dream2nix/modules/flake-parts/writers.nix

{flake-parts-lib, ...}: {
  options.perSystem = flake-parts-lib.mkPerSystemOption ({
    config,
    lib,
    pkgs,
    ...
  }: let
    writers = pkgs.callPackage ../../pkgs/writers {};
  in {
    options.writers = {
      writePureShellScript = lib.mkOption {
        type = lib.types.functionTo (lib.types.functionTo lib.types.package);
        description = ''
          Create a script that runs in a `pure` environment, in the sense that:
            - the behavior is similar to `nix-shell --pure`
            - `PATH` only contains exactly the packages passed via the `PATH` arg
            - `NIX_PATH` is set to the path of the current `pkgs`
            - `TMPDIR` is set up and cleaned up even if the script fails
            - out, if set, is kept as-is
            - all environment variables are unset, except:
              - the ones listed in `keepVars` below
              - ones listed via the `KEEP_VARS` variable
        '';
      };
      writePureShellScriptBin = lib.mkOption {
        type = lib.types.functionTo (lib.types.functionTo (lib.types.functionTo lib.types.package));
        description = ''
          Creates a script in a `bin/` directory in the output; suitable for use with `lib.makeBinPath`, etc.
          See {option}`writers.writePureShellScript`
        '';
      };
    };

    config.writers = {
      inherit
        (writers)
        writePureShellScript
        writePureShellScriptBin
        ;
    };
  });
}