implementation module Yard import StdTuple import StdClass import StdString import StdList import StdInt import Common concat :: ([String] -> String) concat = foldl (+++) "" intersperse :: !a ![a] -> [a] intersperse i [] = [] intersperse i [x] = [x] intersperse i [x:xs] = [x,i:intersperse i xs] runParser :: (Parser a b) [a] -> (Either Error b, [a]) runParser (Parser f) i = f i instance Functor (Parser a) where (<$>) f m = m >>= \x -> pure (f x) instance Applicative (Parser a) where pure a = Parser \i -> (Right a, i) (<*>) sf p = sf >>= \sf` -> p >>= \p` -> pure (sf` p`) instance Monad (Parser a) where (>>=) p f = Parser \i -> case runParser p i of (Right r, rest) = runParser (f r) rest (Left e, _) = (Left e, i) instance Alternative (Parser a) where empty = Parser \i -> (Left $ GenericError "" , i) (<|>) p1 p2 = Parser \i -> case runParser p1 i of (Right r, rest) = (Right r, rest) (Left e1, rest) = case runParser p2 i of (Left e2, rest) = (Left e2, i) (Right r, rest) = (Right r, rest) () :: (Parser a b) Error -> Parser a b () p e = Parser \i -> case runParser p i of (Left e1, rest) = (Left e, rest) (Right r, rest) = (Right r, rest) fail :: Parser a b fail = empty top :: Parser a a top = Parser \i -> case i of [] = (Left $ GenericError "", []) [x:xs] = (Right x, xs) peek :: Parser a a peek = Parser \i -> case i of [] = (Left $ GenericError "", []) [x:xs] = (Right x, [x:xs]) (until) infix 2 :: (Parser a b) (Parser a c) -> Parser a [b] (until) p guard = try $ until` p guard [] where until` :: (Parser a b) (Parser a c) [b] -> Parser a [b] until` p guard acc = Parser \i -> case runParser guard i of (Right _, rest) = (Right acc, rest) (Left _, _) = case runParser p i of (Right r, rest) = runParser (until` p guard [r:acc]) rest (Left e, _) = (Left e, i) try :: (Parser a b) -> Parser a b try p = Parser \i -> case runParser p i of (Left e, _) = (Left e, i) (Right r, rest) = (Right r, rest) satisfy :: (a -> Bool) -> Parser a a satisfy f = top >>= \r -> if (f r) (pure r) fail check :: (a -> Bool) -> Parser a a check f = peek >>= \r -> if (f r) (pure r) fail item :: a -> Parser a a | == a item a = satisfy ((==)a) list :: [a] -> Parser a [a] | == a list as = mapM item as