Amalgamating the Session Types and the Object Oriented Programming Paradigms

We suggest an amalgamation of the session type and the object oriented paradigm whereby sessions are amalgamated with methods; where threads consist of the execution of session bodies on objects and communicate with each other through asynchronously sending/receiving objects on channels; where the choice on how to respond to a session request is based on the name of the request and the class of the object receiving the request; where the choice on how to continue a session is made on the basis of the class of the object sent/received; and where sessions are not first class, but can be delegated to other sessions. We demonstrate our ideas through a small language, STOOP , and an example. We formalize a smaller calculus, FeatherSTOOP , and give a formal definition, and prove subject reduction and progress. The latter property is notoriously difficult and sometimes impossible to achieve in sessions languages, however it holds in FeatherSTOOP .