anchor.diff:        (if githubSupport then curl          else null)
         (if iwSupport     then wirelesstools else null)
         (if mpdSupport    then mpd_clientlib else null)
  +      (if pulseSupport  then libpulseaudio else null)
   
         (if i3Support || i3GapsSupport then jsoncpp else null)
         (if i3Support then i3 else null)
  
positive.code: , iwSupport     ? true,  wirelesstools ? null
  , githubSupport ? false, curl          ? null
  , mpdSupport    ? false, mpd_clientlib ? null
  , i3Support ? false, i3GapsSupport ? false, i3 ? null, i3-gaps ? null, jsoncpp ? null
  }:
  
  
negative.code: assert githubSupport -> curl          != null;
  assert iwSupport     -> wirelesstools != null;
  assert mpdSupport    -> mpd_clientlib != null;
  assert pulseSupport  -> libpulseaudio != null;
  
  assert i3Support     -> ! i3GapsSupport && jsoncpp != null && i3      != null;
  assert i3GapsSupport -> ! i3Support     && jsoncpp != null && i3-gaps != null;
  
  stdenv.mkDerivation rec {
      name = "polybar-${version}";
      version = "3.2.0";
      src = fetchgit {
        url = "https://github.com/jaagr/polybar";
        rev = version;
        sha256 = "0p94brndysvmmbidhl4ds4w3qvddb752s4vryp0qckb0hz3knqk8";
      };
  
      meta = with stdenv.lib; {
  