| 4 Jun 2026 |
 sterni | I think downgrading is no longer an option. https://github.com/NixOS/nixpkgs/pull/527962 | 12:53:48 |
 Artem | sterni: 4.17 is good enough: it doesn't break the PVP... | 12:54:51 |
| Artem | also, sterni , regarding https://github.com/NixOS/nixpkgs/pull/521260#issuecomment-4622508007 let me know what you think. I think https://github.com/NixOS/nixpkgs/pull/520243 looks much better than the last time you looked at it. Even it's LLM-assisted, I think it's a good step forward. | 14:02:50 |
 alexfmpe | on our stackage nightly bump, HLS is broken on 9.10 due to apply-refact
what I don't understand is how we made it work on master as that dep was always there on cabal but was missing from hackage-packages.nix | 14:52:34 |
| alexfmpe | * on our stackage nightly bump, HLS is broken on 9.10 due to its dep, apply-refact, being broken on 9.10 period
what I don't understand is how we made it work on master as that dep was always there on cabal but was missing from hackage-packages.nix | 14:52:47 |
| alexfmpe | huuuuh technically the dependency is on HLS's cabal file, but on the hls-hlint-plugin sublibrary | 14:53:54 |
| alexfmpe | we've been adding apply-refact manually
https://github.com/NixOS/nixpkgs/blob/0a130039b0ecb0f9690581660080baca073fdd5a/pkgs/development/haskell-modules/configuration-common.nix#L237
which makes sense given the dep wasn't on hackage-packages.nix (presumably due to it being behind a cabal conditional)
but then why does the dep show up now | 14:59:46 |
| sterni | because the conditionals are resolved with impl being ghc 9.12 | 17:44:09 |
| alexfmpe | Aaah | 17:44:22 |
| 6 Jun 2026 |
 hellwolf | trying to fixing my part in haskell-updates. however, facing this optics package issue Is it being dealt:
error: Cannot build '/nix/store/6fj48f1agb8y7wyvjxqv8lmc6jabaaxq-optics-0.4.2.1.drv'.
Reason: builder failed with exit code 1.
Output paths:
/nix/store/2gvmjpzcgqa8xhq47mz9xrd5w2hm86pw-optics-0.4.2.1
/nix/store/xkdgyjjf6wvb5lp51m940ffrg81lwywf-optics-0.4.2.1-doc
| 11:38:19 |
| hellwolf | * trying to fixing my part in haskell-updates. however, facing this optics package issue Is it being dealt:
error: Cannot build '/nix/store/6fj48f1agb8y7wyvjxqv8lmc6jabaaxq-optics-0.4.2.1.drv'.
Reason: builder failed with exit code 1.
Output paths:
/nix/store/2gvmjpzcgqa8xhq47mz9xrd5w2hm86pw-optics-0.4.2.1
/nix/store/xkdgyjjf6wvb5lp51m940ffrg81lwywf-optics-0.4.2.1-doc
Last 25 log lines:
> +++ OK, passed 100 tests.
> set (lens f g) = g: OK
> +++ OK, passed 100 tests.
> Prism
> review (prism f g) = f: OK
> +++ OK, passed 100 tests.
> matching (prism f g) = g: OK
> +++ OK, passed 100 tests.
> AffineTraversal
> matching (atraversal f g) = g: OK
> +++ OK, passed 100 tests.
> set (atraversal f g) ~= flip g: OK
> +++ OK, failed as expected. Falsified (after 5 tests and 20 shrinks):
> {2->Left 1, _->Right 1}
> {_->2}
> 2
> 1
> 1 /= 2
> isRight (f s) ==> set (atraversal f g) = flip g: OK
> +++ OK, passed 100 tests; 84 discarded.
>
> 3 out of 127 tests failed (0.01s)
> Test suite optics-tests: FAIL
> Test suite logged to: dist/test/optics-0.4.2.1-optics-tests.log
> 0 of 1 test suites (0 of 1 test cases) passed.
For full logs, run:
nix log /nix/store/6fj48f1agb8y7wyvjxqv8lmc6jabaaxq-optics-0.4.2.1.drv
| 11:38:39 |
| alexfmpe | That looks like a legitimate test failure? Maybe file an issue in the library? | 13:00:45 |
| hellwolf |
- I checked out the latest https://github.com/well-typed/optics
- ran cabal test optics
- with ghc910, passes
- with ghc912, 1 failed.
| 14:01:08 |
| alexfmpe | Huh same seed? Maybe it's some ghc bug or some sketchy optimizations thing | 14:03:11 |
| alexfmpe | Definitely file issue | 14:03:24 |
| hellwolf | same seed.
reported.
