There are various benefits to using a Nixpkgs release
- more likely that things are cached
- easier to update the input without breaking everything
This also renames a lot of things in the flake:
- `nixpkgs-unstable` to `nixpkgs-release` – partially because it’s not
unstable any more, but also because both it and the nixpkgs from
haskell.nix unstable, so it didn’t really clarify anything
- `nixpkgs` to `nixpkgs-haskellNix` – to make it clear where it comes from
- `unstable` to `release-pkgs` – the convention is to use `pkgs` for
derivation attrsets, and the source switched from unstable to release
- `nixpkgs-packages` to `tool-pkgs` – this holds our build tools, so
that seemed clearer than “nixpkgs”
Resolves#4026
I was able to remove some overrides that we were using to get ormolu
0.5.0.1 to build with GHC 8.10.7. It's possible that more cruft can be
removed, but I don't understand it well enough to feel confident in
messing with it. We are no longer explicitly asking for ormolu 0.5.0.1
because I couldn't figure out how to do that, but 0.5.0.1 is the
version in the nixpkgs hash that we are currently locked on.
On my linux box both `stack build && stack test` and HLS support work.
