Years back I had a mentor of sorts very strongly convince me that "degenerate" cases where code doesn't create a valid AST from the perspective of code editing and source control standpoint should be considered something of the "default case". We spend a lot more time on work-in-progress code than we ever do finished compiling code. Invalid states aren't often as "brief" as we think they are, and there are far too many reasons why you want to be able to save and even source control work-in-progress code (including things like "it's the end of the day and I want to make sure I have this backed up" and "maybe my coworker can spot why this isn't parsing because my tired eyes are not seeing it").
> If you have syntax highlighting on, it might briefly mis-highlight (e.g., it may not know what to do with the else block when it's briefly unpaired) but it will let you do it, and it will fix itself once the program is properly parseable again.
This intuition that syntax highlighting token streams already are the most generic "semantic" tool we have readily available, are very resilient to work-in-progress states, and are very fast (because we use them in real time in editors), led me to experimenting with a token-stream based diff tool. [1]
I got some really good results in my experiments with it. It gives you character-based diffs (as opposed to line-based diffs) better (more semantically meaningful) and faster than the other character-based diff tools I compared it to. You could probably use it as diff tool with git projects today if you wanted, but it would mostly just be a UI toy as git is snapshot-based rather than a patch-based source control system. (I explored the idea curious if might be useful to patch-based darcs. Darcs kept exploring the idea of trying to implement a character-based patch format in addition to or in replacement of its line-based patch format, but so far as I saw never did, but if it did, this tool would potentially be quite powerful there.) It's a neat toy/experiment though.
> If you have syntax highlighting on, it might briefly mis-highlight (e.g., it may not know what to do with the else block when it's briefly unpaired) but it will let you do it, and it will fix itself once the program is properly parseable again.
This intuition that syntax highlighting token streams already are the most generic "semantic" tool we have readily available, are very resilient to work-in-progress states, and are very fast (because we use them in real time in editors), led me to experimenting with a token-stream based diff tool. [1]
I got some really good results in my experiments with it. It gives you character-based diffs (as opposed to line-based diffs) better (more semantically meaningful) and faster than the other character-based diff tools I compared it to. You could probably use it as diff tool with git projects today if you wanted, but it would mostly just be a UI toy as git is snapshot-based rather than a patch-based source control system. (I explored the idea curious if might be useful to patch-based darcs. Darcs kept exploring the idea of trying to implement a character-based patch format in addition to or in replacement of its line-based patch format, but so far as I saw never did, but if it did, this tool would potentially be quite powerful there.) It's a neat toy/experiment though.
[1] https://github.com/WorldMaker/tokdiff