Nix, to quote the marketing copy, is a purely functional package manager. That is, a package is an immutable value constructed by a pure function. The value proposition is that packages comprise a closure over a set of dependencies, such that packages are guaranteed to build the same way every time without drift. This also allows for multiple versions of packages (and most notably their dependencies) to coexist on the same system without conflict.

For more features, consult the Nix features page. The full manual is also quite valuable.

Nix the language

Hello, Nix!