[Haskell-cafe] How to create a list of each constructor value

[s9gf4ult]

You can use `generic-arbitrary` like this

```haskell
import Test.QuickCheck.Arbitrary.Generic

data CristalK6C ...
   deriving Generic
   deriving (Arbitrary) via GenericArbitrary CristalK6C
```

On 30.11.2022 21:18, PICCA Frederic-Emmanuel wrote:
> Hello, I have a type like this
>
> data InputType = CristalK6C
>                 | MarsFlyscan
>                 | MarsSbs
>                 | SixsFlyMedH
>                 | SixsFlyMedV
>                 | SixsFlyMedVEiger
>                 | SixsFlyMedVS70
>                 | SixsFlyScanUhv
>                 | SixsFlyScanUhv2
>                 | SixsFlyScanUhvTest
>                 | SixsFlyScanUhvUfxc
>                 | SixsSbsFixedDetector
>                 | SixsSbsMedH
>                 | SixsSbsMedV
>                 | SixsSbsMedVFixDetector
>    deriving (Eq, Show)
>
> I want to create a list of each values in order to create meaningfull error message for the user and simplify my Arbitrary instances.
> I do not want to type two time the values.
>
> instance Arbitrary InputType where
>    arbitrary = oneof (map pure
>                       [ CristalK6C
>                       , MarsFlyscan
>                       , MarsSbs
>                       , SixsFlyMedH
>                       , SixsFlyMedV
>                       , SixsFlyMedVEiger
>                       , SixsFlyMedVS70
>                       , SixsFlyScanUhv
>                       , SixsFlyScanUhv2
>                       , SixsFlyScanUhvTest
>                       , SixsFlyScanUhvUfxc
>                       , SixsSbsFixedDetector
>                       , SixsSbsMedH
>                       , SixsSbsMedV
>                       , SixsSbsMedVFixDetector
>                       ]
>                      )
>
>
> Thanks for your help
>
> Frederic
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