For example I could describe my application with Wasp, write some code generator and generate my own code with it?
Would it make any sense to use it like this?
So yes, you could use just Analyzer to produce AppSpec, and then write your own generator that will based on that AppSpec generate your own code! AppSpec currently exists only as Haskell in-memory data structure, but it could be relatively easy serialized via JSON and then imported in some other language.
You can see more about this in this README, there is a nice diagram showing parts of compiler (Analyzer, AppSpec, Generator): https://github.com/wasp-lang/wasp/tree/main/waspc#readme .
The reason why we already ensured this split was because the plan is in the future to have multiple different Generators, and also to allow users to write either their whole Generators or plugins that modify AST (AppSpec). We haven't explored this further yet, and probably won't push much in this direction until we get to Wasp 1.0, but we certainly want to work on it more in the future!