    {-# LANGUAGE FlexibleInstances #-}
    {-# LANGUAGE TupleSections     #-}
    {- |
       Module      : Text.Pandoc.Readers.Odt.Arrows.State
       Copyright   : Copyright (C) 2015 Martin Linnemann
       License     : GNU GPL, version 2 or above

       Maintainer  : Martin Linnemann <theCodingMarlin@googlemail.com>
       Stability   : alpha
       Portability : portable

    An arrow that transports a state. It is in essence a more powerful version of
    the standard state monad. As it is such a simple extension, there are
    other version out there that do exactly the same.
    The implementation is duplicated, though, to add some useful features.
    Most of these might be implemented without access to innards, but it's much
    faster and easier to implement this way.
    -}

    module Text.Pandoc.Readers.Odt.Arrows.State where

    import Control.Arrow
    import qualified Control.Category as Cat
    import Control.Monad

    import Text.Pandoc.Readers.Odt.Arrows.Utils
    import Text.Pandoc.Readers.Odt.Generic.Fallible

    newtype ArrowState state a b = ArrowState
      { ArrowState state a b -> (state, a) -> (state, b)
    runArrowState :: (state, a) -> (state, b) }

    -- | Constructor
    withState           :: (state -> a -> (state, b)) -> ArrowState state a b
    withState :: (state -> a -> (state, b)) -> ArrowState state a b
    withState            = ((state, a) -> (state, b)) -> ArrowState state a b
    forall state a b.
    ((state, a) -> (state, b)) -> ArrowState state a b
    ArrowState (((state, a) -> (state, b)) -> ArrowState state a b)
    -> ((state -> a -> (state, b)) -> (state, a) -> (state, b))
    -> (state -> a -> (state, b))
    -> ArrowState state a b
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . (state -> a -> (state, b)) -> (state, a) -> (state, b)
    forall a b c. (a -> b -> c) -> (a, b) -> c
    uncurry

    -- | Constructor
    modifyState         :: (state      ->  state    ) -> ArrowState state a a
    modifyState :: (state -> state) -> ArrowState state a a
    modifyState          = ((state, a) -> (state, a)) -> ArrowState state a a
    forall state a b.
    ((state, a) -> (state, b)) -> ArrowState state a b
    ArrowState (((state, a) -> (state, a)) -> ArrowState state a a)
    -> ((state -> state) -> (state, a) -> (state, a))
    -> (state -> state)
    -> ArrowState state a a
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . (state -> state) -> (state, a) -> (state, a)
    forall (a :: * -> * -> *) b c d.
    Arrow a =>
    a b c -> a (b, d) (c, d)
    first

    -- | Constructor
    ignoringState       :: (         a ->         b ) -> ArrowState state a b
    ignoringState :: (a -> b) -> ArrowState state a b
    ignoringState        = ((state, a) -> (state, b)) -> ArrowState state a b
    forall state a b.
    ((state, a) -> (state, b)) -> ArrowState state a b
    ArrowState (((state, a) -> (state, b)) -> ArrowState state a b)
    -> ((a -> b) -> (state, a) -> (state, b))
    -> (a -> b)
    -> ArrowState state a b
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . (a -> b) -> (state, a) -> (state, b)
    forall (a :: * -> * -> *) b c d.
    Arrow a =>
    a b c -> a (d, b) (d, c)
    second

    -- | Constructor
    fromState           :: (state      -> (state, b)) -> ArrowState state a b
    fromState :: (state -> (state, b)) -> ArrowState state a b
    fromState            = ((state, a) -> (state, b)) -> ArrowState state a b
    forall state a b.
    ((state, a) -> (state, b)) -> ArrowState state a b
    ArrowState (((state, a) -> (state, b)) -> ArrowState state a b)
    -> ((state -> (state, b)) -> (state, a) -> (state, b))
    -> (state -> (state, b))
    -> ArrowState state a b
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . ((state -> (state, b))
    -> ((state, a) -> state) -> (state, a) -> (state, b)
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    .(state, a) -> state
    forall a b. (a, b) -> a
    fst)

