The problem with these low level frameworks is that you end up with a lot of bug and security issues you don't even know you have. I mean, for learning purpose

The problem with these low level frameworks is that you end up with a lot of bug and security issues you don't even know you have. I mean, for learning purposes....go ahead. I'll never use it for any production web application which requires authentication, permissions and database access. You end up with an undocumented , poorly tested, half baked version of what Django or rails give you.