yarn
yarn start

yarn test

Loosely based on the Elm Architecture:

• Canvas is handled natively, no VDom or anything
• The tools on the left are rendered and managed with Snabbdom, mostly for DX sake
  • this section of the app are mostly pure functions and the updates are TDD'd
• As far as the app is concerned state is immutable, it's just updated by the dispatcher in index.js
  • for now it's just standard objects for the state since it's relatively flat,
  • as the application gets more complex some kind of immutability solution might need to be brought in.
• The Writing "Instruments" are initialized in the state, so that onDraw the actual instrument being used is abstracted away.

• I think the most challenging requirement was to only have one highlighter-stroke drawn at a time.
• As you can see, I tried 3 different implementations to get it working
  • finally I realized I needed to clear the canvas before redrawing it 🤦‍♂

• With some benchmarks I'd like to see the difference it would make if the mousemove listener weren't running all the time
• extract all the side-effects out into an interpreter rather than being all mixed-in
• the highlighter UX is not as clean as I'd like, would need to look into it more to see how it can be made smoother