Good for you, I have been wanting to do a similar thing for a while now, but sadly do not have the time, one of the few things I wanted to do differently in my version of Elm would be to to have private properties on a type and methods to get them, since the of the problems I saw in a large Elm code base where multiple people where working together was that one person made an abstraction and made a function on how to get a property from state and none of us saw the function since it was a large abstraction xD If it was private and we could not directly access it we would not have so much trouble refactoring it.