Moldable Exceptions

TL;DR

The paper introduces 'moldable exceptions', a lightweight mechanism that allows debuggers to adapt their interface based on contextual information from exceptions, improving debugging in live programming environments.

Contribution

It presents a novel mechanism called 'moldable exceptions' that enables customizable debugger interfaces based on context, simplifying the creation of domain-specific debuggers.

Findings

Moldable exceptions can dynamically adapt debugger interfaces.

Enhances debugging by providing context-aware views and actions.

Facilitates development of custom debuggers for specific domains.

Abstract

Debugging is hard. Interactive debuggers are mostly the same. They show you a stack, a way to sample the state of the stack, and, if the debugger is live, a way to step through execution. The standard interactive debugger for a general-purpose programming language provided by a mainstream IDE mostly offers a low-level interface in terms of generic language constructs to track down and fix bugs. A custom debugger, such as those developed for specific application domains, offers alternative interfaces more suitable to the specific execution context of the program being debugged. Custom debuggers offering contextual debugging views and actions can greatly improve our ability to reason about the current problem. Implementing such custom debuggers, however, is non-trivial, and poses a barrier to improving the debugging experience. In this paper we introduce "moldable exceptions", a lightweight mechanism to adapt a debugger's interface based on contextual information provided by a raised exception. We present, through a series of examples, how moldable exceptions can enhance a live programming environment.