Minor containers API changes

[Felipe Almeida Lessa]

On Sun, Dec 4, 2011 at 3:52 AM, Edward Z. Yang <ezyang at mit.edu> wrote:
> Excerpts from Felipe Almeida Lessa's message of Wed Nov 30 07:51:20 -0500 2011:
>>   reverse' :: Map (Reverse k) a -> Map k a
>>   reverse' = unsafeCoerce . reverse
>>
>> Sorry, couldn't resist =).
>
> I might be confused, but doesn't this break internal invariants in Map?

Which ones?  The Ord instance of 'Reverse (Reverse k)'s should be the
same as that of 'k', right?  Other than that, what invariants could be
broken?

Cheers,

-- 
Felipe.