Unforeseen problem: `buildkite-agent` runs its builds in a separate directory,
so if I want the `nix-build` command to build the newly checked out code, I need
to set <briefcase> to the CWD.
I believe `use_nix` looks for shell.nix and then default.nix files, so I was
wrong earlier when I said that I could get rid of shell.nix files altogether.
I need to learn more about `use_nix` and getting environments from default.nix
files.
I find it bothersome to share the list of Haskell dependencies between my
default.nix and shell.nix files. A few days ago, I created a THIRD file,
shared.nix, that defined the shared code b/w default.nix and shell.nix. This
DRY'd things up, but it also added a new file, which I didn't like.
Today I learned that direnv integrates with Nix using a function called
`use_nix`. Voila! I typically already have .envrc files per-project, so this
doesn't add any unnecessary files, and it allows me to delete my shell.nix
files.
I would use `lorri`, except that I encountered issues using Lorri on my work
computer, which I'm not interested in attempting to resolve now.
