Thank you for writing this - it is more detailed that I could come up with!

I would like to add that I feel like functional approaches are more the "future" of programming than trying to iterate over imperative ones to make them as "nice" to use. So I don't really see the big deal of trying to add-on features to existing languages when you can adopt new ones (or experiment with existing ones e.g. https://github.com/getkyo/kyo for a new take on effects in Scala).