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Tony Hoare's InfoQ talk in which he describes introducing null references in ALGOL W in 1965 and calls it his billion-dollar mistake. He discusses language designer responsibility and run-time checks.

Rich Hickey's Clojure/Conj 2018 keynote argues that Maybe/Option types and rigid type signatures are a poor way to model data that changes over time. He builds the case around optionality, schema growth and compatibility, and presents the ideas behind Clojure spec as an alternative.