Name-passing style GUI programming in the π-calculus-based language Nepi

This paper describes name-passing style Graphic User Interface (GUI) programming in the programming language Nepi whose operational semantics is based on the rendezvous-style name-passing communication of the π-calculus. Nepi is able to have timed behavior by combining the wait prefix with the external choice. We model GUI programs by using channel-based behavioral characterization. We propose a pair of extended syntax elements '?g' and '!g' in Nepi to generate and terminate graphic components. The graphic components are accompanied by event handling processes that convert an event to specified name-passing. In the extended Nepi, a GUI program is described as the composition of graphic components, event handling processes, and function processes that implement the real function. We present an implementation of a GUI extension for Nepi programming language on Allegro Common Lisp to illustrate the features of name-passing style GUI programming in Nepi with examples. Finally, we discuss a formal treatment and verification technique based on the extended reduction semantics of Nepi.