Hi, sorry for not providing a mwe, but while I dig deeper, maybe someone has a “this is typically a problem with X” idea… This is in the context of a Core plugin (Conal’s Compiling to Categories), and I observe an oddity: I have two 'Types' that _should_ be equal, that ppr’int equal, but where eqType says False. The type looks like this: (SymRAD1 windowFunctor_a3e0Q kernelFunctor_a3e0R channelsFunctor_a3e0S numType_a3e0T, SymRAD2 paddedWindowFunctor_a3e0P windowFunctor_a3e0Q kernelFunctor_a3e0R channelsFunctor_a3e0S numType_a3e0T) what might make eqType go False that is _not_ visible in the pretty- printed view? Cheers, Joachim -- Joachim Breitner mail@joachim-breitner.de http://www.joachim-breitner.de/