What are your thoughts on Mathematica/Wolfram Language? Some of these ideas are present in it (like mathematical typesetting, interactive documentation and live code/data updates).
I don’t know much about it. From what I’ve seen it looks like something Stephen Wolfram can use really well but I wonder if other people are able to use it.
I think it has its merit. It is a very _designed_ system which is definitely a side-effect of Stephen Wolfram's attention to it. But despite it being a bit of a singular vision, I do think that it presents a very complete idea of what a programming/computer interaction environment can be. For example it is like Lisp in that it is homoiconic and the whole interface, layout/formatting, the file format and everything builds upon this.