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I worked on this type of problem in the context of structured data in a version managed database, and you need more than just an AST. These types of systems ha

I worked on this type of problem in the context of structured data in a version managed database, and you need more than just an AST. These types of systems have lots of extra cross dependencies and complexities so to resolve changes you need enough to effectively replay changes from one branch onto another. You’ll find points where this will not work and at that point you need to be able to present the user with self consistent alternatives to choose between, and a way to safely save and recover the other data while they do this. That goes through the entire application stack and UI. The stuff I worked on all worked, but every application and customer that built on our core needed to develop custom rules for their work flows, and I’m not sure many ever did.

zokier 5y ago
> you need to be able to present the user with self consistent alternatives to choose between That seems very high bar to aim for compared to git (and other traditional VCS), which do not ensure that the end-result of a merge (or rebase) is in any way sensible.
- aardvark179 5y ago
  It is a high bar, but consider what happens when you get an inconstant merge. With text representing a program you get a compiler or interpreter error and can view and edit the text to fix things up. With something like a CAD drawing you may not be able to open the file, or it might be almost incomprehensible to the user (if you broke coordinate transforms or accidentally combined sub assemblies or something). If you are really unlucky you end up with something that looks okay but subtly breaks the application in a way you will not notice for a long time, and then it’s going to be hard to fix. Oh, and you need to implement this for every file type.