In which I shill you Nix, a purely functional package manager. Why Nix? Joe Armstrong, one of the creators of Erlang, once described Erlang as the quest for programs that you “write once, run forever.” Nix, in comparison, might be the quest for programs that run wherever, whenever. Nix often scares newcomers and experienced devs alike, because it proposes a fairly radical overhaul to how we think