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

[PICCA Frederic-Emmanuel]

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