Fwiw, the haskell-updates build produces 2 more errors. | 14:09:45 |
| 7 Jun 2026 |
| sterni | Let's hope this goes away with GHC 9.12.5-rc1 :) | 19:47:21 |
|  WorldsGoneMad joined the room. | 20:34:18 |
 MangoIV | I’ll try tomorrow. | 21:18:06 |
| MangoIV | Do you have a link to the actual errors (this is missing the errors I think)? Otherwise I can just reproduce tomorrow myself | 21:19:11 |
| 8 Jun 2026 |
| hellwolf | Redacted or Malformed Event | 09:39:22 |
| hellwolf | https://github.com/well-typed/optics/issues/545 | 09:41:08 |
| hellwolf | MangoIV: I am still in zurihac, fwiw. In the work room near aula auditorium. | 09:41:33 |
| hellwolf | is it a ghc bug? | 10:17:26 |
| hellwolf | I am now testing with the tip of ghc's "9.12" branch | 12:50:57 |
| hellwolf | oh, no
<no location info>: error:
panic! (the 'impossible' happened)
GHC version 9.12.4.20260607:
ASSERT failed!
in_scope InScope {ds_aP9t $dMonoid_s26Ke $dFunctor_s26Kg
$dApplicative_s26Ki lvl_s26Ox lvl_s26OA lvl_s26Wj lvl_s26Wk
lvl_s26Wl lvl_s26Wm}
tenv [a1gar :-> f_a1ga3, a1gas :-> t_a1ga4, a1gat :-> a_a1ga5,
a1gau :-> r_a1ga6]
tenvFVs {f_a1ga3, t_a1ga4, a_a1ga5, r_a1ga6}
cenv []
cenvFVs {}
tys []
cos [<t_a1gas a_a1gat -> Traversed f_a1gar r_a1gau>_R
%<'Many>_N ->_R Sym (N:Forget
<Traversed f_a1gar r_a1gau>_R
<ZonkAny 1>_P
<t_a1gas a_a1gat>_R
<()>_P)]
Call stack:
CallStack (from HasCallStack):
assertPpr, called at compiler/GHC/Core/TyCo/Subst.hs:680:5 in ghc-9.12.4.20260607-inplace:GHC.Core.TyCo.Subst
checkValidSubst, called at compiler/GHC/Core/TyCo/Subst.hs:848:17 in ghc-9.12.4.20260607-inplace:GHC.Core.TyCo.Subst
substCo, called at compiler/GHC/Core/Subst.hs:261:39 in ghc-9.12.4.20260607-inplace:GHC.Core.Subst
substExpr, called at compiler/GHC/Core/Subst.hs:268:37 in ghc-9.12.4.20260607-inplace:GHC.Core.Subst
substExpr, called at compiler/GHC/Core/Subst.hs:272:37 in ghc-9.12.4.20260607-inplace:GHC.Core.Subst
substExpr, called at compiler/GHC/Core/Subst.hs:272:37 in ghc-9.12.4.20260607-inplace:GHC.Core.Subst
substExpr, called at compiler/GHC/Core/Subst.hs:306:28 in ghc-9.12.4.20260607-inplace:GHC.Core.Subst
substBind, called at compiler/GHC/Core/Subst.hs:274:44 in ghc-9.12.4.20260607-inplace:GHC.Core.Subst
substExpr, called at compiler/GHC/Core/Subst.hs:272:37 in ghc-9.12.4.20260607-inplace:GHC.Core.Subst
substExpr, called at src/Test/Inspection/Core.hs:609:18 in inspection-testing-0.6.3-152826bba0790f422bcf299ee350f11f2d91c1b0e54a3e3d07dd75e90d5a68a4:Test.Inspection.Core
Please report this as a GHC bug: https://www.haskell.org/ghc/reportabug
| 12:54:12 |
| 10 Jun 2026 |
|  magnolia_mayhem changed their profile picture. | 12:24:25 |
| 11 Jun 2026 |
|  @tillerino:matrix.org left the room. | 07:33:26 |
|  lav joined the room. | 23:50:32 |
| 13 Jun 2026 |
|  klea (she/her) joined the room. | 21:38:54 |
