Conduit.Simple

Please see the project README for more details:

https://github.com/jwiegley/simple-conduit/blob/master/README.md

Also see this blog article:

https://www.newartisans.com/2014/06/simpler-conduit-library

Documentation

newtype Source m a

A Source is a short-circuiting monadic fold.

Source forms a Monad that behaves as ListT; for example:

do x <- yieldMany [1..3]
   line <- sourceFile "foo.txt"
   return (x, line)

This yields the cross-product of [3] and the lines in the files, but only reading chunks from the file as needed by the sink.

To skip to the next value in a Source, use the function skip or mempty; to close the source, use close. For example:

do x <- yieldMany [1..10]
   if x == 2 || x == 9
   then return x
   else if x < 5
        then skip
        else close

This outputs the list [2].

A key difference from the conduit library is that monadic chaining of sources with >> follows ListT, and not concatenation as in conduit. To achieve conduit-style behavior, use the Monoid instance:

>>> sinkList $ yieldMany [1..3] <> yieldMany [4..6]
[1,2,3,4,5,6]

Constructors

Source

Fields

• getSource :: forall r. Cont (r -> EitherT r m r) a

Instances

MonadTrans Source

Methods

lift :: Monad m => m a -> Source m a

MFunctor Source

Methods

hoist :: Monad m => (forall a. m a -> n a) -> Source m b -> Source n b

MMonad Source

Methods

embed :: Monad n => (forall a. m a -> Source n a) -> Source m b -> Source n b

(Functor f, MonadFree f m) => MonadFree f (Source m)

Methods

wrap :: f (Source m a) -> Source m a

MonadError e m => MonadError e (Source m)

Methods

throwError :: e -> Source m a

catchError :: Source m a -> (e -> Source m a) -> Source m a

MonadReader r m => MonadReader r (Source m)

Methods

ask :: Source m r

local :: (r -> r) -> Source m a -> Source m a

reader :: (r -> a) -> Source m a

MonadState s m => MonadState s (Source m)

Methods

get :: Source m s

put :: s -> Source m ()

state :: (s -> (a, s)) -> Source m a

MonadWriter w m => MonadWriter w (Source m)

Methods

writer :: (a, w) -> Source m a

tell :: w -> Source m ()

listen :: Source m a -> Source m (a, w)

pass :: Source m (a, w -> w) -> Source m a

Monad (Source m)

Methods

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

(>>) :: Source m a -> Source m b -> Source m b

return :: a -> Source m a

fail :: String -> Source m a

Functor (Source m)

Methods

fmap :: (a -> b) -> Source m a -> Source m b

(<$) :: a -> Source m b -> Source m a

Applicative (Source m)

Methods

pure :: a -> Source m a

(<*>) :: Source m (a -> b) -> Source m a -> Source m b

(*>) :: Source m a -> Source m b -> Source m b

(<*) :: Source m a -> Source m b -> Source m a

Foldable (Source Identity)

Methods

fold :: Monoid m => Source Identity m -> m

foldMap :: Monoid m => (a -> m) -> Source Identity a -> m

foldr :: (a -> b -> b) -> b -> Source Identity a -> b

foldr' :: (a -> b -> b) -> b -> Source Identity a -> b

foldl :: (b -> a -> b) -> b -> Source Identity a -> b

foldl' :: (b -> a -> b) -> b -> Source Identity a -> b

foldr1 :: (a -> a -> a) -> Source Identity a -> a

foldl1 :: (a -> a -> a) -> Source Identity a -> a

toList :: Source Identity a -> [a]

null :: Source Identity a -> Bool

length :: Source Identity a -> Int

elem :: Eq a => a -> Source Identity a -> Bool

maximum :: Ord a => Source Identity a -> a

minimum :: Ord a => Source Identity a -> a

sum :: Num a => Source Identity a -> a

product :: Num a => Source Identity a -> a

Monad m => MonadPlus (Source m)

Methods

mzero :: Source m a

mplus :: Source m a -> Source m a -> Source m a

MonadIO m => MonadIO (Source m)

Methods

liftIO :: IO a -> Source m a

Monad m => Alternative (Source m)

