Control.Pipe.PutbackPipe

This module contains an alternative pipe implementation, PutbackPipe, providing an additional primitive putback, which allows data to be inserted into the input stream of the current pipe.

PutbackPipes can be used to implement pipes with left-over data, and can be composed vertically (using the Monad instance), but not horizontally.

To make use of a PutbackPipe within a Pipeline, you need to convert it to a regular Pipe using runPutback.

Documentation

newtype PutbackPipe a b m r

The PutbackPipe data type.

Constructors

PutbackPipe

Fields

unPutback :: Pipe (Either a a) (Either b a) m r

Instances

MonadTrans (PutbackPipe a b)

Monad m => Monad (PutbackPipe a b m)

Monad m => Functor (PutbackPipe a b m)

Monad m => Applicative (PutbackPipe a b m)

MonadIO m => MonadIO (PutbackPipe a b m)

fromPipe :: Monad m => Pipe a b m r -> PutbackPipe a b m r

Create a PutbackPipe from a regular pipe.

putback :: Monad m => a -> PutbackPipe a b m ()

Put back an element into the input stream.

yield :: Monad m => b -> PutbackPipe a b m ()

Same as yield for regular pipes.

await :: Monad m => PutbackPipe a b m a

Same as await for regular pipes.

tryAwait :: Monad m => PutbackPipe a b m (Maybe a)

Same as tryAwait for regular pipes.

runPutback :: Monad m => PutbackPipe a b m r -> Pipe a b m r

Convert a PutbackPipe to a regular pipe.