The more I use Elm; and the more I look at other reactive frontends like React+Redux and Vue, the more I love thinking in The Elm Architecture (https://guide.elm-lang.org/architecture/) aka Model-View-Update as a pattern for GUI development.
To wit: Here's a way to implement it with Python and Tkinter for an old school reactive GUI.
https://maldus512.medium.com/how-to-setup-correctly-an-appli...
Elm is awesome! I would really like an equivalent for software/game dev
The Nu game engine might interest you. There's also FuncUI for app dev which is F# + MVU running on Avalonia.