| 21 Jan 2026 |
 teo (they/he) | Would it be worthwhile to add a nix expression that allows one to use ghc nightly bindists with nix? It would basically be the same as the current binary ones but targeting HEAD. I wanted to get your thoughts on this before implementing anything. I basically need to maintain this for head.hackage anyway | 14:01:16 |
| teo (they/he) | * Would it be worthwhile to add a nix expression that allows one to use ghc nightly bindists with nix? It would basically be the same as the current binary ones but targeting HEAD. I wanted to get your thoughts on this before opening a PR. I basically need to maintain this for head.hackage anyway | 14:01:41 |
 dutchie | is there an easy way to get a git version of a cabal library? I would like to use optics with GHC 9.12 but it needs this commit to pass the tests. | 14:04:26 |
 Morj | Something like this? https://github.com/maurges/re/blob/5f92f51cd437664e961b45cb2e7908e3c1bdadca/default.nix#L6-L13 | 14:17:13 |
| dutchie | that looks plausible, does it work in haskellPackages.mkDerivation as well? | 14:26:07 |
 maralorn | Huh, I have also stumbled over the optics problem. I resolved to use 9.10 instead, but that sucks because of missing hlint support in hls on that ghc. | 14:29:47 |
| Morj | I like how developPackage is only documented on the wiki, and mkDerivation is only documented in the nixpkgs manual | 14:33:01 |
| Morj | With mkDerivation can't you just supply the fetchTarball to libraryDepends? | 14:34:31 |
| dutchie | I tried this:
optics = pkgs.haskell.lib.compose.overrideSrc {
src = pkgs.fetchFromGitHub {
owner = "well-typed";
repo = "optics";
rev = "9ef04b58176c77b0ef93076196705d21b6bd6824";
hash = "sha256-TOINPPBBmUg1gbqwOX+FrqyFuch2LRX6i5NdEHUtbEY=";
};
} hpkgs.optics;
but it fails:
Running phase: setupCompilerEnvironmentPhase
Build with /nix/store/h9k9g4l9sq4y59jh5hnizhww0ing5a0a-ghc-9.12.2.
Running phase: unpackPhase
unpacking source archive /nix/store/pnx7r3pv632p5gq7dhpsi4pkpx4g59hi-source
source root is source
Running phase: patchPhase
sed: no input files
| 14:34:34 |
| dutchie | I guess I need to point it at a subdir or something | 14:35:08 |
| dutchie | hmm I can just overrideCabal { doCheck = false; } | 14:44:02 |
| dutchie | or dontCheck actually | 14:53:40 |
| 22 Jan 2026 |
|  Supreme Allied Commander Mayhem, Lord of the Nine Stars changed their display name from Grand Warden Mayhem, Punisher of Deer to Supreme Allied Commander Mayhem, Lord of the Nine Stars. | 01:27:17 |
|  LordMZTE joined the room. | 16:12:54 |
| LordMZTE | It seems like GHCJS isn't in nixpkgs. Does anyone know a good way to set it up in a dev shell?
| 16:14:23 |
 Acid Bong | twas removed: https://github.com/NixOS/nixpkgs/pull/422342 | 16:15:05 |
| Acid Bong | you can still save that recipe and use it locally tho | 16:16:12 |
| LordMZTE | I see. Surely someone must have taken over maintaining this out of tree, right?
| 16:17:10 |
 emily | AIUI the newer GHCJS is a native GHC backend and is accessible with pkgsCross.ghcjs or something | 16:22:15 |
| emily | it was the old GHCJS that was removed | 16:22:19 |
| Acid Bong | oh | 16:22:26 |
| Acid Bong | i can't find ghcjs in the search | 16:22:38 |
| emily | it's a platform, not a package | 16:31:38 |
| maralorn | Yes, the new js backend is supported in nixpkgs. | 16:40:04 |
 alexfmpe | shellFor doesn't work for cross AFAICT, but you can whip something up manually
here'ss one example: https://github.com/bfeitknecht/impli/pull/6/files | 17:09:00 |
| alexfmpe | that reminds me, I haven't checked pkgsCross.ghcjs status with 9.14 | 17:09:46 |
| alexfmpe | nix-build here builds everything with nix, nix-shell grabs the tools from nixpkgs then uses cabal-install for the rest, wrapping it so it uses js backend | 17:12:33 |
| alexfmpe | shellFor, were it to work here, would build all the deps with nix, so cabal-install/ghci(d) would only be used for your own project | 17:13:07 |
| LordMZTE | Thanks!
| 18:02:56 |
|  @wolfgangwalther:matrix.org left the room. | 19:17:01 |
