-1 for changing the Ord Bool instance, due to the likelihood of subtle bugs and regressions. -1 for using the name (==>) due to conflict with QuickCheck, Smallcheck, etc. Ambivalent about adding an implication operator distinct from (<=), mainly because I haven't needed it myself. IMO, the ordering on Bool should be defined so that it coincides with implication, thanks to the relationship to Boolean/Heyting algebras— which the current Ord instance already does. Though I do agree that if implication is given its own name then it ought to be lazy in the second argument, whereas it's not clear that (<=) should share that strictness/laziness. Personally, were I to add something like implication, I'd define it via a type class so that we can unify the things called (==>) in various testing frameworks. Of course, doing this appropriately would mean making a decent hierarchy of type classes for order/lattice theory. But given as we don't have one of those yet, I'd do it in a separate package so it could be played around with until everything fits together nicely, and then aim to get it blessed into HP rather than changing base. -- Live well, ~wren