3d12532 · streamly · git.iko.soy

Changelog.md+1−1

compare with master

unifiedsplit

@@ -7,7 +7,7 @@

7

8### Enhancements

9* Make `cons` right associative and provide an operator form `.:` for it

10−* Add `null`, `tail`, `reverse`, `replicateM`, `scan` stream operations

10+* Add `iterate`, `null`, `tail`, `reverse`, `replicateM`, `scan` stream operations

11* Improve performance of some stream operations (`foldl`, `dropWhile`)

12

13### Bug Fixes

src/Streamly/Prelude.hs+8−1

@@ -24,6 +24,7 @@ module Streamly.Prelude

24 , unfoldr

25 , unfoldrM

26 , each

27+ , iterate

27

28

28 -- * Elimination

29 -- * Elimination

29 -- ** General Folds

30 -- ** General Folds

@@ -85,7 +86,8 @@ import Prelude hiding (filter, drop, dropWhile, take,

85 mapM, mapM_, sequence, all, any,

86 mapM, mapM_, sequence, all, any,

86 sum, product, elem, notElem,

87 sum, product, elem, notElem,

87 maximum, minimum, head, last,

88 maximum, minimum, head, last,

88− tail, length, null, reverse)

89+ tail, length, null, reverse,

90+ iterate)

89import qualified Prelude

91import qualified Prelude

90import qualified System.IO as IO

92import qualified System.IO as IO

91

93

@@ -120,6 +122,11 @@ unfoldrM step = fromStream . go

120each :: (Streaming t, Foldable f) => f a -> t m a

122each :: (Streaming t, Foldable f) => f a -> t m a

121each = Prelude.foldr cons nil

123each = Prelude.foldr cons nil

122

124

125+iterate :: Streaming t => (a -> a) -> a -> t m a

126+iterate f = fromStream . go

127+ where

128+ go s = scons s (Just (go (f s)))

129+

123-- | Read lines from an IO Handle into a stream of Strings.

130-- | Read lines from an IO Handle into a stream of Strings.

124fromHandle :: (Streaming t, MonadIO m) => IO.Handle -> t m String

131fromHandle :: (Streaming t, MonadIO m) => IO.Handle -> t m String

125fromHandle h = fromStream go

132fromHandle h = fromStream go

test/Main.hs+6

@@ -651,6 +651,12 @@ streamOperations (stream, list, len) = do

651 return $ str == lst

652 `shouldReturn` True

653

654+ it "iterate" $ do

655+ let lst = take len $ iterate (+ 1) 0

656+ str <- A.toList . serially . (A.take len) $ (A.iterate (+ 1) (0 :: Int))

657+ return $ str == lst

658+ `shouldReturn` True

659+

654 -- Filtering

660 -- Filtering

655 it "filter all out" $ transform (A.filter (> len)) (filter (> len))

661 it "filter all out" $ transform (A.filter (> len)) (filter (> len))

656 it "filter all in" $ transform (A.filter (<= len)) (filter (<= len))

662 it "filter all in" $ transform (A.filter (<= len)) (filter (<= len))