Interactive debugging with GHCi

Abstract

With my presentation I intend to demonstrate an implementation of breakpoint combinators in GHCi. These combinators are designed to aid the debugging process of Haskell programs by halting the execution and letting the user observe variables of their choice. In contrast to the existing tools (such as Hat, Hood, Buddha and Debug. Trace), which in effect allow something similar, the combinators I will be demonstrating give the user the ability to observe the properties, not just the stringification, of variables. The combinators are a more low-level approach to the problem of debugging and do not provide as advanced features as Hat or Buddha. However, no sophisticated debugging system for Haskell has been really widely adopted by the Haskell community, primarily because they lack support for a variety of commonly used Glasgow Haskell extensions. The breakpoint combinators, on the other hand, are integrated in GHCi and work out-of-the-box with all Glasgow Haskell programs.