Methods

empty :: Source m a

(<|>) :: Source m a -> Source m a -> Source m a

some :: Source m a -> Source m [a]

many :: Source m a -> Source m [a]

MonadThrow m => MonadThrow (Source m)

Methods

throwM :: Exception e => e -> Source m a

MonadCatch m => MonadCatch (Source m)

Methods

catch :: Exception e => Source m a -> (e -> Source m a) -> Source m a

MonadMask m => MonadMask (Source m)

Methods

mask :: ((forall a. Source m a -> Source m a) -> Source m b) -> Source m b

uninterruptibleMask :: ((forall a. Source m a -> Source m a) -> Source m b) -> Source m b

Monad m => Semigroup (Source m a)

Methods

(<>) :: Source m a -> Source m a -> Source m a

sconcat :: NonEmpty (Source m a) -> Source m a

stimes :: Integral b => b -> Source m a -> Source m a

Monad m => Monoid (Source m a)

Methods

mempty :: Source m a

mappend :: Source m a -> Source m a -> Source m a

mconcat :: [Source m a] -> Source m a

type Conduit a m b = Source m a -> Source m b

A Conduit is a "Source homomorphism", or simple a mapping between sources. There is no need for it to be a type synonym, except to save repetition across type signatures.

type Sink a m r = Source m a -> m r

A Sink folds a Source down to its result value. It is simply a convenient type synonym for functions mapping a Source to some result type.

runSource :: Source m a -> r -> (r -> a -> EitherT r m r) -> EitherT r m r

lowerSource :: (Monad m, Monoid a) => Source m a -> m a

source :: (forall r. r -> (r -> a -> EitherT r m r) -> EitherT r m r) -> Source m a

conduit :: (forall r. r -> (r -> b -> EitherT r m r) -> a -> EitherT r m r) -> Conduit a m b

conduitWith :: Monad m => s -> (forall r. (r, s) -> (r -> b -> EitherT (r, s) m (r, s)) -> a -> EitherT (r, s) m (r, s)) -> Conduit a m b

Most of the time conduits pass the fold variable through unmolested, but sometimes you need to ignore that variable and use your own within a stage of the pipeline. This is done by wrapping the fold variable in a tuple and then unwrapping it when the conduit is done. conduitWith makes this transparent.

sink :: forall m a r. Monad m => r -> (r -> a -> EitherT r m r) -> Sink a m r

returnC :: Monad m => m a -> Source m a

Promote any sink to a source. This can be used as if it were a source transformer (aka, a conduit):

>>> sinkList $ returnC $ sumC $ mapC (+1) $ yieldMany [1..10]
[65]

Note that returnC is a synonym for lift.

close :: Monad m => Source m a

skip :: Monad m => Source m a

awaitForever :: (a -> Source m b) -> Conduit a m b

yieldMany :: (Monad m, MonoFoldable mono) => mono -> Source m (Element mono)

sourceList :: Monad m => [a] -> Source m a

unfoldC :: forall m a b. Monad m => (b -> Maybe (a, b)) -> b -> Source m a

enumFromToC :: forall m a. (Monad m, Enum a, Eq a) => a -> a -> Source m a

iterateC :: forall m a. Monad m => (a -> a) -> a -> Source m a

repeatC :: forall m a. Monad m => a -> Source m a

replicateC :: forall m a. Monad m => Int -> a -> Source m a

sourceLazy :: (Monad m, LazySequence lazy strict) => lazy -> Source m strict

repeatMC :: forall m a. Monad m => m a -> Source m a

repeatWhileMC :: forall m a. Monad m => m a -> (a -> Bool) -> Source m a

replicateMC :: forall m a. Monad m => Int -> m a -> Source m a

sourceHandle :: forall m a. (MonadIO m, MonoFoldable a, IOData a) => Handle -> Source m a

sourceFile :: (MonadBaseControl IO m, MonadIO m, MonoFoldable a, IOData a) => FilePath -> Source m a

sourceIOHandle :: (MonadBaseControl IO m, MonadIO m, MonoFoldable a, IOData a) => IO Handle -> Source m a

stdinC :: (MonadBaseControl IO m, MonadIO m, MonoFoldable a, IOData a) => Source m a

