shell.nix

{ nixpkgs ? import <nixpkgs> {}, compiler ? "default", doBenchmark ? false }:

let

  inherit (nixpkgs) pkgs;

  f = { mkDerivation, algebraic-graphs, ansi-wl-pprint, array, base
      , bytestring, containers, filepath, fingertree, groups, hashable
      , JuicyPixels, lens, linear, MemoTrie, psqueues, stdenv, trifecta
      , unordered-containers, vector
      }:
      mkDerivation {
        pname = "advent";
        version = "0.1.0.0";
        src = ./.;
        isLibrary = true;
        isExecutable = true;
        libraryHaskellDepends = [
          ansi-wl-pprint array base bytestring containers
          filepath fingertree groups hashable JuicyPixels lens linear
          MemoTrie psqueues trifecta unordered-containers vector
        ];
        executableHaskellDepends = [
          ansi-wl-pprint array base bytestring containers
          filepath fingertree groups hashable JuicyPixels lens linear
          MemoTrie psqueues trifecta unordered-containers vector
        ];
        license = "unknown";
        hydraPlatforms = stdenv.lib.platforms.none;
      };

  haskellPackages = if compiler == "default"
                       then pkgs.haskellPackages
                       else pkgs.haskell.packages.${compiler};

  variant = if doBenchmark then pkgs.haskell.lib.doBenchmark else pkgs.lib.id;

  drv = variant (haskellPackages.callPackage f {});

in

  if pkgs.lib.inNixShell then drv.env else drv