That's interesting! Could you please elaborate how this is implemented? Thanks, Petr Dne čt 14. 6. 2018 23:12 uživatel Li-yao Xia napsal:

Generators can be interpreted as the sets of values they generate, and "integrated shrinking" makes shrinking produce values that belong to the same set, by deriving it from the generator. In contrast, in QuickCheck, generators and shrinkers are separate, so if a property we want to test has some precondition, we need to remember to make both the generator and the shrinker satisfy these preconditions.

Li-yao

On 06/14/2018 04:24 PM, Petr Pudlák wrote:

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Hi everyone,

I found the above interesting sentence in Hedgehog's [1] documentation. What does this mean? Is construction there somewhat tied to shrinking, perhaps something like going in the reverse direction?

Thanks, Petr

[1] https://github.com/hedgehogqa/haskell-hedgehog#features

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"LX" == Li-yao Xia writes:

LX> The main drawback might be that there is some duplicated work during LX> shrinking ((>>=) applies its second argument to different arguments), but LX> it is quite minor since shrinking is only needed in exceptional cases, and LX> it usually terminates in few steps. I've recently switched from QuickCheck to Hedgehog for my property testing, and having found that the implied shrinking is indeed a very nice behavior. Shrinking is one of those principled ideas that rarely happens in execution, so any methodology for automating it is appreciated. -- John Wiegley GPG fingerprint = 4710 CF98 AF9B 327B B80F http://newartisans.com 60E1 46C4 BD1A 7AC1 4BA2