{-# LANGUAGE CPP #-}

module Internal.Box
  ( Id(Id,unId)
  , Box(Box, unBox)
  , delay_inline, delayed_min 
  ) where

#if !MIN_VERSION_base(4,8,0)
import Control.Applicative (Applicative(pure, (<*>)))
#endif

newtype Id a = Id { unId :: a }

instance Functor Id where
  fmap f (Id x) = Id (f x)

instance Applicative Id where
  pure = Id
  Id f <*> Id x = Id (f x)

instance Monad Id where
  return = pure
  Id x >>= f = f x

newtype Box a = Box { unBox :: a }

instance Functor Box where
  fmap f (Box x) = Box (f x)

instance Applicative Box where
  pure = Box
  Box f <*> Box x = Box (f x)

instance Monad Box where
  return = pure
  Box x >>= f = f x

delay_inline :: (a -> b) -> a -> b
{-# INLINE [0] delay_inline #-}
delay_inline f = f

delayed_min :: Int -> Int -> Int
{-# INLINE [0] delayed_min #-}
delayed_min m n = min m n