[Haskell-cafe] QuickCheck behaving strange

[Miguel Mitrofanov]

I've felt a bit stupid using instance Monoid ()... but it seemed quite  
natural.

On 24 Jul 2009, at 22:33, Jason Dagit wrote:

>
>
> On Fri, Jul 24, 2009 at 11:29 AM, Felipe Lessa  
> <felipe.lessa at gmail.com> wrote:
> On Fri, Jul 24, 2009 at 08:11:12PM +0200, Tobias Olausson wrote:
> > prop_schedule :: Ord t => [Interval a t] -> Bool
> > prop_schedule []        = True
> > prop_schedule [a]       = True
> > prop_schedule (x:y:ys)  = end x <= begin y && prop_schedule (y:ys)
> [..]
> > How come QuickCheck passes 100 tests of random lists? One would  
> think that
> > at least one of the generated lists would be unsorted. It also  
> passes
> > 1000 and even
> > 10000 tests.
>
> Probably it was defaulting to 'Interval () ()'.  Try to do
>
> Cases like this make me feel as though the instance of Ord for ()  
> was  a mistake.
>
> Jason
>
> _______________________________________________
> Haskell-Cafe mailing list
> Haskell-Cafe at haskell.org
> http://www.haskell.org/mailman/listinfo/haskell-cafe