I'm not sure if this commit breaks everything in my monorepo. I think it
will.
Why am I doing this? Perhaps it's a bad idea. I don't fully understand how
readTree works. My ignorance is costing me hours of time spent debugging. In an
effort to better understand readTree, I'm removing the default values for my Nix
expression parameters, which I believe have preventing errors from surfacing.
I previously had an alias defined as `simple_vim`, which would start an instance
of Vim with a bare bones config. I had a to-do to Nixify it. That is
now (mostly) to-done.
When I try and install it with `nix-env -f ~/briefcase -iA tools.simple_vim`,
Nix fails and says that pkgs.stdenv is undefined. I will need to fix this one
day, but it is neither important nor urgent...
