Inheritance and Selective Methods Dispatching in Concurrent Haskell

We incorporate object oriented features into the functional language Haskell: inheritance and methods with super and self references. Parametric polymorphism is retained in object classes. Interfaces are used to describe protocols (as a set of overloaded functional methods) and methods can be defined by default. Object classes implement (or inherit) interface methods. These classes and interfaces are organised in a hierarchical structure. We have integrated our model with Concurrent Haskell. The integrity of object attributes can be guaranteed via a guarded construct, which can also be used to selectively accept messages, depending on the object state and message arguments. The synchronisation mechanism is shown by examples. Our model offers a way out from the inheritance anomaly problem in most cases by incorporating synchronisation constraints into the inheritance hierarchy.