I finally made time to update the GitHub - rpearce/hakyll-nix-template: Hakyll + Nix starter template. While I struggled against nixpkgs + haskell dependencies + macOS for a while, I finally got there, in the end, thanks to GitHub - input-output-hk/haskell.nix: Alternative Haskell Infrastructure for Nixpkgs!
Thanks to that project, I believe the hakyll nix template project will be much easier to keep up-to-date and reproducible over time.
I’m also going to do a write-up on how to use the template project on robertwpearce.com soon, as well.