anchor.diff:      ignoreCollisions = true;
       paths = [
         abcde
  -      bitcoin
         cdparanoia
  -      gitAndTools.git-annex
         pidgin
         fontforge
       ];
  
positive.code:       clang
        gcc
        gdb
        gnumake
        python # 'python' is python2
        python3
        ruby
        cloc
        # android development
        androidsdk_4_4
        android-udev-rules
  
        # Programming libraries
        boehmgc
  
negative.code:       ghc
  
        # Misc userland packages.
        auca
        hledger
        hlint
        shellcheck
        stack
        pandoc
        gitAndTools.git-annex
      ];
    });
  
  