    -- | Constructor
    extractFromState    :: (state      ->         b ) -> ArrowState state x b
    extractFromState :: (state -> b) -> ArrowState state x b
    extractFromState   f :: state -> b
    f = ((state, x) -> (state, b)) -> ArrowState state x b
    forall state a b.
    ((state, a) -> (state, b)) -> ArrowState state a b
    ArrowState (((state, x) -> (state, b)) -> ArrowState state x b)
    -> ((state, x) -> (state, b)) -> ArrowState state x b
    forall a b. (a -> b) -> a -> b
    $ \(state :: state
    state,_) -> (state
    state, state -> b
    f state
    state)

    -- | Constructor
    tryModifyState      :: (state ->  Either f state)
                        -> ArrowState state a (Either f a)
    tryModifyState :: (state -> Either f state) -> ArrowState state a (Either f a)
    tryModifyState     f :: state -> Either f state
    f = ((state, a) -> (state, Either f a))
    -> ArrowState state a (Either f a)
    forall state a b.
    ((state, a) -> (state, b)) -> ArrowState state a b
    ArrowState (((state, a) -> (state, Either f a))
     -> ArrowState state a (Either f a))
    -> ((state, a) -> (state, Either f a))
    -> ArrowState state a (Either f a)
    forall a b. (a -> b) -> a -> b
    $ \(state :: state
    state,a :: a
    a)
                                      -> (state
    state,)(Either f a -> (state, Either f a))
    -> (f -> Either f a) -> f -> (state, Either f a)
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    .f -> Either f a
    forall a b. a -> Either a b
    Left (f -> (state, Either f a))
    -> (state -> (state, Either f a))
    -> Either f state
    -> (state, Either f a)
    forall (a :: * -> * -> *) b d c.
    ArrowChoice a =>
    a b d -> a c d -> a (Either b c) d
    ||| (,a -> Either f a
    forall a b. b -> Either a b
    Right a
    a) (Either f state -> (state, Either f a))
    -> Either f state -> (state, Either f a)
    forall a b. (a -> b) -> a -> b
    $ state -> Either f state
    f state
    state

    instance Cat.Category (ArrowState s) where
      id :: ArrowState s a a
    id                = ((s, a) -> (s, a)) -> ArrowState s a a
    forall state a b.
    ((state, a) -> (state, b)) -> ArrowState state a b
    ArrowState (s, a) -> (s, a)
    forall a. a -> a
    id
      arrow2 :: ArrowState s b c
    arrow2 . :: ArrowState s b c -> ArrowState s a b -> ArrowState s a c
    . arrow1 :: ArrowState s a b
    arrow1   = ((s, a) -> (s, c)) -> ArrowState s a c
    forall state a b.
    ((state, a) -> (state, b)) -> ArrowState state a b
    ArrowState (((s, a) -> (s, c)) -> ArrowState s a c)
    -> ((s, a) -> (s, c)) -> ArrowState s a c
    forall a b. (a -> b) -> a -> b
    $ ArrowState s b c -> (s, b) -> (s, c)
    forall state a b. ArrowState state a b -> (state, a) -> (state, b)
    runArrowState ArrowState s b c
    arrow2 ((s, b) -> (s, c)) -> ((s, a) -> (s, b)) -> (s, a) -> (s, c)
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . ArrowState s a b -> (s, a) -> (s, b)
    forall state a b. ArrowState state a b -> (state, a) -> (state, b)
    runArrowState ArrowState s a b
    arrow1

