\(ghc-version : Text) ->
\(ghc-upgrade : Text) ->
  ''
  { current-version =
      { ghc-xyz-project-stack = "stack.yaml";
        ghc-xyz-project-cabal = "cabal.project";
        ghc-xyz-sha256map = import ./project-nix/ghc-${ghc-version}/sha256map.nix;
      };
    upgrade-version =
      { ghc-xyz-project-stack = "stack.upgrade.yaml";
        ghc-xyz-project-cabal = "cabal.upgrade.project";
        ghc-xyz-sha256map = import ./project-nix/ghc-${ghc-upgrade}/sha256map.nix;
      };
  }
  ''