It's not a reinvention, it's a fork: "Guix is based on the Nix package manager." [https://savannah.gnu.org/projects/guix/]
(More info here: https://lists.gnu.org/archive/html/guile-user/2012-07/msg000..., taken from icebraining below)
(More info here: https://lists.gnu.org/archive/html/guile-user/2012-07/msg000..., taken from icebraining below)