BEEM is a library for making calls to the existing Hive API. HAF lets you define new API calls that can be made. So they do somewhat different things, and HAF doesn't necessarily replace existing API libraries for different languages (although it will create more work for those library maintainers as it should speed up the process at which new API calls are created and need support in those libraries).
That said, depending on your application, it is possible to skip using an API library and just have your application talk directly to a HAF database. In that case, you can just develop your own app-specific API, which will often have some performance advantages. Creating your own API does require some experience writing SQL queries, however. There are several python libraries for talking to SQL databases (e.g. SQLAlchemy).