Safe Haskell	None
Language	Haskell98

Data.Conduit.Internal

Contents

Pipe
Conduit
Fusion (highly experimental!!!)
- Types
- Functions

Synopsis

Pipe

Types

data Pipe l i o u m r Source

The underlying datatype for all the types in this package. In has six type parameters:

l is the type of values that may be left over from this Pipe. A Pipe with no leftovers would use Void here, and one with leftovers would use the same type as the i parameter. Leftovers are automatically provided to the next Pipe in the monadic chain.
i is the type of values for this Pipe's input stream.
o is the type of values for this Pipe's output stream.
u is the result type from the upstream Pipe.
m is the underlying monad.
r is the result type.

A basic intuition is that every Pipe produces a stream of output values (o), and eventually indicates that this stream is terminated by sending a result (r). On the receiving end of a Pipe, these become the i and u parameters.

Since 0.5.0

Constructors

HaveOutput (Pipe l i o u m r) (m ()) o	Provide new output to be sent downstream. This constructor has three fields: the next `Pipe` to be used, a finalization function, and the output value.
NeedInput (i -> Pipe l i o u m r) (u -> Pipe l i o u m r)	Request more input from upstream. The first field takes a new input value and provides a new `Pipe`. The second takes an upstream result value, which indicates that upstream is producing no more results.
Done r	Processing with this `Pipe` is complete, providing the final result.
PipeM (m (Pipe l i o u m r))	Require running of a monadic action to get the next `Pipe`.
Leftover (Pipe l i o u m r) l	Return leftover input, which should be provided to future operations.

Instances

MonadRWS r w s m => MonadRWS r w s (Pipe l i o u m)
MonadBase base m => MonadBase base (Pipe l i o u m)
MonadError e m => MonadError e (Pipe l i o u m)
MonadReader r m => MonadReader r (Pipe l i o u m)
MonadState s m => MonadState s (Pipe l i o u m)
MonadWriter w m => MonadWriter w (Pipe l i o u m)
MFunctor (Pipe l i o u)	Since 1.0.4
MonadTrans (Pipe l i o u)
Monad m => Monad (Pipe l i o u m)
Monad m => Functor (Pipe l i o u m)
Monad m => Applicative (Pipe l i o u m)
MonadThrow m => MonadThrow (Pipe l i o u m)
MonadCatch m => MonadCatch (Pipe l i o u m)
MonadIO m => MonadIO (Pipe l i o u m)
MonadResource m => MonadResource (Pipe l i o u m)
Monad m => Monoid (Pipe l i o u m ())

Primitives

await :: Pipe l i o u m (Maybe i) Source

Wait for a single input value from upstream.

Since 0.5.0

awaitE :: Pipe l i o u m (Either u i) Source

This is similar to await, but will return the upstream result value as Left if available.

Since 0.5.0

awaitForever :: Monad m => (i -> Pipe l i o r m r') -> Pipe l i o r m r Source

Wait for input forever, calling the given inner Pipe for each piece of new input. Returns the upstream result type.

Since 0.5.0

yield Source

Arguments

:: Monad m
=> o	output value
-> Pipe l i o u m ()

Send a single output value downstream. If the downstream Pipe terminates, this Pipe will terminate as well.

Since 0.5.0

yieldM :: Monad m => m o -> Pipe l i o u m () Source

yieldOr Source

Arguments

:: Monad m
=> o
-> m ()	finalizer
-> Pipe l i o u m ()

Similar to yield, but additionally takes a finalizer to be run if the downstream Pipe terminates.

Since 0.5.0

leftover :: l -> Pipe l i o u m () Source

Provide a single piece of leftover input to be consumed by the next pipe in the current monadic binding.

Note: it is highly encouraged to only return leftover values from input already consumed from upstream.

Since 0.5.0

Finalization

bracketP :: MonadResource m => IO a -> (a -> IO ()) -> (a -> Pipe l i o u m r) -> Pipe l i o u m r Source

Perform some allocation and run an inner Pipe. Two guarantees are given about resource finalization:

It will be prompt. The finalization will be run as early as possible.
It is exception safe. Due to usage of resourcet, the finalization will be run in the event of any exceptions.

