src/Bit.hs

   1 -- | The Bit module contains the Bit data type, which is essentially a
   2 --   renamed Boolean, and some convenience functions.
   3 module Bit
   4 where
   5
   6 import Test.QuickCheck (
   7   Arbitrary,
   8   arbitrary,
   9   elements
  10   )
  11
  12
  13 data Bit = Zero | One
  14   deriving (Enum, Eq)
  15
  16 instance Show Bit where
  17   show Zero = "0"
  18   show One  = "1"
  19
  20
  21 instance Arbitrary Bit where
  22   arbitrary = elements [ Zero, One ]
  23
  24
  25 instance Ord Bit where
  26   Zero <= Zero = True
  27   Zero <= One  = True
  28   One  <= Zero = False
  29   One  <= One  = True
  30
  31 instance Bounded Bit where
  32   minBound = Zero
  33   maxBound = One
  34
  35
  36 -- | Convert a Bit to an Int.
  37 bit_to_int :: Bit -> Int
  38 bit_to_int Zero =  0
  39 bit_to_int One  =  1
  40
  41 -- | If we are passed a '0' or '1', convert it
  42 --   appropriately. Otherwise, return Nothing.
  43 bit_from_char :: Char -> Maybe Bit
  44 bit_from_char '0' = Just Zero
  45 bit_from_char '1' = Just One
  46 bit_from_char  _  = Nothing