{ pkgs }:

let
  yolkPath = ./local-pkgs/yolk/default.nix;
  yolk = if builtins.pathExists yolkPath then
    let imp = builtins.tryEval (import yolkPath { inherit pkgs; });
    in if imp.success then imp.value else null
  else
    null;
in
# Return a list of extra packages (possibly empty)
builtins.filter (x: x != null) [
  yolk
]