Extending Record typing to type parametric modules with sharing

We extend term unification techniques used to type extensible records in order to solve the two main typing problems for modules in Standard ML: matching and sharing. We obtain a type system for modules based only on well known unification problems, modulo some equational theories we define. Our formalization is sim- ple and has the elegance of polymorphic type disciplines based on unification. It can be seen as a synthesis of previous work on module and record typing