{ lib, ... }:
let
  # not used in the actual type, because it breaks things. idk why, try it out
  _outputType =
    with lib;
    with types;
    functionTo submodule {
      options = {
        # before first
        options = mkOption {
          type = deferredModule;
          description = "Definition of module exposed by this kind of output";
          default = _: { };
        };
        # between first and second
        specialArgs = mkOption {
          type = attrs;
          description = "Definition of specialArgs passed to the second fixed point";
          default = _: { };
        };
        # after second
        outputs = mkOption {
          type = functionTo attrs;
          description = "Extractor for the produced flake outputs.";
          default = _: { };
        };
      };
    };
in
{
  options = with lib; {
    outputKinds = mkOption {
      type = with types; listOf anything;
      description = ''
        Definition for the kind of flake output.

        Each definition is a lambda, provided with the following variables:
        - `hasSystem`: if the system is known
      '';
      default = [ ];
    };
  };
}