anchor.diff:  
     prevent-ifd-gc = let
       srcs = lib.attrValues sources ++ haskellPackagesWithOverrides.haskell-prevent-ifd-gc;
  -    in writeTextDir "prevent-ifd-gc" (toString srcs + "\n");
  +    in writeTextDir "prevent-ifd-gc" (lib.concatMapStringsSep "\n" toString srcs + "\n");
   
   in build // { inherit env hie; }
  
positive.code: 
    watchexec = (import sources.nixpkgsWatchexec {}).watchexec;
  
    hie = (import sources.hie-nix { pkgs = sources.hie-nixpkgs; }).hie82;
  
  in with (import sources.nixpkgs {}); with (ulib pkgs); let
  
  
negative.code:     };
      hie-nix = (import nixpkgs {}).fetchFromGitHub {
        owner = "domenkozar"; repo = "hie-nix";
        rev = "b8d3fec2d73e43bae11116d0a138168676ae2365";
        sha256 = "1g00a85krcyalyr2p189dk0rs62gsnkj5cjs0pam060nmznqb9j4";
      };
      hie-nix-nixpkgs = import "${hie-nix}/fetch-nixpkgs.nix";
    };
  
    ulib = { lib, ... }: {
  