{-# LANGUAGE CPP #-}
-- |
-- Module      : Streamly.Internal.Data.Unfold
-- Copyright   : (c) 2019 Composewell Technologies
-- License     : BSD3
-- Maintainer  : streamly@composewell.com
-- Stability   : experimental
-- Portability : GHC
--
module Streamly.Internal.Data.Unfold
    (
    -- * Setup
    -- | To execute the code examples provided in this module in ghci, please
    -- run the following commands first.
    --
    -- $setup

    -- * Unfold Type
      Step(..)
    , Unfold

    -- * Unfolds
    -- One to one correspondence with
    -- "Streamly.Internal.Data.Stream.Generate"
    -- ** Basic Constructors
    , mkUnfoldM
    , mkUnfoldrM
    , unfoldrM
    , unfoldr
    , functionM
    , function
    , identity
    , nilM
    , nil
    , consM

    -- ** From Values
    , fromEffect
    , fromPure

    -- ** Generators
    -- | Generate a monadic stream from a seed.
    , repeatM
    , replicateM
    , fromIndicesM
    , iterateM

    -- ** Enumerations
    , Enumerable (..)

    -- ** Enumerate Num
    , enumerateFromNum
    , enumerateFromThenNum
    , enumerateFromStepNum

    -- ** Enumerating 'Bounded 'Integral' Types
    , enumerateFromIntegralBounded
    , enumerateFromThenIntegralBounded
    , enumerateFromToIntegralBounded
    , enumerateFromThenToIntegralBounded

    -- ** Enumerating 'Unounded Integral' Types
    , enumerateFromIntegral
    , enumerateFromThenIntegral
    , enumerateFromToIntegral
    , enumerateFromThenToIntegral

    -- ** Enumerating 'Small Integral' Types
    , enumerateFromSmallBounded
    , enumerateFromThenSmallBounded
    , enumerateFromToSmall
    , enumerateFromThenToSmall

    -- ** Enumerating 'Fractional' Types
    , enumerateFromFractional
    , enumerateFromThenFractional
    , enumerateFromToFractional
    , enumerateFromThenToFractional

    -- ** From Containers
    , fromList
    , fromListM

    -- ** From Memory
    , fromPtr

    -- ** From Stream
    , fromStreamK
    , fromStreamD
    , fromStream

    -- * Combinators
    -- ** Mapping on Input
    , lmap
    , lmapM
    , both
    , first
    , second
    , discardFirst
    , discardSecond
    , swap
    -- coapply
    -- comonad

    -- * Folding
    , fold

    -- XXX Add "WithInput" versions of all these, map2, postscan2, takeWhile2,
    -- filter2 etc.  Alternatively, we can use the default operations with
    -- input, but that might make the common case more inconvenient.

    -- ** Mapping on Output
    , map
    , map2
    , mapM
    , mapM2

    , postscanlM'
    , postscan
    , scan
    , scanMany
    , foldMany
    -- pipe

    -- ** Either Wrapped Input
    , either

    -- ** Filtering
    , takeWhileM
    , takeWhile
    , take
    , filter
    , filterM
    , drop
    , dropWhile
    , dropWhileM

    -- ** Zipping
    , zipWithM
    , zipWith

    -- ** Cross product
    , crossWithM
    , crossWith
    , cross
    , joinInnerGeneric
    , crossApply

    -- ** Nesting
    , ConcatState (..)
    , many
    , many2
    , concatMapM
    , bind

    -- ** Resource Management
    -- | 'bracket' is the most general resource management operation, all other
    -- operations can be expressed using it. These functions have IO suffix
    -- because the allocation and cleanup functions are IO actions. For
    -- generalized allocation and cleanup functions see the functions without
    -- the IO suffix in the "streamly" package.
    , gbracket_
    , gbracketIO
    , before
    , afterIO
    , after_
    , finallyIO
    , finally_
    , bracketIO
    , bracket_

    -- ** Exceptions
    -- | Most of these combinators inhibit stream fusion, therefore, when
    -- possible, they should be called in an outer loop to mitigate the cost.
    -- For example, instead of calling them on a stream of chars call them on a
    -- stream of arrays before flattening it to a stream of chars.
    , onException
    , handle
    )
where

#include "inline.hs"
#include "ArrayMacros.h"

import Control.Exception (Exception, mask_)
import Control.Monad.Catch (MonadCatch)
import Data.Functor (($>))
import GHC.Types (SPEC(..))
import Streamly.Internal.Data.Fold.Type (Fold(..))
import Streamly.Internal.Data.IOFinalizer
    (newIOFinalizer, runIOFinalizer, clearingIOFinalizer)
import Streamly.Internal.Data.Stream.StreamD.Type (Stream(..), Step(..))
import Streamly.Internal.Data.SVar.Type (defState)

import qualified Control.Monad.Catch as MC
import qualified Data.Tuple as Tuple
import qualified Streamly.Internal.Data.Fold.Type as FL
import qualified Streamly.Internal.Data.Stream.StreamD.Type as D
import qualified Streamly.Internal.Data.Stream.StreamK.Type as K
import qualified Prelude

import Streamly.Internal.Data.Unfold.Enumeration
import Streamly.Internal.Data.Unfold.Type
import Prelude
       hiding (map, mapM, takeWhile, take, filter, const, zipWith
              , drop, dropWhile, either)
import Control.Monad.IO.Class (MonadIO (liftIO))
import Foreign (Storable, peek, sizeOf)
import Foreign.Ptr

#include "DocTestDataUnfold.hs"

-- | Convert an 'Unfold' into an unfold accepting a tuple as an argument,
-- using the argument of the original fold as the second element of tuple and
-- discarding the first element of the tuple.
--
-- @
-- discardFirst = Unfold.lmap snd
-- @
--
-- /Pre-release/
--
{-# INLINE_NORMAL discardFirst #-}
discardFirst :: Unfold m a b -> Unfold m (c, a) b
discardFirst :: forall (m :: * -> *) a b c. Unfold m a b -> Unfold m (c, a) b
discardFirst = forall a c (m :: * -> *) b.
(a -> c) -> Unfold m c b -> Unfold m a b
lmap forall a b. (a, b) -> b
snd

-- | Convert an 'Unfold' into an unfold accepting a tuple as an argument,
-- using the argument of the original fold as the first element of tuple and
-- discarding the second element of the tuple.
--
-- @
-- discardSecond = Unfold.lmap fst
-- @
--
-- /Pre-release/
--
{-# INLINE_NORMAL discardSecond #-}
discardSecond :: Unfold m a b -> Unfold m (a, c) b
discardSecond :: forall (m :: * -> *) a b c. Unfold m a b -> Unfold m (a, c) b
discardSecond = forall a c (m :: * -> *) b.
(a -> c) -> Unfold m c b -> Unfold m a b
lmap forall a b. (a, b) -> a
fst

-- | Convert an 'Unfold' that accepts a tuple as an argument into an unfold
-- that accepts a tuple with elements swapped.
--
-- @
-- swap = Unfold.lmap Tuple.swap
-- @
--
-- /Pre-release/
--
{-# INLINE_NORMAL swap #-}
swap :: Unfold m (a, c) b -> Unfold m (c, a) b
swap :: forall (m :: * -> *) a c b. Unfold m (a, c) b -> Unfold m (c, a) b
swap = forall a c (m :: * -> *) b.
(a -> c) -> Unfold m c b -> Unfold m a b
lmap forall a b. (a, b) -> (b, a)
Tuple.swap

-------------------------------------------------------------------------------
-- Output operations
-------------------------------------------------------------------------------

-- XXX Do we need this combinator or the stream based idiom is enough?

-- | Compose an 'Unfold' and a 'Fold'. Given an @Unfold m a b@ and a
-- @Fold m b c@, returns a monadic action @a -> m c@ representing the
-- application of the fold on the unfolded stream.
--
-- >>> Unfold.fold Fold.sum Unfold.fromList [1..100]
-- 5050
--
-- >>> fold f u = Stream.fold f . Stream.unfold u
--
-- /Pre-release/
--
{-# INLINE_NORMAL fold #-}
fold :: Monad m => Fold m b c -> Unfold m a b -> a -> m c
fold :: forall (m :: * -> *) b c a.
Monad m =>
Fold m b c -> Unfold m a b -> a -> m c
fold (Fold s -> b -> m (Step s c)
fstep m (Step s c)
initial s -> m c
extract) (Unfold s -> m (Step s b)
ustep a -> m s
inject) a
a = do
    Step s c
res <- m (Step s c)
initial
    case Step s c
res of
        FL.Partial s
x -> a -> m s
inject a
a forall (m :: * -> *) a b. Monad m => m a -> (a -> m b) -> m b
>>= SPEC -> s -> s -> m c
go SPEC
SPEC s
x
        FL.Done c
b -> forall (m :: * -> *) a. Monad m => a -> m a
return c
b

    where

    {-# INLINE_LATE go #-}
    go :: SPEC -> s -> s -> m c
go !SPEC
_ !s
fs s
st = do
        Step s b
r <- s -> m (Step s b)
ustep s
st
        case Step s b
r of
            Yield b
x s
s -> do
                Step s c
res <- s -> b -> m (Step s c)
fstep s
fs b
x
                case Step s c
res of
                    FL.Partial s
fs1 -> SPEC -> s -> s -> m c
go SPEC
SPEC s
fs1 s
s
                    FL.Done c
c -> forall (m :: * -> *) a. Monad m => a -> m a
return c
c
            Skip s
s -> SPEC -> s -> s -> m c
go SPEC
SPEC s
fs s
s
            Step s b
Stop -> s -> m c
extract s
fs

