Heterogeneous Translation of Scala-Like Function Types in Java-TX

Java-TX (i.e. Type eXtended) is a language based on Java. The two predominant new features are global type inference and real function types for lambda expressions. The latter enables concrete typing of lambda expressions (not only target typing as in Java), subtyping of function types, and direct evaluation of lambda expressions (β–reduction) without the need for additional type casts. In this paper, we extend this work by introducing a heterogeneous translation of those function types, allowing generic type information to be retained at runtime. Furthermore, we provide a concrete implementation for the interoperability between our function types and the target types in Java. Finally, we present how the combination of global type inference, real function types, and heterogeneous translation allows a novel, flexible handling of higher-order functions in Java-like languages.