Could you please take a look at the type error that happens when you apply both of the patches from "[jhc] darcs patch: Check that lhs and rhs have compatible t... (and 1 more)" and then run "perl regress/regress.prl Kleisli"? (Maybe you'll want to unpull the first one and instead just print out both types in printRule...) I'm suspicious of the line: Just (n,_) -> foldl EAp (EVar n) (vs ++ map EVar args) but not sure what it should be...