I'm in the same boat here. I'm very not over the Nix learning curve, so I'm left to conclude that it's actually not easy for some projects.
Last time I tried to use Nix to build a dev environment, it did not go well. I wound up in a Turing tarpit of dependencies, as my Python program needed natively compiled libraries and other things to even get off the ground. I kept having to pull in more of the Nix environment/OS to achieve functional isolation from the parent Ubuntu OS. I also ran into problems with online docs and advice skewing wildly from what the CLI options required of me (probably a skill issue).
And that's when it struck me. Docker has pretty much raised the bar for the developer experience. It can achieve the same amount of isolation for far fewer keystrokes, in less time, and (with docker-compose) has a sharable configuration for others. At the end of the day, a container is just a well isolated process whether it's a webserver or a user shell. And really, that's what you need if you're trying to solve repeatability and isolation. As a bonus, if your software is going to deploy as a container, you're that much closer to emulating the production environment (read: fewer bugs).
I like the Direnv concept and have nothing against Nix or folks trying to share the NixOS experience with others. But from a DevEx perspective, my expectations are set at "as easy or easier than Docker."
Last time I tried to use Nix to build a dev environment, it did not go well. I wound up in a Turing tarpit of dependencies, as my Python program needed natively compiled libraries and other things to even get off the ground. I kept having to pull in more of the Nix environment/OS to achieve functional isolation from the parent Ubuntu OS. I also ran into problems with online docs and advice skewing wildly from what the CLI options required of me (probably a skill issue).
And that's when it struck me. Docker has pretty much raised the bar for the developer experience. It can achieve the same amount of isolation for far fewer keystrokes, in less time, and (with docker-compose) has a sharable configuration for others. At the end of the day, a container is just a well isolated process whether it's a webserver or a user shell. And really, that's what you need if you're trying to solve repeatability and isolation. As a bonus, if your software is going to deploy as a container, you're that much closer to emulating the production environment (read: fewer bugs).
I like the Direnv concept and have nothing against Nix or folks trying to share the NixOS experience with others. But from a DevEx perspective, my expectations are set at "as easy or easier than Docker."