I mostly skimmed the article but isn’t he basically talking about Lisp and the REPL? He dis mention Smalltalk but i’m pretty sure it adopted the interactivity from Lisps.

You don't get instant live update of existing variables in a REPL. The programming paradigm described is called Reactive Functional, it's the model popularized by spreadsheets.

However, spreadsheets can't create new objects programatically; new libraries for web development (React, Vue.js) are popularizing the model, but so far they're using reactive components just for high-level components, not the whole line-by-line program execution. Bret Victor's "Learnable Programming" concept (linked at the end) shows how you could apply the approach to a whole textual program.

I've got a "thisguygetsit" label for tagging web essays showing an insightful description of the fundamental problems of modern computation.

I've tagged this article with it.

What are you using to tag things in this way? I agree entirely and would love to build a collection of "this one gets it"

I'm using Pocket, though I'm planning to install TagSpaces on my NAS and migrate both my notes and bookmarks to it.

Thank you for the implicit praise!

Seems like this would be an interesting list of essays - is it publicly shared?