I expect going digging would reveal that csexp is decades older than msgpack. As a format I agree it doesn't look great though. May 1997 for csexp. https://web

I expect going digging would reveal that csexp is decades older than msgpack. As a format I agree it doesn't look great though. May 1997 for csexp. https://web.archive.org/web/20230219084819/http://people.csail.mit.edu/rivest/Sexp.txt https://web.archive.org/web/20230219084819/http://people.csa... Msgpack less clear, maybe 2008. JSON is 2000ish.