Since 0.5.0

addCleanup Source

Arguments

:: Monad m
=> (Bool -> m ())	`True` if `Pipe` ran to completion, `False` for early termination.
-> Pipe l i o u m r
-> Pipe l i o u m r

Add some code to be run when the given Pipe cleans up.

Since 0.4.1

Composition

idP :: Monad m => Pipe l a a r m r Source

The identity Pipe.

Since 0.5.0

pipe :: Monad m => Pipe l a b r0 m r1 -> Pipe Void b c r1 m r2 -> Pipe l a c r0 m r2 Source

Compose a left and right pipe together into a complete pipe. The left pipe will be automatically closed when the right pipe finishes.

Since 0.5.0

pipeL :: Monad m => Pipe l a b r0 m r1 -> Pipe b b c r1 m r2 -> Pipe l a c r0 m r2 Source

Same as pipe, but automatically applies injectLeftovers to the right Pipe.

Since 0.5.0

runPipe :: Monad m => Pipe Void () Void () m r -> m r Source

Run a pipeline until processing completes.

Since 0.5.0

injectLeftovers :: Monad m => Pipe i i o u m r -> Pipe l i o u m r Source

Transforms a Pipe that provides leftovers to one which does not, allowing it to be composed.

This function will provide any leftover values within this Pipe to any calls to await. If there are more leftover values than are demanded, the remainder are discarded.

Since 0.5.0

(>+>) :: Monad m => Pipe l a b r0 m r1 -> Pipe Void b c r1 m r2 -> Pipe l a c r0 m r2 infixl 9 Source

Fuse together two Pipes, connecting the output from the left to the input of the right.

Notice that the leftover parameter for the Pipes must be Void. This ensures that there is no accidental data loss of leftovers during fusion. If you have a Pipe with leftovers, you must first call injectLeftovers.

Since 0.5.0

(<+<) :: Monad m => Pipe Void b c r1 m r2 -> Pipe l a b r0 m r1 -> Pipe l a c r0 m r2 infixr 9 Source

Same as >+>, but reverse the order of the arguments.

Since 0.5.0

Exceptions

catchP :: (MonadBaseControl IO m, Exception e) => Pipe l i o u m r -> (e -> Pipe l i o u m r) -> Pipe l i o u m r Source

See catchC for more details.

Since 1.0.11

handleP :: (MonadBaseControl IO m, Exception e) => (e -> Pipe l i o u m r) -> Pipe l i o u m r -> Pipe l i o u m r Source

The same as flip catchP.

Since 1.0.11

tryP :: (MonadBaseControl IO m, Exception e) => Pipe l i o u m r -> Pipe l i o u m (Either e r) Source

See tryC for more details.

Since 1.0.11

Utilities

transPipe :: Monad m => (forall a. m a -> n a) -> Pipe l i o u m r -> Pipe l i o u n r Source

Transform the monad that a Pipe lives in.

Note that the monad transforming function will be run multiple times, resulting in unintuitive behavior in some cases. For a fuller treatment, please see:

https://github.com/snoyberg/conduit/wiki/Dealing-with-monad-transformers

This function is just a synonym for hoist.

Since 0.4.0

mapOutput :: Monad m => (o1 -> o2) -> Pipe l i o1 u m r -> Pipe l i o2 u m r Source

Apply a function to all the output values of a Pipe.

This mimics the behavior of fmap for a Source and Conduit in pre-0.4 days.

Since 0.4.1

mapOutputMaybe :: Monad m => (o1 -> Maybe o2) -> Pipe l i o1 u m r -> Pipe l i o2 u m r Source

Same as mapOutput, but use a function that returns Maybe values.

Since 0.5.0

mapInput Source

Arguments

:: Monad m
=> (i1 -> i2)	map initial input to new input
-> (l2 -> Maybe l1)	map new leftovers to initial leftovers
-> Pipe l2 i2 o u m r
-> Pipe l1 i1 o u m r

Apply a function to all the input values of a Pipe.