-- {-# ANN type FoldMany Fuse #-}
data FoldMany s fs b a
    = FoldManyStart s
    | FoldManyFirst fs s
    | FoldManyLoop s fs
    | FoldManyYield b (FoldMany s fs b a)
    | FoldManyDone

-- | Apply a fold multiple times on the output of an unfold.
--
-- /Pre-release/
{-# INLINE_NORMAL foldMany #-}
foldMany :: Monad m => Fold m b c -> Unfold m a b -> Unfold m a c
foldMany :: forall (m :: * -> *) b c a.
Monad m =>
Fold m b c -> Unfold m a b -> Unfold m a c
foldMany (Fold s -> b -> m (Step s c)
fstep m (Step s c)
initial s -> m c
extract) (Unfold s -> m (Step s b)
ustep a -> m s
inject1) =
    forall (m :: * -> *) a b s.
(s -> m (Step s b)) -> (a -> m s) -> Unfold m a b
Unfold forall {a}. FoldMany s s c a -> m (Step (FoldMany s s c a) c)
step forall {fs} {b} {a}. a -> m (FoldMany s fs b a)
inject

    where

    inject :: a -> m (FoldMany s fs b a)
inject a
x = do
        s
r <- a -> m s
inject1 a
x
        forall (m :: * -> *) a. Monad m => a -> m a
return (forall s fs b a. s -> FoldMany s fs b a
FoldManyStart s
r)

    {-# INLINE consume #-}
    consume :: b -> s -> s -> m (Step (FoldMany s s c a) a)
consume b
x s
s s
fs = do
        Step s c
res <- s -> b -> m (Step s c)
fstep s
fs b
x
        forall (m :: * -> *) a. Monad m => a -> m a
return
            forall a b. (a -> b) -> a -> b
$ forall s a. s -> Step s a
Skip
            forall a b. (a -> b) -> a -> b
$ case Step s c
res of
                  FL.Done c
b -> forall s fs b a. b -> FoldMany s fs b a -> FoldMany s fs b a
FoldManyYield c
b (forall s fs b a. s -> FoldMany s fs b a
FoldManyStart s
s)
                  FL.Partial s
ps -> forall s fs b a. s -> fs -> FoldMany s fs b a
FoldManyLoop s
s s
ps

    {-# INLINE_LATE step #-}
    step :: FoldMany s s c a -> m (Step (FoldMany s s c a) c)
step (FoldManyStart s
st) = do
        Step s c
r <- m (Step s c)
initial
        forall (m :: * -> *) a. Monad m => a -> m a
return
            forall a b. (a -> b) -> a -> b
$ forall s a. s -> Step s a
Skip
            forall a b. (a -> b) -> a -> b
$ case Step s c
r of
                  FL.Done c
b -> forall s fs b a. b -> FoldMany s fs b a -> FoldMany s fs b a
FoldManyYield c
b (forall s fs b a. s -> FoldMany s fs b a
FoldManyStart s
st)
                  FL.Partial s
fs -> forall s fs b a. fs -> s -> FoldMany s fs b a
FoldManyFirst s
fs s
st
    step (FoldManyFirst s
fs s
st) = do
        Step s b
r <- s -> m (Step s b)
ustep s
st
        case Step s b
r of
            Yield b
x s
s -> forall {s} {a} {a}. b -> s -> s -> m (Step (FoldMany s s c a) a)
consume b
x s
s s
fs
            Skip s
s -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. s -> Step s a
Skip (forall s fs b a. fs -> s -> FoldMany s fs b a
FoldManyFirst s
fs s
s)
            Step s b
Stop -> forall (m :: * -> *) a. Monad m => a -> m a
return forall s a. Step s a
Stop
    step (FoldManyLoop s
st s
fs) = do
        Step s b
r <- s -> m (Step s b)
ustep s
st
        case Step s b
r of
            Yield b
x s
s -> forall {s} {a} {a}. b -> s -> s -> m (Step (FoldMany s s c a) a)
consume b
x s
s s
fs
            Skip s
s -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. s -> Step s a
Skip (forall s fs b a. s -> fs -> FoldMany s fs b a
FoldManyLoop s
s s
fs)
            Step s b
Stop -> do
                c
b <- s -> m c
extract s
fs
                forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. s -> Step s a
Skip (forall s fs b a. b -> FoldMany s fs b a -> FoldMany s fs b a
FoldManyYield c
b forall s fs b a. FoldMany s fs b a
FoldManyDone)
    step (FoldManyYield c
b FoldMany s s c a
next) = forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. a -> s -> Step s a
Yield c
b FoldMany s s c a
next
    step FoldMany s s c a
FoldManyDone = forall (m :: * -> *) a. Monad m => a -> m a
return forall s a. Step s a
Stop

-------------------------------------------------------------------------------
-- Either
-------------------------------------------------------------------------------

-- | Choose left or right unfold based on an either input.
--
-- /Pre-release/
{-# INLINE_NORMAL either #-}
either :: Applicative m =>
    Unfold m a c -> Unfold m b c -> Unfold m (Either a b) c
either :: forall (m :: * -> *) a c b.
Applicative m =>
Unfold m a c -> Unfold m b c -> Unfold m (Either a b) c
either (Unfold s -> m (Step s c)
stepL a -> m s
injectL) (Unfold s -> m (Step s c)
stepR b -> m s
injectR) = forall (m :: * -> *) a b s.
(s -> m (Step s b)) -> (a -> m s) -> Unfold m a b
Unfold Either s s -> m (Step (Either s s) c)
step Either a b -> m (Either s s)
inject

    where

    inject :: Either a b -> m (Either s s)
inject (Left a
x) = forall a b. a -> Either a b
Left forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> a -> m s
injectL a
x
    inject (Right b
x) = forall a b. b -> Either a b
Right forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> b -> m s
injectR b
x

    {-# INLINE_LATE step #-}
    step :: Either s s -> m (Step (Either s s) c)
step (Left s
st) = do
        (\case
            Yield c
x s
s -> forall s a. a -> s -> Step s a
Yield c
x (forall a b. a -> Either a b
Left s
s)
            Skip s
s -> forall s a. s -> Step s a
Skip (forall a b. a -> Either a b
Left s
s)
            Step s c
Stop -> forall s a. Step s a
Stop) forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> s -> m (Step s c)
stepL s
st
    step (Right s
st) = do
        (\case
            Yield c
x s
s -> forall s a. a -> s -> Step s a
Yield c
x (forall a b. b -> Either a b
Right s
s)
            Skip s
s -> forall s a. s -> Step s a
Skip (forall a b. b -> Either a b
Right s
s)
            Step s c
Stop -> forall s a. Step s a
Stop) forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> s -> m (Step s c)
stepR s
st

-- postscan2 :: Monad m => Refold m a b c -> Unfold m a b -> Unfold m a c

-- | Scan the output of an 'Unfold' to change it in a stateful manner.
--
-- /Pre-release/
{-# INLINE_NORMAL postscan #-}
postscan :: Monad m => Fold m b c -> Unfold m a b -> Unfold m a c
postscan :: forall (m :: * -> *) b c a.
Monad m =>
Fold m b c -> Unfold m a b -> Unfold m a c
postscan (Fold s -> b -> m (Step s c)
stepF m (Step s c)
initial s -> m c
extract) (Unfold s -> m (Step s b)
stepU a -> m s
injectU) =
    forall (m :: * -> *) a b s.
(s -> m (Step s b)) -> (a -> m s) -> Unfold m a b
Unfold Maybe (s, s) -> m (Step (Maybe (s, s)) c)
step a -> m (Maybe (s, s))
inject

    where

    inject :: a -> m (Maybe (s, s))
inject a
a =  do
        Step s c
r <- m (Step s c)
initial
        case Step s c
r of
            FL.Partial s
fs -> forall a. a -> Maybe a
Just forall b c a. (b -> c) -> (a -> b) -> a -> c
. (s
fs,) forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> a -> m s
injectU a
a
            FL.Done c
_ -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a. Maybe a
Nothing

    {-# INLINE_LATE step #-}
    step :: Maybe (s, s) -> m (Step (Maybe (s, s)) c)
step (Just (s
fs, s
us)) = do
        Step s b
ru <- s -> m (Step s b)
stepU s
us
        case Step s b
ru of
            Yield b
x s
s -> do
                Step s c
rf <- s -> b -> m (Step s c)
stepF s
fs b
x
                case Step s c
rf of
                    FL.Done c
v -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. a -> s -> Step s a
Yield c
v forall a. Maybe a
Nothing
                    FL.Partial s
fs1 -> do
                        c
v <- s -> m c
extract s
fs1
                        forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. a -> s -> Step s a
Yield c
v (forall a. a -> Maybe a
Just (s
fs1, s
s))
            Skip s
s -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. s -> Step s a
Skip (forall a. a -> Maybe a
Just (s
fs, s
s))
            Step s b
Stop -> forall (m :: * -> *) a. Monad m => a -> m a
return forall s a. Step s a
Stop

    step Maybe (s, s)
Nothing = forall (m :: * -> *) a. Monad m => a -> m a
return forall s a. Step s a
Stop

data ScanState s f = ScanInit s | ScanDo s !f | ScanDone

{-# INLINE_NORMAL scanWith #-}
scanWith :: Monad m => Bool -> Fold m b c -> Unfold m a b -> Unfold m a c
scanWith :: forall (m :: * -> *) b c a.
Monad m =>
Bool -> Fold m b c -> Unfold m a b -> Unfold m a c
scanWith Bool
restart (Fold s -> b -> m (Step s c)
fstep m (Step s c)
initial s -> m c
extract) (Unfold s -> m (Step s b)
stepU a -> m s
injectU) =
    forall (m :: * -> *) a b s.
(s -> m (Step s b)) -> (a -> m s) -> Unfold m a b
Unfold ScanState s s -> m (Step (ScanState s s) c)
step forall {f}. a -> m (ScanState s f)
inject

    where

    inject :: a -> m (ScanState s f)
inject a
a = forall s f. s -> ScanState s f
ScanInit forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> a -> m s
injectU a
a

