Position.hs

{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE StandaloneDeriving #-}
{-# LANGUAGE FlexibleInstances #-}

module Position where

import GHC.Generics (Generic)
import Foreign.Ptr (Ptr )
import Data.Word (Word8)

data Position f =
  Position
  { x :: Double
  , y :: Double
  , next :: f (Position f)
  } deriving Generic

data TaggedPosition a =
  TaggedPosition
  { t1 :: Word8
  , pos :: a
  } deriving Generic

-- TaggedPosition (Ptr (Position Ptr))  -- for C

-- TaggedPosition (Maybe (Position Maybe))  -- for Haskell

deriving instance Eq (Position Maybe)
deriving instance Eq (TaggedPosition (Maybe (Position Maybe)))

deriving instance Show (Position Maybe)
deriving instance Show (TaggedPosition (Maybe (Position Maybe)))