Recursive override

[anpryl]

Is it possible to override ToJSON for all fields in nested records?

newtype ZeroInt = ZeroInt Int

instance ToJSON ZeroInt where
  toJSON _ = toJSON (0 :: Int)

data MyRec = MyRec
  { x :: X,
    y :: Int
  }
  deriving (Show, Eq, Generic, ToJSON)

data X = X {x :: Int}
  deriving (Show, Eq, Generic, ToJSON)

newtype MyRecZeroInt = MyRecZeroInt MyRe
  deriving (ToJSON) via Override MyRecZeroInt '[Int `As` ZeroInt]

ghci:

 Data.ByteString.Lazy.Char8.putStrLn $ encode $ MyRecZeroInt $ MyRec  ( X 1) 2
{"x":{"x":1},"y":0}

I want x to become zero too.

[carymrobbins]

It might be possible, but it's not currently implemented. I'd also be concerned with how unpredictable it might be. If one of the nested records does not have a Generic instance, should recursive override fail to compile? Should it succeed but ignore that record? There are likely lots of questions and edge cases that need to be accounted for first. I am open to suggestions and PRs, although for the latter it's better to discuss the approach first.