    instance Arrow (ArrowState state) where
      arr :: (b -> c) -> ArrowState state b c
    arr               = (b -> c) -> ArrowState state b c
    forall a b state. (a -> b) -> ArrowState state a b
    ignoringState
      first :: ArrowState state b c -> ArrowState state (b, d) (c, d)
    first  a :: ArrowState state b c
    a          = ((state, (b, d)) -> (state, (c, d)))
    -> ArrowState state (b, d) (c, d)
    forall state a b.
    ((state, a) -> (state, b)) -> ArrowState state a b
    ArrowState (((state, (b, d)) -> (state, (c, d)))
     -> ArrowState state (b, d) (c, d))
    -> ((state, (b, d)) -> (state, (c, d)))
    -> ArrowState state (b, d) (c, d)
    forall a b. (a -> b) -> a -> b
    $ \(s :: state
    s,(aF :: b
    aF,aS :: d
    aS))
                                        -> (c -> (c, d)) -> (state, c) -> (state, (c, d))
    forall (a :: * -> * -> *) b c d.
    Arrow a =>
    a b c -> a (d, b) (d, c)
    second (,d
    aS) ((state, c) -> (state, (c, d))) -> (state, c) -> (state, (c, d))
    forall a b. (a -> b) -> a -> b
    $ ArrowState state b c -> (state, b) -> (state, c)
    forall state a b. ArrowState state a b -> (state, a) -> (state, b)
    runArrowState ArrowState state b c
    a (state
    s,b
    aF)
      second :: ArrowState state b c -> ArrowState state (d, b) (d, c)
    second a :: ArrowState state b c
    a          = ((state, (d, b)) -> (state, (d, c)))
    -> ArrowState state (d, b) (d, c)
    forall state a b.
    ((state, a) -> (state, b)) -> ArrowState state a b
    ArrowState (((state, (d, b)) -> (state, (d, c)))
     -> ArrowState state (d, b) (d, c))
    -> ((state, (d, b)) -> (state, (d, c)))
    -> ArrowState state (d, b) (d, c)
    forall a b. (a -> b) -> a -> b
    $ \(s :: state
    s,(aF :: d
    aF,aS :: b
    aS))
                                        -> (c -> (d, c)) -> (state, c) -> (state, (d, c))
    forall (a :: * -> * -> *) b c d.
    Arrow a =>
    a b c -> a (d, b) (d, c)
    second (d
    aF,) ((state, c) -> (state, (d, c))) -> (state, c) -> (state, (d, c))
    forall a b. (a -> b) -> a -> b
    $ ArrowState state b c -> (state, b) -> (state, c)
    forall state a b. ArrowState state a b -> (state, a) -> (state, b)
    runArrowState ArrowState state b c
    a (state
    s,b
    aS)

    instance ArrowChoice (ArrowState state) where
      left :: ArrowState state b c -> ArrowState state (Either b d) (Either c d)
    left   a :: ArrowState state b c
    a          = ((state, Either b d) -> (state, Either c d))
    -> ArrowState state (Either b d) (Either c d)
    forall state a b.
    ((state, a) -> (state, b)) -> ArrowState state a b
    ArrowState (((state, Either b d) -> (state, Either c d))
     -> ArrowState state (Either b d) (Either c d))
    -> ((state, Either b d) -> (state, Either c d))
    -> ArrowState state (Either b d) (Either c d)
    forall a b. (a -> b) -> a -> b
    $ \(s :: state
    s,e :: Either b d
    e) -> case Either b d
    e of
                                     Left  l :: b
    l -> (c -> Either c d) -> (state, c) -> (state, Either c d)
    forall (a :: * -> * -> *) b c d.
    Arrow a =>
    a b c -> a (d, b) (d, c)
    second c -> Either c d
    forall a b. a -> Either a b
    Left  ((state, c) -> (state, Either c d))
    -> (state, c) -> (state, Either c d)
    forall a b. (a -> b) -> a -> b
    $ ArrowState state b c -> (state, b) -> (state, c)
    forall state a b. ArrowState state a b -> (state, a) -> (state, b)
    runArrowState ArrowState state b c
    a (state
    s,b
    l)
                                     Right r :: d
    r -> (state
    s, d -> Either c d
    forall a b. b -> Either a b
    Right d
    r)
      right :: ArrowState state b c -> ArrowState state (Either d b) (Either d c)
    right  a :: ArrowState state b c
    a          = ((state, Either d b) -> (state, Either d c))
    -> ArrowState state (Either d b) (Either d c)
    forall state a b.
    ((state, a) -> (state, b)) -> ArrowState state a b
    ArrowState (((state, Either d b) -> (state, Either d c))
     -> ArrowState state (Either d b) (Either d c))
    -> ((state, Either d b) -> (state, Either d c))
    -> ArrowState state (Either d b) (Either d c)
    forall a b. (a -> b) -> a -> b
    $ \(s :: state
    s,e :: Either d b
    e) -> case Either d b
    e of
                                     Left  l :: d
    l -> (state
    s, d -> Either d c
    forall a b. a -> Either a b
    Left d
    l)
                                     Right r :: b
    r -> (c -> Either d c) -> (state, c) -> (state, Either d c)
    forall (a :: * -> * -> *) b c d.
    Arrow a =>
    a b c -> a (d, b) (d, c)
    second c -> Either d c
    forall a b. b -> Either a b
    Right ((state, c) -> (state, Either d c))
    -> (state, c) -> (state, Either d c)
    forall a b. (a -> b) -> a -> b
    $ ArrowState state b c -> (state, b) -> (state, c)
    forall state a b. ArrowState state a b -> (state, a) -> (state, b)
    runArrowState ArrowState state b c
    a (state
    s,b
    r)

