{
  npins ? import ../npins,
  lib ? import "${(import ../npins).nixpkgs}/lib",
  ...
}:

let
  # read the current directorys files and pipe the result through a list of functions
  overlays = builtins.foldl' (x: f: f x) (builtins.readDir ./.) [
    # convert to a list containing just the attribute names
    (builtins.attrNames)
    # drop "default.nix" from the list
    (builtins.filter (name: name != "default.nix"))
    # map the list to a name-value pair with a name that has the last  4 chars (".nix") stripped, and a value that is the contents of that given file
    (builtins.map (name: {
      inherit name;
      value = import ./${name} { inherit npins; };
    }))
    # convert the resulting list to an attribute set
    (builtins.listToAttrs)
  ];

in
overlays
// {
  default = lib.flatten (builtins.attrValues overlays);
}