{-# LANGUAGE Safe #-}
{-# LANGUAGE StandaloneKindSignatures #-} -- because of -Weverything
{-# LANGUAGE StandaloneDeriving #-} -- to specify contexts
{-# LANGUAGE FlexibleContexts #-} -- 'non type-variable argument'
{-# LANGUAGE UndecidableInstances #-} -- instance head no smaller...
module Language.Scalie.Core.Module (Module(..)) where

import Data.Kind (Type)
import Language.Scalie.Core.Definition (Definition)
import Data.Map.Implicit (ImplicitMap)

-- | A module groups multiple related variable definitions.
--
-- >>> import Data.Functor.Identity (Identity(..))
-- >>> import Data.Map.Implicit qualified as ImplicitMap
-- >>> Module (Identity ImplicitMap.empty)
-- Module {definitions = Identity ImplicitMapElems []}
--
-- >>> import Data.Maybe (Maybe(..))
-- >>> Module Nothing
-- Module {definitions = Nothing}
--
-- >>> import Text.Read (readMaybe)
-- >>> readMaybe "Module { definitions = Just (ImplicitMapElems []) }" :: Maybe (Module Maybe)
-- Just (Module {definitions = Just ImplicitMapElems []})
--
-- >>> readMaybe "Module { definitions = Just (ImplicitMapElems [Definition { signature = Nothing, name = Just \"x\", body = Nothing } ]) }" :: Maybe (Module Maybe)
-- Just (Module {definitions = Just ImplicitMapElems [Definition {signature = Nothing, name = Just "x", body = Nothing}]})

type Module :: (Type -> Type) -> Type
type role Module nominal
newtype Module f = Module
  { definitions :: f (ImplicitMap (Definition f))
  }

deriving stock instance (Show (f (ImplicitMap (Definition f)))) => Show (Module f)
deriving stock instance (Read (f (ImplicitMap (Definition f)))) => Read (Module f)