Between the many options for functional programming on the JVM, Frege is the only one that is pure. It follows the syntax and behavior of Haskell with super-strong type safety, Hindley-Milner type inference, higher-rank types, typeclasses, lazy evaluation per default, and announcing all effects in the type system. Frege is also unique in the way that it interoperates with Java: it does not compromise its language guarantees in terms of purity and type safety when calling into Java! Come and see how you can achieve pure functional programming on the JVM.