Bugfix for QuickCheck 1.1.0.0
Jed Brown
jed at 59A2.org
Tue Sep 2 13:52:32 EDT 2008
On Tue 2008-09-02 09:46, Patrick Perry wrote:
>
> Jed Brown wrote:
>> The idea with QC is that you start with `simple' random input and
>> progress to more `complicated' input. If say, you are testing a
>> function that builds a list with length equal to the output of the
>> QC-generated function (Double->Int) (with positive precondition) you
>> could be building a huge list very early. This wouldn't happen with
>> other types since `simple' QC-generated functions for, say, (Int->Int)
>> will map small integers to small integers.
>
> I don't think this has anything to do with the definition of
> coarbitrary. As I understand things:
> coarbitrary is a function of type x -> StdGen
> arbitrary is a function of type StdGen -> Int -> x
> For the type "x -> y", arbitrary is equal to
> \g n -> (\x -> let g' = coarbitrary x in arbitrary g' n)
>
> I did an experiment in QC1 (with patch). Here are two properties:
> prop_f (f :: Double -> Int) x = trace (show $ f x) True
> prop_g (f :: Int -> Int) x = trace (show $ f x) True
>
> Below is the output. Do you think that one is "more simple" than the
> other?
Hmm, I guess I should have run the test before speculating. It looks
like the logarithmic factor keeps it all in control.
Jed
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