Functional Type Assignment for Featherweight Java

Abstract. We consider functional type assignment for the class-based objectoriented calculus Featherweight Java. We start with an intersection type assignment systems for this calculus for which types are preserved under conversion. We then define a variant for which type assignment is decidable, and define a notion of unification as well as a principal typeing algorithm. We show the expressivity of both our calculus and our type system by defining an encoding of Combinatory Logic into our calculus and showing that this encoding preserves typeability. We thus demonstrate that the great capabilities of functional types can be applied to the context of class-based object orientated programming