initRepeat :: Monad m => m seed -> (seed -> m a) -> Source m a

initReplicate :: Monad m => m seed -> (seed -> m a) -> Int -> Source m a

sourceRandom :: (Variate a, MonadIO m) => Source m a

sourceRandomN :: (Variate a, MonadIO m) => Int -> Source m a

sourceRandomGen :: (Variate a, MonadBase base m, PrimMonad base) => Gen (PrimState base) -> Source m a

sourceRandomNGen :: (Variate a, MonadBase base m, PrimMonad base) => Gen (PrimState base) -> Int -> Source m a

sourceDirectory :: forall m. MonadBaseControl IO m => FilePath -> Source m FilePath

sourceDirectoryDeep :: forall m. MonadBaseControl IO m => Bool -> FilePath -> Source m FilePath

dropC :: Monad m => Int -> Conduit a m a

dropCE :: (Monad m, IsSequence seq) => Index seq -> Conduit seq m seq

dropWhileC :: Monad m => (a -> Bool) -> Conduit a m a

dropWhileCE :: (Monad m, IsSequence seq) => (Element seq -> Bool) -> Conduit seq m seq

foldC :: (Monad m, Monoid a) => Sink a m a

foldCE :: (Monad m, MonoFoldable mono, Monoid (Element mono)) => Sink mono m (Element mono)

foldlC :: Monad m => (a -> b -> a) -> a -> Sink b m a

foldlCE :: (Monad m, MonoFoldable mono) => (a -> Element mono -> a) -> a -> Sink mono m a

foldMapC :: (Monad m, Monoid b) => (a -> b) -> Sink a m b

foldMapCE :: (Monad m, MonoFoldable mono, Monoid w) => (Element mono -> w) -> Sink mono m w

allC :: Monad m => (a -> Bool) -> Sink a m Bool

allCE :: (Monad m, MonoFoldable mono) => (Element mono -> Bool) -> Sink mono m Bool

anyC :: Monad m => (a -> Bool) -> Sink a m Bool

anyCE :: (Monad m, MonoFoldable mono) => (Element mono -> Bool) -> Sink mono m Bool

andC :: Monad m => Sink Bool m Bool

andCE :: (Monad m, MonoFoldable mono, Element mono ~ Bool) => Sink mono m Bool

orC :: Monad m => Sink Bool m Bool

orCE :: (Monad m, MonoFoldable mono, Element mono ~ Bool) => Sink mono m Bool

elemC :: (Monad m, Eq a) => a -> Sink a m Bool

elemCE :: (Monad m, MonoFoldable seq, Eq (Element seq)) => Element seq -> Sink seq m Bool

notElemC :: (Monad m, Eq a) => a -> Sink a m Bool

notElemCE :: (Monad m, MonoFoldable seq, Eq (Element seq)) => Element seq -> Sink seq m Bool

sinkLazy :: (Monad m, LazySequence lazy strict) => Sink strict m lazy

sinkList :: Monad m => Sink a m [a]

sinkVector :: (MonadBase base m, Vector v a, PrimMonad base) => Sink a m (v a)

sinkBuilder :: (Monad m, Monoid builder, ToBuilder a builder) => Sink a m builder

sinkLazyBuilder :: (Monad m, Monoid builder, ToBuilder a builder, Builder builder lazy) => Sink a m lazy

sinkNull :: Monad m => Sink a m ()

awaitNonNull :: (Monad m, MonoFoldable a) => Conduit a m (Maybe (NonNull a))

headCE :: (Monad m, IsSequence seq) => Sink seq m (Maybe (Element seq))

lastC :: Monad m => Sink a m (Maybe a)

lastCE :: (Monad m, IsSequence seq) => Sink seq m (Maybe (Element seq))

lengthC :: (Monad m, Num len) => Sink a m len

lengthCE :: (Monad m, Num len, MonoFoldable mono) => Sink mono m len

lengthIfC :: (Monad m, Num len) => (a -> Bool) -> Sink a m len

lengthIfCE :: (Monad m, Num len, MonoFoldable mono) => (Element mono -> Bool) -> Sink mono m len

maximumC :: (Monad m, Ord a) => Sink a m (Maybe a)

maximumCE :: (Monad m, MonoFoldable seq) => Sink seq m (Maybe (Element seq))

