There's a constant tension between bit-packing and rich semantics older than me! As you likely know C.A.R. Hoare calls `null` his "billion-dollar mistake": http

There's a constant tension between bit-packing and rich semantics older than me! As you likely know C.A.R. Hoare calls `null` his "billion-dollar mistake": https://www.youtube.com/watch?v=ybrQvs4x0Ps https://www.youtube.com/watch?v=ybrQvs4x0Ps. I linked the Cliff Click talk because it's the best example that I know about of someone using some semi-formal rigor around valid states and the transitions between them in the context of raw atomic operations to get a quite clearly correct result with a legitimate performance imperative: he had a machine with 768 cores, customers who bought that machine to have 768 threads jump on a hash table all at once and wanted ~~700x more throughput having paid for the machine. But even Cliff Click made sure that both his conceptual states and their physical representations were going A -> B -> C w.r.t. a given conceptual "register". I'm not trying to knock the serious concurrency pros who need atomic and/or relaxed operations in some super hot path: there are unambiguous use cases for this stuff. I've legitimately needed these things once or twice myself. Lock-free is a bad default. Even the elite concurrency pros work very hard to get something that's both robust and still a win after the constant factors. I'm saying "proceed with high caution, and on the basis of measurement", not "never ever do this".