Recently, I've found myself wanting to make changes to code that works inside code where TyCons are knot-tied [1]. But I've found myself unable to make much progress, since my ability to debug this code is severely limited by the fact that I can't seem to trace anything. That is, if I try tracing anything that comes from a knot-tied TyCon, GHC will go into an infinite loop! This prevents me from learning *anything* about the types floating around in the code I want to fix, which is hugely annoying. How do others work around this problem? There must be *some* way to glean information about the types inside a typechecker knot, since others seem to be able to work within this space. How do you do it? And will you consider sharing your secrets? Ryan S. ----- [1] See Note [Type-checking inside the knot] at http://git.haskell.org/ghc.git/blob/884bd21a917f607b5a44e038e06f78d0b765ea63...