Minimal Session Types for the π-calculus

Session types are a discipline for the static verification of message-passing programs. A session type specifies a channel's protocol as sequences of exchanges. It is most relevant to investigate session-based concurrency by identifying the essential notions that enable program specification and verification. Following that perspective, prior work identified minimal session types (MSTs), a sub-class of session types without the sequentiality construct, which specifies the structure of communication actions. This formulation of session types led to establish a minimality result: every process typable with standard session types can be compiled down to a process typable using MSTs, which mimics sequentiality in types via additional process synchronizations. Such a minimality result is significant because it justifies session types in terms of themselves, without resorting to external notions; it was proven for a higher-order session π-calculus, in which values are abstractions (functions from names to processes).