final: prev:
  let
    inherit (prev.stdenv) mkDerivation;
    inherit (prev.lib.trivial) flip pipe;
    inherit (prev.haskell.lib)
      appendPatch
      appendConfigureFlags
      dontCheck
      doJailbreak;

    withPatch = flip appendPatch;
    withFlags = flip appendConfigureFlags;

    haskellCompiler = "ghc884";
  in {
    myHaskellPackages = prev.haskell.packages.${haskellCompiler}.override {
      overrides = hpFinal: hpPrev:
        rec {
          hakyll = pipe hpPrev.hakyll [
            doJailbreak
            dontCheck
            # (withPatch ./hakyll.patch)
            (withFlags [ "-f" "watch" ])
          ];

          pandoc = pipe hpPrev.pandoc [
            doJailbreak
            dontCheck
          ];

          slugger = hpPrev.slugger;

          ssg = hpPrev.callCabal2nix "ssg" ../ssg {};

          website = prev.stdenv.mkDerivation {
            #__contentAddressed = true; # uncomment if using cas: https://www.tweag.io/blog/2020-09-10-nix-cas/
            name = "website";
            buildInputs = [
              ssg
              final.graphviz
            ];
            src = prev.nix-gitignore.gitignoreSourcePure [
              ../.gitignore
              "../.git"
              "../.github"
            ] ../.;

            # LANG and LOCALE_ARCHIVE are fixes pulled from the community:
            #   https://github.com/jaspervdj/hakyll/issues/614#issuecomment-411520691
            #   https://github.com/NixOS/nix/issues/318#issuecomment-52986702
            #   https://github.com/MaxDaten/brutal-recipes/blob/source/default.nix#L24
            LANG = "en_US.UTF-8";
            LOCALE_ARCHIVE = prev.lib.optionalString
              (prev.buildPlatform.libc == "glibc")
              "${prev.glibcLocales}/lib/locale/locale-archive";

            buildPhase = ''
              hakyll-site build --verbose
            '';

            installPhase = ''
              mkdir -p "$out"
              cp -r dist/* "$out"
            '';
          };
        };
    };
}