showList ts = error $ "internal error: bad list format (list arguments are always 0 or 2, but\n"
                ++ "  this list has " ++ show (length ts) ++ " arguments.\n"
                ++ "  The list arguments are: " ++ show ts
showList ts = error $ "internal error: bad list format (list arguments are always 0 or 2, but\n"
                ++ "  this list has " ++ show (length ts) ++ " arguments.\n"
                ++ "  The list arguments are: " ++ show ts
showList ts = error $ "internal error: bad list format (list arguments are always 0 or 2, but\n"
                ++ "  this list has " ++ show (length ts) ++ " arguments.\n"
                ++ "  The list arguments are: " ++ show ts