9fabfacd

By: Greg Pfeil <greg@technomadic.org>

Restructuring Haskell config

- install GHCup on darwin (because it doesn’t currently work via Nix/NixOS) so
  we can try other GHC versions when necessary;
- get rid of outdated Cabal config (assuming we’re going to have 3.10 all the
  time 🤞);
- tell GHCup to use XDG locations;
- add a Haskeline config;
- tell Stack to not try to install GHC ever; and
- set Stack’s `work-dir` to shove stuff in project-local .cache/.

Because of the global install of GHCup via Homebrew, I had to change the Haskell
module to be loadable in nix-darwin, which meant propagating that through the
other programming language modules. Hooray for `multiConfig` … but I wish it
were a little less intrusive.

Timeline