Elixir 1.17 has been released, introducing set-theoretic types into the language, which will help developers find bugs earlier and give more confidence when refactoring code. The release also adds support for Erlang/OTP 27 and a new calendar-related data type called Duration. The type system is still in its early stages, but it already provides benefits to developers in the form of new warnings for common mistakes. The development of the type system was made possible through a partnership between CNRS and Remote, and is sponsored by several companies.