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

let

  inherit (nixpkgs) pkgs;

  f = { mkDerivation, base, bound, lib, llvm-codegen
      , recursion-schemes
      }:
        mkDerivation {
          pname = "haskell";
          version = "0.1.0.0";
          src = ./.;
          isLibrary = false;
          isExecutable = true;
          executableHaskellDepends = [
            base bound llvm-codegen recursion-schemes
          ];
          license = "unknown";
          mainProgram = "haskell";
        };

  haskellPackages = if compiler == "default"
                    then pkgs.callPackage ./pkgs {}
                    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