Ever tried to build distribution packages? If it works for you, doesn't mean it works everywhere. Slight errors in the dependency specifications of a package

Ever tried to build distribution packages? If it works for you, doesn't mean it works everywhere. Slight errors in the dependency specifications of a package may make it fail if you have wrongly versioned/missing libraries etc. It's often very difficult to verify that package dependencies are 100% correct. Sometimes package builds are not reproducable, as autoconf doesn't care about the build dependencies you defined but just adds any dependency it can auto-detect at compile-time. So you have to double-test your package when build on a build server etc. etc. AFAIU the Nix package manager fixes that by trying to assure bit-for-bit matching dependant packages are present by making every package version a hash of the installed files, hashed with the hash of all dependencies (similar somehow to how the filesystem/history data are managed in Git, BTW). The Nix package builder (named hydra) on the other hand makes sure that builds are performed in complete isolation via enhanced chroots, so that every build is 100% reproducible. It locks the build process down so much that it can't even access the network nor would the process be able to observe varying host names. [1] This is why they call it a "purely functional" build system. As in purely functional programming: there's no state at all. Inputs completely define the output. Now Guix sits on top of Nix and somehow attempts to make its features available on a higher level via a Scheme API (Nix uses its own language for package dependency and build descriptions) I haven't used Nix before, just read about it, but having suffered through writing complex package build recipies for OpenWrt, I very much appreciate the approach. [1] http://hydra.nixos.org/build/2860022/download/3/release-notes/ http://hydra.nixos.org/build/2860022/download/3/release-note...