This builds on examples and code from https://package.elm-lang.org/packages/joakin/elm-canvas/latest/ Thanks!

Setup: Use elm-live from https://www.npmjs.com/package/elm-live

Command to build with hot-reload elm-live src/Ball.elm --open -- --output=ball.js --debug

Building a regular version elm-live src/Ball.elm --open -- --output=ball.js

To build and optimize use, and make sure index.html points at ball.min.js ./optmize.sh src/Ball.elm

Files that should be zipped ball.min.js elm-canvas.js elm.json index.html

elm-live src/DynamicParticles.elm --open -- --output=DynamicParticles.js