| 2 Dec 2025 |
 maralorn | iqubic (she/her): We use ghc 9.12 at work. It’s released and working in nixpkgs. | 18:29:22 |
 iqubic (she/her) | How can I switch my shell.nix to using 9.12? | 18:30:07 |
| maralorn | Replace all occurences of haskellPackages with haskell.packages.ghc912 | 18:30:46 |
| iqubic (she/her) | Does it still have the HLint issue? | 18:59:51 |
| iqubic (she/her) | * Does HLS for 9.12 still have the HLint issue? | 19:01:16 |
| maralorn | No | 19:16:34 |
| iqubic (she/her) | Cool! I have it built it now. | 19:45:16 |
| iqubic (she/her) | maralorn: One last issue:
It doesn't actually look like I have the HLS for 9.12 in this dev environment.
I'm getting this error from the Emacs LSP mode:
haskell-language-server exe candidates: ["haskell-language-server-9.12.2","haskell-language-server"]
Failed to find a HLS version for GHC 9.12.2
Executable names we failed to find: haskell-language-server-9.12.2, haskell-language-server
| 23:34:07 |
|  @jan:smittie.de left the room. | 23:34:50 |
| iqubic (she/her) | This is true. The only HLS related executables I have in scope are haskell-language-server-9.10.3 and haskell-language-server-wrapper | 23:35:03 |
| iqubic (she/her) | Using this shell.nix:
{ pkgs ? import <nixpkgs> {} }:
let
src = pkgs.nix-gitignore.gitignoreSource [] ./.;
myPkg = pkgs.haskell.packages.ghc912.callCabal2nix "aoc25" src {};
in
pkgs.stdenv.mkDerivation {
name = "aoc-shell";
buildInputs = [
myPkg.env.nativeBuildInputs
pkgs.cabal-install
pkgs.haskell-language-server
pkgs.hlint
pkgs.ormolu
];
}
| 23:35:33 |
| iqubic (she/her) | How can I make this work? If it's just a case of telling Emacs's lsp-mode to use a specific binary for the 9.12.2 HLS, then I can do that. However, I'm not currently seeing any relevant binaries on the $PATH | 23:48:29 |
| 3 Dec 2025 |
| maralorn | I works when you follow | 00:19:22 |
| maralorn | this | 00:20:04 |
| maralorn | and this | 00:20:21 |
| maralorn | literally | 00:20:29 |
| iqubic (she/her) | Sorry... I missed the first thing you said... I'm a dummy! Sorry | 00:28:30 |
|  iopq joined the room. | 10:56:53 |
| iopq | I'm having difficulty compiling a project with another version of nixpkgs | 10:57:16 |
| iopq | it works fine on my laptop | 10:57:22 |
| iopq | and infinite loops on my desktop | 10:57:28 |
| iopq | https://nest.pijul.com/iopq/proxy | 10:59:19 |
| 4 Dec 2025 |
| iopq | reverting to an older nixpkgs revision fixes the issue | 07:47:37 |
 sterni (he/him) | this is not enough information to help you with your issue since we can’t guess what you are trying to do with what versions of nixpkgs what the error is | 10:50:02 |
| 5 Dec 2025 |
 Magnus | I'm having problems with HLS for ghc 9.10.3 in nix 25.11. It dies and prints the following on stderr:
.haskell-language-server-9.10.3-unwrapped: internal error: ARR_WORDS object (0x4243c25cd8) entered!
Stack trace:
.haskell-language-server-9.10.3-unwrapped: Failed to get stack frames of current process: No DWARF information found: Success
0x74bfae92b970 set_initial_registers (/nix/store/6xdv0kj7ycq56l9sqip2hmxp237j78h4-ghc-9.10.3/lib/ghc-9.10.3/lib/x86_64-linux-ghc-9.10.3/libHSrts-1.0.2_thr-ghc9.10.3.so)
0x74bfae3becd0 dwfl_thread_getframes (/nix/store/1nqqjacc6dnj61jlpgz5hk9zdjbfidbr-elfutils-0.194/lib/libdw-0.194.so)
0x74bfae3be6eb get_one_thread_cb (/nix/store/1nqqjacc6dnj61jlpgz5hk9zdjbfidbr-elfutils-0.194/lib/libdw-0.194.so)
0x74bfae3bead4 dwfl_getthreads (/nix/store/1nqqjacc6dnj61jlpgz5hk9zdjbfidbr-elfutils-0.194/lib/libdw-0.194.so)
0x74bfae3bf042 dwfl_getthread_frames (/nix/store/1nqqjacc6dnj61jlpgz5hk9zdjbfidbr-elfutils-0.194/lib/libdw-0.194.so)
0x74bfae92c0b7 libdwGetBacktrace (/nix/store/6xdv0kj7ycq56l9sqip2hmxp237j78h4-ghc-9.10.3/lib/ghc-9.10.3/lib/x86_64-linux-ghc-9.10.3/libHSrts-1.0.2_thr-ghc9.10.3.so)
0x74bfae935437 rtsFatalInternalErrorFn (/nix/store/6xdv0kj7ycq56l9sqip2hmxp237j78h4-ghc-9.10.3/lib/ghc-9.10.3/lib/x86_64-linux-ghc-9.10.3/libHSrts-1.0.2_thr-ghc9.10.3.so)
0x74bfae93568f barf (/nix/store/6xdv0kj7ycq56l9sqip2hmxp237j78h4-ghc-9.10.3/lib/ghc-9.10.3/lib/x86_64-linux-ghc-9.10.3/libHSrts-1.0.2_thr-ghc9.10.3.so)
0x74bfae975d9b stg_ARR_WORDS_info (/nix/store/6xdv0kj7ycq56l9sqip2hmxp237j78h4-ghc-9.10.3/lib/ghc-9.10.3/lib/x86_64-linux-ghc-9.10.3/libHSrts-1.0.2_thr-ghc9.10.3.so)
(GHC version 9.10.3 for x86_64_unknown_linux)
Please report this as a GHC bug: https://www.haskell.org/ghc/reportabug
Anyone else seeing this, or able to offer some advice?
| 13:18:06 |
 Teo (he/him) | I think this might be: https://github.com/haskell/haskell-language-server/issues/4674 | 13:18:59 |
| maralorn | Magnus: Yes. You need to disable the hlint plugin. And someone needs to upstream this to nixpkgs master for now. | 13:20:03 |
| maralorn | Use (pkgs.haskell.lib.compose.disableCabalFlag "hlint" pkgs.haskellPackages.haskell-language-server) | 13:20:50 |
| maralorn | (and for clarification, this is agreeing with and supplementing teo (they/he)s answer.) | 13:21:27 |
| Magnus | Ah, OK... losing hlint is a bit of a blow to the usability though :( | 13:23:18 |
