Minor issues/suggestions on flake.nix and .gitignore

[LEXUGE]

ARTIQ Feature Request

Problem this request addresses

Several minor issues/suggestions on flake.nix and .gitignore

• add result produced by nix to .gitignore, and refactor .gitignore.
• format flake.nix by nixpkgs-fmt, a formatter used by nixpkgs.
• use flake-utils to avoid boilerplates like openocd-bscanspi-f and manually writing out pkgs-aarch64 and pkgs
• use pre-commit-hooks to automatically check formatting and lints with flake8, nixpkgs-fmt, and rustfmt before commit and with nix flake check.

Additional context

I locally tested flake8 lint, it seems the python codebase has a lot of lint errors.

[sbourdeauducq]

• to automatically check formatting and lints with flake8, nixpkgs-fmt

Is nixpkgs-fmt available on non-Nix platforms?

[LEXUGE]

You can install by cargo.

[bloxx12]

• format flake.nix by nixpkgs-fmt, a formatter used by nixpkgs.

archived by now, nixfmt is the new replacement. (there's alejandra as well.)

• use flake-utils to avoid boilerplates like openocd-bscanspi-f and manually writing out pkgs-aarch64 and pkgs

I'd heavily advise against this, the same thing can be done using a few lines of simple nix code. flake-utils just adds an extra abstraction layer. Furthermore, artiq only outputs stuff for two different architectures, so you'd be defining the systems in a list anyways, and at this point it'd be much easier to just do that without an abstraction library.

[bloxx12]

A minor follow up to this: adding a formatter would make working in the flake a lot easier. Alejandra and nixfmt are both great choices, and flakes output a formatter.<system> option, which would make adding a formatter as easy as adding formatter.x86-64-linux = pkgs.nixfmt-classic/pkgs.nixfmt-rfc-style/pkgs.alejandra to the flake and then running nix fmt in the repository.