parsers/Parsers/Utils.hs

   1 module Parsers.Utils
   2   ( module Parsers.Utils
   3   , w2c
   4   )
   5   where
   6
   7 import Data.Char (Char)
   8 import Data.Function ((.), id)
   9 import Data.Word (Word8)
  10 import Prelude (Enum(..))
  11 import Data.ByteString.Internal (w2c, c2w)
  12
  13 -- * Class 'CoerceEnum'
  14 -- | Convenient helper to write generic grammars
  15 -- consuming either 'Word8' or 'Char'.
  16 class CoerceEnum a b where
  17   coerceEnum :: a -> b
  18   default coerceEnum :: Enum a => Enum b => a -> b
  19   coerceEnum = toEnum . fromEnum
  20 instance CoerceEnum Word8 Char where
  21   coerceEnum = w2c
  22 instance CoerceEnum Char Word8 where
  23   coerceEnum = c2w
  24 instance CoerceEnum Char Char where
  25   coerceEnum = id