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

let

  inherit (nixpkgs) pkgs;

  f = { mkDerivation, aeson, base, bytestring, cassava, containers
      , data-default-class, fmt, lens, lib, regex-tdfa, servant
      , servant-docs, servant-server, servant-swagger, stm, swagger2
      , text, time, uuid, vector, wai-extra, warp, zip-archive
      }:
      mkDerivation {
        pname = "haskell-gtfs";
        version = "0.1.0.0";
        src = ./.;
        isLibrary = true;
        isExecutable = true;
        libraryHaskellDepends = [
          aeson base bytestring cassava containers fmt lens regex-tdfa
          servant servant-docs servant-server servant-swagger stm swagger2
          text time uuid vector warp zip-archive
        ];
        executableHaskellDepends = [
          aeson base bytestring data-default-class fmt time wai-extra warp
        ];
        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 {});

in

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