{ nixpkgs ? null, doBenchmark ? false } :
let
  pinnedPkg = builtins.fetchGit {
    name = "nixos-unstable-2020-12-26";
    url = https://github.com/nixos/nixpkgs/;
    rev = "a60a1340b7dbd1402a8ef97de8bc4760961a722f";
  };
  npkgs = if nixpkgs == null
          then import pinnedPkg {}
          else import nixpkgs {};
  learnopengl = npkgs.pkgs.haskellPackages.callCabal2nix "learnopengl-haskell" (./.) {};
in
learnopengl