minimumC :: (Monad m, Ord a) => Sink a m (Maybe a)

minimumCE :: (Monad m, MonoFoldable seq) => Sink seq m (Maybe (Element seq))

sumC :: (Monad m, Num a) => Sink a m a

sumCE :: (Monad m, MonoFoldable mono, Num (Element mono)) => Sink mono m (Element mono)

productC :: (Monad m, Num a) => Sink a m a

productCE :: (Monad m, MonoFoldable mono, Num (Element mono)) => Sink mono m (Element mono)

findC :: Monad m => (a -> Bool) -> Sink a m (Maybe a)

mapM_C :: Monad m => (a -> m ()) -> Sink a m ()

mapM_CE :: (Monad m, MonoFoldable mono) => (Element mono -> m ()) -> Sink mono m ()

foldMC :: Monad m => (a -> b -> m a) -> a -> Sink b m a

foldMCE :: (Monad m, MonoFoldable mono) => (a -> Element mono -> m a) -> a -> Sink mono m a

foldMapMC :: (Monad m, Monoid w) => (a -> m w) -> Sink a m w

foldMapMCE :: (Monad m, MonoFoldable mono, Monoid w) => (Element mono -> m w) -> Sink mono m w

sinkFile :: (MonadBaseControl IO m, MonadIO m, IOData a) => FilePath -> Sink a m ()

sinkHandle :: (MonadIO m, IOData a) => Handle -> Sink a m ()

sinkIOHandle :: (MonadBaseControl IO m, MonadIO m, IOData a) => IO Handle -> Sink a m ()

printC :: (Show a, MonadIO m) => Sink a m ()

stdoutC :: (MonadIO m, IOData a) => Sink a m ()

stderrC :: (MonadIO m, IOData a) => Sink a m ()

mapC :: Monad m => (a -> b) -> Conduit a m b

mapCE :: (Monad m, Functor f) => (a -> b) -> Conduit (f a) m (f b)

omapCE :: (Monad m, MonoFunctor mono) => (Element mono -> Element mono) -> Conduit mono m mono

concatMapC :: (Monad m, MonoFoldable mono) => (a -> mono) -> Conduit a m (Element mono)

concatMapCE :: (Monad m, MonoFoldable mono, Monoid w) => (Element mono -> w) -> Conduit mono m w

takeC :: Monad m => Int -> Conduit a m a

takeCE :: (Monad m, IsSequence seq) => Index seq -> Conduit seq m seq

takeWhileC :: Monad m => (a -> Bool) -> Conduit a m a

This function reads one more element than it yields, which would be a problem if Sinks were monadic, as they are in conduit or pipes. There is no such concept as "resuming where the last conduit left off" in this library.

takeWhileCE :: (Monad m, IsSequence seq) => (Element seq -> Bool) -> Conduit seq m seq

takeExactlyC :: Monad m => Int -> Conduit a m b -> Conduit a m b

takeExactlyCE :: (Monad m, IsSequence a) => Index a -> Conduit a m b -> Conduit a m b

concatC :: (Monad m, MonoFoldable mono) => Conduit mono m (Element mono)

filterC :: Monad m => (a -> Bool) -> Conduit a m a

filterCE :: (IsSequence seq, Monad m) => (Element seq -> Bool) -> Conduit seq m seq

mapWhileC :: Monad m => (a -> Maybe b) -> Conduit a m b

conduitVector :: (MonadBase base m, Vector v a, PrimMonad base) => Int -> Conduit a m (v a)

Collect elements into a vector until the size maxSize is reached, then yield that vector downstream.