    instance ArrowApply (ArrowState state) where
       app :: ArrowState state (ArrowState state b c, b) c
    app             = ((state, (ArrowState state b c, b)) -> (state, c))
    -> ArrowState state (ArrowState state b c, b) c
    forall state a b.
    ((state, a) -> (state, b)) -> ArrowState state a b
    ArrowState (((state, (ArrowState state b c, b)) -> (state, c))
     -> ArrowState state (ArrowState state b c, b) c)
    -> ((state, (ArrowState state b c, b)) -> (state, c))
    -> ArrowState state (ArrowState state b c, b) c
    forall a b. (a -> b) -> a -> b
    $ \(s :: state
    s, (f :: ArrowState state b c
    f,b :: b
    b)) -> ArrowState state b c -> (state, b) -> (state, c)
    forall state a b. ArrowState state a b -> (state, a) -> (state, b)
    runArrowState ArrowState state b c
    f (state
    s,b
    b)

    -- | Switches the type of the state temporarily.
    -- Drops the intermediate result state, behaving like a fallible
    -- identity arrow, save for side effects in the state.
    withSubStateF  :: ArrowState s  x (Either f s')
                   -> ArrowState s' s (Either f s )
                   -> ArrowState s  x (Either f x )
    withSubStateF :: ArrowState s x (Either f s')
    -> ArrowState s' s (Either f s) -> ArrowState s x (Either f x)
    withSubStateF  unlift :: ArrowState s x (Either f s')
    unlift a :: ArrowState s' s (Either f s)
    a = ArrowState s x (Either f s') -> ArrowState s x (x, Either f s')
    forall (a :: * -> * -> *) b c. Arrow a => a b c -> a b (b, c)
    keepingTheValue (ArrowState s x (Either f s')
    -> ArrowState s' s (Either f s) -> ArrowState s x (Either f s')
    forall s x f s'.
    ArrowState s x (Either f s')
    -> ArrowState s' s (Either f s) -> ArrowState s x (Either f s')
    withSubStateF' ArrowState s x (Either f s')
    unlift ArrowState s' s (Either f s)
    a)
                              ArrowState s x (x, Either f s')
    -> ((x, Either f s') -> Either f x) -> ArrowState s x (Either f x)
    forall (a :: * -> * -> *) b c d.
    Arrow a =>
    a b c -> (c -> d) -> a b d
    >>^ (x, Either f s') -> Either f (x, s')
    forall (v :: * -> *) f a.
    ChoiceVector v =>
    v (Either f a) -> Either f (v a)
    spreadChoice
                              ((x, Either f s') -> Either f (x, s'))
    -> (Either f (x, s') -> Either f x)
    -> (x, Either f s')
    -> Either f x
    forall (a :: * -> * -> *) b c d.
    Arrow a =>
    a b c -> (c -> d) -> a b d
    >>^ ((x, s') -> x) -> Either f (x, s') -> Either f x
    forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
    fmap (x, s') -> x
    forall a b. (a, b) -> a
    fst

