anchor.diff:    pname = "work-on-multi--combined-pkg";
     version = "0";
     license = null;
  -})).env;
  +})).env
  
positive.code:   inherit (nixpkgs) lib;
  in
  
  { env, packageNames, tools ? _: [], shellToolOverrides ? _: _: {} }:
  
  let
    inherit (builtins) listToAttrs filter attrValues all concatLists;
  
negative.code:     })).out;
      notInTargetPackageSet = p: all (pname: (p.pname or "") != pname) packageNames;
      baseTools = generalDevTools' {};
      env = envFunc reflex-platform;
      overriddenTools = baseTools // shellToolOverrides env baseTools;
      depAttrs = lib.mapAttrs (_: v: filter notInTargetPackageSet v) (concatCombinableAttrs (concatLists [
        (map getHaskellConfig (lib.attrVals packageNames env))
  