Generic validation using generic-sop

Person.hs

{-# LANGUAGE DeriveAnyClass #-}
{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE TypeFamilies #-}
module Person where

import Generics.SOP
import qualified GHC.Generics as GHC

data Person' f =
  Person
    { pName :: HKD f String
    , pAge  :: HKD f Int
    } deriving (GHC.Generic, Generic)

type family HKD (f :: * -> *) (a :: *) :: * where
  HKD I a = a
  HKD f a = f a

type Person      = Person' I
type MaybePerson = Person' Maybe

validate ::
  ( Generic (a f), Generic (a I), Applicative f
  , AllZip2 (LiftedCoercible I f) (Code (a f)) (Code (a I))
  ) => a f -> f (a I)
validate =
  (to <$>) . hsequence . hcoerce . from

validatePerson :: Person' Maybe -> Maybe (Person' I)
validatePerson = validate

invalidatePerson :: Person' I -> Person' Maybe
invalidatePerson = to . hcoerce . hmap (Just . unI) . from

Generalising a bit:

invalidate
    :: ( Generic (a f)
       , Generic (a I)
       , AllZip2 (LiftedCoercible f I) (Code (a I)) (Code (a f))
       )
    => (forall b. b -> f b)
    -> a I
    -> a f
invalidate f = to . hcoerce . hmap (f . unI) . from