anchor.diff:      ++ optional withPHP73 php73
       ++ optional withPerl perl
       ++ optional withPerldevel perldevel
  -    ++ optional withRuby_2_3 ruby_2_3
       ++ optional withRuby_2_4 ruby_2_4
       ++ optional withRuby ruby
       ++ optional withSSL openssl;
  
positive.code: , withPHP73 ? false, php73
  , withPerl ? true, perl
  , withPerldevel ? false, perldevel
  , withRuby_2_3 ? false, ruby_2_3
  , withRuby_2_4 ? false, ruby_2_4
  , withRuby ? true, ruby
  , withSSL ? true, openssl ? null
  
negative.code:     ${optionalString withPHP73      "./configure php     --module=php73     --config=${php73.dev}/bin/php-config  --lib-path=${php73}/lib"}
      ${optionalString withPerl       "./configure perl    --module=perl      --perl=${perl}/bin/perl"}
      ${optionalString withPerldevel  "./configure perl    --module=perl529   --perl=${perldevel}/bin/perl"}
      ${optionalString withRuby_2_4   "./configure ruby    --module=ruby24    --ruby=${ruby_2_4}/bin/ruby"}
      ${optionalString withRuby       "./configure ruby    --module=ruby      --ruby=${ruby}/bin/ruby"}
    '';
  