> So its not that far from the build system we already have. Yup. The key contribution Nix brings is arranging the outputs of builds into the nix store, in su

> So its not that far from the build system we already have. Yup. The key contribution Nix brings is arranging the outputs of builds into the nix store, in such a way that you can trust that building a package with the same set of inputs will result in a package that behaves the same way. (This then allows e.g. different versions of the same package). There's some friction, since with some software, if you try and build things but disallow writing to arbitrary files (e.g. no writing to $HOME), the tools might have assumed they could, so things might not work. -- That's 'purity' in some sense, in that what inputs the package building uses is totally declared. I liked the analogy introduced from a tweag post from a couple of weeks ago https://www.tweag.io/blog/2022-07-14-taming-unix-with-nix/ https://www.tweag.io/blog/2022-07-14-taming-unix-with-nix/ (big discussion yesterday https://news.ycombinator.com/item?id=32355327 https://news.ycombinator.com/item?id=32355327) that illustrated nix as 'pure', but interacting with the Unix system by way of files. -- You have a pure way of managing an impure system. (Which is loosely comparable to how Haskell can be pure, but still do impure stuff like Input/Output).