lib.formats.keyValue: init

  };

  keyValue = {

    # Represents lists as duplicate keys

    listsAsDuplicateKeys ? false,

    # Alternative to listsAsDuplicateKeys, converts list to non-list

    # listToValue :: [Atom] -> Atom

    listToValue ? null,

    ...

    }@args:

    assert !listsAsDuplicateKeys || listToValue == null;

    {

    type = with lib.types; let

      singleAtom = nullOr (oneOf [

        bool

        int

        float

        str

      ]) // {

        description = "atom (null, bool, int, float or string)";

      };

      atom =

        if listsAsDuplicateKeys then

          coercedTo singleAtom lib.singleton (listOf singleAtom) // {

            description = singleAtom.description + " or a list of them for duplicate keys";

          }

        else if listToValue != null then

          coercedTo singleAtom lib.singleton (nonEmptyListOf singleAtom) // {

            description = singleAtom.description + " or a non-empty list of them";

          }

        else

          singleAtom;

    in attrsOf atom;

    generate = name: value:

      let

        transformedValue =

          if listToValue != null

          then

            lib.mapAttrs (key: val:

              if lib.isList val then listToValue val else val

            ) value

          else value;

      in pkgs.writeText name (lib.generators.toKeyValue (removeAttrs args ["listToValue"]) transformedValue);

  };

  gitIni = { listsAsDuplicateKeys ? false, ... }@args: {

    type = with lib.types; let