anchor.diff:  
     postInstall = lib.optionalString withEmacs ''
       moveToOutput bin/notmuch-emacs-mua $emacs
  +  '' + lib.optionalString withRuby ''
  +    make -C bindings/ruby install \
  +      vendordir=$out/lib/ruby \
  +      SHELL=$SHELL \
  +      $makeFlags "''${makeFlagsArray[@]}" \
  +      $installFlags "''${installFlagsArray[@]}"
     '';
   
     passthru = {
  
positive.code: , ruby
  , which, dtach, openssl, bash, gdb, man
  , withEmacs ? true
  }:
  
  stdenv.mkDerivation rec {
  
negative.code:     "--infodir=${placeholder "info"}/share/info"
    ] ++ lib.optional (!withEmacs) "--without-emacs"
      ++ lib.optional withEmacs "--emacslispdir=${placeholder "emacs"}/share/emacs/site-lisp"
      ++ lib.optional (!withRuby) "--without-ruby";
  
    # Notmuch doesn't use autoconf and consequently doesn't tag --bindir and
    # friends
  