anchor.diff:  
     gtk = callPackage ../development/libraries/haskell/gtk {
       inherit (pkgs.gtkLibs) gtk;
  +    glibc = if pkgs.stdenv.isDarwin then null else pkgs.glibc;
     };
   
     gtk2hsBuildtools = callPackage ../development/libraries/haskell/gtk2hs-buildtools {};
  
positive.code: 
    pango = callPackage ../development/libraries/haskell/pango {
      inherit (pkgs.gtkLibs) pango;
    };
  
    parallel_1_1_0_1 = callPackage ../development/libraries/haskell/parallel/1.1.0.1.nix {};
  
negative.code: 
    cairo = callPackage ../development/libraries/haskell/cairo {
      inherit (pkgs) cairo zlib;
      glibc = if pkgs.stdenv.isDarwin then null else pkgs.glibc;
    };
  
    caseInsensitive_0_3 = callPackage ../development/libraries/haskell/case-insensitive/0.3.nix {};
  