anchor.diff:  let
     # various binaries (compiled)
     bin = callPackage ./bin.nix {
  -    poppler = poppler_min; # otherwise depend on various X stuff
       ghostscript = ghostscriptX;
       harfbuzz = harfbuzz.override {
         withIcu = true; withGraphite2 = true;
  
positive.code:         }
      );
    }
  
  
negative.code: */
  
  { stdenv, lib, fetchurl, runCommand, writeText, buildEnv
  , callPackage, ghostscriptX, harfbuzz, poppler
  , makeWrapper, perl, python, ruby
  , useFixedHashes ? true
  , recurseIntoAttrs
  