Since 0.5.0

sourceList :: Monad m => [a] -> Pipe l i a u m () Source

Convert a list into a source.

Since 0.3.0

withUpstream :: Monad m => Pipe l i o u m r -> Pipe l i o u m (u, r) Source

Returns a tuple of the upstream and downstream results. Note that this will force consumption of the entire input stream.

Since 0.5.0

enumFromTo :: (Enum o, Eq o, Monad m) => o -> o -> Pipe l i o u m () Source

generalizeUpstream :: Monad m => Pipe l i o () m r -> Pipe l i o u m r Source

Generalize the upstream return value for a Pipe from unit to any type.

Since 1.1.5

Conduit

Types

newtype ConduitM i o m r Source

Core datatype of the conduit package. This type represents a general component which can consume a stream of input values i, produce a stream of output values o, perform actions in the m monad, and produce a final result r. The type synonyms provided here are simply wrappers around this type.

Since 1.0.0

Constructors

ConduitM
Fields unConduitM :: forall b. (r -> Pipe i i o () m b) -> Pipe i i o () m b

Instances

MonadRWS r w s m => MonadRWS r w s (ConduitM i o m)
MonadBase base m => MonadBase base (ConduitM i o m)
MonadError e m => MonadError e (ConduitM i o m)
MonadReader r m => MonadReader r (ConduitM i o m)
MonadState s m => MonadState s (ConduitM i o m)
MonadWriter w m => MonadWriter w (ConduitM i o m)
MFunctor (ConduitM i o)
MonadTrans (ConduitM i o)
Monad (ConduitM i o m)
Functor (ConduitM i o m)
Applicative (ConduitM i o m)
MonadThrow m => MonadThrow (ConduitM i o m)
MonadCatch m => MonadCatch (ConduitM i o m)
MonadIO m => MonadIO (ConduitM i o m)
MonadResource m => MonadResource (ConduitM i o m)
Monad m => Monoid (ConduitM i o m ())

type Source m o = ConduitM () o m () Source

Provides a stream of output values, without consuming any input or producing a final result.

Since 0.5.0

type Producer m o = forall i. ConduitM i o m () Source

A component which produces a stream of output values, regardless of the input stream. A Producer is a generalization of a Source, and can be used as either a Source or a Conduit.

Since 1.0.0

type Sink i = ConduitM i Void Source

Consumes a stream of input values and produces a final result, without producing any output.

type Sink i m r = ConduitM i Void m r

Since 0.5.0

type Consumer i m r = forall o. ConduitM i o m r Source

A component which consumes a stream of input values and produces a final result, regardless of the output stream. A Consumer is a generalization of a Sink, and can be used as either a Sink or a Conduit.

Since 1.0.0

type Conduit i m o = ConduitM i o m () Source

Consumes a stream of input values and produces a stream of output values, without producing a final result.

Since 0.5.0

data ResumableSource m o Source

A Source which has been started, but has not yet completed.

This type contains both the current state of the Source, and the finalizer to be run to close it.

Since 0.5.0

Constructors

ResumableSource (Pipe () () o () m ()) (m ())

Instances

MFunctor ResumableSource

Since 1.0.13

data ResumableConduit i m o Source

A generalization of ResumableSource. Allows to resume an arbitrary conduit, keeping its state and using it later (or finalizing it).

Since 1.0.17

Constructors

ResumableConduit (Pipe i i o () m ()) (m ())

data Flush a Source

Provide for a stream of data that can be flushed.

A number of Conduits (e.g., zlib compression) need the ability to flush the stream at some point. This provides a single wrapper datatype to be used in all such circumstances.

Since 0.3.0

Constructors

Chunk a
Flush

Instances

Functor Flush
Eq a => Eq (Flush a)
Ord a => Ord (Flush a)
Show a => Show (Flush a)

Newtype wrappers

newtype ZipSource m o Source

A wrapper for defining an Applicative instance for Sources which allows to combine sources together, generalizing zipSources. A combined source will take input yielded from each of its Sources until any of them stop producing output.

