:seti -XTypeFamilies -XDuplicateRecordFields -XDerivingStrategies
data family D a
data instance D Int  = MkD0 | MkDInt { x :: Int, y :: Bool } deriving Show
data instance D Bool = MkDBool { x :: Int }
f r = r { y = True, x = 14 }
f (MkDInt 3 False)