Lambda the Ultimate

Is this possible? Have static typing, meaning all types are defined at compile time, and at the same time have direct read/write access to the abstract syntax tree of the program?

Maybe this is possible if type definitions are not part of the AST.

Maybe I am missing or confusing sth. here...

Let me ask a more practical question: How would ANSI C, as an example, would have to be extended in order to provide direct read and write access to the abstract syntax tree at runtime while not loosing its compile-time type-checking feature.

edit: I like to clarify that what I mean by "AST" is not nessessarily a datastructure representing the entire program's contents but can also be seen as a typed representation of the program's entities: e.g. the language exposes the functions etc. as editable values. So the question is: If the program entities (is there a better word?) may be manipulated at runtime, is it still possible to type-check the program at compile-time? Or what restrictions must be applied to the access in order to not loose the compile-time-check-ability.