anchor.diff: -{ stdenv, fetchurl
  +{ stdenv, fetchurl, pkgconfig, libtool
   
   # Optional Dependencies
   , gpm ? null
  
positive.code:     ln -svf . $out/include/ncursesw
      ln -svf . $out/include/ncurses
  
      # Create non-unicode compatability
      libs="$(find $out/lib -name \*w.a | sed 's,.*lib\(.*\)w.a.*,\1,g')"
      for lib in $libs; do
        if [ -e "$out/lib/lib''${lib}w.so" ]; then
          ln -svf lib''${lib}w.so $out/lib/lib$lib.so
          ln -svf lib''${lib}w.so.${abiVersion} $out/lib/lib$lib.so.${abiVersion}
        fi
        ln -svf lib''${lib}w.a $out/lib/lib$lib.a
        ln -svf ''${lib}w.pc $out/lib/pkgconfig/$lib.pc
      done
  
      # Create curses compatability
      ln -svf libncursesw.so $out/lib/libcursesw.so
      ln -svf libncursesw.so $out/lib/libcurses.so
    '' + stdenv.lib.optionalString stdenv.isCygwin ''
      for lib in $libs; do
        if test -e $out/lib/lib''${lib}w.dll.a; then
            ln -svf lib''${lib}w.dll.a $out/lib/lib$lib.dll.a
        fi
      done
    '') else ''
  
negative.code: 
  with stdenv.lib;
  let
    optGpm = stdenv.shouldUsePkg gpm;
  in
  stdenv.mkDerivation rec {
  