iterateM package:streamly-core

Generate an infinite stream with the first element generated by the action m and each successive element derived by applying the monadic function f on the previous element.

>>> :{
Stream.iterateM (\x -> print x >> return (x + 1)) (return 0)
& Stream.take 3
& Stream.toList
:}
0
1
[0,1,2]

Generates an infinite stream starting with the given seed and applying the given function repeatedly.

>>> iterateM f m = m >>= \a -> return a `StreamK.consM` iterateM f (f a)

Generate an infinite stream with the first element generated by the action m and each successive element derived by applying the monadic function f on the previous element.

>>> :{
StreamK.iterateM (\x -> print x >> return (x + 1)) (return 0)
& StreamK.take 3
& StreamK.toList
:}
0
1
[0,1,2]

Iterate a fold generator on a stream. The initial value b is used to generate the first fold, the fold is applied on the stream and the result of the fold is used to generate the next fold and so on.

>>> import Data.Monoid (Sum(..))

>>> f x = return (Fold.take 2 (Fold.sconcat x))

>>> s = fmap Sum $ Stream.fromList [1..10]

>>> Stream.fold Fold.toList $ fmap getSum $ Stream.foldIterateM f (pure 0) s
[3,10,21,36,55,55]

This is the streaming equivalent of monad like sequenced application of folds where next fold is dependent on the previous fold. Pre-release

Like foldIterateM but using the Refold type instead. This could be much more efficient due to stream fusion. Internal