This is great--you're on to something big!

[breck7]

Really liked your demo on YouTube. A few thoughts:

• Is there an online demo, or just downloadable?
• transformation-based editing and dev time term rewriting are very clear ways of naming what I think could be the only way people program in 10 years (though making the dev experience seamless is a loooot of work. Text editors have a many decades head start, although they had to build themselves with relatively primitive tools).
• Instead of the term "holes", I prefer the term "cells". Once you start thinking of programs in 2 dimensions, you start seeing web forms and spreadsheets as editors, and there's a nice symmetry between a spreadsheet "cell" and a "hole" in your and Hazel's terminology.
• I think there's a lot of overlap with what you are doing here and what we are working on with TreeNotation (http://treenotation.org/sandbox/build/) and Ohayo (https://github.com/breck7/ohayo). Not sure what your ultimate goals are with this project, but ours are to drastically improve medical science, and if there are any ways we could help each other please reach out -- yunits@hawaii.edu.
• One thing we are working a lot on is training deep learning models to write code. IMO, our early results (eventually to be incorporated into Ohayo) are pretty conclusive--it's the future of coding and autocomplete. I would pay attention to that field (deep learning for program synthesis), as I think it's where the puck is headed and will have ramifications to what you are doing with Fructure.

[disconcision]

Thanks Breck! Unfortunately there's no clear path to taking racket code web-facing at the moment. I love Racket, but my next project will probably use something different for this reason. I also like the cell terminology, but don't currently use it as I feel it connotes fancier live/FRP stuff which I'm not currently doing (though hope to eventually!). My docket is a tad full at the moment but what you're working on is very intriguing and I'll be paying attention. I am definitely following the synthesis and learning aspects of editing; probably what I'll be looking at in detail the soonest is autocompletion along the lines of TabNine.