> Nix can create isolated environments, but as far as I see, you can only install the tools Nix repo supports. And the official examples only give toy examples --here's a simple python script you can run with Nix-- but I can just run this simple script in a virtual env, or docker if I have 2-3 different scripts.

Well, for one, someone send me a random Python script with a dependency on a PostgreSQL driver (that probably needs to compile some C library). Just the script, no `requirements.txt` or `Pipfile.lock` or `pyproject.toml` files declaring the dependencies. I could have just created a virtualenv and tried to install it using pip, that would probably fail because I don't have a proper C compiler setup. Or maybe I have but it is missing headers. Maybe it will work because there is already a wheel for my system, but maybe it will not because some other random reason.

Instead, I just wrote two lines for shebang:

#! /usr/bin/env nix-shell
#! nix-shell -i python3 -p python3 python3Packages.psycopg2

And them `chmod +x ./script.py && ./script.py`, and everything is working.

> What problem is Nix solving? What pain does it fix that is so important it would justify me spending 6 months on it?

Really the meme that you need to spend months just to use Nix properly needs to die. I literally skimped the docs and got a working NixOS install at my first try on the system [1]. The default configuration is really well documented with examples, and I think most people can get what they want quickly.

Eventually I wanted to use something that was not packaged on nixpkgs, or I started to want to upgrade some specific packages without using unstable. At that point it was when I started to think Nix was kinda of painful (not because it was difficult to do, however the documentation is not good and you end up searching a lot until you find some answers). At that point yes, it is kinda a journey, but it is very similar to learning a new language: you eventually can get very proficient at it, but you never stop learning.

> And then there is NixOS, which again, I have no idea-- I can create my own Linux distribution that is what, reproducible? Again, is this a real problem anyone faces (and that isnt fixed by docker or ansible or any of the other hundreds of tools)?

Try to have reproducible system with Ansible. Yeah, I tried. It simply doesn't work well. Ansible is always a pain because steps randomly fail in a new machine, and you can waste hours of debugging for simply issues. Not NixOS: if your configuration builds there is a great chance that everything will work.

NixOS is the only system that I am sure that I have the exactly same configuration as my other systems, as long I am running the same commit from my nix-configs repository. Can't say the same for Ansible: if I setup a machine using Ansible right now and 2 days from now, pretty sure they will have different package versions (since the repository will have changed them), for example.

Also, you don't have rollbacks with Ansible. Yeah, you can have ZFS/Btrfs taking periodic snapshots and use this for rollbacks. This is not the same though. The UX in NixOS is simply so much better (reboot your system and select which generation you want to boot).

> My point is: Why is Nix getting so much hype when I dont see them solving any real problems? Sure, they promise a lot, but I have yet to see any real solutions.

Well, my point is: Nix solves real problems. Maybe you are not bitten as much as I am with them, maybe you think that spend half a hour trying to get a random Python script to work is fine. And I completely concur with you. It doesn't mean that Nix is not worth your time though.

[1]: Now, I think the fact that I used Arch Linux before really helped, since both NixOS and Arch Linux have an installation process that is completely terminal based instead of a proper installer.