Escaping the event loop: an alternative control structure for multi-threaded GUIs

The event-driven, or reactive, programming style of the contemporary GUI is a major reason they are difficult to program. This is compounded in a distributed application. The reactive style, however, reflects the mismatch between multithreaded interfaces and a single threaded process, and is actually the equivalent of continuation passing style, a source code transformation used by some compilers. Using continuations for callbacks eliminates much of the difficulty of the reactive style. We describe a toolkit for managing the multiple threads of control which can be combined with existing GUI toolkits and which supports distributed applications.