    {-# INLINE runStep #-}
    runStep :: s -> m (Step s c) -> m (Step (ScanState s s) c)
runStep s
us m (Step s c)
action = do
        Step s c
r <- m (Step s c)
action
        case Step s c
r of
            FL.Partial s
fs -> do
                !c
b <- s -> m c
extract s
fs
                forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. a -> s -> Step s a
Yield c
b (forall s f. s -> f -> ScanState s f
ScanDo s
us s
fs)
            FL.Done c
b ->
                let next :: ScanState s f
next = if Bool
restart then forall s f. s -> ScanState s f
ScanInit s
us else forall s f. ScanState s f
ScanDone
                 in forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. a -> s -> Step s a
Yield c
b forall {f}. ScanState s f
next

    {-# INLINE_LATE step #-}
    step :: ScanState s s -> m (Step (ScanState s s) c)
step (ScanInit s
us) = forall {s}. s -> m (Step s c) -> m (Step (ScanState s s) c)
runStep s
us m (Step s c)
initial
    step (ScanDo s
us s
fs) = do
        Step s b
res <- s -> m (Step s b)
stepU s
us
        case Step s b
res of
            Yield b
x s
s -> forall {s}. s -> m (Step s c) -> m (Step (ScanState s s) c)
runStep s
s (s -> b -> m (Step s c)
fstep s
fs b
x)
            Skip s
s -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. s -> Step s a
Skip forall a b. (a -> b) -> a -> b
$ forall s f. s -> f -> ScanState s f
ScanDo s
s s
fs
            Step s b
Stop -> forall (m :: * -> *) a. Monad m => a -> m a
return forall s a. Step s a
Stop
    step ScanState s s
ScanDone = forall (m :: * -> *) a. Monad m => a -> m a
return forall s a. Step s a
Stop

-- | Scan the output of an 'Unfold' to change it in a stateful manner.
-- Once fold is done it will restart from its initial state.
--
-- >>> u = Unfold.scanMany (Fold.take 2 Fold.sum) Unfold.fromList
-- >>> Unfold.fold Fold.toList u [1,2,3,4,5]
-- [0,1,3,0,3,7,0,5]
--
-- /Pre-release/
{-# INLINE_NORMAL scanMany #-}
scanMany :: Monad m => Fold m b c -> Unfold m a b -> Unfold m a c
scanMany :: forall (m :: * -> *) b c a.
Monad m =>
Fold m b c -> Unfold m a b -> Unfold m a c
scanMany = forall (m :: * -> *) b c a.
Monad m =>
Bool -> Fold m b c -> Unfold m a b -> Unfold m a c
scanWith Bool
True

-- scan2 :: Monad m => Refold m a b c -> Unfold m a b -> Unfold m a c

-- | Scan the output of an 'Unfold' to change it in a stateful manner.
-- Once fold is done it will stop.
--
-- >>> u = Unfold.scan (Fold.take 2 Fold.sum) Unfold.fromList
-- >>> Unfold.fold Fold.toList u [1,2,3,4,5]
-- [0,1,3]
--
-- /Pre-release/
{-# INLINE_NORMAL scan #-}
scan :: Monad m => Fold m b c -> Unfold m a b -> Unfold m a c
scan :: forall (m :: * -> *) b c a.
Monad m =>
Fold m b c -> Unfold m a b -> Unfold m a c
scan = forall (m :: * -> *) b c a.
Monad m =>
Bool -> Fold m b c -> Unfold m a b -> Unfold m a c
scanWith Bool
False

-- | Scan the output of an 'Unfold' to change it in a stateful manner.
--
-- /Pre-release/
{-# INLINE_NORMAL postscanlM' #-}
postscanlM' :: Monad m => (b -> a -> m b) -> m b -> Unfold m c a -> Unfold m c b
postscanlM' :: forall (m :: * -> *) b a c.
Monad m =>
(b -> a -> m b) -> m b -> Unfold m c a -> Unfold m c b
postscanlM' b -> a -> m b
f m b
z = forall (m :: * -> *) b c a.
Monad m =>
Fold m b c -> Unfold m a b -> Unfold m a c
postscan (forall (m :: * -> *) b a.
Monad m =>
(b -> a -> m b) -> m b -> Fold m a b
FL.foldlM' b -> a -> m b
f m b
z)

-------------------------------------------------------------------------------
-- Convert streams into unfolds
-------------------------------------------------------------------------------

{-# INLINE_NORMAL fromStreamD #-}
fromStreamD :: Applicative m => Unfold m (Stream m a) a
fromStreamD :: forall (m :: * -> *) a. Applicative m => Unfold m (Stream m a) a
fromStreamD = forall (m :: * -> *) a b s.
(s -> m (Step s b)) -> (a -> m s) -> Unfold m a b
Unfold forall {m :: * -> *} {a}.
Functor m =>
Stream m a -> m (Step (Stream m a) a)
step forall (f :: * -> *) a. Applicative f => a -> f a
pure

    where

    {-# INLINE_LATE step #-}
    step :: Stream m a -> m (Step (Stream m a) a)
step (UnStream State StreamK m a -> s -> m (Step s a)
step1 s
state1) =
        (\case
            Yield a
x s
s -> forall s a. a -> s -> Step s a
Yield a
x (forall (m :: * -> *) a s.
(State StreamK m a -> s -> m (Step s a)) -> s -> Stream m a
Stream State StreamK m a -> s -> m (Step s a)
step1 s
s)
            Skip s
s    -> forall s a. s -> Step s a
Skip (forall (m :: * -> *) a s.
(State StreamK m a -> s -> m (Step s a)) -> s -> Stream m a
Stream State StreamK m a -> s -> m (Step s a)
step1 s
s)
            Step s a
Stop      -> forall s a. Step s a
Stop) forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> State StreamK m a -> s -> m (Step s a)
step1 forall (t :: (* -> *) -> * -> *) (m :: * -> *) a. State t m a
defState s
state1

{-# INLINE_NORMAL fromStreamK #-}
fromStreamK :: Applicative m => Unfold m (K.StreamK m a) a
fromStreamK :: forall (m :: * -> *) a. Applicative m => Unfold m (StreamK m a) a
fromStreamK = forall (m :: * -> *) a b s.
(s -> m (Step s b)) -> (a -> m s) -> Unfold m a b
Unfold forall {f :: * -> *} {a}.
Applicative f =>
StreamK f a -> f (Step (StreamK f a) a)
step forall (f :: * -> *) a. Applicative f => a -> f a
pure

    where

    {-# INLINE_LATE step #-}
    step :: StreamK f a -> f (Step (StreamK f a) a)
step StreamK f a
stream = do
        (\case
            Just (a
x, StreamK f a
xs) -> forall s a. a -> s -> Step s a
Yield a
x StreamK f a
xs
            Maybe (a, StreamK f a)
Nothing -> forall s a. Step s a
Stop) forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> forall (m :: * -> *) a.
Applicative m =>
StreamK m a -> m (Maybe (a, StreamK m a))
K.uncons StreamK f a
stream

{-# INLINE fromStream #-}
fromStream :: Applicative m => Unfold m (Stream m a) a
fromStream :: forall (m :: * -> *) a. Applicative m => Unfold m (Stream m a) a
fromStream = forall (m :: * -> *) a. Applicative m => Unfold m (Stream m a) a
fromStreamD

-------------------------------------------------------------------------------
-- Unfolds
-------------------------------------------------------------------------------

-- | Lift a monadic function into an unfold generating a nil stream with a side
-- effect.
--
{-# INLINE nilM #-}
nilM :: Applicative m => (a -> m c) -> Unfold m a b
nilM :: forall (m :: * -> *) a c b.
Applicative m =>
(a -> m c) -> Unfold m a b
nilM a -> m c
f = forall (m :: * -> *) a b s.
(s -> m (Step s b)) -> (a -> m s) -> Unfold m a b
Unfold forall {s} {a}. a -> m (Step s a)
step forall (f :: * -> *) a. Applicative f => a -> f a
pure

    where

    {-# INLINE_LATE step #-}
    step :: a -> m (Step s a)
step a
x = a -> m c
f a
x forall (f :: * -> *) a b. Functor f => f a -> b -> f b
$> forall s a. Step s a
Stop

-- | An empty stream.
{-# INLINE nil #-}
nil :: Applicative m => Unfold m a b
nil :: forall (m :: * -> *) a b. Applicative m => Unfold m a b
nil = forall (m :: * -> *) a b s.
(s -> m (Step s b)) -> (a -> m s) -> Unfold m a b
Unfold (forall a b. a -> b -> a
Prelude.const (forall (f :: * -> *) a. Applicative f => a -> f a
pure forall s a. Step s a
Stop)) forall (f :: * -> *) a. Applicative f => a -> f a
pure

