Nix

Base syntax

Prefer 'set patterns' over named attribute sets in function declarations for all functions except overlays:

{x, y, z}: x + y + z;

rather than:

foo: foo.x + foo.y + foo.z;

For overlays, use prev and final as arguments over self and super. For overlays which are not top-level (i.e. to overlay a set contained within pkgs), use similar naming (e.g. for a ROS overlay, use rosPrev and rosFinal).

Use string interpolation over string concatenation where possible:

foo = "Hello";
bar = "${foo} World";

over:

foo = "Hello";
bar = foo + " World";

Flakes

Inputs

Ensure there are no duplicate inputs (e.g. a dependency pulls in something that another input also pulls in) so less downloads are needed. If there are differences in versioning, use the newer version of the dependency. The exception to this is if two versions of an input are desired (e.g. nixpkgs-25.11 and nixpkgs-unstable).

Outputs

ROAR uses two architectures: x86_64-linux and aarch64-linux. For anything that is to be run at competition, both of these should be used in the outputs of the flake. For anything to be run only during development, only x86_64-linux is needed. When in doubt (or for simplicity), use the flake-utils eachDefaultSystem.

Formatting

All nix code should be formatted with nixfmt.