[Haskell-cafe] Hedgehog - Integrated shrinking, shrinks obey invariants by construction.

Li-yao Xia lysxia at gmail.com
Thu Jun 14 21:11:31 UTC 2018

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.


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