Nix ecosystem
The Nix Ecosystem is a collection of technologies built around the Nix Package Manager and the purely functional Nix Expression Language. Nix expressions are pure functions taking dependencies as arguments and producing derivation specifying a reproducible build environment for the package. The package is then built the Nix store, receiving a unique address specified by a cryptographic hash of the build's dependency graph followed by the package name and version, for example /nix/store/nawl092prjblbhvv16kxxbk6j9gkgcqm-git-2.14.1
. This allows Nix to install side by side different versions of the same package, and even different builds of the same version.