This paper is an attempt to apply the reasoning principles and calculational style underlying the so-called Bird-Meertens formalism to the design of process calculi, parametrized by a behaviour model. In particular, basically equational and pointfree proofs of process properties are given, relying on the universal characterisation of anamorphisms and therefore avoiding the explicit construction of bisimulations. The developed calculi can be directly implemented on a functional language supporting coinductive types, which provides a convenient way to prototype processes and assess alternative design decisions.(undefined