Stricter type (alias) for module parser?

The parser result is a list of statements at the moment. Are there any plans to add a stricter/richer type or type alias to only support valid combinations of statements, like only one module declaration at the top of the file? This is partially related to the question in https://github.com/Bogdanp/elm-ast/pull/7. Or should something like this be done in some elm-ast-extra package?