-- | Prepend a monadic single element generator function to an 'Unfold'. The
-- same seed is used in the action as well as the unfold.
--
-- /Pre-release/
{-# INLINE_NORMAL consM #-}
consM :: Applicative m => (a -> m b) -> Unfold m a b -> Unfold m a b
consM :: forall (m :: * -> *) a b.
Applicative m =>
(a -> m b) -> Unfold m a b -> Unfold m a b
consM a -> m b
action Unfold m a b
unf = forall (m :: * -> *) a b s.
(s -> m (Step s b)) -> (a -> m s) -> Unfold m a b
Unfold forall {a}.
Either a (Stream m b) -> m (Step (Either a (Stream m b)) b)
step forall {a} {b}. a -> m (Either a b)
inject

    where

    inject :: a -> m (Either a b)
inject = forall (f :: * -> *) a. Applicative f => a -> f a
pure forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a b. a -> Either a b
Left

    {-# INLINE_LATE step #-}
    step :: Either a (Stream m b) -> m (Step (Either a (Stream m b)) b)
step (Left a
a) = (forall s a. a -> s -> Step s a
`Yield` forall a b. b -> Either a b
Right (forall (m :: * -> *) a b.
Applicative m =>
Unfold m a b -> a -> Stream m b
D.unfold Unfold m a b
unf a
a)) forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> a -> m b
action a
a
    step (Right (UnStream State StreamK m b -> s -> m (Step s b)
step1 s
st)) = do
        (\case
            Yield b
x s
s -> forall s a. a -> s -> Step s a
Yield b
x (forall a b. b -> Either a b
Right (forall (m :: * -> *) a s.
(State StreamK m a -> s -> m (Step s a)) -> s -> Stream m a
Stream State StreamK m b -> s -> m (Step s b)
step1 s
s))
            Skip s
s -> forall s a. s -> Step s a
Skip (forall a b. b -> Either a b
Right (forall (m :: * -> *) a s.
(State StreamK m a -> s -> m (Step s a)) -> s -> Stream m a
Stream State StreamK m b -> s -> m (Step s b)
step1 s
s))
            Step s b
Stop -> forall s a. Step s a
Stop) forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> State StreamK m b -> s -> m (Step s b)
step1 forall (t :: (* -> *) -> * -> *) (m :: * -> *) a. State t m a
defState s
st

-- | Convert a list of monadic values to a 'Stream'
--
{-# INLINE_LATE fromListM #-}
fromListM :: Applicative m => Unfold m [m a] a
fromListM :: forall (m :: * -> *) a. Applicative m => Unfold m [m a] a
fromListM = forall (m :: * -> *) a b s.
(s -> m (Step s b)) -> (a -> m s) -> Unfold m a b
Unfold forall {f :: * -> *} {a}.
Applicative f =>
[f a] -> f (Step [f a] a)
step forall (f :: * -> *) a. Applicative f => a -> f a
pure

    where

    {-# INLINE_LATE step #-}
    step :: [f a] -> f (Step [f a] a)
step (f a
x:[f a]
xs) = (forall s a. a -> s -> Step s a
`Yield` [f a]
xs) forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> f a
x
    step [] = forall (f :: * -> *) a. Applicative f => a -> f a
pure forall s a. Step s a
Stop

{-# INLINE fromPtr #-}
fromPtr :: forall m a. (MonadIO m, Storable a) => Unfold m (Ptr a) a
fromPtr :: forall (m :: * -> *) a.
(MonadIO m, Storable a) =>
Unfold m (Ptr a) a
fromPtr = forall (m :: * -> *) a b s.
(s -> m (Step s b)) -> (a -> m s) -> Unfold m a b
Unfold forall {m :: * -> *} {a} {b}.
(MonadIO m, Storable a) =>
Ptr a -> m (Step (Ptr b) a)
step forall (m :: * -> *) a. Monad m => a -> m a
return

    where

    {-# INLINE_LATE step #-}
    step :: Ptr a -> m (Step (Ptr b) a)
step Ptr a
p = do
        a
x <- forall (m :: * -> *) a. MonadIO m => IO a -> m a
liftIO forall a b. (a -> b) -> a -> b
$ forall a. Storable a => Ptr a -> IO a
peek Ptr a
p
        forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. a -> s -> Step s a
Yield a
x (PTR_NEXT(p, a))

------------------------------------------------------------------------------
-- Specialized Generation
------------------------------------------------------------------------------

-- | Given a seed @(n, action)@, generates a stream replicating the @action@ @n@
-- times.
--
{-# INLINE replicateM #-}
replicateM :: Applicative m => Unfold m (Int, m a) a
replicateM :: forall (m :: * -> *) a. Applicative m => Unfold m (Int, m a) a
replicateM = forall (m :: * -> *) a b s.
(s -> m (Step s b)) -> (a -> m s) -> Unfold m a b
Unfold forall {a} {f :: * -> *} {a}.
(Ord a, Num a, Applicative f) =>
(a, f a) -> f (Step (a, f a) a)
step forall {f :: * -> *} {a}. Applicative f => a -> f a
inject

    where

    inject :: a -> f a
inject a
seed = forall (f :: * -> *) a. Applicative f => a -> f a
pure a
seed

    {-# INLINE_LATE step #-}
    step :: (a, f a) -> f (Step (a, f a) a)
step (a
i, f a
action) =
        if a
i forall a. Ord a => a -> a -> Bool
<= a
0
        then forall (f :: * -> *) a. Applicative f => a -> f a
pure forall s a. Step s a
Stop
        else (\a
x -> forall s a. a -> s -> Step s a
Yield a
x (a
i forall a. Num a => a -> a -> a
- a
1, f a
action)) forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> f a
action

-- | Generates an infinite stream repeating the seed.
--
{-# INLINE repeatM #-}
repeatM :: Applicative m => Unfold m (m a) a
repeatM :: forall (m :: * -> *) a. Applicative m => Unfold m (m a) a
repeatM = forall (m :: * -> *) a b s.
(s -> m (Step s b)) -> (a -> m s) -> Unfold m a b
Unfold forall {f :: * -> *} {a}. Functor f => f a -> f (Step (f a) a)
step forall (f :: * -> *) a. Applicative f => a -> f a
pure

    where

    {-# INLINE_LATE step #-}
    step :: f a -> f (Step (f a) a)
step f a
action = (forall s a. a -> s -> Step s a
`Yield` f a
action) forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> f a
action

-- | Generates an infinite stream starting with the given seed and applying the
-- given function repeatedly.
--
{-# INLINE iterateM #-}
iterateM :: Applicative m => (a -> m a) -> Unfold m (m a) a
iterateM :: forall (m :: * -> *) a.
Applicative m =>
(a -> m a) -> Unfold m (m a) a
iterateM a -> m a
f = forall (m :: * -> *) a b s.
(s -> m (Step s b)) -> (a -> m s) -> Unfold m a b
Unfold a -> m (Step a a)
step forall a. a -> a
id

    where

    {-# INLINE_LATE step #-}
    step :: a -> m (Step a a)
step a
x = forall s a. a -> s -> Step s a
Yield a
x forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> a -> m a
f a
x

-- | @fromIndicesM gen@ generates an infinite stream of values using @gen@
-- starting from the seed.
--
-- @
-- fromIndicesM f = Unfold.mapM f $ Unfold.enumerateFrom 0
-- @
--
-- /Pre-release/
--
{-# INLINE_NORMAL fromIndicesM #-}
fromIndicesM :: Applicative m => (Int -> m a) -> Unfold m Int a
fromIndicesM :: forall (m :: * -> *) a.
Applicative m =>
(Int -> m a) -> Unfold m Int a
fromIndicesM Int -> m a
gen = forall (m :: * -> *) a b s.
(s -> m (Step s b)) -> (a -> m s) -> Unfold m a b
Unfold Int -> m (Step Int a)
step forall (f :: * -> *) a. Applicative f => a -> f a
pure

    where

    {-# INLINE_LATE step #-}
    step :: Int -> m (Step Int a)
step Int
i = (forall s a. a -> s -> Step s a
`Yield` (Int
i forall a. Num a => a -> a -> a
+ Int
1)) forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> Int -> m a
gen Int
i

-------------------------------------------------------------------------------
-- Filtering
-------------------------------------------------------------------------------

-- |
-- >>> u = Unfold.take 2 Unfold.fromList
-- >>> Unfold.fold Fold.toList u [1..100]
-- [1,2]
--
{-# INLINE_NORMAL take #-}
take :: Applicative m => Int -> Unfold m a b -> Unfold m a b
take :: forall (m :: * -> *) a b.
Applicative m =>
Int -> Unfold m a b -> Unfold m a b
take Int
n (Unfold s -> m (Step s b)
step1 a -> m s
inject1) = forall (m :: * -> *) a b s.
(s -> m (Step s b)) -> (a -> m s) -> Unfold m a b
Unfold (s, Int) -> m (Step (s, Int) b)
step forall {t}. Num t => a -> m (s, t)
inject

    where

    inject :: a -> m (s, t)
inject a
x = (, t
0) forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> a -> m s
inject1 a
x

    {-# INLINE_LATE step #-}
    step :: (s, Int) -> m (Step (s, Int) b)
step (s
st, Int
i) | Int
i forall a. Ord a => a -> a -> Bool
< Int
n = do
        (\case
            Yield b
x s
s -> forall s a. a -> s -> Step s a
Yield b
x (s
s, Int
i forall a. Num a => a -> a -> a
+ Int
1)
            Skip s
s -> forall s a. s -> Step s a
Skip (s
s, Int
i)
            Step s b
Stop   -> forall s a. Step s a
Stop) forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> s -> m (Step s b)
step1 s
st
    step (s
_, Int
_) = forall (f :: * -> *) a. Applicative f => a -> f a
pure forall s a. Step s a
Stop

