yard.icl

   1 implementation module yard
   2
   3 import StdTuple
   4 import StdClass
   5 import Data.Functor
   6 import Data.Either
   7 import Control.Monad
   8 import Control.Applicative
   9 from Data.Func import $
  10
  11 runParser :: (Parser a b) [a] -> (Either Error b, [a])
  12 runParser (Parser f) i = f i
  13
  14 instance Functor (Parser a) where
  15     //fmap f m = liftM f m
  16     fmap g p = Parser \i -> case runParser p i of
  17         (Right r, rest) = (Right $ g r, rest)
  18         (Left e, rest)  = (Left e, rest)
  19
  20 instance Applicative (Parser a) where
  21     pure a      = Parser \i -> (Right a, i)
  22     //(<*>) sf p  = ap sf p
  23     (<*>) pf p  = Parser \i -> case runParser pf i of
  24         (Right f, rest) = runParser (fmap f p) rest
  25         (Left e, rest)   = (Left e, rest)
  26
  27 instance Monad (Parser a) where
  28     bind p f    = Parser \i -> case runParser p i of
  29         (Right r, rest) = runParser (f r) rest
  30         (Left e, rest)  = (Left e, rest)
  31
  32 //some, many, optional and l
  33 instance Alternative (Parser a) where
  34     empty       = Parser \i -> (Left ParseException, i)
  35     (<|>) p1 p2 = Parser \i -> case runParser p1 i of
  36         (Right r, rest) = (Right r, rest)
  37         (Left _, rest)  = runParser p2 i
  38
  39 fail :: Parser a b
  40 fail = empty
  41
  42 top :: Parser a a
  43 top = Parser \i -> case i of
  44     []      = (Left ParseException, [])
  45     [x:xs]  = (Right x, xs)
  46
  47 satisfy :: (a -> Bool) -> Parser a a
  48 satisfy f = top >>= \r -> if (f r) (return r) fail
  49
  50 item :: a -> Parser a a | Eq a
  51 item a  = satisfy ((==)a)
  52
  53 list :: [a] -> Parser a [a] | Eq a
  54 list as = mapM item as