    -- | Switches the type of the state temporarily.
    -- Returns the resulting sub-state.
    withSubStateF' :: ArrowState s  x (Either f s')
                   -> ArrowState s' s (Either f s )
                   -> ArrowState s  x (Either f s')
    withSubStateF' :: ArrowState s x (Either f s')
    -> ArrowState s' s (Either f s) -> ArrowState s x (Either f s')
    withSubStateF' unlift :: ArrowState s x (Either f s')
    unlift a :: ArrowState s' s (Either f s)
    a = ((s, x) -> (s, Either f s')) -> ArrowState s x (Either f s')
    forall state a b.
    ((state, a) -> (state, b)) -> ArrowState state a b
    ArrowState (s, x) -> (s, Either f s')
    go
      where go :: (s, x) -> (s, Either f s')
    go p :: (s, x)
    p@(s :: s
    s,_) = ArrowState s x (Either f s')
    -> ((s', s) -> (s, Either f s')) -> (s, x) -> (s, Either f s')
    forall b a a a b.
    ArrowState b a (Either a a)
    -> ((a, b) -> (s, Either a b)) -> (b, a) -> (s, Either a b)
    tryRunning ArrowState s x (Either f s')
    unlift
                                    ( ArrowState s' s (Either f s)
    -> ((s, s') -> (s, Either f s')) -> (s', s) -> (s, Either f s')
    forall b a a a b.
    ArrowState b a (Either a a)
    -> ((a, b) -> (s, Either a b)) -> (b, a) -> (s, Either a b)
    tryRunning ArrowState s' s (Either f s)
    a ((s' -> Either f s') -> (s, s') -> (s, Either f s')
    forall (a :: * -> * -> *) b c d.
    Arrow a =>
    a b c -> a (d, b) (d, c)
    second s' -> Either f s'
    forall a b. b -> Either a b
    Right) )
                                    (s, x)
    p
              where tryRunning :: ArrowState b a (Either a a)
    -> ((a, b) -> (s, Either a b)) -> (b, a) -> (s, Either a b)
    tryRunning a' :: ArrowState b a (Either a a)
    a' b :: (a, b) -> (s, Either a b)
    b v :: (b, a)
    v = case ArrowState b a (Either a a) -> (b, a) -> (b, Either a a)
    forall state a b. ArrowState state a b -> (state, a) -> (state, b)
    runArrowState ArrowState b a (Either a a)
    a' (b, a)
    v of
                                          (_ , Left  f :: a
    f) -> (s
    s, a -> Either a b
    forall a b. a -> Either a b
    Left a
    f)
                                          (x :: b
    x , Right y :: a
    y) -> (a, b) -> (s, Either a b)
    b (a
    y,b
    x)

    -- | Fold a state arrow through something 'Foldable'. Collect the results
    -- in a 'Monoid'.
    -- Intermediate form of a fold between one with "only" a 'Monoid'
    -- and one with any function.
    foldS :: (Foldable f, Monoid m) => ArrowState s x m -> ArrowState s (f x) m
    foldS :: ArrowState s x m -> ArrowState s (f x) m
    foldS a :: ArrowState s x m
    a = ((s, f x) -> (s, m)) -> ArrowState s (f x) m
    forall state a b.
    ((state, a) -> (state, b)) -> ArrowState state a b
    ArrowState (((s, f x) -> (s, m)) -> ArrowState s (f x) m)
    -> ((s, f x) -> (s, m)) -> ArrowState s (f x) m
    forall a b. (a -> b) -> a -> b
    $ \(s :: s
    s,f :: f x
    f) -> (x -> (s, m) -> (s, m)) -> (s, m) -> f x -> (s, m)
    forall (t :: * -> *) a b.
    Foldable t =>
    (a -> b -> b) -> b -> t a -> b
    foldr x -> (s, m) -> (s, m)
    a' (s
    s,m
    forall a. Monoid a => a
    mempty) f x
    f
      where a' :: x -> (s, m) -> (s, m)
    a' x :: x
    x (s' :: s
    s',m :: m
    m) = (m -> m) -> (s, m) -> (s, m)
    forall (a :: * -> * -> *) b c d.
    Arrow a =>
    a b c -> a (d, b) (d, c)
    second (m -> m -> m
    forall a. Monoid a => a -> a -> a
    mappend m
    m)  ((s, m) -> (s, m)) -> (s, m) -> (s, m)
    forall a b. (a -> b) -> a -> b
    $ ArrowState s x m -> (s, x) -> (s, m)
    forall state a b. ArrowState state a b -> (state, a) -> (state, b)
    runArrowState ArrowState s x m
    a (s
    s',x
    x)

