Language/DTC/Utils.hs

   1 module Language.DTC.Utils where
   2
   3 import Control.Applicative (Applicative(..))
   4 import Data.Eq (Eq)
   5 import Data.Function (($), (.))
   6 import Data.Functor (Functor(..), (<$>))
   7 import Text.Show (Show)
   8
   9 -- * Type 'PaddedList'
  10 data PaddedList a
  11  =   PaddedList { padded :: [a]
  12                 , padder :: a
  13                 } deriving (Eq, Show)
  14
  15 instance Functor PaddedList where
  16         fmap = (<*>) . pure
  17 instance Applicative PaddedList where
  18         pure = PaddedList []
  19         PaddedList xs x <*> PaddedList ys y =
  20                 zapp xs ys `PaddedList` x y
  21                 where
  22                 zapp [] bs = x <$> bs
  23                 zapp as [] = ($ y) <$> as
  24                 zapp (a : as) (b : bs) = a b : zapp as bs
  25