Nullable Type Inference, by Michel Mauny and Benoît Vaugon

We present type inference algorithms for nullable types in ML-like programming languages. Starting with a sim- ple system, presented as an algorithm, whose only inter- est is to introduce the formalism that we use, we replace unification by subtyping constraints and obtain a more in- teresting system. We state the usual properties for both systems. This is work in progress.