Move Streamly.Data.Unfold module to streamly-core package (#1771)

* Move Streamly.Data.Unfold to streamly-core package

* Remove readStream, just use the monomorphic fromStream

Co-authored-by: Harendra Kumar <harendra@composewell.com>

core/src/Streamly/Data/Unfold.hs

@@ -160,7 +160,7 @@ module Streamly.Data.Unfold
 
     -- * Unfolds
     -- One to one correspondence with
-    -- "Streamly.Internal.Data.Stream.IsStream.Generate"
+    -- "Streamly.Internal.Data.Stream.Generate"
 
     -- ** Basic Constructors
     , unfoldrM
@@ -212,22 +212,4 @@ import Prelude hiding
     ( concat, map, mapM, takeWhile, take, filter, const, drop, dropWhile
     , zipWith
     )
-import Streamly.Internal.Data.Stream.IsStream.Type (IsStream)
-import Streamly.Internal.Data.Unfold hiding (fromStream)
-
-import qualified Streamly.Internal.Data.Stream.IsStream.Type as IsStream
-import qualified Streamly.Internal.Data.Unfold as Unfold
-
--- XXX Using Unfold.fromStreamD seems to be faster (using cross product test
--- case) than using fromStream even if it is implemented using fromStreamD.
--- Check if StreamK to StreamD rewrite rules are working correctly when
--- implementing fromStream using fromStreamD.
-
--- | Convert a stream into an 'Unfold'. Note that a stream converted to an
--- 'Unfold' may not be as efficient as an 'Unfold' in some situations.
---
--- /Since: 0.8.0/
---
-{-# INLINE_NORMAL fromStream #-}
-fromStream :: (IsStream t, Applicative m) => Unfold m (t m a) a
-fromStream = lmap IsStream.toStream Unfold.fromStreamK
+import Streamly.Internal.Data.Unfold

core/streamly-core.cabal

@@ -344,6 +344,7 @@ library
                      , Streamly.Data.Fold
                      , Streamly.Data.Fold.Tee
                      , Streamly.Data.Array.Unboxed
+                     , Streamly.Data.Unfold
 
     build-depends:
                     -- Core libraries shipped with ghc, the min and max

docs/User/ProjectRelated/Changelog.md

@@ -14,6 +14,8 @@
     writeWithBufferOf -> writeWith
     writeChunksWithBufferOf -> writeChunksWith
 
+* Signature changed: Streamly.Data.Unfold.fromStream
+
 ### Deprecations
 
 * In `Streamly.Data.Fold`:

src/Streamly/Internal/Data/Stream/IsStream/Common.hs

@@ -569,7 +569,6 @@ concatMapM f m = fromStreamD $ D.concatMapM (fmap toStreamD . f) (toStreamD m)
 -- >>> concatMap f = Stream.concatMapM (return . f)
 -- >>> concatMap f = Stream.concatMapWith Stream.serial f
 -- >>> concatMap f = Stream.concat . Stream.map f
--- >>> concatMap f = Stream.unfoldMany (Unfold.lmap f Unfold.fromStream)
 --
 -- @since 0.6.0
 {-# INLINE concatMap #-}

src/Streamly/Internal/Data/Stream/IsStream/Reduce.hs

@@ -1289,10 +1289,6 @@ ejectExpired reset ejectPred extract session@SessionState{..} curTime = do
                 assert (IsMap.mapNull mp) (return ())
                 return (hp, mp, out, cnt)
 
-{-# INLINE readSerial #-}
-readSerial :: Applicative m => Unfold.Unfold m (IsStream.SerialT m a) a
-readSerial = Unfold.fromStream
-
 -- XXX Use mutable IORef in accumulator
 {-# INLINE classifySessionsByGeneric #-}
 classifySessionsByGeneric
@@ -1307,7 +1303,7 @@ classifySessionsByGeneric
     -> t m (Key f, b) -- ^ session key, fold result
 classifySessionsByGeneric _ tick reset ejectPred tmout
     (Fold step initial extract) input =
-    Expand.unfoldMany (Unfold.lmap sessionOutputStream readSerial)
+    Expand.unfoldMany (Unfold.lmap sessionOutputStream Unfold.fromStream)
         $ scanlMAfter' sstep (return szero) (flush extract)
         $ interjectSuffix tick (return Nothing)
         $ map Just input

streamly.cabal

@@ -215,6 +215,7 @@ extra-source-files:
     core/src/Streamly/Data/Stream.hs
     core/src/Streamly/Data/Fold.hs
     core/src/Streamly/Data/Fold/Tee.hs
+    core/src/Streamly/Data/Unfold.hs
     core/src/Streamly/Internal/Data/Fold/Window.hs
     core/src/Streamly/Data/Array/Unboxed.hs
     core/src/Streamly/Internal/Data/Time/Clock/Darwin.c
@@ -436,10 +437,7 @@ library
                      -- dependency order To view dependency graph:
                      -- graphmod | dot -Tps > deps.ps
 
-                     -- XXX To be moved to streamly-core
-                       Streamly.Data.Unfold
-
-                     , Streamly.Internal.Data.IsMap.HashMap
+                       Streamly.Internal.Data.IsMap.HashMap
 
                      -- XXX To be removed or put under dev flag
                      , Streamly.Internal.Data.SmallArray.Type
@@ -637,6 +635,7 @@ library
                      , Streamly.Internal.Data.Stream.StreamK
 
                      -- streamly-core exposed modules
+                     , Streamly.Data.Unfold
                      , Streamly.Data.Stream
                      , Streamly.Data.Fold
                      , Streamly.Data.Fold.Tee