[Feature Request]: nix flake formatter output

[Familex]

Checklist

• I am using an up-to-date version.
• I have read the documentation.
• I have searched existing issues.

Description

outputs.formatter.<system> output used by nix fmt and formats all .nix files in project. I believe, the flake.nix is manually formatted at this point...

Solution

https://github.com/NixOS/nixfmt can be used

Alternatives

No response

[zierf]

Just checked, I have nix lsp (nil) and formatter (nixpkgs-fmt) installed.

Using it on my provided Flake in #200 doesn't change anything in the file, it "is already formatted". And it doesn't seem too far off what @xarvex was using when we fixed video playback on Nix and enabled hardware acceleration (#417). I triggered the formatter and it was changing nothing (though I was expecting many little changes).

However, the formatter has some very strong opinions about line breaks near curly braces (e.g. after let statements) and doesn't care at all about those when merging lists ([ ]) ++ ([ ]).
I've seen better, the formatter is far from rustfmt.

I simply chose one at the time and I don't have any strong preferences. But this topic seems to provide an abundance of choices for different alternatives instead of a common standard tool.

I'm still rather open to this, but ideally it should be simple, automatic and available for most code editors out there.

[Familex]

@zierf nix fmt don't interact with code editor. It is just a command to run before commit.

I don't think it makes much difference which package we should use (because there is only one file). I'm simply suggesting to pin something.

I use alejandra as default nix formatter and it messes file up.

[xarvex]

Thus far I have been using nixfmt-rfc-style as the formatter, as that is the official formatter used in nixpkgs. I can totally go ahead and expose the formatter attribute, I had forgotten about that.

[xarvex]

Ouch, was a bit of a diff after that nix fmt, I think at some point I had removed the formatter from my PATH from my Nix configuration as I was putting all development tools into shells. But, at least the problem won't occur again. 😅