-- | Same as 'filter' but with a monadic predicate.
--
{-# INLINE_NORMAL filterM #-}
filterM :: Monad m => (b -> m Bool) -> Unfold m a b -> Unfold m a b
filterM :: forall (m :: * -> *) b a.
Monad m =>
(b -> m Bool) -> Unfold m a b -> Unfold m a b
filterM b -> m Bool
f (Unfold s -> m (Step s b)
step1 a -> m s
inject1) = forall (m :: * -> *) a b s.
(s -> m (Step s b)) -> (a -> m s) -> Unfold m a b
Unfold s -> m (Step s b)
step a -> m s
inject1
  where
    {-# INLINE_LATE step #-}
    step :: s -> m (Step s b)
step s
st = do
        Step s b
r <- s -> m (Step s b)
step1 s
st
        case Step s b
r of
            Yield b
x s
s -> do
                Bool
b <- b -> m Bool
f b
x
                forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ if Bool
b then forall s a. a -> s -> Step s a
Yield b
x s
s else forall s a. s -> Step s a
Skip s
s
            Skip s
s -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. s -> Step s a
Skip s
s
            Step s b
Stop   -> forall (m :: * -> *) a. Monad m => a -> m a
return forall s a. Step s a
Stop

-- | Include only those elements that pass a predicate.
--
{-# INLINE filter #-}
filter :: Monad m => (b -> Bool) -> Unfold m a b -> Unfold m a b
filter :: forall (m :: * -> *) b a.
Monad m =>
(b -> Bool) -> Unfold m a b -> Unfold m a b
filter b -> Bool
f = forall (m :: * -> *) b a.
Monad m =>
(b -> m Bool) -> Unfold m a b -> Unfold m a b
filterM (forall (m :: * -> *) a. Monad m => a -> m a
return forall b c a. (b -> c) -> (a -> b) -> a -> c
. b -> Bool
f)

-- | @drop n unf@ drops @n@ elements from the stream generated by @unf@.
--
{-# INLINE_NORMAL drop #-}
drop :: Applicative m => Int -> Unfold m a b -> Unfold m a b
drop :: forall (m :: * -> *) a b.
Applicative m =>
Int -> Unfold m a b -> Unfold m a b
drop Int
n (Unfold s -> m (Step s b)
step a -> m s
inject) = forall (m :: * -> *) a b s.
(s -> m (Step s b)) -> (a -> m s) -> Unfold m a b
Unfold forall {b}. (Ord b, Num b) => (s, b) -> m (Step (s, b) b)
step' a -> m (s, Int)
inject'

    where

    inject' :: a -> m (s, Int)
inject' a
a = (, Int
n) forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> a -> m s
inject a
a

    {-# INLINE_LATE step' #-}
    step' :: (s, b) -> m (Step (s, b) b)
step' (s
st, b
i)
        | b
i forall a. Ord a => a -> a -> Bool
> b
0 = do
            (\case
                  Yield b
_ s
s -> forall s a. s -> Step s a
Skip (s
s, b
i forall a. Num a => a -> a -> a
- b
1)
                  Skip s
s -> forall s a. s -> Step s a
Skip (s
s, b
i)
                  Step s b
Stop -> forall s a. Step s a
Stop) forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> s -> m (Step s b)
step s
st
        | Bool
otherwise = do
            (\case
                  Yield b
x s
s -> forall s a. a -> s -> Step s a
Yield b
x (s
s, b
0)
                  Skip s
s -> forall s a. s -> Step s a
Skip (s
s, b
0)
                  Step s b
Stop -> forall s a. Step s a
Stop) forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> s -> m (Step s b)
step s
st

-- | @dropWhileM f unf@ drops elements from the stream generated by @unf@ while
-- the condition holds true. The condition function @f@ is /monadic/ in nature.
--
{-# INLINE_NORMAL dropWhileM #-}
dropWhileM :: Monad m => (b -> m Bool) -> Unfold m a b -> Unfold m a b
dropWhileM :: forall (m :: * -> *) b a.
Monad m =>
(b -> m Bool) -> Unfold m a b -> Unfold m a b
dropWhileM b -> m Bool
f (Unfold s -> m (Step s b)
step a -> m s
inject) = forall (m :: * -> *) a b s.
(s -> m (Step s b)) -> (a -> m s) -> Unfold m a b
Unfold Either s s -> m (Step (Either s s) b)
step' forall {b}. a -> m (Either s b)
inject'

    where

    inject' :: a -> m (Either s b)
inject' a
a = do
        s
b <- a -> m s
inject a
a
        forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall a b. a -> Either a b
Left s
b

    {-# INLINE_LATE step' #-}
    step' :: Either s s -> m (Step (Either s s) b)
step' (Left s
st) = do
        Step s b
r <- s -> m (Step s b)
step s
st
        case Step s b
r of
            Yield b
x s
s -> do
                Bool
b <- b -> m Bool
f b
x
                forall (m :: * -> *) a. Monad m => a -> m a
return
                    forall a b. (a -> b) -> a -> b
$ if Bool
b
                      then forall s a. s -> Step s a
Skip (forall a b. a -> Either a b
Left s
s)
                      else forall s a. a -> s -> Step s a
Yield b
x (forall a b. b -> Either a b
Right s
s)
            Skip s
s -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. s -> Step s a
Skip (forall a b. a -> Either a b
Left s
s)
            Step s b
Stop -> forall (m :: * -> *) a. Monad m => a -> m a
return forall s a. Step s a
Stop
    step' (Right s
st) = do
        Step s b
r <- s -> m (Step s b)
step s
st
        forall (m :: * -> *) a. Monad m => a -> m a
return
            forall a b. (a -> b) -> a -> b
$ case Step s b
r of
                  Yield b
x s
s -> forall s a. a -> s -> Step s a
Yield b
x (forall a b. b -> Either a b
Right s
s)
                  Skip s
s -> forall s a. s -> Step s a
Skip (forall a b. b -> Either a b
Right s
s)
                  Step s b
Stop -> forall s a. Step s a
Stop

-- | Similar to 'dropWhileM' but with a pure condition function.
--
{-# INLINE dropWhile #-}
dropWhile :: Monad m => (b -> Bool) -> Unfold m a b -> Unfold m a b
dropWhile :: forall (m :: * -> *) b a.
Monad m =>
(b -> Bool) -> Unfold m a b -> Unfold m a b
dropWhile b -> Bool
f = forall (m :: * -> *) b a.
Monad m =>
(b -> m Bool) -> Unfold m a b -> Unfold m a b
dropWhileM (forall (m :: * -> *) a. Monad m => a -> m a
return forall b c a. (b -> c) -> (a -> b) -> a -> c
. b -> Bool
f)

{-# INLINE_NORMAL joinInnerGeneric #-}
joinInnerGeneric :: Monad m =>
    (b -> c -> Bool) -> Unfold m a b -> Unfold m a c -> Unfold m a (b, c)
joinInnerGeneric :: forall (m :: * -> *) b c a.
Monad m =>
(b -> c -> Bool)
-> Unfold m a b -> Unfold m a c -> Unfold m a (b, c)
joinInnerGeneric b -> c -> Bool
eq Unfold m a b
s1 Unfold m a c
s2 = forall (m :: * -> *) b a.
Monad m =>
(b -> Bool) -> Unfold m a b -> Unfold m a b
filter (\(b
a, c
b) -> b
a b -> c -> Bool
`eq` c
b) forall a b. (a -> b) -> a -> b
$ forall (m :: * -> *) a b c.
Monad m =>
Unfold m a b -> Unfold m a c -> Unfold m a (b, c)
cross Unfold m a b
s1 Unfold m a c
s2

------------------------------------------------------------------------------
-- Exceptions
------------------------------------------------------------------------------

-- | Like 'gbracketIO' but with following differences:
--
-- * alloc action @a -> m c@ runs with async exceptions enabled
-- * cleanup action @c -> m d@ won't run if the stream is garbage collected
--   after partial evaluation.
--
-- /Inhibits stream fusion/
--
-- /Pre-release/
--
{-# INLINE_NORMAL gbracket_ #-}
gbracket_
    :: Monad m
    => (a -> m c)                           -- ^ before
    -> (forall s. m s -> m (Either e s))    -- ^ try (exception handling)
    -> (c -> m d)                           -- ^ after, on normal stop
    -> Unfold m (c, e) b                    -- ^ on exception
    -> Unfold m c b                         -- ^ unfold to run
    -> Unfold m a b
gbracket_ :: forall (m :: * -> *) a c e d b.
Monad m =>
(a -> m c)
-> (forall s. m s -> m (Either e s))
-> (c -> m d)
-> Unfold m (c, e) b
-> Unfold m c b
-> Unfold m a b
gbracket_ a -> m c
bef forall s. m s -> m (Either e s)
exc c -> m d
aft (Unfold s -> m (Step s b)
estep (c, e) -> m s
einject) (Unfold s -> m (Step s b)
step1 c -> m s
inject1) =
    forall (m :: * -> *) a b s.
(s -> m (Step s b)) -> (a -> m s) -> Unfold m a b
Unfold Either s (s, c) -> m (Step (Either s (s, c)) b)
step forall {a}. a -> m (Either a (s, c))
inject

    where

    inject :: a -> m (Either a (s, c))
inject a
x = do
        c
r <- a -> m c
bef a
x
        s
s <- c -> m s
inject1 c
r
        forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall a b. b -> Either a b
Right (s
s, c
r)

