1. Hoare’s legacy is celebrated in every corner of the thread
“C.A.R. Hoare…invented quicksort, CSP, Hoare logic, and the ‘billion‑dollar mistake’” – pram
“CSP and Hoare logic were brilliant. He was a huge proponent of formal methods.” – nextos
2. The “billion‑dollar mistake” fuels a debate over nulls and optional types
“The null reference was my billion dollar mistake responsible for innumerable errors, vulnerabilities and system crashes.” – riazrizvi
“The mistake is not the use of nulls per se, the mistake is type‑systems that do not make them explicit.” – bazoom42
3. Formal verification and its limited adoption remain a recurring theme
“CSP and Hoare logic…were brilliant…He famously gave up on making formal methods mainstream, but I believe there will be a comeback quite soon.” – nextos
“The first formal verification of an FPU…could have been avoided had Intel been using the verification methods that the Inmos and University teams pioneered.” – dboreham
4. Personal anecdotes and emotional tributes underscore the human side of the loss
“I first came across Tony Hoare about 24 years ago…he was a gentle intellectual giant.” – susam
“I remember Jim Woodcock as really inspirational…he was a kind, nice person who is delightful to chat with.” – tombert
“I was lucky enough to see Sir Tony Hoare speak…he was a gentle intellectual giant.” – fooker
These four threads—legacy, null‑reference debate, formal methods, and personal remembrance—capture the most prevalent opinions in the discussion.