It seems like to make this work, we need clarity around what's the public interface and what's the implementation. Some implementation details need to be visib

It seems like to make this work, we need clarity around what's the public interface and what's the implementation. Some implementation details need to be visible to debuggers and for analysis, but hidden in "regular" code so that you can substitute a different implementation without invalidating constraints. For example, functions normally have names for debugging purposes, but the names can't be relied on in "regular" code or you wouldn't be able to rename them without breaking things. It may be better if the names aren't visible at runtime at all. The reason Python function decorators have these issues is due to a lack of structure; a lot of metadata is just there for anybody to use, with no constraints. It's also possible to do this by convention - for example, many things in Go's reflection package will break abstraction boundaries if you use them the wrong way. It's less of an issue if you have strong language conventions against doing that. In many scripting languages, the conventions for when you can use metadata are weaker.