Retire Superman: Handling Exceptions Seamlessly in a Declarative Visual Programming Language

Exception handling is widely regarded as a necessity in programming languages today, and almost every programming language in current use supports some form of it. Unfortunately however, most approaches to exception handling involve constructs with unusual powers, and even deviations from the language's evaluation model. To avoid such devices in our declarative visual programming language, we have devised a full-featured approach to exception handling that fits seamlessly into languages that are declarative and visual. Using this approach allows designers of declarative visual programming languages to provide the expressive power previously available only through complex exception handling techniques.