Data.Iteratee.Base
Contents
Description
Monadic Iteratees: incremental input parsers, processors and transformers
- data Stream c
- = EOF (Maybe SomeException)
- | Chunk c
- data StreamStatus
- module Data.Iteratee.Exception
- newtype Iteratee s m a = Iteratee {}
- run :: Monad m => Iteratee s m a -> m a
- tryRun :: (Exception e, Monad m) => Iteratee s m a -> m (Either e a)
- mapIteratee :: (NullPoint s, Monad n, Monad m) => (m a -> n b) -> Iteratee s m a -> Iteratee s n b
- ilift :: (Monad m, Monad n) => (forall r. m r -> n r) -> Iteratee s m a -> Iteratee s n a
- idone :: Monad m => a -> Stream s -> Iteratee s m a
- icont :: (Stream s -> Iteratee s m a) -> Maybe SomeException -> Iteratee s m a
- liftI :: Monad m => (Stream s -> Iteratee s m a) -> Iteratee s m a
- idoneM :: Monad m => a -> Stream s -> m (Iteratee s m a)
- icontM :: Monad m => (Stream s -> Iteratee s m a) -> Maybe SomeException -> m (Iteratee s m a)
- setEOF :: Stream c -> SomeException
Types
A stream is a (continuing) sequence of elements bundled in Chunks. The first variant indicates termination of the stream. Chunk a gives the currently available part of the stream. The stream is not terminated yet. The case (null Chunk) signifies a stream with no currently available data but which is still continuing. A stream processor should, informally speaking, ``suspend itself'' and wait for more data to arrive.
Constructors
| EOF (Maybe SomeException) | |
| Chunk c |
data StreamStatus Source
Describe the status of a stream of data.
Constructors
| DataRemaining | |
| EofNoError | |
| EofError SomeException |
Instances
Exception types
module Data.Iteratee.Exception
Iteratees
Monadic iteratee
Constructors
| Iteratee | |
Instances
| NullPoint s => MonadTrans (Iteratee s) | |
| (Monad m, Nullable s) => Monad (Iteratee s m) | |
| (Functor m, Monad m) => Functor (Iteratee s m) | |
| (Functor m, Monad m, Nullable s) => Applicative (Iteratee s m) | |
| (MonadCatchIO m, Nullable s, NullPoint s) => MonadCatchIO (Iteratee s m) | |
| (MonadIO m, Nullable s, NullPoint s) => MonadIO (Iteratee s m) |
Functions
Control functions
run :: Monad m => Iteratee s m a -> m aSource
Send EOF to the Iteratee and disregard the unconsumed part of the
stream. If the iteratee is in an exception state, that exception is
thrown with Control.Exception.throw. Iteratees that do not terminate
on EOF will throw EofException.
tryRun :: (Exception e, Monad m) => Iteratee s m a -> m (Either e a)Source
Run an iteratee, returning either the result or the iteratee exception.
Note that only internal iteratee exceptions will be returned; exceptions
thrown with Control.Exception.throw or Control.Monad.CatchIO.throw will
not be returned.
See IFException for details.
mapIteratee :: (NullPoint s, Monad n, Monad m) => (m a -> n b) -> Iteratee s m a -> Iteratee s n bSource
Transform a computation inside an Iteratee.
ilift :: (Monad m, Monad n) => (forall r. m r -> n r) -> Iteratee s m a -> Iteratee s n aSource
Lift a computation in the inner monad of an iteratee.
A simple use would be to lift a logger iteratee to a monad stack.
logger :: Iteratee String IO () logger = mapChunksM_ putStrLn loggerG :: MonadIO m => Iteratee String m () loggerG = ilift liftIO logger
A more complex example would involve lifting an iteratee to work with
interleaved streams. See the example at Data.Iteratee.ListLike.merge.
Creating Iteratees
icontM :: Monad m => (Stream s -> Iteratee s m a) -> Maybe SomeException -> m (Iteratee s m a)Source
Stream Functions
setEOF :: Stream c -> SomeExceptionSource
Produce the EOF error message. If the stream was terminated because
of an error, keep the error message.