{ nixpkgs ? import <nixpkgs> {}, compiler ? "ghc8107", doBenchmark ? false }:

let

  inherit (nixpkgs) pkgs;

  f = { mkDerivation, aeson, base, blaze-html, blaze-markup
      , bytestring, cassava, conduit, conferer, conferer-aeson
      , conferer-warp, conferer-yaml, containers, data-default-class
      , directory, either, extra, fmt, http-api-data, http-media, lens
      , lib, monad-logger, mtl, path-pieces, persistent
      , persistent-postgresql, protocol-buffers
      , protocol-buffers-descriptor, regex-tdfa, resource-pool, servant
      , servant-docs, servant-server, servant-swagger, servant-websockets
      , shakespeare, stm, swagger2, text, time, timezone-olson
      , timezone-series, transformers, unliftio-core, uuid, vector
      , vector-algorithms, wai-extra, warp, websockets, yesod, yesod-form
      , zip-archive, prometheus-client, prometheus-metrics-ghc
      }:
      mkDerivation {
        pname = "tracktrain";
        version = "0.1.0.0";
        src = ./.;
        isLibrary = true;
        isExecutable = true;
        libraryHaskellDepends = [
          aeson base blaze-html blaze-markup bytestring cassava conduit
          conferer conferer-warp containers either extra fmt http-api-data
          http-media lens monad-logger mtl path-pieces persistent
          persistent-postgresql protocol-buffers protocol-buffers-descriptor
          regex-tdfa resource-pool servant servant-docs servant-server
          servant-swagger servant-websockets shakespeare stm swagger2 text
          time timezone-olson timezone-series transformers unliftio-core uuid
          vector vector-algorithms warp websockets yesod yesod-form
          zip-archive prometheus-client prometheus-metrics-ghc
        ];
        executableHaskellDepends = [
          aeson base bytestring conferer conferer-aeson conferer-yaml
          data-default-class directory extra fmt monad-logger
          persistent-postgresql protocol-buffers time wai-extra warp
        ];
        doHaddock = false;
        description = "tracktrain tracks trains on their traintracks";
        license = "unknown";
        hydraPlatforms = 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 {});

  # this removes the /lib directory from the built derivation, which depends on ghc.
  # this dramatically reduces closure size
  stripLib = drv: pkgs.stdenv.mkDerivation {
    name = drv.name + "-without-lib";
    src = drv.outPath;
    buildPhase = ''
      mkdir -p $out
      cp -r $src/bin $out
    '';
    phases = [ "buildPhase" ];
  };
in stripLib drv