Lambda the Ultimate

NixOS is a Linux distribution based on Nix, a purely functional package management system. NixOS is an experiment to see if we can build an operating system in which software packages, configuration files, boot scripts and the like are all managaed in a purely functional way, that is, they are all built by deterministic functions and they never change after they have been built. Such an operating system should have all the nice characteristics that the Nix package manager has.

An excellent example of how useful functional databases can be when applied to problems which require persistence.