Nix 2.4 is the first Nix release to include the flakes feature, so this is the first chance for Nix users who don't want to run cuts right off the Nix master br

Nix 2.4 is the first Nix release to include the flakes feature, so this is the first chance for Nix users who don't want to run cuts right off the Nix master branch to see what flakes are like, experiment with them, and give feedback. (Previously, to use flakes you'd be running a bleeding edge build of Nix itself as well.) This is a pretty big deal, since flakes bring a new level of determinism to `nix` as you might use it at the CLI, and other built-in Nix tools like `nixos-rebuild`, making it ‘easy’ to pin Nixpkgs and other package sources in your configs. The greater determinism (‘pure evaluation by default’, in Nix lingo) also improves performance, because it provides the Nix language evaluator with more caching opportunities. Flakes are still contentious in some ways inside the community, and the outputs schema of flake.nix files themselves is also kinda verbose (imo), so use of helper libraries to generate outputs is pretty common. My hope as a Nix user is that this release means we can overcome both of those issues in the next year or two and make some solution for deterministic evaluation by default official in the next year or two.