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Merge pull request #25 from Abhiroop/last

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Fix last for streams that end with "stop" continuation
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Harendra Kumar 2018-03-15 13:48:17 +05:30 committed by GitHub
commit f5a21bcae9
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2 changed files with 4 additions and 9 deletions
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3
Changelog.md
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@ -5,7 +5,8 @@
* Improve performance of some stream operations (`foldl`, `dropWhile`)
### Bug Fixes
* Fix the `product` operation. Earlier, it always returned 0 due to a bug.
* Fix the `product` operation. Earlier, it always returned 0 due to a bug
* Fix the `last` operation, which returned `Nothing` for singleton streams
## 0.1.0

10
src/Streamly/Prelude.hs
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@ -87,7 +87,6 @@ import qualified System.IO as IO
import Streamly.Core
import Streamly.Streams
------------------------------------------------------------------------------
-- Construction
------------------------------------------------------------------------------
@ -334,14 +333,9 @@ head m =
in (runStream (toStream m)) Nothing stop yield
-- | Extract the last element of the stream, if any.
{-# INLINE last #-}
last :: (Streaming t, Monad m) => t m a -> m (Maybe a)
last m = go (toStream m)
where
go m1 =
let stop = return Nothing
yield a Nothing = return (Just a)
yield _ (Just x) = go x
in (runStream m1) Nothing stop yield
last = foldl (\_ y -> Just y) Nothing id
-- | Determine whether an element is present in the stream.
elem :: (Streaming t, Monad m, Eq a) => a -> t m a -> m Bool