Since 1.0.13

Constructors

ZipSource
Fields getZipSource :: Source m o

Instances

Monad m => Functor (ZipSource m)
Monad m => Applicative (ZipSource m)

newtype ZipSink i m r Source

A wrapper for defining an Applicative instance for Sinks which allows to combine sinks together, generalizing zipSinks. A combined sink distributes the input to all its participants and when all finish, produces the result. This allows to define functions like

sequenceSinks :: (Monad m)
          => [Sink i m r] -> Sink i m [r]
sequenceSinks = getZipSink . sequenceA . fmap ZipSink

Note that the standard Applicative instance for conduits works differently. It feeds one sink with input until it finishes, then switches to another, etc., and at the end combines their results.

Since 1.0.13

Constructors

ZipSink
Fields getZipSink :: Sink i m r

Instances

Monad m => Functor (ZipSink i m)
Monad m => Applicative (ZipSink i m)

newtype ZipConduit i o m r Source

Provides an alternative Applicative instance for ConduitM. In this instance, every incoming value is provided to all ConduitMs, and output is coalesced together. Leftovers from individual ConduitMs will be used within that component, and then discarded at the end of their computation. Output and finalizers will both be handled in a left-biased manner.

As an example, take the following program:

main :: IO ()
main = do
    let src = mapM_ yield [1..3 :: Int]
        conduit1 = CL.map (+1)
        conduit2 = CL.concatMap (replicate 2)
        conduit = getZipConduit $ ZipConduit conduit1 <* ZipConduit conduit2
        sink = CL.mapM_ print
    src $$ conduit =$ sink

It will produce the output: 2, 1, 1, 3, 2, 2, 4, 3, 3

Since 1.0.17

Constructors

ZipConduit
Fields getZipConduit :: ConduitM i o m r

Instances

Functor (ZipConduit i o m)
Monad m => Applicative (ZipConduit i o m)

Primitives

await :: Monad m => Consumer i m (Maybe i) Source

Wait for a single input value from upstream. If no data is available, returns Nothing.

Since 0.5.0

awaitForever :: Monad m => (i -> ConduitM i o m r) -> ConduitM i o m () Source

Wait for input forever, calling the given inner component for each piece of new input. Returns the upstream result type.

This function is provided as a convenience for the common pattern of awaiting input, checking if it's Just and then looping.

Since 0.5.0

yield Source

Arguments

:: Monad m
=> o	output value
-> ConduitM i o m ()

Send a value downstream to the next component to consume. If the downstream component terminates, this call will never return control. If you would like to register a cleanup function, please use yieldOr instead.

Since 0.5.0

yieldM :: Monad m => m o -> ConduitM i o m () Source

yieldOr Source

Arguments

:: Monad m
=> o
-> m ()	finalizer
-> ConduitM i o m ()

Similar to yield, but additionally takes a finalizer to be run if the downstream component terminates.

Since 0.5.0

leftover :: i -> ConduitM i o m () Source

Provide a single piece of leftover input to be consumed by the next component in the current monadic binding.

Note: it is highly encouraged to only return leftover values from input already consumed from upstream.

Since 0.5.0

runConduit :: Monad m => ConduitM () Void m r -> m r Source

Run a pipeline until processing completes.

Since 1.2.1

Composition

connectResume :: Monad m => ResumableSource m o -> Sink o m r -> m (ResumableSource m o, r) Source

Connect a Source to a Sink until the latter closes. Returns both the most recent state of the Source and the result of the Sink.

We use a ResumableSource to keep track of the most recent finalizer provided by the Source.

Since 0.5.0

connectResumeConduit :: Monad m => ResumableConduit i m o -> Sink o m r -> Sink i m (ResumableConduit i m o, r) Source

Connect a ResumableConduit to a sink and return the output of the sink together with a new ResumableConduit.

Since 1.0.17

fuseLeftovers :: Monad m => ([b] -> [a]) -> ConduitM a b m () -> ConduitM b c m r -> ConduitM a c m r Source

Similar to fuseReturnLeftovers, but use the provided function to convert downstream leftovers to upstream leftovers.

