Simulated namespacing of checks

[mightyiam]

I'm working on a feature for numtide/devshell that creates a check for each devshell.

In a flake, all checks share a single namespace. So I'm thinking those devshell check names should be formatted like

"devshell${separator}${shellName}"

to simulate a namespace for them to prevent collision and distinguish them from the rest of the arbitrary checks a flake may have.

To me, this looks like an opportunity to formalize this naming scheme in flake-parts.

Perhaps something like

options.separator = lib.mkOption {
  type = lib.types.str;
  default = "/";
};

which flake-part modules could use?

Perhaps flake-part modules could use perSystem.checks as set and flake-parts would flatten it using a separator?

perSystem.checks = {
  devshell = shells;
  packages = config.packages;
};