    -- | Fold a state arrow through something 'Foldable'. Collect the results in a
    -- 'MonadPlus'.
    iterateS :: (Foldable f, MonadPlus m)
             => ArrowState s    x     y
             -> ArrowState s (f x) (m y)
    iterateS :: ArrowState s x y -> ArrowState s (f x) (m y)
    iterateS a :: ArrowState s x y
    a = ((s, f x) -> (s, m y)) -> ArrowState s (f x) (m y)
    forall state a b.
    ((state, a) -> (state, b)) -> ArrowState state a b
    ArrowState (((s, f x) -> (s, m y)) -> ArrowState s (f x) (m y))
    -> ((s, f x) -> (s, m y)) -> ArrowState s (f x) (m y)
    forall a b. (a -> b) -> a -> b
    $ \(s :: s
    s,f :: f x
    f) -> (x -> (s, m y) -> (s, m y)) -> (s, m y) -> f x -> (s, m y)
    forall (t :: * -> *) a b.
    Foldable t =>
    (a -> b -> b) -> b -> t a -> b
    foldr x -> (s, m y) -> (s, m y)
    forall (m :: * -> *). MonadPlus m => x -> (s, m y) -> (s, m y)
    a' (s
    s,m y
    forall (m :: * -> *) a. MonadPlus m => m a
    mzero) f x
    f
      where a' :: x -> (s, m y) -> (s, m y)
    a' x :: x
    x (s' :: s
    s',m :: m y
    m) = (y -> m y) -> (s, y) -> (s, m y)
    forall (a :: * -> * -> *) b c d.
    Arrow a =>
    a b c -> a (d, b) (d, c)
    second (m y -> m y -> m y
    forall (m :: * -> *) a. MonadPlus m => m a -> m a -> m a
    mplus m y
    m(m y -> m y) -> (y -> m y) -> y -> m y
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    .y -> m y
    forall (m :: * -> *) a. Monad m => a -> m a
    return) ((s, y) -> (s, m y)) -> (s, y) -> (s, m y)
    forall a b. (a -> b) -> a -> b
    $ ArrowState s x y -> (s, x) -> (s, y)
    forall state a b. ArrowState state a b -> (state, a) -> (state, b)
    runArrowState ArrowState s x y
    a (s
    s',x
    x)

    -- | Fold a state arrow through something 'Foldable'. Collect the results in a
    -- 'MonadPlus'.
    iterateSL :: (Foldable f, MonadPlus m)
              => ArrowState s    x     y
              -> ArrowState s (f x) (m y)
    iterateSL :: ArrowState s x y -> ArrowState s (f x) (m y)
    iterateSL a :: ArrowState s x y
    a = ((s, f x) -> (s, m y)) -> ArrowState s (f x) (m y)
    forall state a b.
    ((state, a) -> (state, b)) -> ArrowState state a b
    ArrowState (((s, f x) -> (s, m y)) -> ArrowState s (f x) (m y))
    -> ((s, f x) -> (s, m y)) -> ArrowState s (f x) (m y)
    forall a b. (a -> b) -> a -> b
    $ \(s :: s
    s,f :: f x
    f) -> ((s, m y) -> x -> (s, m y)) -> (s, m y) -> f x -> (s, m y)
    forall (t :: * -> *) b a.
    Foldable t =>
    (b -> a -> b) -> b -> t a -> b
    foldl (s, m y) -> x -> (s, m y)
    forall (m :: * -> *). MonadPlus m => (s, m y) -> x -> (s, m y)
    a' (s
    s,m y
    forall (m :: * -> *) a. MonadPlus m => m a
    mzero) f x
    f
      where a' :: (s, m y) -> x -> (s, m y)
    a' (s' :: s
    s',m :: m y
    m) x :: x
    x = (y -> m y) -> (s, y) -> (s, m y)
    forall (a :: * -> * -> *) b c d.
    Arrow a =>
    a b c -> a (d, b) (d, c)
    second (m y -> m y -> m y
    forall (m :: * -> *) a. MonadPlus m => m a -> m a -> m a
    mplus m y
    m(m y -> m y) -> (y -> m y) -> y -> m y
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    .y -> m y
    forall (m :: * -> *) a. Monad m => a -> m a
    return) ((s, y) -> (s, m y)) -> (s, y) -> (s, m y)
    forall a b. (a -> b) -> a -> b
    $ ArrowState s x y -> (s, x) -> (s, y)
    forall state a b. ArrowState state a b -> (state, a) -> (state, b)
    runArrowState ArrowState s x y
    a (s
    s',x
    x)