Since 1.0.17

fuseReturnLeftovers :: Monad m => ConduitM a b m () -> ConduitM b c m r -> ConduitM a c m (r, [b]) Source

Same as normal fusion (e.g. =$=), except instead of discarding leftovers from the downstream component, return them.

Since 1.0.17

($$+) :: Monad m => Source m a -> Sink a m b -> m (ResumableSource m a, b) infixr 0 Source

The connect-and-resume operator. This does not close the Source, but instead returns it to be used again. This allows a Source to be used incrementally in a large program, without forcing the entire program to live in the Sink monad.

Mnemonic: connect + do more.

Since 0.5.0

($$++) :: Monad m => ResumableSource m a -> Sink a m b -> m (ResumableSource m a, b) infixr 0 Source

Continue processing after usage of $$+.

Since 0.5.0

($$+-) :: Monad m => ResumableSource m a -> Sink a m b -> m b infixr 0 Source

Complete processing of a ResumableSource. This will run the finalizer associated with the ResumableSource. In order to guarantee process resource finalization, you must use this operator after using $$+ and $$++.

Since 0.5.0

($=+) :: Monad m => ResumableSource m a -> Conduit a m b -> ResumableSource m b infixl 1 Source

Left fusion for a resumable source.

Since 1.0.16

(=$$+) :: Monad m => Conduit a m b -> Sink b m r -> Sink a m (ResumableConduit a m b, r) infixr 0 Source

The connect-and-resume operator. This does not close the Conduit, but instead returns it to be used again. This allows a Conduit to be used incrementally in a large program, without forcing the entire program to live in the Sink monad.

Leftover data returned from the Sink will be discarded.

Mnemonic: connect + do more.

Since 1.0.17

(=$$++) :: Monad m => ResumableConduit i m o -> Sink o m r -> Sink i m (ResumableConduit i m o, r) infixr 0 Source

Continue processing after usage of =$$+. Connect a ResumableConduit to a sink and return the output of the sink together with a new ResumableConduit.

Since 1.0.17

(=$$+-) :: Monad m => ResumableConduit i m o -> Sink o m r -> Sink i m r infixr 0 Source

Complete processing of a ResumableConduit. This will run the finalizer associated with the ResumableConduit. In order to guarantee process resource finalization, you must use this operator after using =$$+ and =$$++.

Since 1.0.17

($$) :: Monad m => Source m a -> Sink a m b -> m b infixr 0 Source

The connect operator, which pulls data from a source and pushes to a sink. If you would like to keep the Source open to be used for other operations, use the connect-and-resume operator $$+.

Since 0.4.0

($=) :: Monad m => Conduit a m b -> ConduitM b c m r -> ConduitM a c m r infixl 1 Source

Left fuse, combining a source and a conduit together into a new source.

Both the Source and Conduit will be closed when the newly-created Source is closed.

Leftover data from the Conduit will be discarded.

Note: Since version 1.0.18, this operator has been generalized to be identical to =$=.

Since 0.4.0

(=$) :: Monad m => Conduit a m b -> ConduitM b c m r -> ConduitM a c m r infixr 2 Source

Right fuse, combining a conduit and a sink together into a new sink.

Both the Conduit and Sink will be closed when the newly-created Sink is closed.

Leftover data returned from the Sink will be discarded.

Note: Since version 1.0.18, this operator has been generalized to be identical to =$=.

Since 0.4.0

(=$=) :: Monad m => Conduit a m b -> ConduitM b c m r -> ConduitM a c m r infixr 2 Source

Fusion operator, combining two Conduits together into a new Conduit.

Both Conduits will be closed when the newly-created Conduit is closed.

Leftover data returned from the right Conduit will be discarded.

Since 0.4.0

Generalizing

sourceToPipe :: Monad m => Source m o -> Pipe l i o u m () Source

sinkToPipe :: Monad m => Sink i m r -> Pipe l i o u m r Source

conduitToPipe :: Monad m => Conduit i m o -> Pipe l i o u m () Source

toProducer :: Monad m => Source m a -> Producer m a Source

Generalize a Source to a Producer.

