Nix

Nix is the purely functional package manager and build system that guarantees reproducible, declarative, and reliable deployments across all Unix-like systems.

Nix operates as a cross-platform package manager, invented in 2003 by Eelco Dolstra, employing a purely functional model. It installs every package into a unique, immutable directory (e.g., `/nix/store/hash-package-version`). This directory name is a cryptographic hash of all build inputs and dependencies, ensuring content-addressability and eliminating 'dependency hell' by allowing concurrent installation of different versions. This core design enables atomic upgrades, reliable rollbacks, and trivial sharing of development environments, all defined declaratively using the Nix Expression Language.

https://nixos.org/