I'm using GHC 5.04.2 on Windows.

I made some changes which broke my application, in that certain input now causes *** Exception: <<loop>>

I can't work out what I did to introduce an infinite loop. Is there something I can do to extract more information to narrow this down?

Any pointers appreciated

You can try compiling the program with -prof -auto-all, and running it with +RTS -xc. This is a primitive debugging tool for diagnosing the location of exceptions. See: http://www.haskell.org/ghc/docs/latest/html/users_guide/runtime-control.html... Cheers, Simon