The Hat tracer for Haskell is a very powerful tool for debugging and comprehending programs. However, it was written largely before the Cabal library packaging system was developed. It is difficult to get any non-trivial program to work with Hat, if the program uses any pre-packaged libraries outside the haskell'98 standard.

The aims of this project are:

    (a) to fix Hat so that it adequately traces hierarchical library packages

    (b) to integrate support for tracing into Cabal, so a user can simply ask for the 'tracing' version of a package in addition to the 'normal' and 'profiling' versions.

    (c) to develop a 'wrapping' scheme whereby the code inside libraries does not in fact need to be traced at all, but instead Hat would treat the library functions as abstract entities.