:27 +0100pavonia(~user@user/siracusa) (Quit: Bye!)
2024-11-08 19:41:49 +0100longlongdouble(~longlongd@2405:201:5c16:135:1989:242:cab1:419a)
2024-11-08 19:41:20 +0100merijn(~merijn@128-137-045-062.dynamic.caiway.nl) merijn