anchor.diff:  { stdenv, fetchurl, bzip2, gfortran, libX11, libXmu, libXt, libjpeg, libpng
   , libtiff, ncurses, pango, pcre, perl, readline, tcl, texLive, tk, xz, zlib
   , less, texinfo, graphviz, icu, pkgconfig, bison, imake, which, jdk, openblas
  -, curl, Cocoa, Foundation, cf-private, libobjc, tzdata, fetchpatch
  +, curl, Cocoa, Foundation, cf-private, libobjc, libcxx, tzdata, fetchpatch
   , withRecommendedPackages ? true
   , enableStrictBarrier ? false
   }:
  
positive.code:     pango pcre perl readline texLive xz zlib less texinfo graphviz icu
      pkgconfig bison imake which jdk openblas curl
    ] ++ stdenv.lib.optionals (!stdenv.isDarwin) [ tcl tk ]
      ++ stdenv.lib.optionals stdenv.isDarwin [ Cocoa Foundation libobjc ];
  
    patches = [ ./no-usr-local-search-paths.patch ];
  
  
negative.code:       --without-aqua
        --disable-R-framework
        OBJC="clang"
        CPPFLAGS="-isystem ${libcxx}/include/c++/v1"
        LDFLAGS="-L${libcxx}/lib"
    '' + ''
      )
      echo >>etc/Renviron.in "TCLLIBPATH=${tk}/lib"
  