    -- | Fold a fallible state arrow through something 'Foldable'.
    -- Collect the results in a 'MonadPlus'.
    -- If the iteration fails, the state will be reset to the initial one.
    iterateS' :: (Foldable f, MonadPlus m)
              => ArrowState s    x  (Either e    y )
              -> ArrowState s (f x) (Either e (m y))
    iterateS' :: ArrowState s x (Either e y) -> ArrowState s (f x) (Either e (m y))
    iterateS' a :: ArrowState s x (Either e y)
    a = ((s, f x) -> (s, Either e (m y)))
    -> ArrowState s (f x) (Either e (m y))
    forall state a b.
    ((state, a) -> (state, b)) -> ArrowState state a b
    ArrowState (((s, f x) -> (s, Either e (m y)))
     -> ArrowState s (f x) (Either e (m y)))
    -> ((s, f x) -> (s, Either e (m y)))
    -> ArrowState s (f x) (Either e (m y))
    forall a b. (a -> b) -> a -> b
    $ \(s :: s
    s,f :: f x
    f) -> (x -> (s, Either e (m y)) -> (s, Either e (m y)))
    -> (s, Either e (m y)) -> f x -> (s, Either e (m y))
    forall (t :: * -> *) a b.
    Foldable t =>
    (a -> b -> b) -> b -> t a -> b
    foldr (s -> x -> (s, Either e (m y)) -> (s, Either e (m y))
    forall (m :: * -> *).
    MonadPlus m =>
    s -> x -> (s, Either e (m y)) -> (s, Either e (m y))
    a' s
    s) (s
    s,m y -> Either e (m y)
    forall a b. b -> Either a b
    Right m y
    forall (m :: * -> *) a. MonadPlus m => m a
    mzero) f x
    f
      where a' :: s -> x -> (s, Either e (m y)) -> (s, Either e (m y))
    a' s :: s
    s x :: x
    x (s' :: s
    s',Right m :: m y
    m) = case ArrowState s x (Either e y) -> (s, x) -> (s, Either e y)
    forall state a b. ArrowState state a b -> (state, a) -> (state, b)
    runArrowState ArrowState s x (Either e y)
    a (s
    s',x
    x) of
                                    (s'' :: s
    s'',Right m' :: y
    m') -> (s
    s'',m y -> Either e (m y)
    forall a b. b -> Either a b
    Right (m y -> Either e (m y)) -> m y -> Either e (m y)
    forall a b. (a -> b) -> a -> b
    $ m y -> m y -> m y
    forall (m :: * -> *) a. MonadPlus m => m a -> m a -> m a
    mplus m y
    m (m y -> m y) -> m y -> m y
    forall a b. (a -> b) -> a -> b
    $ y -> m y
    forall (m :: * -> *) a. Monad m => a -> m a
    return y
    m')
                                    (_  ,Left  e :: e
    e ) -> (s
    s  ,e -> Either e (m y)
    forall a b. a -> Either a b
    Left  e
    e )
            a' _ _   e :: (s, Either e (m y))
    e          = (s, Either e (m y))
    e