{ lib }:

let mkProfileAttrs =
  /**
    Synopsis: mkProfileAttrs _path_

    Recursively collect the subdirs of _path_ containing a default.nix into attrs.
    This sets a contract, eliminating ambiguity for _default.nix_ living under the
    profile directory.

    Example:
    let profiles = mkProfileAttrs ./profiles; in
    assert profiles ? core.default; 0
    **/
  dir:
  let
    imports =
      let
        files = lib.safeReadDir dir;

        p = n: v:
          v == "directory"
          && n != "profiles";
      in
      lib.filterAttrs p files;

    f = n: _:
      lib.optionalAttrs
        (lib.pathExists "${dir}/${n}/default.nix")
        { default = "${dir}/${n}"; }
      // mkProfileAttrs "${dir}/${n}";
  in
  lib.mapAttrs f imports;
in mkProfileAttrs