This is an implementation of ddmin, one of the tools of delta debugging. Briefly, delta debugging attempts to minimize an input to some other tool that causes an error; ddmin takes the input and tries to make it smaller while still causing the same error.
This is an implementation in Haskell that tries to offer some flexible regular-expression based failure matching criteria.
More documentation coming soon, hopefully. I think this will also need a bit of work to build on a newer Haskell Platform.