Over 10 years ago, I had this sort of a prediction that, with the massive adoption of a dynamic language like javascript on both client/server sides and test-driven development gaining a lot of ground, the future of programming would be dynamic and "feedback-driven". As in, you would immediately see the results of your code as you type, based on the tests you created. To naively simplify, imagine a split screen of your code editor and a console view showing relevant watch expressions from the code you're typing.
Instead what happened was the industry's focus shifted to type safety and smart compilers, and I followed along. I'm just not smart enough to question where the whole industry was heading. And my speck of imagination on how coding would have looked like in the future wasn't completely thought out. It was just that, a speck of imagination that occurred to me as I was debugging something tedious.
Now, most of the programming language world, seem to be focusing on smarter compilers. But is there some language or platform, that focus instead on a different kind of programming paradigm (not sort of OOP, FP paradigm, may be call it the programming workflow paradigm?). May be it comes with a really strong debugger tooling that's constantly giving you feedback on what your code is actually doing. Think REPL on steroids. I can imagine there would be challenges with parsing/evaluating incomplete code syntax and functions. So I guess, the whole compiler/translator side has to be thought out from the ground up as well.
Disclaimer: There's a good chance I simply don't know what I'm talking about because I'm no language designer or even close to understanding how programming languages and it's ecosystems are created. Just sharing some thoughts I had as a junior dev back in the day.
I am familiar with hot reloads. What I had in mind was something more fine-grained, not just the UI. A simple example would be that I declared a function signature. Then I write a test. As I start to implement the function, there would be constant feedback visible based on the inputs to the functions from test I wrote. If I declare a variable 'x' by adding function params 'let x = y + z', the feedback view would show a watch expression of x based on the test's input. If I changed it to 'let x = y * z', the watch expression would immediately change. I would be constantly seeing the result of my actions. May be this is asking for too much with the current technology we have. I don't know.
Okay, sounds more like infinitest, but sadly that is Java only.
I've never really played with it, but jupyter might also be closish to your vision?
https://jupyter.org/
Let's you do python stuff and see results of your code near realtime I think?
I've looked into Elixir livebook that's probably inspired by jupyter before. Yeah, something like that but for a much more general use case.