{-# LANGUAGE ScopedTypeVariables, TypeFamilies, FlexibleContexts, MultiParamTypeClasses #-}
{-# LANGUAGE DataKinds, GADTs, RankNTypes, NoMonomorphismRestriction #-}
module Control.Effects.List
( module Control.Effects.List
, module ListT ) where
import Prelude hiding (splitAt, head)
import Import
import ListT hiding (take)
import Control.Effects
data NonDeterminism
instance Effect NonDeterminism where
data EffMethods NonDeterminism m = NonDeterminismMethods
{ _choose :: forall a. [a] -> m a }
liftThrough (NonDeterminismMethods c) = NonDeterminismMethods (lift . c)
mergeContext m = NonDeterminismMethods (\a -> do
lm <- m
_choose lm a)
choose :: forall a m. MonadEffect NonDeterminism m => [a] -> m a
NonDeterminismMethods choose = effect
instance Monad m => MonadEffect NonDeterminism (ListT m) where
effect = NonDeterminismMethods fromFoldable
deadEnd :: MonadEffect NonDeterminism m => m a
deadEnd = choose []
evaluateToList :: Monad m => ListT m a -> m [a]
evaluateToList = toList
traverseAllResults :: Monad m => (a -> m ()) -> ListT m a -> m ()
traverseAllResults = traverse_
foldAllResults :: Monad m => (r -> a -> m r) -> r -> ListT m a -> m r
foldAllResults = fold
foldWithEarlyTermination :: Monad m => (r -> a -> m (Maybe r)) -> r -> ListT m a -> m r
foldWithEarlyTermination = foldMaybe
evaluateNResults :: Monad m => Int -> ListT m a -> m [a]
evaluateNResults n = fmap fst . splitAt n
evaluateOneResult :: Monad m => ListT m a -> m (Maybe a)
evaluateOneResult = head
evaluateAll :: Monad m => ListT m a -> m ()
evaluateAll = void . evaluateToList