    {-# INLINE_LATE step #-}
    step :: Either s (s, c) -> m (Step (Either s (s, c)) b)
step (Right (s
st, c
v)) = do
        Either e (Step s b)
res <- forall s. m s -> m (Either e s)
exc forall a b. (a -> b) -> a -> b
$ s -> m (Step s b)
step1 s
st
        case Either e (Step s b)
res of
            Right Step s b
r -> case Step s b
r of
                Yield b
x s
s -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. a -> s -> Step s a
Yield b
x (forall a b. b -> Either a b
Right (s
s, c
v))
                Skip s
s    -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. s -> Step s a
Skip (forall a b. b -> Either a b
Right (s
s, c
v))
                Step s b
Stop      -> c -> m d
aft c
v forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> forall (m :: * -> *) a. Monad m => a -> m a
return forall s a. Step s a
Stop
            -- XXX Do not handle async exceptions, just rethrow them.
            Left e
e -> do
                s
r <- (c, e) -> m s
einject (c
v, e
e)
                forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. s -> Step s a
Skip (forall a b. a -> Either a b
Left s
r)
    step (Left s
st) = do
        Step s b
res <- s -> m (Step s b)
estep s
st
        forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ case Step s b
res of
            Yield b
x s
s -> forall s a. a -> s -> Step s a
Yield b
x (forall a b. a -> Either a b
Left s
s)
            Skip s
s    -> forall s a. s -> Step s a
Skip (forall a b. a -> Either a b
Left s
s)
            Step s b
Stop      -> forall s a. Step s a
Stop

-- | Run the alloc action @a -> m c@ with async exceptions disabled but keeping
-- blocking operations interruptible (see 'Control.Exception.mask').  Use the
-- output @c@ as input to @Unfold m c b@ to generate an output stream. When
-- unfolding use the supplied @try@ operation @forall s. m s -> m (Either e s)@
-- to catch synchronous exceptions. If an exception occurs run the exception
-- handling unfold @Unfold m (c, e) b@.
--
-- The cleanup action @c -> m d@, runs whenever the stream ends normally, due
-- to a sync or async exception or if it gets garbage collected after a partial
-- lazy evaluation.  See 'bracket' for the semantics of the cleanup action.
--
-- 'gbracket' can express all other exception handling combinators.
--
-- /Inhibits stream fusion/
--
-- /Pre-release/
{-# INLINE_NORMAL gbracketIO #-}
gbracketIO
    :: MonadIO m
    => (a -> IO c)                           -- ^ before
    -> (c -> IO d)                           -- ^ after, on normal stop, or GC
    -> (c -> IO ())                          -- ^ action on exception
    -> Unfold m e b                          -- ^ stream on exception
    -> (forall s. m s -> IO (Either e s))    -- ^ try (exception handling)
    -> Unfold m c b                         -- ^ unfold to run
    -> Unfold m a b
gbracketIO :: forall (m :: * -> *) a c d e b.
MonadIO m =>
(a -> IO c)
-> (c -> IO d)
-> (c -> IO ())
-> Unfold m e b
-> (forall s. m s -> IO (Either e s))
-> Unfold m c b
-> Unfold m a b
gbracketIO a -> IO c
bef c -> IO d
aft c -> IO ()
onExc (Unfold s -> m (Step s b)
estep e -> m s
einject) forall s. m s -> IO (Either e s)
ftry (Unfold s -> m (Step s b)
step1 c -> m s
inject1) =
    forall (m :: * -> *) a b s.
(s -> m (Step s b)) -> (a -> m s) -> Unfold m a b
Unfold Either s (s, c, IOFinalizer)
-> m (Step (Either s (s, c, IOFinalizer)) b)
step forall {a}. a -> m (Either a (s, c, IOFinalizer))
inject

    where

    inject :: a -> m (Either a (s, c, IOFinalizer))
inject a
x = do
        -- Mask asynchronous exceptions to make the execution of 'bef' and
        -- the registration of 'aft' atomic. See comment in 'D.gbracketIO'.
        (c
r, IOFinalizer
ref) <- forall (m :: * -> *) a. MonadIO m => IO a -> m a
liftIO forall a b. (a -> b) -> a -> b
$ forall a. IO a -> IO a
mask_ forall a b. (a -> b) -> a -> b
$ do
            c
r <- a -> IO c
bef a
x
            IOFinalizer
ref <- forall (m :: * -> *) a. MonadIO m => IO a -> m IOFinalizer
newIOFinalizer (c -> IO d
aft c
r)
            forall (m :: * -> *) a. Monad m => a -> m a
return (c
r, IOFinalizer
ref)
        s
s <- c -> m s
inject1 c
r
        forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall a b. b -> Either a b
Right (s
s, c
r, IOFinalizer
ref)

    {-# INLINE_LATE step #-}
    step :: Either s (s, c, IOFinalizer)
-> m (Step (Either s (s, c, IOFinalizer)) b)
step (Right (s
st, c
v, IOFinalizer
ref)) = do
        Either e (Step s b)
res <- forall (m :: * -> *) a. MonadIO m => IO a -> m a
liftIO forall a b. (a -> b) -> a -> b
$ forall s. m s -> IO (Either e s)
ftry forall a b. (a -> b) -> a -> b
$ s -> m (Step s b)
step1 s
st
        case Either e (Step s b)
res of
            Right Step s b
r -> case Step s b
r of
                Yield b
x s
s -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. a -> s -> Step s a
Yield b
x (forall a b. b -> Either a b
Right (s
s, c
v, IOFinalizer
ref))
                Skip s
s    -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. s -> Step s a
Skip (forall a b. b -> Either a b
Right (s
s, c
v, IOFinalizer
ref))
                Step s b
Stop      -> do
                    forall (m :: * -> *). MonadIO m => IOFinalizer -> m ()
runIOFinalizer IOFinalizer
ref
                    forall (m :: * -> *) a. Monad m => a -> m a
return forall s a. Step s a
Stop
            -- XXX Do not handle async exceptions, just rethrow them.
            Left e
e -> do
                -- Clearing of finalizer and running of exception handler must
                -- be atomic wrt async exceptions. Otherwise if we have cleared
                -- the finalizer and have not run the exception handler then we
                -- may leak the resource.
                forall (m :: * -> *) a. MonadIO m => IO a -> m a
liftIO forall a b. (a -> b) -> a -> b
$ forall (m :: * -> *) a. MonadIO m => IOFinalizer -> IO a -> m a
clearingIOFinalizer IOFinalizer
ref (c -> IO ()
onExc c
v)
                s
r <- e -> m s
einject e
e
                forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. s -> Step s a
Skip (forall a b. a -> Either a b
Left s
r)
    step (Left s
st) = do
        Step s b
res <- s -> m (Step s b)
estep s
st
        forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ case Step s b
res of
            Yield b
x s
s -> forall s a. a -> s -> Step s a
Yield b
x (forall a b. a -> Either a b
Left s
s)
            Skip s
s    -> forall s a. s -> Step s a
Skip (forall a b. a -> Either a b
Left s
s)
            Step s b
Stop      -> forall s a. Step s a
Stop

-- | Run a side effect @a -> m c@ on the input @a@ before unfolding it using
-- @Unfold m a b@.
--
-- > before f = lmapM (\a -> f a >> return a)
--
-- /Pre-release/
{-# INLINE_NORMAL before #-}
before :: (a -> m c) -> Unfold m a b -> Unfold m a b
before :: forall a (m :: * -> *) c b.
(a -> m c) -> Unfold m a b -> Unfold m a b
before a -> m c
action (Unfold s -> m (Step s b)
step a -> m s
inject) = forall (m :: * -> *) a b s.
(s -> m (Step s b)) -> (a -> m s) -> Unfold m a b
Unfold s -> m (Step s b)
step (a -> m c
action forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> a -> m s
inject)

-- The custom implementation of "after_" is slightly faster (5-7%) than
-- "_after".  This is just to document and make sure that we can always use
-- gbracket to implement after_ The same applies to other combinators as well.
--
{-# INLINE_NORMAL _after #-}
_after :: Monad m => (a -> m c) -> Unfold m a b -> Unfold m a b
_after :: forall (m :: * -> *) a c b.
Monad m =>
(a -> m c) -> Unfold m a b -> Unfold m a b
_after a -> m c
aft = forall (m :: * -> *) a c e d b.
Monad m =>
(a -> m c)
-> (forall s. m s -> m (Either e s))
-> (c -> m d)
-> Unfold m (c, e) b
-> Unfold m c b
-> Unfold m a b
gbracket_ forall (m :: * -> *) a. Monad m => a -> m a
return (forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap forall a b. b -> Either a b
Right) a -> m c
aft forall a. HasCallStack => a
undefined

-- | Like 'after' with following differences:
--
-- * action @a -> m c@ won't run if the stream is garbage collected
--   after partial evaluation.
-- * Monad @m@ does not require any other constraints.
--
-- /Pre-release/
{-# INLINE_NORMAL after_ #-}
after_ :: Monad m => (a -> m c) -> Unfold m a b -> Unfold m a b
after_ :: forall (m :: * -> *) a c b.
Monad m =>
(a -> m c) -> Unfold m a b -> Unfold m a b
after_ a -> m c
action (Unfold s -> m (Step s b)
step1 a -> m s
inject1) = forall (m :: * -> *) a b s.
(s -> m (Step s b)) -> (a -> m s) -> Unfold m a b
Unfold (s, a) -> m (Step (s, a) b)
step a -> m (s, a)
inject

    where

    inject :: a -> m (s, a)
inject a
x = do
        s
s <- a -> m s
inject1 a
x
        forall (m :: * -> *) a. Monad m => a -> m a
return (s
s, a
x)

