Enhancing Regular Corecursion

Nowadays, data structures which are conceptually infinite, such as streams or infinite trees, are very common in computer science. When it comes to their manipulation, one major problem to face is how to finitely represent and deal with them without incurring in non-terminating behaviours. Regular corecursion is a solution relying on finite representation of regular data structures, and detection of cyclic calls. The topics in the thesis revolve around two enhancements of regular corecursion in different directions. In the first part, we present Corecursive Featherweight Java (coFJ), an object-oriented calculus which supports flexible regular corecursion, that is, allows the programmer to specify the behaviour when a cyclic call is found. In the second part, instead, we extend regular corecursion beyond regular terms, focusing on the significant case of stream definitions.