>I see words like “flakes” and “derivations,” and I currently don’t know what they mean.
>So far, I don’t get how it’s deterministic.
To make nix deterministic you can specify a hash in non-flakes (or a git rev) for your dependencies, but flakes make this easier. When you "run" a flake (be it nix build, nix shell, nix develop), nix pulls the latest (if no explicit rev given in the flake.nix already) version of whatever is specified in flake.nix that it can find, and creates a `flake.lock` file that specifies the exact version that was used. This file is very similar to cargo's Cargo.lock, and specifies the exact version that was captured by ref/hash. The next time nix is "run", it uses the lock file to get the exact same version as it had previously.
One can develop a flake.nix locally, install, check if everything works, and alternatively change the refs in the lock file to make everything work. When this is done you can move the nix and lock file to another machine and get the same exact build there (with the exception of architecture differences).
Because you can put flake.nix and flake.lock inside of git, you can also share the exact same dependencies with other people using a repository. Whenever I see a repository using these I know that building will be a breeze because I don't have to do any dependency hunting.
>So far, I don’t get how it’s deterministic.
To make nix deterministic you can specify a hash in non-flakes (or a git rev) for your dependencies, but flakes make this easier. When you "run" a flake (be it nix build, nix shell, nix develop), nix pulls the latest (if no explicit rev given in the flake.nix already) version of whatever is specified in flake.nix that it can find, and creates a `flake.lock` file that specifies the exact version that was used. This file is very similar to cargo's Cargo.lock, and specifies the exact version that was captured by ref/hash. The next time nix is "run", it uses the lock file to get the exact same version as it had previously.
One can develop a flake.nix locally, install, check if everything works, and alternatively change the refs in the lock file to make everything work. When this is done you can move the nix and lock file to another machine and get the same exact build there (with the exception of architecture differences).
Because you can put flake.nix and flake.lock inside of git, you can also share the exact same dependencies with other people using a repository. Whenever I see a repository using these I know that building will be a breeze because I don't have to do any dependency hunting.