Nothing from project4 builds correctly

[andrewthad]

For example:

$ nix-build release0.nix
...
Configuring optparse-applicative-0.13.0.0...
CallStack (from HasCallStack):
  die', called at libraries/Cabal/Cabal/Distribution/Simple/Configure.hs:948:20 in Cabal-2.0.1.0:Distribution.Simple.Configure
  configureFinalizedPackage, called at libraries/Cabal/Cabal/Distribution/Simple/Configure.hs:470:12 in Cabal-2.0.1.0:Distribution.Simple.Con
figure
  configure, called at libraries/Cabal/Cabal/Distribution/Simple.hs:570:20 in Cabal-2.0.1.0:Distribution.Simple
  confHook, called at libraries/Cabal/Cabal/Distribution/Simple/UserHooks.hs:67:5 in Cabal-2.0.1.0:Distribution.Simple.UserHooks
  configureAction, called at libraries/Cabal/Cabal/Distribution/Simple.hs:174:19 in Cabal-2.0.1.0:Distribution.Simple
  defaultMainHelper, called at libraries/Cabal/Cabal/Distribution/Simple.hs:119:27 in Cabal-2.0.1.0:Distribution.Simple
  defaultMain, called at Setup.hs:2:8 in main:Main
Setup: Encountered missing dependencies:
process >=1.0 && <1.5
builder for '/nix/store/lml5p667kaialx856knj14yx7xr4zs8b-optparse-applicative-0.13.0.0.drv' failed with exit code 1
cannot build derivation '/nix/store/h2xlpmmd6ffbfz6d3sdinbfjyq2ax4sy-tasty-1.0.1.1.drv': 1 dependencies couldn't be built
cannot build derivation '/nix/store/sanz1lf30sa950hacfada0f8raw9gshq-turtle-1.3.2.drv': 1 dependencies couldn't be built
cannot build derivation '/nix/store/n5mz1g9dq5qywgndicdgmapvs6hcf6rl-project4-1.0.0.drv': 1 dependencies couldn't be built
error: build of '/nix/store/n5mz1g9dq5qywgndicdgmapvs6hcf6rl-project4-1.0.0.drv' failed

[Gabriella439]

Yeah, I'm aiming either this weekend or the next to revisit that entire section and pin it to a specific version of Nixpkgs so that it's lower maintenance