Show instance not working for first/default enum values

[mleone11]

I've got the following defined in a protobuf (proto3)

...

enum SODirection {
  SO_DIRECTION_FORWARD = 0;
  SO_DIRECTION_BACKWARD = 1;
}

message SOAccountEvent {
  bytes event_id = 1;
  uint64 order_number = 2;
  uint64 account_number = 3;
  SOStatus from_status = 4;
  SOStatus to_status = 5;
  SOStatus target_status = 6;
  SODirection direction = 7;
  string bump_user = 8;
}

...

which I've generated into the following haskell code with the compiler

...

{- | Fields :
     
         * 'Proto.SoEvent_Fields.eventId' @:: Lens' SOAccountEvent Data.ByteString.ByteString@
         * 'Proto.SoEvent_Fields.orderNumber' @:: Lens' SOAccountEvent Data.Word.Word64@
         * 'Proto.SoEvent_Fields.accountNumber' @:: Lens' SOAccountEvent Data.Word.Word64@
         * 'Proto.SoEvent_Fields.fromStatus' @:: Lens' SOAccountEvent SOStatus@
         * 'Proto.SoEvent_Fields.toStatus' @:: Lens' SOAccountEvent SOStatus@
         * 'Proto.SoEvent_Fields.targetStatus' @:: Lens' SOAccountEvent SOStatus@
         * 'Proto.SoEvent_Fields.direction' @:: Lens' SOAccountEvent SODirection@
         * 'Proto.SoEvent_Fields.bumpUser' @:: Lens' SOAccountEvent Data.Text.Text@ -}
data SOAccountEvent
  = SOAccountEvent'_constructor {_SOAccountEvent'eventId :: !Data.ByteString.ByteString,
                                 _SOAccountEvent'orderNumber :: !Data.Word.Word64,
                                 _SOAccountEvent'accountNumber :: !Data.Word.Word64,
                                 _SOAccountEvent'fromStatus :: !SOStatus,
                                 _SOAccountEvent'toStatus :: !SOStatus,
                                 _SOAccountEvent'targetStatus :: !SOStatus,
                                 _SOAccountEvent'direction :: !SODirection,
                                 _SOAccountEvent'bumpUser :: !Data.Text.Text,
                                 _SOAccountEvent'_unknownFields :: !Data.ProtoLens.FieldSet}
  deriving stock (Prelude.Eq, Prelude.Ord)

...

newtype SODirection'UnrecognizedValue
  = SODirection'UnrecognizedValue Data.Int.Int32
  deriving stock (Prelude.Eq, Prelude.Ord, Prelude.Show)
data SODirection
  = SO_DIRECTION_FORWARD |
    SO_DIRECTION_BACKWARD |
    SODirection'Unrecognized !SODirection'UnrecognizedValue
  deriving stock (Prelude.Show, Prelude.Eq, Prelude.Ord)
instance Data.ProtoLens.MessageEnum SODirection where
  maybeToEnum 0 = Prelude.Just SO_DIRECTION_FORWARD
  maybeToEnum 1 = Prelude.Just SO_DIRECTION_BACKWARD
  maybeToEnum k
    = Prelude.Just
        (SODirection'Unrecognized
           (SODirection'UnrecognizedValue (Prelude.fromIntegral k)))
  showEnum SO_DIRECTION_FORWARD = "SO_DIRECTION_FORWARD"
  showEnum SO_DIRECTION_BACKWARD = "SO_DIRECTION_BACKWARD"
  showEnum
    (SODirection'Unrecognized (SODirection'UnrecognizedValue k))
    = Prelude.show k
  readEnum k
    | (Prelude.==) k "SO_DIRECTION_FORWARD"
    = Prelude.Just SO_DIRECTION_FORWARD
    | (Prelude.==) k "SO_DIRECTION_BACKWARD"
    = Prelude.Just SO_DIRECTION_BACKWARD
    | Prelude.otherwise
    = (Prelude.>>=) (Text.Read.readMaybe k) Data.ProtoLens.maybeToEnum
instance Prelude.Bounded SODirection where
  minBound = SO_DIRECTION_FORWARD
  maxBound = SO_DIRECTION_BACKWARD
instance Prelude.Enum SODirection where
  toEnum k__
    = Prelude.maybe
        (Prelude.error
           ((Prelude.++)
              "toEnum: unknown value for enum SODirection: " (Prelude.show k__)))
        Prelude.id (Data.ProtoLens.maybeToEnum k__)
  fromEnum SO_DIRECTION_FORWARD = 0
  fromEnum SO_DIRECTION_BACKWARD = 1
  fromEnum
    (SODirection'Unrecognized (SODirection'UnrecognizedValue k))
    = Prelude.fromIntegral k
  succ SO_DIRECTION_BACKWARD
    = Prelude.error
        "SODirection.succ: bad argument SO_DIRECTION_BACKWARD. This value would be out of bounds."
  succ SO_DIRECTION_FORWARD = SO_DIRECTION_BACKWARD
  succ (SODirection'Unrecognized _)
    = Prelude.error
        "SODirection.succ: bad argument: unrecognized value"
  pred SO_DIRECTION_FORWARD
    = Prelude.error
        "SODirection.pred: bad argument SO_DIRECTION_FORWARD. This value would be out of bounds."
  pred SO_DIRECTION_BACKWARD = SO_DIRECTION_FORWARD
  pred (SODirection'Unrecognized _)
    = Prelude.error
        "SODirection.pred: bad argument: unrecognized value"
  enumFrom = Data.ProtoLens.Message.Enum.messageEnumFrom
  enumFromTo = Data.ProtoLens.Message.Enum.messageEnumFromTo
  enumFromThen = Data.ProtoLens.Message.Enum.messageEnumFromThen
  enumFromThenTo = Data.ProtoLens.Message.Enum.messageEnumFromThenTo
instance Data.ProtoLens.FieldDefault SODirection where
  fieldDefault = SO_DIRECTION_FORWARD
instance Control.DeepSeq.NFData SODirection where
  rnf x__ = Prelude.seq x__ ()

...

and when I use this in my test project and I try to show the whole record

...

mkSOAccountEvent ::
     ByteString
  -> Word64
  -> Word64
  -> SOStatus
  -> SOStatus
  -> SODirection
  -> Text
  -> SOAccountEvent
mkSOAccountEvent e o a f t d b =
  defMessage
  & eventId .~ e
  & orderNumber .~ o
  & accountNumber .~ a
  & fromStatus .~ f
  & toStatus .~ t
  & targetStatus .~ t
  & direction .~ d
  & bumpUser .~ b

...

let ev1 = mkSOAccountEvent "e1" 1 11 SO_STATUS_DISPATCH SO_STATUS_QA SO_DIRECTION_FORWARD "Tester1"
putStrLn $ show ev1
let ev2 = mkSOAccountEvent "e2" 2 22 SO_STATUS_DISPATCH SO_STATUS_QA SO_DIRECTION_BACKWARD "Tester2"
putStrLn $ show ev2

...

but it doesn't print the direction field when I have it set to the first/default value

{event_id: "e1" order_number: 1 account_number: 11 from_status: SO_STATUS_DISPATCH to_status: SO_STATUS_QA target_status: SO_STATUS_QA bump_user: "Tester1"}
{event_id: "e2" order_number: 2 account_number: 22 from_status: SO_STATUS_DISPATCH to_status: SO_STATUS_QA target_status: SO_STATUS_QA direction: SO_DIRECTION_BACKWARD bump_user: "Tester2"}

I think that I've removed all doubt that my custom code/protobuf has caused this behavior, and for some reason the generated haskell types are the culprit