What is functional programming? Andreas grabs his whiteboard and his Turing machine, and starts from laziness, while Lars thinks of immutability, functions, and data. Is syntax important for being functional or not? The functionalness of various languages are delved into, from Haskell to Rust via Python, Go, and Ruby. And, of course, the evil version of Elixir. A good pipeline can be really nice. Oh, and you shouldn't use witchcraft anymore. Links Functional programming Haskell Lazy evaluation Lambda calculus Turing machines Alonzo Church Gödel - "A German guy" who formalized the definition general recursive functions Immutability Pure functions Witchcraft Continuation passing Partial application Currying The ML language family Why the lucky stiff Sam Aaron Sonic pi Roc Clojure AST - abstract syntax tree UV The UV company: Astral Memoization Singleton