FROM CML TO ITS PROCESS ALGEBRA

Reppy's language CML extends Standard ML of Milner et al. with primiti ves for communication. It thus inherits a notion of strong polymorphic typing and may be equipped with a structural operational semantics. A s a first step we formulate an effect system for statically expressing the communication behaviours of CML programs as these are not reflect ed in the types. As a second step we adapt the structural operational semantics of CML so as to incorporate behaviours. We then show how typ es and behaviours evolve in the course of computation: types may decre ase and behaviours may lose prefixes as well as decrease. As the synta x of behaviours is rather similar to that of a process algebra our mai n result may therefore be viewed as regarding the semantics of a proce ss algebra as an abstraction of the semantics of an underlying program ming language. This establishes a new kind of connection between ''rea listic'' concurrent programming languages and ''theoretical'' process algebras.