But the hard part isn't dealing with invalid parses and error recovery. The hard part is dealing with completely valid bits of code that aren't yet finished:
(doseq [x (range|cursor|)]
)
Text also doesn't provide you with stable IDs. If I previously had function "foo" in a file and now that's gone, but there's a function "bar" in the same place with roughly the same code, does that mean it was renamed? Or did foo get deleted and we need to surface that anything using foo is an error? How would you know? The only thing you have to go on is position and position can change for all sorts of other reasons. I ran into this problem with trying to do functions in single editors: when the file can change in any way, reconciling that file with your previous view of the world is tremendously difficult.