Safe Haskell  None 

 data Pipe l i o u m r
 type Source m o = Pipe () () o () m ()
 type GSource m o = forall l i u. Pipe l i o u m ()
 type Sink i m r = Pipe i i Void () m r
 type GSink i m r = forall l o u. Pipe l i o u m r
 type GLSink i m r = forall o u. Pipe i i o u m r
 type GInfSink i m = forall l o r. Pipe l i o r m r
 type GLInfSink i m = forall o r. Pipe i i o r m r
 type Conduit i m o = Pipe i i o () m ()
 type GConduit i m o = forall l u. Pipe l i o u m ()
 type GLConduit i m o = forall u. Pipe i i o u m ()
 type GInfConduit i m o = forall l r. Pipe l i o r m r
 type GLInfConduit i m o = forall r. Pipe i i o r m r
 data ResumableSource m o = ResumableSource (Source m o) (m ())
 await :: Pipe l i o u m (Maybe i)
 awaitE :: Pipe l i o u m (Either u i)
 awaitForever :: Monad m => (i > Pipe l i o r m r') > Pipe l i o r m r
 yield :: Monad m => o > Pipe l i o u m ()
 yieldOr :: Monad m => o > m () > Pipe l i o u m ()
 leftover :: l > Pipe l i o u m ()
 bracketP :: MonadResource m => IO a > (a > IO ()) > (a > Pipe l i o u m r) > Pipe l i o u m r
 addCleanup :: Monad m => (Bool > m ()) > Pipe l i o u m r > Pipe l i o u m r
 idP :: Monad m => Pipe l a a r m r
 pipe :: Monad m => Pipe l a b r0 m r1 > Pipe Void b c r1 m r2 > Pipe l a c r0 m r2
 pipeL :: Monad m => Pipe l a b r0 m r1 > Pipe b b c r1 m r2 > Pipe l a c r0 m r2
 connectResume :: Monad m => ResumableSource m o > Sink o m r > m (ResumableSource m o, r)
 runPipe :: Monad m => Pipe Void () Void () m r > m r
 injectLeftovers :: Monad m => Pipe i i o u m r > Pipe l i o u m r
 sourceToPipe :: Monad m => Source m o > Pipe l i o u m ()
 sinkToPipe :: Monad m => Sink i m r > Pipe l i o u m r
 conduitToPipe :: Monad m => Conduit i m o > Pipe l i o u m ()
 transPipe :: Monad m => (forall a. m a > n a) > Pipe l i o u m r > Pipe l i o u n r
 mapOutput :: Monad m => (o1 > o2) > Pipe l i o1 u m r > Pipe l i o2 u m r
 mapOutputMaybe :: Monad m => (o1 > Maybe o2) > Pipe l i o1 u m r > Pipe l i o2 u m r
 mapInput :: Monad m => (i1 > i2) > (l2 > Maybe l1) > Pipe l2 i2 o u m r > Pipe l1 i1 o u m r
 sourceList :: Monad m => [a] > Pipe l i a u m ()
 withUpstream :: Monad m => Pipe l i o u m r > Pipe l i o u m (u, r)
 unwrapResumable :: MonadIO m => ResumableSource m o > m (Source m o, m ())
Types
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
. APipe
with no leftovers would useVoid
here, and one with leftovers would use the same type as the i parameter. Leftovers are automatically provided to the nextPipe
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
HaveOutput (Pipe l i o u m r) (m ()) o  Provide new output to be sent downstream. This constructor has three
fields: the next 
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 
Done r  Processing with this 
PipeM (m (Pipe l i o u m r))  Require running of a monadic action to get the next 
Leftover (Pipe l i o u m r) l  Return leftover input, which should be provided to future operations. 
(Applicative base, Applicative (Pipe l i o u m), Monad base, Monad (Pipe l i o u m), MonadBase base m) => MonadBase base (Pipe l i o u m)  
MonadTrans (Pipe l i o u)  
Monad m => Monad (Pipe l i o u m)  
Monad m => Functor (Pipe l i o u m)  
(Functor (Pipe l i o u m), Monad m) => Applicative (Pipe l i o u m)  
(Monad (Pipe l i o u m), MonadIO m) => MonadIO (Pipe l i o u m)  
(Monad (Pipe l i o u m), MonadThrow m) => MonadThrow (Pipe l i o u m)  
(Monad (Pipe l i o u m), MonadUnsafeIO m) => MonadUnsafeIO (Pipe l i o u m)  
(Monad (Pipe l i o u m), MonadActive m) => MonadActive (Pipe l i o u m)  
Monad m => Monoid (Pipe l i o u m ()) 
type Source m o = Pipe () () o () m ()Source
Provides a stream of output values, without consuming any input or producing a final result.
Since 0.5.0
type Sink i m r = Pipe i i Void () m rSource
Consumes a stream of input values and produces a final result, without producing any output.
Since 0.5.0
type GSink i m r = forall l o u. Pipe l i o u m rSource
Generalized Sink
without leftovers.
Since 0.5.0
type GInfSink i m = forall l o r. Pipe l i o r m rSource
Generalized Sink
without leftovers returning upstream result.
Since 0.5.0
type GLInfSink i m = forall o r. Pipe i i o r m rSource
Generalized Sink
with leftovers returning upstream result.
Since 0.5.0
type Conduit i m o = Pipe i 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
type GConduit i m o = forall l u. Pipe l i o u m ()Source
Generalized conduit without leftovers.
Since 0.5.0
type GLConduit i m o = forall u. Pipe i i o u m ()Source
Generalized conduit with leftovers.
Since 0.5.0
type GInfConduit i m o = forall l r. Pipe l i o r m rSource
Generalized conduit without leftovers returning upstream result.
Since 0.5.0
type GLInfConduit i m o = forall r. Pipe i i o r m rSource
Generalized conduit with leftovers returning upstream 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
ResumableSource (Source m o) (m ()) 
Primitives
await :: Pipe l i o u m (Maybe i)Source
Wait for a single input value from upstream, terminating immediately if no data is available.
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 rSource
Wait for input forever, calling the given inner Pipe
for each piece of
new input. Returns the upstream result type.
Since 0.5.0
Send a single output value downstream. If the downstream Pipe
terminates, this Pipe
will terminate as well.
Since 0.5.0
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 rSource
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
:: Monad m  
=> (Bool > m ()) 

> 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
pipe :: Monad m => Pipe l a b r0 m r1 > Pipe Void b c r1 m r2 > Pipe l a c r0 m r2Source
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 r2Source
Same as pipe
, but automatically applies injectLeftovers
to the right Pipe
.
Since 0.5.0
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
runPipe :: Monad m => Pipe Void () Void () m r > m rSource
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 rSource
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
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 rSource
conduitToPipe :: Monad m => Conduit i m o > Pipe l i o u m ()Source
Utilities
transPipe :: Monad m => (forall a. m a > n a) > Pipe l i o u m r > Pipe l i o u n rSource
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/Dealingwithmonadtransformers
Since 0.4.0
mapOutputMaybe :: Monad m => (o1 > Maybe o2) > Pipe l i o1 u m r > Pipe l i o2 u m rSource
Same as mapOutput
, but use a function that returns Maybe
values.
Since 0.5.0
:: 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
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