I don't care one way or the other about the creation of implies, I'm happy
to bow to popular opinion either way.
I do care about changing the strictness of the comparisons in Ord Bool,
however, and that would require a rather massive survey of what breaks, and
what gets slower -- one that we simply haven't done -- before I'd even
start to be comfortable with it.
-Edward
On Mon, Jan 25, 2016 at 12:27 PM, wren romano
-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 _______________________________________________ Libraries mailing list Libraries@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries