{-# LANGUAGE DeriveTraversable, FlexibleInstances, MultiParamTypeClasses, RankNTypes, TypeOperators, UndecidableInstances #-}

{- | Provides 'NonDetC', a carrier for 'NonDet' effects providing choice and failure.

Under the hood, it uses a Church-encoded structure and a binary tree to prevent the problems associated with a naïve list-based implementation.

@since 1.0.0.0
-}

module Control.Carrier.NonDet.Church
( -- * NonDet carrier
  runNonDet
, runNonDetA
, runNonDetM
, NonDetC(..)
  -- * NonDet effects
, module Control.Effect.NonDet
) where

import Control.Algebra
import Control.Applicative (liftA2)
import Control.Effect.NonDet
import qualified Control.Monad.Fail as Fail
import Control.Monad.Fix
import Control.Monad.IO.Class
import Control.Monad.Trans.Class
import Data.Coerce (coerce)
import Data.Functor.Identity

-- | Run a 'NonDet' effect, using the provided functions to interpret choice, leaf results, and failure.
--
-- @since 1.0.0.0
runNonDet
  :: (m b -> m b -> m b) -- ^ Handles choice ('<|>')
  -> (a -> m b)          -- ^ Handles embedding results ('pure')
  -> m b                 -- ^ Handles failure ('empty')
  -> NonDetC m a         -- ^ A nondeterministic computation to execute
  -> m b
runNonDet :: (m b -> m b -> m b) -> (a -> m b) -> m b -> NonDetC m a -> m b
runNonDet fork :: m b -> m b -> m b
fork leaf :: a -> m b
leaf nil :: m b
nil (NonDetC m :: forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b
m) = (m b -> m b -> m b) -> (a -> m b) -> m b -> m b
forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b
m m b -> m b -> m b
fork a -> m b
leaf m b
nil

-- | Run a 'NonDet' effect, collecting all branches’ results into an 'Alternative' functor.
--
-- Using @[]@ as the 'Alternative' functor will produce all results, while 'Maybe' will return only the first. However, unless used with 'Control.Effect.Cull.cull', this will still enumerate the entire search space before returning, meaning that it will diverge for infinite search spaces, even when using 'Maybe'.
--
-- @
-- 'runNonDetA' ('pure' a) = 'pure' [a]
-- @
-- @
-- 'runNonDetA' ('pure' a) = 'pure' ('Just' a)
-- @
--
-- @since 1.0.0.0
runNonDetA :: (Alternative f, Applicative m) => NonDetC m a -> m (f a)
runNonDetA :: NonDetC m a -> m (f a)
runNonDetA = (m (f a) -> m (f a) -> m (f a))
-> (a -> m (f a)) -> m (f a) -> NonDetC m a -> m (f a)
forall (m :: * -> *) b a.
(m b -> m b -> m b) -> (a -> m b) -> m b -> NonDetC m a -> m b
runNonDet ((f a -> f a -> f a) -> m (f a) -> m (f a) -> m (f a)
forall (f :: * -> *) a b c.
Applicative f =>
(a -> b -> c) -> f a -> f b -> f c
liftA2 f a -> f a -> f a
forall (f :: * -> *) a. Alternative f => f a -> f a -> f a
(<|>)) (f a -> m (f a)
forall (f :: * -> *) a. Applicative f => a -> f a
pure (f a -> m (f a)) -> (a -> f a) -> a -> m (f a)
forall b c a. (b -> c) -> (a -> b) -> a -> c
. a -> f a
forall (f :: * -> *) a. Applicative f => a -> f a
pure) (f a -> m (f a)
forall (f :: * -> *) a. Applicative f => a -> f a
pure f a
forall (f :: * -> *) a. Alternative f => f a
empty)

-- | Run a 'NonDet' effect, mapping results into a 'Monoid'.
--
-- @since 1.0.0.0
runNonDetM :: (Applicative m, Monoid b) => (a -> b) -> NonDetC m a -> m b
runNonDetM :: (a -> b) -> NonDetC m a -> m b
runNonDetM leaf :: a -> b
leaf = (m b -> m b -> m b) -> (a -> m b) -> m b -> NonDetC m a -> m b
forall (m :: * -> *) b a.
(m b -> m b -> m b) -> (a -> m b) -> m b -> NonDetC m a -> m b
runNonDet ((b -> b -> b) -> m b -> m b -> m b
forall (f :: * -> *) a b c.
Applicative f =>
(a -> b -> c) -> f a -> f b -> f c
liftA2 b -> b -> b
forall a. Monoid a => a -> a -> a
mappend) (b -> m b
forall (f :: * -> *) a. Applicative f => a -> f a
pure (b -> m b) -> (a -> b) -> a -> m b
forall b c a. (b -> c) -> (a -> b) -> a -> c
. a -> b
leaf) (b -> m b
forall (f :: * -> *) a. Applicative f => a -> f a
pure b
forall a. Monoid a => a
mempty)

-- | A carrier for 'NonDet' effects based on Ralf Hinze’s design described in [Deriving Backtracking Monad Transformers](https://www.cs.ox.ac.uk/ralf.hinze/publications/#P12).
--
-- @since 1.0.0.0
newtype NonDetC m a = NonDetC (forall b . (m b -> m b -> m b) -> (a -> m b) -> m b -> m b)
  deriving (a -> NonDetC m b -> NonDetC m a
(a -> b) -> NonDetC m a -> NonDetC m b
(forall a b. (a -> b) -> NonDetC m a -> NonDetC m b)
-> (forall a b. a -> NonDetC m b -> NonDetC m a)
-> Functor (NonDetC m)
forall a b. a -> NonDetC m b -> NonDetC m a
forall a b. (a -> b) -> NonDetC m a -> NonDetC m b
forall (f :: * -> *).
(forall a b. (a -> b) -> f a -> f b)
-> (forall a b. a -> f b -> f a) -> Functor f
forall (m :: * -> *) a b. a -> NonDetC m b -> NonDetC m a
forall (m :: * -> *) a b. (a -> b) -> NonDetC m a -> NonDetC m b
<$ :: a -> NonDetC m b -> NonDetC m a
$c<$ :: forall (m :: * -> *) a b. a -> NonDetC m b -> NonDetC m a
fmap :: (a -> b) -> NonDetC m a -> NonDetC m b
$cfmap :: forall (m :: * -> *) a b. (a -> b) -> NonDetC m a -> NonDetC m b
Functor)

instance Applicative (NonDetC m) where
  pure :: a -> NonDetC m a
pure a :: a
a = (forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b)
-> NonDetC m a
forall (m :: * -> *) a.
(forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b)
-> NonDetC m a
NonDetC (\ _ leaf :: a -> m b
leaf _ -> a -> m b
leaf a
a)
  {-# INLINE pure #-}
  NonDetC f :: forall b. (m b -> m b -> m b) -> ((a -> b) -> m b) -> m b -> m b
f <*> :: NonDetC m (a -> b) -> NonDetC m a -> NonDetC m b
<*> NonDetC a :: forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b
a = (forall b. (m b -> m b -> m b) -> (b -> m b) -> m b -> m b)
-> NonDetC m b
forall (m :: * -> *) a.
(forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b)
-> NonDetC m a
NonDetC ((forall b. (m b -> m b -> m b) -> (b -> m b) -> m b -> m b)
 -> NonDetC m b)
-> (forall b. (m b -> m b -> m b) -> (b -> m b) -> m b -> m b)
-> NonDetC m b
forall a b. (a -> b) -> a -> b
$ \ fork :: m b -> m b -> m b
fork leaf :: b -> m b
leaf nil :: m b
nil ->
    (m b -> m b -> m b) -> ((a -> b) -> m b) -> m b -> m b
forall b. (m b -> m b -> m b) -> ((a -> b) -> m b) -> m b -> m b
f m b -> m b -> m b
fork (\ f' :: a -> b
f' -> (m b -> m b -> m b) -> (a -> m b) -> m b -> m b
forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b
a m b -> m b -> m b
fork (b -> m b
leaf (b -> m b) -> (a -> b) -> a -> m b
forall b c a. (b -> c) -> (a -> b) -> a -> c
. a -> b
f') m b
nil) m b
nil
  {-# INLINE (<*>) #-}

instance Alternative (NonDetC m) where
  empty :: NonDetC m a
empty = (forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b)
-> NonDetC m a
forall (m :: * -> *) a.
(forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b)
-> NonDetC m a
NonDetC (\ _ _ nil :: m b
nil -> m b
nil)
  {-# INLINE empty #-}
  NonDetC l :: forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b
l <|> :: NonDetC m a -> NonDetC m a -> NonDetC m a
<|> NonDetC r :: forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b
r = (forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b)
-> NonDetC m a
forall (m :: * -> *) a.
(forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b)
-> NonDetC m a
NonDetC ((forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b)
 -> NonDetC m a)
-> (forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b)
-> NonDetC m a
forall a b. (a -> b) -> a -> b
$ \ fork :: m b -> m b -> m b
fork leaf :: a -> m b
leaf nil :: m b
nil -> m b -> m b -> m b
fork ((m b -> m b -> m b) -> (a -> m b) -> m b -> m b
forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b
l m b -> m b -> m b
fork a -> m b
leaf m b
nil) ((m b -> m b -> m b) -> (a -> m b) -> m b -> m b
forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b
r m b -> m b -> m b
fork a -> m b
leaf m b
nil)
  {-# INLINE (<|>) #-}

instance Monad (NonDetC m) where
  NonDetC a :: forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b
a >>= :: NonDetC m a -> (a -> NonDetC m b) -> NonDetC m b
>>= f :: a -> NonDetC m b
f = (forall b. (m b -> m b -> m b) -> (b -> m b) -> m b -> m b)
-> NonDetC m b
forall (m :: * -> *) a.
(forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b)
-> NonDetC m a
NonDetC ((forall b. (m b -> m b -> m b) -> (b -> m b) -> m b -> m b)
 -> NonDetC m b)
-> (forall b. (m b -> m b -> m b) -> (b -> m b) -> m b -> m b)
-> NonDetC m b
forall a b. (a -> b) -> a -> b
$ \ fork :: m b -> m b -> m b
fork leaf :: b -> m b
leaf nil :: m b
nil ->
    (m b -> m b -> m b) -> (a -> m b) -> m b -> m b
forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b
a m b -> m b -> m b
fork ((m b -> m b -> m b) -> (b -> m b) -> m b -> NonDetC m b -> m b
forall (m :: * -> *) b a.
(m b -> m b -> m b) -> (a -> m b) -> m b -> NonDetC m a -> m b
runNonDet m b -> m b -> m b
fork b -> m b
leaf m b
nil (NonDetC m b -> m b) -> (a -> NonDetC m b) -> a -> m b
forall b c a. (b -> c) -> (a -> b) -> a -> c
. a -> NonDetC m b
f) m b
nil
  {-# INLINE (>>=) #-}

instance Fail.MonadFail m => Fail.MonadFail (NonDetC m) where
  fail :: String -> NonDetC m a
fail s :: String
s = m a -> NonDetC m a
forall (t :: (* -> *) -> * -> *) (m :: * -> *) a.
(MonadTrans t, Monad m) =>
m a -> t m a
lift (String -> m a
forall (m :: * -> *) a. MonadFail m => String -> m a
Fail.fail String
s)
  {-# INLINE fail #-}

-- | Separate fixpoints are computed for each branch.
instance MonadFix m => MonadFix (NonDetC m) where
  mfix :: (a -> NonDetC m a) -> NonDetC m a
mfix f :: a -> NonDetC m a
f = (forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b)
-> NonDetC m a
forall (m :: * -> *) a.
(forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b)
-> NonDetC m a
NonDetC ((forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b)
 -> NonDetC m a)
-> (forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b)
-> NonDetC m a
forall a b. (a -> b) -> a -> b
$ \ fork :: m b -> m b -> m b
fork leaf :: a -> m b
leaf nil :: m b
nil ->
    ([a] -> m [a]) -> m [a]
forall (m :: * -> *) a. MonadFix m => (a -> m a) -> m a
mfix (NonDetC m a -> m [a]
forall (f :: * -> *) (m :: * -> *) a.
(Alternative f, Applicative m) =>
NonDetC m a -> m (f a)
runNonDetA (NonDetC m a -> m [a]) -> ([a] -> NonDetC m a) -> [a] -> m [a]
forall b c a. (b -> c) -> (a -> b) -> a -> c
. a -> NonDetC m a
f (a -> NonDetC m a) -> ([a] -> a) -> [a] -> NonDetC m a
forall b c a. (b -> c) -> (a -> b) -> a -> c
. [a] -> a
forall a. [a] -> a
head)
    m [a] -> ([a] -> m b) -> m b
forall (m :: * -> *) a b. Monad m => m a -> (a -> m b) -> m b
>>= (m b -> m b -> m b) -> (a -> m b) -> m b -> NonDetC m a -> m b
forall (m :: * -> *) b a.
(m b -> m b -> m b) -> (a -> m b) -> m b -> NonDetC m a -> m b
runNonDet m b -> m b -> m b
fork a -> m b
leaf m b
nil (NonDetC m a -> m b) -> ([a] -> NonDetC m a) -> [a] -> m b
forall b c a. (b -> c) -> (a -> b) -> a -> c
. (a -> NonDetC m a -> NonDetC m a)
-> NonDetC m a -> [a] -> NonDetC m a
forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr
      (\ a :: a
a _ -> a -> NonDetC m a
forall (f :: * -> *) a. Applicative f => a -> f a
pure a
a NonDetC m a -> NonDetC m a -> NonDetC m a
forall (f :: * -> *) a. Alternative f => f a -> f a -> f a
<|> (a -> NonDetC m a) -> NonDetC m a
forall (m :: * -> *) a. MonadFix m => (a -> m a) -> m a
mfix (m [a] -> NonDetC m a
forall (m :: * -> *) (t :: * -> *) a.
(Monad m, Foldable t) =>
m (t a) -> NonDetC m a
liftAll (m [a] -> NonDetC m a) -> (a -> m [a]) -> a -> NonDetC m a
forall b c a. (b -> c) -> (a -> b) -> a -> c
. ([a] -> [a]) -> m [a] -> m [a]
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap [a] -> [a]
forall a. [a] -> [a]
tail (m [a] -> m [a]) -> (a -> m [a]) -> a -> m [a]
forall b c a. (b -> c) -> (a -> b) -> a -> c
. NonDetC m a -> m [a]
forall (f :: * -> *) (m :: * -> *) a.
(Alternative f, Applicative m) =>
NonDetC m a -> m (f a)
runNonDetA (NonDetC m a -> m [a]) -> (a -> NonDetC m a) -> a -> m [a]
forall b c a. (b -> c) -> (a -> b) -> a -> c
. a -> NonDetC m a
f))
      NonDetC m a
forall (f :: * -> *) a. Alternative f => f a
empty where
    liftAll :: m (t a) -> NonDetC m a
liftAll m :: m (t a)
m = (forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b)
-> NonDetC m a
forall (m :: * -> *) a.
(forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b)
-> NonDetC m a
NonDetC ((forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b)
 -> NonDetC m a)
-> (forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b)
-> NonDetC m a
forall a b. (a -> b) -> a -> b
$ \ fork :: m b -> m b -> m b
fork leaf :: a -> m b
leaf nil :: m b
nil -> m (t a)
m m (t a) -> (t a -> m b) -> m b
forall (m :: * -> *) a b. Monad m => m a -> (a -> m b) -> m b
>>= (a -> m b -> m b) -> m b -> t a -> m b
forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr (m b -> m b -> m b
fork (m b -> m b -> m b) -> (a -> m b) -> a -> m b -> m b
forall b c a. (b -> c) -> (a -> b) -> a -> c
. a -> m b
leaf) m b
nil
  {-# INLINE mfix #-}

instance MonadIO m => MonadIO (NonDetC m) where
  liftIO :: IO a -> NonDetC m a
liftIO io :: IO a
io = m a -> NonDetC m a
forall (t :: (* -> *) -> * -> *) (m :: * -> *) a.
(MonadTrans t, Monad m) =>
m a -> t m a
lift (IO a -> m a
forall (m :: * -> *) a. MonadIO m => IO a -> m a
liftIO IO a
io)
  {-# INLINE liftIO #-}

instance MonadPlus (NonDetC m)

instance MonadTrans NonDetC where
  lift :: m a -> NonDetC m a
lift m :: m a
m = (forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b)
-> NonDetC m a
forall (m :: * -> *) a.
(forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b)
-> NonDetC m a
NonDetC (\ _ leaf :: a -> m b
leaf _ -> m a
m m a -> (a -> m b) -> m b
forall (m :: * -> *) a b. Monad m => m a -> (a -> m b) -> m b
>>= a -> m b
leaf)
  {-# INLINE lift #-}

instance (Algebra sig m, Effect sig) => Algebra (NonDet :+: sig) (NonDetC m) where
  alg :: (:+:) NonDet sig (NonDetC m) a -> NonDetC m a
alg (L (L Empty))      = NonDetC m a
forall (f :: * -> *) a. Alternative f => f a
empty
  alg (L (R (Choose k :: Bool -> NonDetC m a
k))) = Bool -> NonDetC m a
k Bool
True NonDetC m a -> NonDetC m a -> NonDetC m a
forall (f :: * -> *) a. Alternative f => f a -> f a -> f a
<|> Bool -> NonDetC m a
k Bool
False
  alg (R other :: sig (NonDetC m) a
other)          = (forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b)
-> NonDetC m a
forall (m :: * -> *) a.
(forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b)
-> NonDetC m a
NonDetC ((forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b)
 -> NonDetC m a)
-> (forall b. (m b -> m b -> m b) -> (a -> m b) -> m b -> m b)
-> NonDetC m a
forall a b. (a -> b) -> a -> b
$ \ fork :: m b -> m b -> m b
fork leaf :: a -> m b
leaf nil :: m b
nil -> sig m (NonDetC Identity a) -> m (NonDetC Identity a)
forall (sig :: (* -> *) -> * -> *) (m :: * -> *) a.
Algebra sig m =>
sig m a -> m a
alg (NonDetC Identity ()
-> (forall x.
    NonDetC Identity (NonDetC m x) -> m (NonDetC Identity x))
-> sig (NonDetC m) a
-> sig m (NonDetC Identity a)
forall (sig :: (* -> *) -> * -> *) (ctx :: * -> *) (m :: * -> *)
       (n :: * -> *) a.
(Effect sig, Functor ctx, Monad m) =>
ctx ()
-> (forall x. ctx (m x) -> n (ctx x)) -> sig m a -> sig n (ctx a)
thread (() -> NonDetC Identity ()
forall (f :: * -> *) a. Applicative f => a -> f a
pure ()) forall x. NonDetC Identity (NonDetC m x) -> m (NonDetC Identity x)
forall (m :: * -> *) a.
Applicative m =>
NonDetC Identity (NonDetC m a) -> m (NonDetC Identity a)
dst sig (NonDetC m) a
other) m (NonDetC Identity a) -> (NonDetC Identity a -> m b) -> m b
forall (m :: * -> *) a b. Monad m => m a -> (a -> m b) -> m b
>>= Identity (m b) -> m b
forall a. Identity a -> a
runIdentity (Identity (m b) -> m b)
-> (NonDetC Identity a -> Identity (m b))
-> NonDetC Identity a
-> m b
forall b c a. (b -> c) -> (a -> b) -> a -> c
. (Identity (m b) -> Identity (m b) -> Identity (m b))
-> (a -> Identity (m b))
-> Identity (m b)
-> NonDetC Identity a
-> Identity (m b)
forall (m :: * -> *) b a.
(m b -> m b -> m b) -> (a -> m b) -> m b -> NonDetC m a -> m b
runNonDet ((m b -> m b -> m b)
-> Identity (m b) -> Identity (m b) -> Identity (m b)
forall a b. Coercible a b => a -> b
coerce m b -> m b -> m b
fork) ((a -> m b) -> a -> Identity (m b)
forall a b. Coercible a b => a -> b
coerce a -> m b
leaf) (m b -> Identity (m b)
forall a b. Coercible a b => a -> b
coerce m b
nil) where
    dst :: Applicative m => NonDetC Identity (NonDetC m a) -> m (NonDetC Identity a)
    dst :: NonDetC Identity (NonDetC m a) -> m (NonDetC Identity a)
dst = Identity (m (NonDetC Identity a)) -> m (NonDetC Identity a)
forall a. Identity a -> a
runIdentity (Identity (m (NonDetC Identity a)) -> m (NonDetC Identity a))
-> (NonDetC Identity (NonDetC m a)
    -> Identity (m (NonDetC Identity a)))
-> NonDetC Identity (NonDetC m a)
-> m (NonDetC Identity a)
forall b c a. (b -> c) -> (a -> b) -> a -> c
. (Identity (m (NonDetC Identity a))
 -> Identity (m (NonDetC Identity a))
 -> Identity (m (NonDetC Identity a)))
-> (NonDetC m a -> Identity (m (NonDetC Identity a)))
-> Identity (m (NonDetC Identity a))
-> NonDetC Identity (NonDetC m a)
-> Identity (m (NonDetC Identity a))
forall (m :: * -> *) b a.
(m b -> m b -> m b) -> (a -> m b) -> m b -> NonDetC m a -> m b
runNonDet ((m (NonDetC Identity a)
 -> m (NonDetC Identity a) -> m (NonDetC Identity a))
-> Identity (m (NonDetC Identity a))
-> Identity (m (NonDetC Identity a))
-> Identity (m (NonDetC Identity a))
forall (f :: * -> *) a b c.
Applicative f =>
(a -> b -> c) -> f a -> f b -> f c
liftA2 ((NonDetC Identity a -> NonDetC Identity a -> NonDetC Identity a)
-> m (NonDetC Identity a)
-> m (NonDetC Identity a)
-> m (NonDetC Identity a)
forall (f :: * -> *) a b c.
Applicative f =>
(a -> b -> c) -> f a -> f b -> f c
liftA2 NonDetC Identity a -> NonDetC Identity a -> NonDetC Identity a
forall (f :: * -> *) a. Alternative f => f a -> f a -> f a
(<|>))) (m (NonDetC Identity a) -> Identity (m (NonDetC Identity a))
forall a. a -> Identity a
Identity (m (NonDetC Identity a) -> Identity (m (NonDetC Identity a)))
-> (NonDetC m a -> m (NonDetC Identity a))
-> NonDetC m a
-> Identity (m (NonDetC Identity a))
forall b c a. (b -> c) -> (a -> b) -> a -> c
. NonDetC m a -> m (NonDetC Identity a)
forall (f :: * -> *) (m :: * -> *) a.
(Alternative f, Applicative m) =>
NonDetC m a -> m (f a)
runNonDetA) (m (NonDetC Identity a) -> Identity (m (NonDetC Identity a))
forall (f :: * -> *) a. Applicative f => a -> f a
pure (NonDetC Identity a -> m (NonDetC Identity a)
forall (f :: * -> *) a. Applicative f => a -> f a
pure NonDetC Identity a
forall (f :: * -> *) a. Alternative f => f a
empty))
  {-# INLINE alg #-}