| 3 Jul 2025 |
 Teo (he/him) | I was profiling eval time of nixpkgs recently and I noticed that a lot of time was spent doing hasPrefix when evalling the haskell package set. I think this is caused by the hasPrefix call to check if stuff is part of amazonka and each call of hasPrefix re-checks if the needle is a path lol https://github.com/NixOS/nixpkgs/issues/419216
We could optimise the hasPrefix call, but maybe we should just add the list of amazonka packages to this file rather than traversing the entire haskell package set?
https://github.com/NixOS/nixpkgs/blob/a44903b927ab16b829a76f51f84bca02a7f89a0f/pkgs/development/haskell-modules/configuration-common.nix#L3352 | 19:19:35 |
 alexfmpe |
I was profiling eval time of nixpkgs
how does one even do this? I always wondered
| 20:24:38 |
| Teo (he/him) | In reply to @alexfmpe:matrix.org
I was profiling eval time of nixpkgs
how does one even do this? I always wondered
This is what I used https://github.com/NixOS/nix/pull/13220 | 20:30:51 |
| alexfmpe | Ooooh | 20:37:45 |
| 4 Jul 2025 |
 lxsameer | hey folks,do we support cabal 3.14 for development? | 15:16:38 |
| alexfmpe | not sure what "for development" means, does this answer it?
$ nix-build -A cabal-install
/nix/store/diig4i6ln0ia8xvv4kqs99klpjhlpzfl-cabal-install-3.14.2.0
| 15:38:44 |
| lxsameer | sorry for the confusion, apparently, cabal2nix does not like the cabal-version: 3.14 | 15:51:24 |
| lxsameer | in a cabal file | 15:51:28 |
 maralorn | That was I think fixed very recently on the haskell-updates. | 15:52:48 |
 ners | I found a package that has outdated dependency bounds. Trying to build it with doJailbreak , I would expect it to either succeed or fail at compile time, but:
Configuring OTP-0.1.0.0...
CallStack (from HasCallStack):
withMetadata, called at libraries/Cabal/Cabal/src/Distribution/Simple/Utils.hs:368:14 in Cabal-3.10.3.0-ab3d:Distribution.Simple.Utils
Error: Setup: Encountered missing or private dependencies:
base >=4.5.0.0 && <4.14,
bytestring >=0.9.2.0 && <0.11,
time >=1.4 && <1.10
| 16:40:27 |
| alexfmpe | cabal2nix doesn't handle conditionals properly (for now), and the deps are behind a if, so they don't survive the conversion to .nix | 17:01:15 |
| alexfmpe | https://hackage.haskell.org/package/OTP-0.1.0.0/src/OTP.cabal | 17:01:16 |
| alexfmpe | You can workaround by shoving them in with addBuildDepends | 17:01:41 |
| alexfmpe | You can see examples in the configuration-ghcjs-9.x and configuration-darwin files | 17:02:26 |
 Collin Arnett | How can I get the haddoc html files for dependencies of my project when using shellFor? I have doHaddoc turned on for my dependencies. | 18:35:27 |
| alexfmpe | It's on by default I think? | 19:35:28 |
| alexfmpe | Easiest way is to run hoogle locally | 19:35:41 |
| alexfmpe | hoogle server --local -p 8080 | 19:36:18 |
| alexfmpe | might need withHoogle = true, don't remember if default in shellFor | 19:36:48 |
| Collin Arnett | Does the hoogle server serve the haddocs as well? I'm not really sure what I'm looking for so I would like to browse the docs like I would on hackage. | 20:44:03 |
| Collin Arnett | Oh I see it does link them locally after you click on the package from hoogle. Thank you :D | 20:49:02 |
| 5 Jul 2025 |
| alexfmpe | is there a way for a nixpkgs-using project to apply an override to all haskell.packages.ghc123 like configuration-common.nix do?
or do we always need the nixpkgs.haskell.packages.${version} override cascade ? | 20:20:02 |
 sterni (he/him) | alexfmpe: haskell.packageOverrides | 23:57:26 |
| sterni (he/him) | which is the default argument for overrides passed to any specific package set, so you can't use that to further extend without doing that explicitly | 23:57:57 |
| 6 Jul 2025 |
| alexfmpe | ah damn actually this one time in particular I want the specific version thing | 00:05:26 |
| alexfmpe | because I'm messing with a boot package | 00:05:39 |
| alexfmpe | so using packageOverrides rebuilds the world | 00:05:54 |
 Alex | In reply to @alexfmpe:matrix.org
might need withHoogle = true, don't remember if default in shellFor Not default, unless it has changed recently. | 00:10:58 |
| alexfmpe | indeed | 00:12:02 |
| alexfmpe | https://github.com/NixOS/nixpkgs/blob/a697a033bd07502703b151797085e5c7b64c6f31/pkgs/development/haskell-modules/make-package-set.nix#L453 | 00:12:03 |