    {-# INLINE_LATE step #-}
    step :: (s, a) -> m (Step (s, a) b)
step (s
st, a
v) = do
        Step s b
res <- s -> m (Step s b)
step1 s
st
        case Step s b
res of
            Yield b
x s
s -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. a -> s -> Step s a
Yield b
x (s
s, a
v)
            Skip s
s    -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. s -> Step s a
Skip (s
s, a
v)
            Step s b
Stop      -> a -> m c
action a
v forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> forall (m :: * -> *) a. Monad m => a -> m a
return forall s a. Step s a
Stop

-- | Unfold the input @a@ using @Unfold m a b@, run an action on @a@ whenever
-- the unfold stops normally, or if it is garbage collected after a partial
-- lazy evaluation.
--
-- The semantics of the action @a -> m c@ are similar to the cleanup action
-- semantics in 'bracket'.
--
-- /See also 'after_'/
--
-- /Pre-release/
{-# INLINE_NORMAL afterIO #-}
afterIO :: MonadIO m
    => (a -> IO c) -> Unfold m a b -> Unfold m a b
afterIO :: forall (m :: * -> *) a c b.
MonadIO m =>
(a -> IO c) -> Unfold m a b -> Unfold m a b
afterIO a -> IO c
action (Unfold s -> m (Step s b)
step1 a -> m s
inject1) = forall (m :: * -> *) a b s.
(s -> m (Step s b)) -> (a -> m s) -> Unfold m a b
Unfold (s, IOFinalizer) -> m (Step (s, IOFinalizer) b)
step a -> m (s, IOFinalizer)
inject

    where

    inject :: a -> m (s, IOFinalizer)
inject a
x = do
        s
s <- a -> m s
inject1 a
x
        IOFinalizer
ref <- forall (m :: * -> *) a. MonadIO m => IO a -> m a
liftIO forall a b. (a -> b) -> a -> b
$ forall (m :: * -> *) a. MonadIO m => IO a -> m IOFinalizer
newIOFinalizer (a -> IO c
action a
x)
        forall (m :: * -> *) a. Monad m => a -> m a
return (s
s, IOFinalizer
ref)

    {-# INLINE_LATE step #-}
    step :: (s, IOFinalizer) -> m (Step (s, IOFinalizer) b)
step (s
st, IOFinalizer
ref) = do
        Step s b
res <- s -> m (Step s b)
step1 s
st
        case Step s b
res of
            Yield b
x s
s -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. a -> s -> Step s a
Yield b
x (s
s, IOFinalizer
ref)
            Skip s
s    -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. s -> Step s a
Skip (s
s, IOFinalizer
ref)
            Step s b
Stop      -> do
                forall (m :: * -> *). MonadIO m => IOFinalizer -> m ()
runIOFinalizer IOFinalizer
ref
                forall (m :: * -> *) a. Monad m => a -> m a
return forall s a. Step s a
Stop

{-# INLINE_NORMAL _onException #-}
_onException :: MonadCatch m => (a -> m c) -> Unfold m a b -> Unfold m a b
_onException :: forall (m :: * -> *) a c b.
MonadCatch m =>
(a -> m c) -> Unfold m a b -> Unfold m a b
_onException a -> m c
action =
    forall (m :: * -> *) a c e d b.
Monad m =>
(a -> m c)
-> (forall s. m s -> m (Either e s))
-> (c -> m d)
-> Unfold m (c, e) b
-> Unfold m c b
-> Unfold m a b
gbracket_ forall (m :: * -> *) a. Monad m => a -> m a
return forall (m :: * -> *) e a.
(MonadCatch m, Exception e) =>
m a -> m (Either e a)
MC.try
        (\a
_ -> forall (m :: * -> *) a. Monad m => a -> m a
return ())
        (forall (m :: * -> *) a c b.
Applicative m =>
(a -> m c) -> Unfold m a b
nilM (\(a
a, SomeException
e :: MC.SomeException) -> a -> m c
action a
a forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> forall (m :: * -> *) e a. (MonadThrow m, Exception e) => e -> m a
MC.throwM SomeException
e))

-- | Unfold the input @a@ using @Unfold m a b@, run the action @a -> m c@ on
-- @a@ if the unfold aborts due to an exception.
--
-- /Inhibits stream fusion/
--
-- /Pre-release/
{-# INLINE_NORMAL onException #-}
onException :: MonadCatch m => (a -> m c) -> Unfold m a b -> Unfold m a b
onException :: forall (m :: * -> *) a c b.
MonadCatch m =>
(a -> m c) -> Unfold m a b -> Unfold m a b
onException a -> m c
action (Unfold s -> m (Step s b)
step1 a -> m s
inject1) = forall (m :: * -> *) a b s.
(s -> m (Step s b)) -> (a -> m s) -> Unfold m a b
Unfold (s, a) -> m (Step (s, a) b)
step a -> m (s, a)
inject

    where

    inject :: a -> m (s, a)
inject a
x = do
        s
s <- a -> m s
inject1 a
x
        forall (m :: * -> *) a. Monad m => a -> m a
return (s
s, a
x)

    {-# INLINE_LATE step #-}
    step :: (s, a) -> m (Step (s, a) b)
step (s
st, a
v) = do
        Step s b
res <- s -> m (Step s b)
step1 s
st forall (m :: * -> *) a b. MonadCatch m => m a -> m b -> m a
`MC.onException` a -> m c
action a
v
        forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ case Step s b
res of
            Yield b
x s
s -> forall s a. a -> s -> Step s a
Yield b
x (s
s, a
v)
            Skip s
s    -> forall s a. s -> Step s a
Skip (s
s, a
v)
            Step s b
Stop      -> forall s a. Step s a
Stop

{-# INLINE_NORMAL _finally #-}
_finally :: MonadCatch m => (a -> m c) -> Unfold m a b -> Unfold m a b
_finally :: forall (m :: * -> *) a c b.
MonadCatch m =>
(a -> m c) -> Unfold m a b -> Unfold m a b
_finally a -> m c
action =
    forall (m :: * -> *) a c e d b.
Monad m =>
(a -> m c)
-> (forall s. m s -> m (Either e s))
-> (c -> m d)
-> Unfold m (c, e) b
-> Unfold m c b
-> Unfold m a b
gbracket_ forall (m :: * -> *) a. Monad m => a -> m a
return forall (m :: * -> *) e a.
(MonadCatch m, Exception e) =>
m a -> m (Either e a)
MC.try a -> m c
action
        (forall (m :: * -> *) a c b.
Applicative m =>
(a -> m c) -> Unfold m a b
nilM (\(a
a, SomeException
e :: MC.SomeException) -> a -> m c
action a
a forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> forall (m :: * -> *) e a. (MonadThrow m, Exception e) => e -> m a
MC.throwM SomeException
e))

-- | Like 'finallyIO' with following differences:
--
-- * action @a -> m c@ won't run if the stream is garbage collected
--   after partial evaluation.
--
-- /Inhibits stream fusion/
--
-- /Pre-release/
{-# INLINE_NORMAL finally_ #-}
finally_ :: MonadCatch m => (a -> m c) -> Unfold m a b -> Unfold m a b
finally_ :: forall (m :: * -> *) a c b.
MonadCatch m =>
(a -> m c) -> Unfold m a b -> Unfold m a b
finally_ a -> m c
action (Unfold s -> m (Step s b)
step1 a -> m s
inject1) = forall (m :: * -> *) a b s.
(s -> m (Step s b)) -> (a -> m s) -> Unfold m a b
Unfold (s, a) -> m (Step (s, a) b)
step a -> m (s, a)
inject

    where

    inject :: a -> m (s, a)
inject a
x = do
        s
s <- a -> m s
inject1 a
x
        forall (m :: * -> *) a. Monad m => a -> m a
return (s
s, a
x)

    {-# INLINE_LATE step #-}
    step :: (s, a) -> m (Step (s, a) b)
step (s
st, a
v) = do
        Step s b
res <- s -> m (Step s b)
step1 s
st forall (m :: * -> *) a b. MonadCatch m => m a -> m b -> m a
`MC.onException` a -> m c
action a
v
        case Step s b
res of
            Yield b
x s
s -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. a -> s -> Step s a
Yield b
x (s
s, a
v)
            Skip s
s    -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. s -> Step s a
Skip (s
s, a
v)
            Step s b
Stop      -> a -> m c
action a
v forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> forall (m :: * -> *) a. Monad m => a -> m a
return forall s a. Step s a
Stop

-- | Unfold the input @a@ using @Unfold m a b@, run an action on @a@ whenever
-- the unfold stops normally, aborts due to an exception or if it is garbage
-- collected after a partial lazy evaluation.
--
-- The semantics of the action @a -> m c@ are similar to the cleanup action
-- semantics in 'bracket'.
--
-- @
-- finally release = bracket return release
-- @
--
-- /See also 'finally_'/
--
-- /Inhibits stream fusion/
--
-- /Pre-release/
{-# INLINE_NORMAL finallyIO #-}
finallyIO :: (MonadIO m, MonadCatch m)
    => (a -> IO c) -> Unfold m a b -> Unfold m a b
finallyIO :: forall (m :: * -> *) a c b.
(MonadIO m, MonadCatch m) =>
(a -> IO c) -> Unfold m a b -> Unfold m a b
finallyIO a -> IO c
action (Unfold s -> m (Step s b)
step1 a -> m s
inject1) = forall (m :: * -> *) a b s.
(s -> m (Step s b)) -> (a -> m s) -> Unfold m a b
Unfold (s, IOFinalizer) -> m (Step (s, IOFinalizer) b)
step a -> m (s, IOFinalizer)
inject

    where

    inject :: a -> m (s, IOFinalizer)
inject a
x = do
        s
s <- a -> m s
inject1 a
x
        IOFinalizer
ref <- forall (m :: * -> *) a. MonadIO m => IO a -> m a
liftIO forall a b. (a -> b) -> a -> b
$ forall (m :: * -> *) a. MonadIO m => IO a -> m IOFinalizer
newIOFinalizer (a -> IO c
action a
x)
        forall (m :: * -> *) a. Monad m => a -> m a
return (s
s, IOFinalizer
ref)

