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Added Control.Applicative instances

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This commit is contained in:
Derek Elkins 2008-01-13 23:54:41 +00:00
parent 034c9fbbe9
commit 4cc1a98ba9
1 changed files with 7 additions and 4 deletions
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11
Text/Parsec/Prim.hs
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@ -16,6 +16,7 @@
module Text.Parsec.Prim where
import Control.Applicative
import Control.Monad
import Control.Monad.Trans
import Control.Monad.Identity
@ -57,14 +58,16 @@ instance Functor (Reply s u) where
fmap f (Ok x s e) = Ok (f x) s e
fmap f (Error e) = Error e -- XXX
instance (Functor f) => Functor (ParsecT s u f) where
instance (Monad m) => Functor (ParsecT s u m) where
fmap f p = parsecMap f p
parsecMap :: (Functor f) => (a -> b) -> ParsecT s u f a -> ParsecT s u f b
parsecMap :: (Monad m) => (a -> b) -> ParsecT s u m a -> ParsecT s u m b
parsecMap f p
= ParsecT $ \s -> fmap (fmap (fmap (fmap f))) (runParsecT p s)
= ParsecT $ \s -> liftM (fmap (liftM (fmap f))) (runParsecT p s)
-- | Monad: return, bind (>>=) and fail
instance (Monad m) => Applicative (ParsecT s u m) where
pure = return
(<*>) = ap
instance (Monad m) => Monad (ParsecT s u m) where
return x = parserReturn x