[Haskell-cafe] the purpose of QuickCheck's size parameter
oleg.grenrus at iki.fi
Sat Jun 16 16:11:49 UTC 2018
Not only avoid extremely large trees, but in general guarantee termination of the generation process
Sent from my iPhone
> On 15 Jun 2018, at 0.31, David Feuer <david.feuer at gmail.com> wrote:
> data Foo a = Leaf a | Node [Foo a]
> Without the size parameter, it's a bit tricky to control the distribution to avoid generating extremely large trees. I certainly agree, however, that the size parameter is an ugly and ill-specified hack.
>> On Thu, Jun 14, 2018, 4:20 PM Petr Pudlák <petr.mvd at gmail.com> wrote:
>> Hi everyone,
>> I'd like to better understand the principles behind the 'size' parameter. Looking at quickCheckWithResult , its computation seems to be somewhat non-trivial, or even arbitrary. As far as I understand it, the size is varied throughout tests, increasing from small to larger values. I see two main purposes:
>> - Test on smaller as well as larger values. But with generators having proper distribution of values, this should happen anyway, just as if we had a constant, larger 'size' parameter.
>> - Starting with smaller sizes allows to find smaller count-examples first. But with shrinking, it doesn't matter that much, big counter-examples are shrunk to smaller ones anyway in most cases.
>> So is this parameter actually necessary? Would anything change considerably if it was dropped?
>>  http://hackage.haskell.org/package/QuickCheck-2.11.3/docs/src/Test-QuickCheck-Test.html#quickCheckWithResult
>> Haskell-Cafe mailing list
>> To (un)subscribe, modify options or view archives go to:
>> Only members subscribed via the mailman list are allowed to post.
> Haskell-Cafe mailing list
> To (un)subscribe, modify options or view archives go to:
> Only members subscribed via the mailman list are allowed to post.
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the Haskell-Cafe