scanlC :: Monad m => (a -> b -> a) -> a -> Conduit b m a

concatMapAccumC :: Monad m => (a -> accum -> (accum, [b])) -> accum -> Conduit a m b

intersperseC :: Monad m => a -> Source m a -> Source m a

encodeBase64C :: Monad m => Conduit ByteString m ByteString

decodeBase64C :: Monad m => Conduit ByteString m ByteString

encodeBase64URLC :: Monad m => Conduit ByteString m ByteString

decodeBase64URLC :: Monad m => Conduit ByteString m ByteString

encodeBase16C :: Monad m => Conduit ByteString m ByteString

decodeBase16C :: Monad m => Conduit ByteString m ByteString

mapMC :: Monad m => (a -> m b) -> Conduit a m b

mapMCE :: (Monad m, Traversable f) => (a -> m b) -> Conduit (f a) m (f b)

omapMCE :: (Monad m, MonoTraversable mono) => (Element mono -> m (Element mono)) -> Conduit mono m mono

concatMapMC :: (Monad m, MonoFoldable mono) => (a -> m mono) -> Conduit a m (Element mono)

filterMC :: Monad m => (a -> m Bool) -> Conduit a m a

filterMCE :: (Monad m, IsSequence seq) => (Element seq -> m Bool) -> Conduit seq m seq

iterMC :: Monad m => (a -> m ()) -> Conduit a m a

scanlMC :: Monad m => (a -> b -> m a) -> a -> Conduit b m a

concatMapAccumMC :: Monad m => (a -> accum -> m (accum, [b])) -> accum -> Conduit a m b

encodeUtf8C :: Monad m => Conduit Text m ByteString

decodeUtf8C :: MonadThrow m => Conduit ByteString m Text

lineC :: (Monad m, IsSequence seq, Element seq ~ Char) => Conduit seq m o -> Conduit seq m o

lineAsciiC :: (Monad m, IsSequence seq, Element seq ~ Word8) => Conduit seq m o -> Conduit seq m o

unlinesC :: (Monad m, IsSequence seq, Element seq ~ Char) => Conduit seq m seq

unlinesAsciiC :: (Monad m, IsSequence seq, Element seq ~ Word8) => Conduit seq m seq

linesUnboundedC_ :: forall m seq. (Monad m, IsSequence seq, Eq (Element seq), Semigroup seq) => Element seq -> Conduit seq m seq

linesUnboundedC :: (Monad m, IsSequence seq, Element seq ~ Char, Semigroup seq) => Conduit seq m seq

linesC :: (Monad m, IsSequence seq, Element seq ~ Char, Semigroup seq) => Conduit seq m seq

linesUnboundedAsciiC :: (Monad m, IsSequence seq, Element seq ~ Word8, Semigroup seq) => Conduit seq m seq

linesAsciiC :: (Monad m, IsSequence seq, Element seq ~ Word8, Semigroup seq) => Conduit seq m seq

sourceMaybeMVar :: forall m a. MonadIO m => MVar (Maybe a) -> Source m a

Keep taking from an MVar (Maybe a) until it yields Nothing.

sourceMaybeTMVar :: forall a. TMVar (Maybe a) -> Source STM a

Keep taking from an TMVar (Maybe a) until it yields Nothing.

asyncC :: (MonadBaseControl IO m, Monad m) => (a -> m b) -> Conduit a m (Async (StM m b))

sourceTChan :: forall a. TChan a -> Source STM a

A Source for exhausting a TChan, but blocks if it is initially empty.

sourceTQueue :: forall a. TQueue a -> Source STM a

sourceTBQueue :: forall a. TBQueue a -> Source STM a

untilMC :: forall m a. Monad m => m a -> m Bool -> Source m a

whileMC :: forall m a. Monad m => m Bool -> m a -> Source m a

zipSinks :: forall a m r r'. (MonadBaseControl IO m, MonadIO m) => Sink a m r -> Sink a m r' -> Sink a m (r, r')

($=) :: a -> (a -> b) -> b infixl 1

Compose a Source and a Conduit into a new Source. Note that this is just flipped function application, so ($) can be used to achieve the same thing.

(=$) :: (a -> b) -> (b -> c) -> a -> c infixr 2

Compose a Conduit and a Sink into a new Sink. Note that this is just function composition, so (.) can be used to achieve the same thing.

(=$=) :: (a -> b) -> (b -> c) -> a -> c infixr 2

Compose two Conduit. This is also just function composition.

($$) :: a -> (a -> b) -> b infixr 0

Compose a Source and a Sink and compute the result. Note that this is just flipped function application, so ($) can be used to achieve the same thing.

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

Sequence a collection of sources.

>>> sinkList $ sequenceSources [yieldOne 1, yieldOne 2, yieldOne 3]
[[1,2,3]]