yard.icl

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