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Update the docs of scan and postscan

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This commit is contained in:
Harendra Kumar 2024-02-05 20:13:54 +05:30
parent 154528fc16
commit fd071fdede
1 changed files with 13 additions and 2 deletions
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15
core/src/Streamly/Internal/Data/Stream/Transform.hs
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@ -415,7 +415,16 @@ trace_ eff = mapM (\x -> eff >> return x)
data ScanState s f = ScanInit s | ScanDo s !f | ScanDone
-- | Postscan a stream using the given monadic fold.
-- | Postscan a stream using the given fold. A postscan omits the initial
-- (default) value of the accumulator and includes the final value.
--
-- >>> Stream.toList $ Stream.postscan Fold.latest (Stream.fromList [])
-- []
--
-- Compare with 'scan' which includes the initial value as well:
--
-- >>> Stream.toList $ Stream.scan Fold.latest (Stream.fromList [])
-- [Nothing]
--
-- The following example extracts the input stream up to a point where the
-- running average of elements is no more than 10:
@ -497,7 +506,9 @@ scanWith restart (Fold fstep initial extract final) (Stream sstep state) =
-- can return new accumulator and the value to be emitted. The signature would
-- be more like mapAccumL.
-- | Strict left scan. Scan a stream using the given monadic fold.
-- | Strict left scan. Scan a stream using the given fold. Scan includes
-- the initial (default) value of the accumulator as well as the final value.
-- Compare with 'postscan' which omits the initial value.
--
-- >>> s = Stream.fromList [1..10]
-- >>> Stream.fold Fold.toList $ Stream.takeWhile (< 10) $ Stream.scan Fold.sum s