`Arbitrary` instances for GADTs

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1

I have a need to define QuickCheck Arbitrary instances for GADTs, of course genericArbitrary does not work, because GHC does not derive Generic for GADTs. But kind-generics: Generic programming in GHC style for arbitrary kinds and GADTs. uses Template Haskell to define a instances for a class GenericK , so I think the missing piece would be a function genericKArbitrary, analogous to generic-randoms genericArbitrary.

Does that exist somewhere?

What else do people use to write property tests over GADTs?

2

Personally, on the rare occasion I do need to property test over GADTs I just write the instances manually. The same goes for e.g. JSON instances and similar stuff.