Tony Hoare has died

Overall reaction

• Widespread sadness and respect at the death of a foundational computer scientist.
• Many describe him as one of the “greats” whose work underpins large parts of modern computing.
• Several express surprise and disappointment that mainstream media largely ignored his passing.

Key contributions remembered

• Frequently cited: Quicksort; Communicating Sequential Processes (CSP); Hoare logic; monitors; work on ALGOL and structured programming; unifying theories of programming.
• Some argue his most important legacy is Hoare logic and its influence on program reasoning and modern tools (e.g., Dafny, correctness‑by‑construction).
• CSP seen as a core foundation for Occam, the Transputer, Go channels, Erlang-style concurrency, OpenMP ideas, and more.

Null reference and type systems

• The “billion dollar mistake” talk is heavily referenced.
• Consensus: the real problem is making all references implicitly nullable, not the existence of null itself.
• Proposed solutions: optional/maybe types, sum/union types, or explicit “nullable” annotations with non-null as default.
• Debate over ergonomics: some prefer strict typing requiring explicit checks; others want concise syntax but warn against coercing options into booleans.

Formal methods and verification

• Several lament that his dream of mainstream formal verification never fully materialized, despite early successes (e.g., FPU verification).
• Others are cautiously optimistic that code generation plus AI could make proof-assisted development and CbC approaches more practical.
• Linked papers discuss why software became relatively reliable without full proofs and reflect on limits of his original axiomatic program.

Concurrency and system design

• CSP vs. Actor model vs. Software Transactional Memory is debated; some claim actors don’t compose correctness as well as transactional approaches.
• Some worry modern async/await style is discarding the conceptual clarity of process calculi.
• Hoare’s aphorisms about simplicity vs. complexity and the price of reliability are frequently invoked and related to current “move fast” culture.

Personal anecdotes and character

• Many recount lectures and one‑to‑one interactions: he is remembered as humble, sharp into his 80s, generous with students, and unusually kind.
• Stories from Oxford, Cambridge, and various conferences highlight his warmth and gentle humor (including building‑name puns and room dedications).

History and language design debates

• Long subthread on the history of pointers, references, and nulls: multiple early languages and machines are cited; chronology and priority remain contested.
• Discussion of his influence on language keywords (case, class, new), record/structure ideas, optional types, and enumeration types.
• Some note how small, elegant ideas (like Quicksort or CSP) had outsized and enduring impact compared to today’s vast but often forgettable systems.