The most compiler-ish work I ever worked on is a yaml to yaml transpiler. I mean, yeah...at least I got to write some recursions.

https://tangled.sh/ . Example repos: https://tangled.sh/@rockorager.dev/lsr https://tangled.sh/@tangled.sh/core

> 9(3) is shorthand for 999

I did some cobol work in the past and know 9(3) but you can write 999? And how is 4 chars shorthand for 3?

But, as an over-30 on HN, I'd be afraid that having the word "mainframe" on my resume would alienate a 20-something co-founder or hiring manager. :)

OK, OK, I did once do a little bit of mainframe-related work. It was reverse-engineering a small part of a certain domain-specific mainframe network protocol, with the goal of replacing at least one of the companies' mainframes with... 21st century Linux servers running... Lisp. (IMHO, the HN karma should at least balance out there by using Lisp, like the post did by using Rust.)