Since 1.0.0

toConsumer :: Monad m => Sink a m b -> Consumer a m b Source

Generalize a Sink to a Consumer.

Since 1.0.0

Cleanup

bracketP :: MonadResource m => IO a -> (a -> IO ()) -> (a -> ConduitM i o m r) -> ConduitM i o m r Source

Perform some allocation and run an inner component. Two guarantees are given about resource finalization:

It will be prompt. The finalization will be run as early as possible.
It is exception safe. Due to usage of resourcet, the finalization will be run in the event of any exceptions.

Since 0.5.0

addCleanup :: Monad m => (Bool -> m ()) -> ConduitM i o m r -> ConduitM i o m r Source

Add some code to be run when the given component cleans up.

The supplied cleanup function will be given a True if the component ran to completion, or False if it terminated early due to a downstream component terminating.

Note that this function is not exception safe. For that, please use bracketP.

Since 0.4.1

Exceptions

catchC :: (MonadBaseControl IO m, Exception e) => ConduitM i o m r -> (e -> ConduitM i o m r) -> ConduitM i o m r Source

Catch all exceptions thrown by the current component of the pipeline.

Note: this will not catch exceptions thrown by other components! For example, if an exception is thrown in a Source feeding to a Sink, and the Sink uses catchC, the exception will not be caught.

Due to this behavior (as well as lack of async exception handling), you should not try to implement combinators such as onException in terms of this primitive function.

Note also that the exception handling will not be applied to any finalizers generated by this conduit.

Since 1.0.11

handleC :: (MonadBaseControl IO m, Exception e) => (e -> ConduitM i o m r) -> ConduitM i o m r -> ConduitM i o m r Source

The same as flip catchC.

Since 1.0.11

tryC :: (MonadBaseControl IO m, Exception e) => ConduitM i o m r -> ConduitM i o m (Either e r) Source

A version of try for use within a pipeline. See the comments in catchC for more details.

Since 1.0.11

Utilities

transPipe :: Monad m => (forall a. m a -> n a) -> ConduitM i o m r -> ConduitM i o n r Source

Transform the monad that a ConduitM lives in.

Note that the monad transforming function will be run multiple times, resulting in unintuitive behavior in some cases. For a fuller treatment, please see:

https://github.com/snoyberg/conduit/wiki/Dealing-with-monad-transformers

This function is just a synonym for hoist.

Since 0.4.0

mapOutput :: Monad m => (o1 -> o2) -> ConduitM i o1 m r -> ConduitM i o2 m r Source

Apply a function to all the output values of a ConduitM.

This mimics the behavior of fmap for a Source and Conduit in pre-0.4 days. It can also be simulated by fusing with the map conduit from Data.Conduit.List.

Since 0.4.1

mapOutputMaybe :: Monad m => (o1 -> Maybe o2) -> ConduitM i o1 m r -> ConduitM i o2 m r Source

Same as mapOutput, but use a function that returns Maybe values.

Since 0.5.0

mapInput Source

Arguments

:: Monad m
=> (i1 -> i2)	map initial input to new input
-> (i2 -> Maybe i1)	map new leftovers to initial leftovers
-> ConduitM i2 o m r
-> ConduitM i1 o m r

Apply a function to all the input values of a ConduitM.

Since 0.5.0

closeResumableSource :: Monad m => ResumableSource m a -> m () Source

Execute the finalizer associated with a ResumableSource, rendering the ResumableSource invalid for further use.

This is just a more explicit version of $$+- return ().

Since 1.1.3

unwrapResumable :: MonadIO m => ResumableSource m o -> m (Source m o, m ()) Source

Unwraps a ResumableSource into a Source and a finalizer.

A ResumableSource represents a Source which has already been run, and therefore has a finalizer registered. As a result, if we want to turn it into a regular Source, we need to ensure that the finalizer will be run appropriately. By appropriately, I mean:

If a new finalizer is registered, the old one should not be called.
If the old one is called, it should not be called again.

