If you're interested in this kind of thing, definitely also check out the upcoming HOPL conference -- co-located (whatever that means for a virtual conference) with PLDI this June. Matthias was on the program committee, along with a bunch of other PL OGs.
Website: https://hopl4.sigplan.org Papers: https://dl.acm.org/toc/pacmpl/2020/4/HOPL