    {-# INLINE_LATE step #-}
    step :: (s, IOFinalizer) -> m (Step (s, IOFinalizer) b)
step (s
st, IOFinalizer
ref) = do
        Step s b
res <- s -> m (Step s b)
step1 s
st forall (m :: * -> *) a b. MonadCatch m => m a -> m b -> m a
`MC.onException` forall (m :: * -> *). MonadIO m => IOFinalizer -> m ()
runIOFinalizer IOFinalizer
ref
        case Step s b
res of
            Yield b
x s
s -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. a -> s -> Step s a
Yield b
x (s
s, IOFinalizer
ref)
            Skip s
s    -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. s -> Step s a
Skip (s
s, IOFinalizer
ref)
            Step s b
Stop      -> do
                forall (m :: * -> *). MonadIO m => IOFinalizer -> m ()
runIOFinalizer IOFinalizer
ref
                forall (m :: * -> *) a. Monad m => a -> m a
return forall s a. Step s a
Stop

{-# INLINE_NORMAL _bracket #-}
_bracket :: MonadCatch m
    => (a -> m c) -> (c -> m d) -> Unfold m c b -> Unfold m a b
_bracket :: forall (m :: * -> *) a c d b.
MonadCatch m =>
(a -> m c) -> (c -> m d) -> Unfold m c b -> Unfold m a b
_bracket a -> m c
bef c -> m d
aft =
    forall (m :: * -> *) a c e d b.
Monad m =>
(a -> m c)
-> (forall s. m s -> m (Either e s))
-> (c -> m d)
-> Unfold m (c, e) b
-> Unfold m c b
-> Unfold m a b
gbracket_ a -> m c
bef forall (m :: * -> *) e a.
(MonadCatch m, Exception e) =>
m a -> m (Either e a)
MC.try c -> m d
aft (forall (m :: * -> *) a c b.
Applicative m =>
(a -> m c) -> Unfold m a b
nilM (\(c
a, SomeException
e :: MC.SomeException) -> c -> m d
aft c
a forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>>
    forall (m :: * -> *) e a. (MonadThrow m, Exception e) => e -> m a
MC.throwM SomeException
e))

-- | Like 'bracketIO' but with following differences:
--
-- * alloc action @a -> m c@ runs with async exceptions enabled
-- * cleanup action @c -> m d@ won't run if the stream is garbage collected
--   after partial evaluation.
--
-- /Inhibits stream fusion/
--
-- /Pre-release/
{-# INLINE_NORMAL bracket_ #-}
bracket_ :: MonadCatch m
    => (a -> m c) -> (c -> m d) -> Unfold m c b -> Unfold m a b
bracket_ :: forall (m :: * -> *) a c d b.
MonadCatch m =>
(a -> m c) -> (c -> m d) -> Unfold m c b -> Unfold m a b
bracket_ a -> m c
bef c -> m d
aft (Unfold s -> m (Step s b)
step1 c -> m s
inject1) = forall (m :: * -> *) a b s.
(s -> m (Step s b)) -> (a -> m s) -> Unfold m a b
Unfold (s, c) -> m (Step (s, c) b)
step a -> m (s, c)
inject

    where

    inject :: a -> m (s, c)
inject a
x = do
        c
r <- a -> m c
bef a
x
        s
s <- c -> m s
inject1 c
r
        forall (m :: * -> *) a. Monad m => a -> m a
return (s
s, c
r)

    {-# INLINE_LATE step #-}
    step :: (s, c) -> m (Step (s, c) b)
step (s
st, c
v) = do
        Step s b
res <- s -> m (Step s b)
step1 s
st forall (m :: * -> *) a b. MonadCatch m => m a -> m b -> m a
`MC.onException` c -> m d
aft c
v
        case Step s b
res of
            Yield b
x s
s -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. a -> s -> Step s a
Yield b
x (s
s, c
v)
            Skip s
s    -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. s -> Step s a
Skip (s
s, c
v)
            Step s b
Stop      -> c -> m d
aft c
v forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> forall (m :: * -> *) a. Monad m => a -> m a
return forall s a. Step s a
Stop

-- | Run the alloc action @a -> m c@ with async exceptions disabled but keeping
-- blocking operations interruptible (see 'Control.Exception.mask').  Use the
-- output @c@ as input to @Unfold m c b@ to generate an output stream.
--
-- @c@ is usually a resource under the state of monad @m@, e.g. a file
-- handle, that requires a cleanup after use. The cleanup action @c -> m d@,
-- runs whenever the stream ends normally, due to a sync or async exception or
-- if it gets garbage collected after a partial lazy evaluation.
--
-- 'bracket' only guarantees that the cleanup action runs, and it runs with
-- async exceptions enabled. The action must ensure that it can successfully
-- cleanup the resource in the face of sync or async exceptions.
--
-- When the stream ends normally or on a sync exception, cleanup action runs
-- immediately in the current thread context, whereas in other cases it runs in
-- the GC context, therefore, cleanup may be delayed until the GC gets to run.
--
-- /See also: 'bracket_', 'gbracket'/
--
-- /Inhibits stream fusion/
--
-- /Pre-release/
{-# INLINE_NORMAL bracketIO #-}
bracketIO :: (MonadIO m, MonadCatch m)
    => (a -> IO c) -> (c -> IO d) -> Unfold m c b -> Unfold m a b
bracketIO :: forall (m :: * -> *) a c d b.
(MonadIO m, MonadCatch m) =>
(a -> IO c) -> (c -> IO d) -> Unfold m c b -> Unfold m a b
bracketIO a -> IO c
bef c -> IO d
aft (Unfold s -> m (Step s b)
step1 c -> m s
inject1) = forall (m :: * -> *) a b s.
(s -> m (Step s b)) -> (a -> m s) -> Unfold m a b
Unfold (s, IOFinalizer) -> m (Step (s, IOFinalizer) b)
step a -> m (s, IOFinalizer)
inject

    where

    inject :: a -> m (s, IOFinalizer)
inject a
x = do
        -- Mask asynchronous exceptions to make the execution of 'bef' and
        -- the registration of 'aft' atomic. See comment in 'D.gbracketIO'.
        (c
r, IOFinalizer
ref) <- forall (m :: * -> *) a. MonadIO m => IO a -> m a
liftIO forall a b. (a -> b) -> a -> b
$ forall a. IO a -> IO a
mask_ forall a b. (a -> b) -> a -> b
$ do
            c
r <- a -> IO c
bef a
x
            IOFinalizer
ref <- forall (m :: * -> *) a. MonadIO m => IO a -> m IOFinalizer
newIOFinalizer (c -> IO d
aft c
r)
            forall (m :: * -> *) a. Monad m => a -> m a
return (c
r, IOFinalizer
ref)
        s
s <- c -> m s
inject1 c
r
        forall (m :: * -> *) a. Monad m => a -> m a
return (s
s, IOFinalizer
ref)

    {-# INLINE_LATE step #-}
    step :: (s, IOFinalizer) -> m (Step (s, IOFinalizer) b)
step (s
st, IOFinalizer
ref) = do
        Step s b
res <- s -> m (Step s b)
step1 s
st forall (m :: * -> *) a b. MonadCatch m => m a -> m b -> m a
`MC.onException` forall (m :: * -> *). MonadIO m => IOFinalizer -> m ()
runIOFinalizer IOFinalizer
ref
        case Step s b
res of
            Yield b
x s
s -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. a -> s -> Step s a
Yield b
x (s
s, IOFinalizer
ref)
            Skip s
s    -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall s a. s -> Step s a
Skip (s
s, IOFinalizer
ref)
            Step s b
Stop      -> do
                forall (m :: * -> *). MonadIO m => IOFinalizer -> m ()
runIOFinalizer IOFinalizer
ref
                forall (m :: * -> *) a. Monad m => a -> m a
return forall s a. Step s a
Stop

-- | When unfolding @Unfold m a b@ if an exception @e@ occurs, unfold @e@ using
-- @Unfold m e b@.
--
-- /Inhibits stream fusion/
--
-- /Pre-release/
{-# INLINE_NORMAL handle #-}
handle :: (MonadCatch m, Exception e)
    => Unfold m e b -> Unfold m a b -> Unfold m a b
handle :: forall (m :: * -> *) e b a.
(MonadCatch m, Exception e) =>
Unfold m e b -> Unfold m a b -> Unfold m a b
handle Unfold m e b
exc =
    forall (m :: * -> *) a c e d b.
Monad m =>
(a -> m c)
-> (forall s. m s -> m (Either e s))
-> (c -> m d)
-> Unfold m (c, e) b
-> Unfold m c b
-> Unfold m a b
gbracket_ forall (m :: * -> *) a. Monad m => a -> m a
return forall (m :: * -> *) e a.
(MonadCatch m, Exception e) =>
m a -> m (Either e a)
MC.try (\a
_ -> forall (m :: * -> *) a. Monad m => a -> m a
return ()) (forall (m :: * -> *) a b c. Unfold m a b -> Unfold m (c, a) b
discardFirst Unfold m e b
exc)