Streamly.Internal.Data.Stream.Prelude

Stream Conversion

fromStreamS :: (IsStream t, Monad m) => Stream m a -> t m a

toStreamS :: (IsStream t, Monad m) => t m a -> Stream m a

Running Effects

drain :: (IsStream t, Monad m) => t m a -> m ()

Conversion operations

fromList :: (Monad m, IsStream t) => [a] -> t m a

fromList = foldr cons nil

Construct a stream from a list of pure values. This is more efficient than fromFoldable for serial streams.

Since: 0.4.0

toList :: (Monad m, IsStream t) => t m a -> m [a]

Convert a stream into a list in the underlying monad.

Since: 0.1.0

Fold operations

foldrM :: (Monad m, IsStream t) => (a -> m b -> m b) -> m b -> t m a -> m b

foldrMx :: (Monad m, IsStream t) => (a -> m x -> m x) -> m x -> (m x -> m b) -> t m a -> m b

foldr :: (Monad m, IsStream t) => (a -> b -> b) -> b -> t m a -> m b

foldlx' :: (IsStream t, Monad m) => (x -> a -> x) -> x -> (x -> b) -> t m a -> m b

Strict left fold with an extraction function. Like the standard strict left fold, but applies a user supplied extraction function (the third argument) to the folded value at the end. This is designed to work with the foldl library. The suffix x is a mnemonic for extraction.

Since: 0.7.0

foldlMx' :: (IsStream t, Monad m) => (x -> a -> m x) -> m x -> (x -> m b) -> t m a -> m b

Like foldlx', but with a monadic step function.

Since: 0.7.0

foldl' :: (Monad m, IsStream t) => (b -> a -> b) -> b -> t m a -> m b

Strict left associative fold.

Since: 0.2.0

runFold :: (Monad m, IsStream t) => Fold m a b -> t m a -> m b

parselMx' :: (IsStream t, MonadThrow m) => (s -> a -> m (Step s b)) -> m s -> (s -> m b) -> t m a -> m b

foldlS :: IsStream t => (t m b -> a -> t m b) -> t m b -> t m a -> t m b

foldlT :: (Monad m, IsStream t, Monad (s m), MonadTrans s) => (s m b -> a -> s m b) -> s m b -> t m a -> s m b

Lazy left fold to a transformer monad.

For example, to reverse a stream:

S.toList $ S.foldlT (flip S.cons) S.nil $ (S.fromList [1..5] :: SerialT IO Int)

scanlx' :: (IsStream t, Monad m) => (x -> a -> x) -> x -> (x -> b) -> t m a -> t m b

Strict left scan with an extraction function. Like scanl', but applies a user supplied extraction function (the third argument) at each step. This is designed to work with the foldl library. The suffix x is a mnemonic for extraction.

Since: 0.7.0

scanlMx' :: (IsStream t, Monad m) => (x -> a -> m x) -> m x -> (x -> m b) -> t m a -> t m b

postscanlx' :: (IsStream t, Monad m) => (x -> a -> x) -> x -> (x -> b) -> t m a -> t m b

postscanlMx' :: (IsStream t, Monad m) => (x -> a -> m x) -> m x -> (x -> m b) -> t m a -> t m b

Zip style operations

eqBy :: (IsStream t, Monad m) => (a -> b -> Bool) -> t m a -> t m b -> m Bool

Compare two streams for equality

Since: 0.5.3

cmpBy :: (IsStream t, Monad m) => (a -> b -> Ordering) -> t m a -> t m b -> m Ordering

Compare two streams

Since: 0.5.3

Foldable instance

minimum :: (IsStream t, Monad m, Ord a) => t m a -> m (Maybe a)

maximum :: (IsStream t, Monad m, Ord a) => t m a -> m (Maybe a)

Nesting

concatMapBy :: IsStream t => (forall c. t m c -> t m c -> t m c) -> (a -> t m b) -> t m a -> t m b

Perform a concatMap using a specified concat strategy. The first argument specifies a merge or concat function that is used to merge the streams generated by the map function. For example, the concat function could be serial, parallel, async, ahead or any other zip or merge function.

Since: 0.7.0

concatMap :: IsStream t => (a -> t m b) -> t m a -> t m b

Fold Utilities

foldWith :: (IsStream t, Foldable f) => (t m a -> t m a -> t m a) -> f (t m a) -> t m a

A variant of fold that allows you to fold a Foldable container of streams using the specified stream sum operation.

foldWith async $ map return [1..3]

Equivalent to:

foldWith f = S.foldMapWith f id

Since: 0.1.0 (Streamly)

foldMapWith :: (IsStream t, Foldable f) => (t m b -> t m b -> t m b) -> (a -> t m b) -> f a -> t m b

A variant of foldMap that allows you to map a monadic streaming action on a Foldable container and then fold it using the specified stream merge operation.

foldMapWith async return [1..3]

Equivalent to:

foldMapWith f g xs = S.concatMapWith f g (S.fromFoldable xs)

Since: 0.1.0 (Streamly)

forEachWith :: (IsStream t, Foldable f) => (t m b -> t m b -> t m b) -> f a -> (a -> t m b) -> t m b

Like foldMapWith but with the last two arguments reversed i.e. the monadic streaming function is the last argument.

Equivalent to:

forEachWith = flip S.foldMapWith

Since: 0.1.0 (Streamly)