Polymorphic type inference for a simple object oriented programming language with state

We show how type inference for object oriented programming languages with state can be performed without type declarations. Our type inference system is based on the works of Remy and Wand which can in turn be traced back directly to Milner's classical type inference algorithm. O'small a simple object oriented language, is translated into mathcal{L}, a language of lambda-calculus with records and imperative features. Type inference rules are given for mathcal{L}. O'small-programs are type checked after being translated into mathcal{L}. We show that for translations of O'small-programs one can have a type system with principal types