There is another interesting (I would say more challenging) talk of Sam Rowe called “Complex Animations Done Well” which tries to introduce complexity into the elm architecture, i.e. multiple states management: true state, current visual state, target visual state instead of just one single state.
This is promising and I wish the community will one day tackle these problems and succeed. Kind of vuejs philosophy to fit small AND big (= complex) projects ( The Progressive JavaScript Framework ).
If you are reading Sam:
Could you make a repo on your github demonstrating the spring and exit animation examples using this states management?
Do you plan to publish a package?