[moregrist]

I use a notebook extensively for certain kinds of work and problems. I’ll point out specific ways that I use it to answer your questions.

> The post here mentions hypotheses, but I don't do experiments for the most part.

Debugging any hard bug is essentially making a series of hypotheses and testing them. I use a notebook to keep track and make notes when I’m knee-deep in some hairy bug.

> It mentions writing down in the notebook before writing code, but I can't test my notes, I can't really send my notes for code review.

I use a notebook primarily for design work, especially algorithmic design work.

It’s really handy for numerical stuff where I often want to transform some expression or equation and prove to myself that it’s equivalent or has certain properties.

It’s also handy for working through any algorithm where you’re manipulating a tree or a graph.

> I guess you could use it for design, but you'd lose all the advantages of word processing such as editing, links, context, etc.

I find it much faster to sketch the things I mentioned (especially diagrams!) with pen and paper when working through them. If I need to present the work or share it, I might scan the notes or I can polish them in a word processor or slide deck or whatever.

For what it’s worth, my background is in a computational science (not CS) and I do quite a lot of work on numerical and algorithmic problems that come up in actual hardware and sensors. I also like to work on compiler-y things in my spare time.

Ultimately you end up using tools that are useful for you. So none of this may have any value for your work. But hopefully it answers what someone might write in a notebook.