Sometimes I bake Nix into my personal Makefiles.

This means that we lose the non-Nix build processes, but I get to keep the best of both worlds, and don't have to run `nix shell` or setup direnv.

"Uhm, actually" I use Guix, but the idea is the same:

  SHELL = guix shell -m manifest.scm -- bash
  public: hugo content
      emacs $(pwd) --batch -l export.el
  [...]

Or without an external manifest:

  SHELL = guix shell --pure bash coreutils emacs emacs-ox-hugo hugo -- bash

This is equivalent to the common shebang trick:

  #!/use/bin/env -S guix shell -m manifest.scm -- bash

Or just invoking Guix inside the recipe:

  public: hugo content
      guix shell -m manifest.scm -- emacs $(pwd) --batch -l export.el

Depending on the complexity of `export.el` (< 5 lines?), I'll often keep that inside the Makefile too; the less files, the better!

But I get it if one wants that file available to call from elsewhere.