2024/11/15

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2024-11-15 01:23:00 +0100Leary(~Leary@user/Leary/x-0910699) Leary
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2024-11-15 01:17:40 +0100Lord_of_Life(~Lord@user/lord-of-life/x-2819915) Lord_of_Life
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2024-11-15 00:56:35 +0100peterbecich(~Thunderbi@syn-047-229-123-186.res.spectrum.com) peterbecich
2024-11-15 00:49:10 +0100arthurvl(~arthurvl@77-174-49-144.fixed.kpn.net) earthy
2024-11-15 00:48:39 +0100 <sm> found!
2024-11-15 00:48:37 +0100 <lambdabot> Good to know.
2024-11-15 00:48:36 +0100 <sm> @where+ wiwik https://gotchamana.github.io/wiwinwlh What I Wish I Knew When Learning Haskell, Stephen Diehl
2024-11-15 00:47:05 +0100jle`(~jle`@2603:8001:3b02:84d4:4ba:cd34:52ca:7a5) jle`
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2024-11-15 00:41:13 +0100acidjnk(~acidjnk@p200300d6e7283f73687bc11ede7922f8.dip0.t-ipconnect.de) (Ping timeout: 245 seconds)
2024-11-15 00:34:10 +0100ljdarj1ljdarj
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2024-11-15 00:31:05 +0100ljdarj1(~Thunderbi@user/ljdarj) ljdarj
2024-11-15 00:30:32 +0100 <carbolymer> ah
2024-11-15 00:30:01 +0100aljazmc(~aljazmc@user/aljazmc) (Remote host closed the connection)
2024-11-15 00:29:03 +0100 <jackdk> The problem is I didn't know `a` at the time. (I was trying to write some servant-flavoured stuff, and wanted to provide an analogue to `ToServantApi` that extracted a single field). So I don't actually know the final type (because there are other TFs involved) but I know GHC does
2024-11-15 00:26:44 +0100 <carbolymer> jackdk: maybe something in this direction https://paste.tomsmeding.com/Og2LnIpN ?
2024-11-15 00:24:54 +0100nek0(~nek0@user/nek0) (Quit: The Lounge - https://thelounge.chat)
2024-11-15 00:20:06 +0100 <carbolymer> s/though/tough
2024-11-15 00:19:05 +0100 <carbolymer> jackdk: ah, you can't modify the original class - that' s though
2024-11-15 00:10:34 +0100rvalue-rvalue
2024-11-15 00:07:19 +0100rvalue(~rvalue@user/rvalue) (Ping timeout: 260 seconds)
2024-11-15 00:06:26 +0100rvalue-(~rvalue@user/rvalue) rvalue
2024-11-15 00:03:51 +0100 <jackdk> carbolymer: I don't understand your suggestion. The typeclass I want to type-family-ify exists and I cannot change it (concrete example: `GHC.Records.HasField`), but I want a type family that can select the field type. This example fails with "The RHS of an associated type declaration mentions out-of-scope variable ‘z’ All such variables must be bound on the LHS" https://www.irccloud.com/pastebin/4aygJmq9/MakeATypeFamily.hs
2024-11-14 23:54:44 +0100xff0x(~xff0x@2405:6580:b080:900:4913:54f9:72cb:8a89)
2024-11-14 23:50:18 +0100 <carbolymer> or `class (F x y ~ z) => Foo x y z where F x y :: Type`
2024-11-14 23:49:53 +0100 <carbolymer> F x y :: Type
2024-11-14 23:49:53 +0100 <carbolymer> class Foo' x y where
2024-11-14 23:49:53 +0100 <carbolymer> jackdk: well why not:
2024-11-14 23:48:37 +0100 <carbolymer> https://wiki.haskell.org/Functional_dependencies_vs._type_families
2024-11-14 23:48:37 +0100 <carbolymer> https://gitlab.haskell.org/ghc/ghc/-/wikis/tf-vs-fd
2024-11-14 23:48:37 +0100 <carbolymer> thanks geekosaur. I've found some resources on tf vs fd:
2024-11-14 23:48:22 +0100tromp(~textual@92-110-219-57.cable.dynamic.v4.ziggo.nl) (Quit: My iMac has gone to sleep. ZZZzzz…)
2024-11-14 23:45:53 +0100 <geekosaur> (aside from the big one, that ghc isn't going to get actual type lambdas that way possibly ever)
2024-11-14 23:45:32 +0100 <jackdk> I had hoped that there was a decent idiom for writing a type family that could compute z from `class Foo x y z | x y -> z` but nobody could tell me one
2024-11-14 23:45:26 +0100JuanDaugherty(~juan@user/JuanDaugherty) (Quit: JuanDaugherty)
2024-11-14 23:45:19 +0100 <geekosaur> does this mean there are still some issues with tyfams?
2024-11-14 23:45:01 +0100 <geekosaur> huh
2024-11-14 23:44:44 +0100 <geekosaur> I mean, we've already ditched backward compatibility in so many other ways, anyone who wants to stay with mtl+fundeps can keep using mtl2
2024-11-14 23:44:30 +0100 <jackdk> Just yesterday I wanted to turn a relation expressed in fundeps into a type-family-shaped thing and the best suggestion I got was "don't, pick over the type using generics instead"
2024-11-14 23:44:19 +0100 <shapr> The Revenge of, uh, something
2024-11-14 23:44:02 +0100Everything(~Everythin@178-133-104-20.mobile.vf-ua.net) Everything
2024-11-14 23:43:48 +0100 <geekosaur> …but that was over a decade ago. maybe it's time for mtl3: the type families edition
2024-11-14 23:43:10 +0100 <geekosaur> (and maybe a performance issue)
2024-11-14 23:42:52 +0100 <geekosaur> (IIRC there were a few problems with type families back then that meant the mtl folks went with monads-fd, including a bug in older ghcs)
2024-11-14 23:42:29 +0100michalz(~michalz@185.246.207.203) (Remote host closed the connection)