[trishume]

This is a really cool example of tree diffing via path finding. I noticed that this was the approach I used when I did tree diffing, and sure enough looks like this was inspired by autochrome which was inspired by my post (https://thume.ca/2017/06/17/tree-diffing/).

I'm curious exactly why A* failed here. It worked great for me, as long as you design a good heuristic. I imagine it might have been complicated to design a good heuristic with an expanded move set. I see autochrome had to abandon A* and has an explanation of why, but that explanation shouldn't apply to difftastic I think.

[dan-robertson]

I think (maybe I’m wrong) that your graph searches correspond to diffing single lists and you can have an expensive diagonal step to recurse into two sublists whereas the tool in this post has extra nodes for every token and extra edges for inserting/deleting delimiters. That seems to be the biggest difference to me and I guess is what you mean by it being complicated to design a good heuristic for the expanded move set. I agree it sounds complicated. I think that my guess was that bigger graphs would make things harder but that isn’t a reason for A* to fail.