content: {-# LANGUAGE PackageImports #-}
  {-# LANGUAGE AllowAmbiguousTypes    #-}
  {-# LANGUAGE FlexibleContexts       #-}
  {-# LANGUAGE FlexibleInstances      #-}
  {-# LANGUAGE FunctionalDependencies #-}
  {-# LANGUAGE MonoLocalBinds         #-}
  {-# LANGUAGE ScopedTypeVariables    #-}
  {-# LANGUAGE TypeInType             #-}
  {-# LANGUAGE UndecidableInstances   #-}
  
  -----------------------------------------------------------------------------
  -- |
  -- Module      :  Data.Generics.Product.HList
  -- Copyright   :  (C) 2020 Csongor Kiss
  -- License     :  BSD3
  -- Maintainer  :  Csongor Kiss <kiss.csongor.kiss@gmail.com>
  -- Stability   :  experimental
  -- Portability :  non-portable
  --
  -- Derive an isomorphism between a product type and a flat HList.
  --
  -----------------------------------------------------------------------------
  
  module Data.Generics.Product.HList
    ( IsList (..)
    ) where
  
  import "this" Data.Generics.Internal.Optics
  
  import "generic-lens-core" Data.Generics.Internal.Profunctor.Iso (repIso)
  import qualified "generic-lens-core" Data.Generics.Product.Internal.HList as Core
  
  import Data.Kind
  import GHC.Generics
  
  class IsList
    (f :: Type)
    (g :: Type)
    (as :: [Type])
    (bs :: [Type]) | f -> as, g -> bs where
    list  :: Iso f g (Core.HList as) (Core.HList bs)
  
  instance
    ( Generic f
    , Generic g
    , Core.GIsList (Rep f) (Rep g) as bs
    ) => IsList f g as bs where
    list = normaliseIso (Optic (repIso . Core.glist))
    {-# INLINE list #-}
  