| 16 Apr 2026 |
 EsperLily [she/her] | i haven't used flake-parts myself. looking at it right now, it has a whole perSystem thing and it looks like you're supposed to do something like perSystem = { config, pkgs, ... }: { packages.foo = pkgs.callPackage ./foo.nix {}; }? my inclination would be to figure out how you look up the current system (is it just pkgs.stdenv.hostPlatform.system or is there a better way to check, such as is it available just as an argument here?) and to then just conditionally expose a packages.aerospace-focus-fzf package depending on whether that system is darwin. something like perSystem = { lib, config, pkgs, ... }: { packages.${lib.optionalDrvAttr pkgs.stdenv.hostPlatform.isDarwin "aerospace-focus-fzf"} = aerospace-focus-fzf; } | 09:26:49 |
 Randy Eckenrode | I remember the previous discussion about hardening flags, so LGTM. I approved and added it to the merge queue. | 10:42:28 |
 xored | I tried this with mkIf and some part of flake-parts was referencing the missing platform, I’m not sure what optionalDrv… does but I’ll try later | 12:25:06 |
| Randy Eckenrode | I second the suggestion to set meta.platforms to lib.platforms.darwin. That flakes allow packages to vary per system feels like a footgun. You’ll get a worse error message on unsupported platforms (i.e., Nix will complain about a missing attribute instead of telling you the platform is unsupported), and it adds complexity to the flake definition. | 13:15:08 |
| Randy Eckenrode | I can understand the motivation (avoiding the need to eval the package to determine supported platforms), but it makes the UX worse. | 13:18:05 |
| xored | the problem is I have more than one package that has this issue, e.g the arrs don't build on darwin at this point, so I need to force them on linux only, i've been experimenting with patching pkgs-by-name-for-flake-parts (which handles the linux ones), but I'd need to need how to have it behave properly to begin with | 17:36:53 |
| xored | and I have meta.badPlatforms on the arrs btw, nix screams on refusing to evaluate | 17:37:34 |
| xored | * the problem is I have more than one package that has this issue, e.g the arrs don't build on darwin at this point, so I need to force them on linux only, i've been experimenting with patching pkgs-by-name-for-flake-parts (which handles the linux ones), but I'd need to know how to have it behave properly to begin with | 17:39:36 |
| EsperLily [she/her] | optionalDrvAttr cond s is just if cond then s else null, so this avoids defining the key unless the condition holds | 18:03:52 |
| EsperLily [she/her] | (technically that method exists to use for derivation attributes, because nulls get omitted from the environment, but it works equally well as shorthand for "${if cond then "key" else null} = value syntax) | 18:04:56 |
| EsperLily [she/her] | * (technically that method exists to use for derivation attributes, because nulls get omitted from the environment, but it works equally well as shorthand for "${if cond then "key" else null} = value; syntax) | 18:05:06 |
| EsperLily [she/her] | i guess the other idea is to see if you can do this in the top-level flake section, if you define e.g. flake.packages.aarch64-darwin.aerospace-focus-fzf maybe that will get merged with the perSystem stuff? | 18:07:34 |
| xored | unfortunately flake-parts does something weird with flake.packages and i can't seem to export packages that way (i believe it tries to transpose system into it, I might be wrong | 18:10:56 |
| EsperLily [she/her] | does it give you some sort of error? I'm digging into the code but there's a lot here. it looks to me like perSystem is a deferred module (which is a thing i haven't really explored how it works yet) and it uses that to construct config.allSystems as a lazy attrset where each attr is a system and the value is the perSystem module module set evaluated with that system. And then for each of the options defined in perSystem it also defines flake.${option}.${system} = config.allSystems.${system}.${option}. The packages attrset is lazy so you can't write packages.foo = mkIf (or rather if you do I think what will happen is accessing that package from any system where that evaluates false will throw an error as package doesn't define an empty value). But defining packages.${if stdenv.hostPlatform.isDarwin then "aerospace-focus-fzf" else null} = aerospace-focus-fzf; still seems like it should work? and similarly, just defining flake.packages.aarch64-darwin.aerospace-focus-fzf should also work? | 19:45:39 |
| EsperLily [she/her] | * does it give you some sort of error? I'm digging into the code but there's a lot here. it looks to me like perSystem is a deferred module and it uses that to construct config.allSystems as a lazy attrset where each attr is a system and the value is the perSystem module module set evaluated with that system. And then for each of the options defined in perSystem it also defines flake.${option}.${system} = config.allSystems.${system}.${option}. The packages attrset is lazy so you can't write packages.foo = mkIf (or rather if you do I think what will happen is accessing that package from any system where that evaluates false will throw an error as package doesn't define an empty value). But defining packages.${if stdenv.hostPlatform.isDarwin then "aerospace-focus-fzf" else null} = aerospace-focus-fzf; still seems like it should work? and similarly, just defining flake.packages.aarch64-darwin.aerospace-focus-fzf should also work? | 19:46:21 |
| EsperLily [she/her] | * does it give you some sort of error? I'm digging into the code but there's a lot here. it looks to me like perSystem is a deferred module and it uses that to construct config.allSystems as a lazy attrset where each attr is a system and the value is the perSystem module set evaluated with that system. And then for each of the options defined in perSystem it also defines flake.${option}.${system} = config.allSystems.${system}.${option}. The packages attrset is lazy so you can't write packages.foo = mkIf (or rather if you do I think what will happen is accessing that package from any system where that evaluates false will throw an error as package doesn't define an empty value). But defining packages.${if stdenv.hostPlatform.isDarwin then "aerospace-focus-fzf" else null} = aerospace-focus-fzf; still seems like it should work? and similarly, just defining flake.packages.aarch64-darwin.aerospace-focus-fzf should also work? | 19:46:34 |
| xored | when i tried it back with mkIf I got option packages.aarch64-darwin.foo option was accessed but not defined kind of error | 19:47:30 |
| EsperLily [she/her] | with mkIf I'd expect an error that looks like "The option `${showOption loc}' was accessed but has no value defined. Try setting the option." | 19:48:02 |
| xored | yeah | 19:48:09 |
| xored | i'll try in a sec fixing my rust crap :P | 19:48:19 |
| xored | i meant crab, surely :kappa: | 19:48:25 |
| EsperLily [she/her] | that's what happens with a lazyAttrsOf when the element type doesn't define an empty value | 19:48:26 |
| EsperLily [she/her] | * that's what happens with a lazyAttrsOf when the element type doesn't define an empty value and you use mkIf | 19:48:40 |
| EsperLily [she/her] | but if you got it accessing packages.aarch64-darwin.foo then that means your mkIf condition was wrong | 19:49:28 |
| EsperLily [she/her] | because that error should only show up when the mkIf condition evaluates to false | 19:49:43 |
| EsperLily [she/her] | but again i'm recommending you do the dynamic attribute approach rather than the mkIf so that way it's simply not defined in non-darwin package sets | 19:50:14 |
| EsperLily [she/her] | you only need mkIf if you're relying on other parts of the config. it looks like for perSystem, the argument system is a specialArgs so you can use that strictly. actually I suggested before writing ${if stdenv.hostPlatform.isDarwin then … } but you can't actually do that as stdenv comes from pkgs which is presumably not a special arg. you can refer to the system arg safely this way though | 19:52:37 |
| xored | EsperLily [she/her] Randy Eckenrode that seems to have worked, thank you both | 20:09:41 |
| xored | now i just need to figure out the hellhole that is packagesFromDirectoryRecursive to make the auto packages exclude a platform somehow | 20:10:55 |
| xored | but for manual packages seems to have done the trick | 20:11:06 |
