For my personal projects I am drifting towards the simple side. More and more I try to stick with a simple single level key value configuration. But if you do

For my personal projects I am drifting towards the simple side. More and more I try to stick with a simple single level key value configuration. But if you do require a complex configuration, I think it is beneficial to both yourself and your users to invest in a openbsd style parse.y like solution rather than just shovel the usual json or yaml slop. https://cvsweb.openbsd.org/cgi-bin/cvsweb/~checkout~/src/usr.sbin/smtpd/parse.y?rev=1.299&content-type=text/plain https://cvsweb.openbsd.org/cgi-bin/cvsweb/~checkout~/src/usr... By which I mean it does not have to be yacc, but taking the time to think about the language of your configurations improves the ui dramaticly.