Brief introduction to a nix based project workflow. Background For CarpentryCon@Home 2020, along with Amrita Goswami, I am to prepare and deliver a workshop on “Reproducible Environments with the Nix Packaging System”. In particular, as a community of practice lesson, the focus is not on packaging (as is typical of most Nix tutorials) nor on the Nix expression language itself, but instead on the use of Nix as a replacement for virtual environments using mkShell.