Hey! I am currently on the jouney of learning nix and modularizing my config. I tried adding a basePath to my flake.nix because I thought it's a good idea to make the paths absolute but now when I try to rebuild I get the error

"error: cannot coerce a set to a string"

and I have no clue what that even means and also didn't find a clear explanation on the internet.

It would be amazing if someone could help me.

my code for flake.nix looks like this:

{
 description = "NixOS configuration";

  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
    home-manager.url = "github:nix-community/home-manager";
    home-manager.inputs.nixpkgs.follows = "nixpkgs";
    alejandra.url = "github:kamadorueda/alejandra/3.0.0";
    alejandra.inputs.nixpkgs.follows = "nixpkgs";
  };

  outputs = inputs @ {
    nixpkgs,
    home-manager,
    alejandra,
    ...
  }: 
let 
        homeDir = builtins.getEnv "HOME";
        basePath = homeDir + "/nixos-config";
in 
{
     nixosConfigurations = {
      tunix = nixpkgs.lib.nixosSystem {
        system = "x86_64-linux";
        modules = [
          builtins.toPath "${basePath}/hosts/lat"
          builtins.toPath "${basePath}/configuration.nix"
          {
            _module.args = {inherit alejandra;};
          }
          home-manager.nixosModules.home-manager
          {
            home-manager.useGlobalPkgs = true;
            home-manager.useUserPackages = true;
            home-manager.users.marri = import builtins.toPath "${basePath}/home.nix";

            # Optionally, use home-manager.extraSpecialArgs to pass
            # arguments to home.nix
          }
        ];
      };
    };
  };
}

The reason the let in is not at the start but at the outputs section is this issue:
https://github.com/NixOS/nix/issues/3966

In reply to @accelbread:matrix.org
Is the flake.lock file format documented anywhere?

https://github.com/NixOS/nix/blob/bff5c94184e0eee2a093f3e04d4cec5010de81c7/src/nix/flake.md#lock-files

This goes technical in-detail, overall searching for flake.lock inside nix.git might also help understanding it on a lower-level: https://github.com/search?q=repo%3ANixOS%2Fnix%20flake.lock&type=code

In reply to @phileas:asra.gr

https://github.com/NixOS/nix/blob/bff5c94184e0eee2a093f3e04d4cec5010de81c7/src/nix/flake.md#lock-files

This goes technical in-detail, overall searching for flake.lock inside nix.git might also help understanding it on a lower-level: https://github.com/search?q=repo%3ANixOS%2Fnix%20flake.lock&type=code