let sources = import ./nix/sources.nix;
in { compiler ? "ghc8104", pkgs ? import sources.nixpkgs { } }:

let
  inherit (pkgs.lib.trivial) flip pipe;
  inherit (pkgs.haskell.lib) appendPatch appendConfigureFlags;

  haskellPackages = pkgs.haskell.packages.${compiler}.override {
    overrides = hpNew: hpOld: {
      hakyll = pipe hpOld.hakyll [
        (flip appendPatch ./hakyll.patch)
        (flip appendConfigureFlags [ "-f" "watchServer" "-f" "previewServer" ])
      ];

      voc-web = hpNew.callCabal2nix "voc-web" ./. { };

      niv = import sources.niv { };
    };
  };

  project = haskellPackages.voc-web;
in {
  project = project;

  shell = haskellPackages.shellFor {
    packages = p: with p; [ project ];
    buildInputs = with haskellPackages; [
      ghcid # GHCi based IDE
      hlint # or ormolu
      pkgs.niv # Nix dependency management
    ];
    withHoogle = true;
  };
}