This function returns both a Source and a finalizer which ensures that the above two conditions hold. Once you call that finalizer, the Source is invalidated and cannot be used.

Since 0.5.2

unwrapResumableConduit :: MonadIO m => ResumableConduit i m o -> m (Conduit i m o, m ()) Source

Unwraps a ResumableConduit into a Conduit and a finalizer.

Since unwrapResumable for more information.

Since 1.0.17

newResumableSource :: Monad m => Source m o -> ResumableSource m o Source

Turn a Source into a ResumableSource with no attached finalizer.

Since 1.1.4

newResumableConduit :: Monad m => Conduit i m o -> ResumableConduit i m o Source

Turn a Conduit into a ResumableConduit with no attached finalizer.

Since 1.1.4

zipSinks :: Monad m => Sink i m r -> Sink i m r' -> Sink i m (r, r') Source

Combines two sinks. The new sink will complete when both input sinks have completed.

Any leftovers are discarded.

Since 0.4.1

zipSources :: Monad m => Source m a -> Source m b -> Source m (a, b) Source

Combines two sources. The new source will stop producing once either source has been exhausted.

Since 1.0.13

zipSourcesApp :: Monad m => Source m (a -> b) -> Source m a -> Source m b Source

Combines two sources. The new source will stop producing once either source has been exhausted.

Since 1.0.13

zipConduitApp :: Monad m => ConduitM i o m (x -> y) -> ConduitM i o m x -> ConduitM i o m y Source

Since 1.0.17

passthroughSink Source

Arguments

:: Monad m
=> Sink i m r
-> (r -> m ())	finalizer
-> Conduit i m i

Turn a Sink into a Conduit in the following way:

All input passed to the Sink is yielded downstream.
When the Sink finishes processing, the result is passed to the provided to the finalizer function.

Note that the Sink will stop receiving input as soon as the downstream it is connected to shuts down.

An example usage would be to write the result of a Sink to some mutable variable while allowing other processing to continue.

Since 1.1.0

fuseBoth :: Monad m => ConduitM a b m r1 -> ConduitM b c m r2 -> ConduitM a c m (r1, r2) Source

Fuse two ConduitMs together, and provide the return value of both. Note that this will force the entire upstream ConduitM to be run to produce the result value, even if the downstream terminates early.

Since 1.1.5

fuseUpstream :: Monad m => ConduitM a b m r -> Conduit b m c -> ConduitM a c m r Source

Same as fuseBoth, but ignore the return value from the downstream Conduit. Same caveats of forced consumption apply.

Since 1.1.5

sequenceSources :: (Traversable f, Monad m) => f (Source m o) -> Source m (f o) Source

Coalesce all values yielded by all of the Sources.

Implemented on top of ZipSource, see that data type for more details.

Since 1.0.13

sequenceSinks :: (Traversable f, Monad m) => f (Sink i m r) -> Sink i m (f r) Source

Send incoming values to all of the Sink providing, and ultimately coalesce together all return values.

Implemented on top of ZipSink, see that data type for more details.

Since 1.0.13

sequenceConduits :: (Traversable f, Monad m) => f (ConduitM i o m r) -> ConduitM i o m (f r) Source

Provide identical input to all of the Conduits and combine their outputs into a single stream.

Implemented on top of ZipConduit, see that data type for more details.

Since 1.0.17

Fusion (highly experimental!!!)

Types

data Step s o r Source

This is the same as stream fusion's Step. Constructors are renamed to avoid confusion with conduit names.

Constructors

Emit s o
Skip s
Stop r

data Stream m o r Source

Constructors

forall s . Stream (s -> m (Step s o r)) (m s)

data StreamConduit i o m r Source

Functions

streamConduit :: ConduitM i o m r -> (Stream m i () -> Stream m o r) -> StreamConduit i o m r Source

streamSource :: Monad m => Stream m o () -> StreamConduit i o m () Source

streamSourcePure :: Monad m => Stream Identity o () -> StreamConduit i o m () Source

unstream :: StreamConduit i o m r -> ConduitM i o m r Source