Elixir v1.20 ships gradual type system

Elixir's approach to typing is a masterclass in adding types to a dynamic language without alienating its community or sacrificing performance.

* Complete type inference for all constructs means developers get the benefits of bug detection out of the box without changing a line of code or adding verbose annotations.

* The choice of set-theoretic typing and a sound dynamic() type addresses the typical pitfalls of gradual typing, ensuring robust type safety where needed.

* Crucially, compiling to unmodified BEAM bytecode avoids any runtime performance penalty, keeping Elixir's hallmark concurrency and speed intact.