Control.Monad.Hefty.NonDet

Interpreters for the non-determinism effects.

Documentation

choice :: forall (ef :: [EffectF]) a (eh :: [EffectH]). (Choose <| ef, Empty <| ef) => [a] -> Eff eh ef a

Selects one element from the list nondeterministically, branching the control as many times as the number of elements.

runNonDet :: forall f (ef :: [Type -> Type]) a. Alternative f => Eff ('[] :: [EffectH]) (Choose ': (Empty ': ef)) a -> Eff ('[] :: [EffectH]) ef (f a)

NonDet effects handler for alternative answer type.

runNonDetMonoid :: forall ans (ef :: [EffectF]) a. Monoid ans => (a -> Eff ('[] :: [EffectH]) ef ans) -> Eff ('[] :: [EffectH]) (Choose ': (Empty ': ef)) a -> Eff ('[] :: [EffectH]) ef ans

NonDet effects handler for monoidal answer type.

runChoose :: forall f (ef :: [Type -> Type]) a. Alternative f => Eff ('[] :: [EffectH]) (Choose ': ef) a -> Eff ('[] :: [EffectH]) ef (f a)

Choose effect handler for alternative answer type.

runChooseMonoid :: forall ans (ef :: [EffectF]) a. Semigroup ans => (a -> Eff ('[] :: [EffectH]) ef ans) -> Eff ('[] :: [EffectH]) (Choose ': ef) a -> Eff ('[] :: [EffectH]) ef ans

Choose effect handler for monoidal answer type.

runEmpty :: forall a (ef :: [Type -> Type]). Eff ('[] :: [EffectH]) (Empty ': ef) a -> Eff ('[] :: [EffectH]) ef (Maybe a)

Empty effect handler.

runChooseH :: forall (ef :: [EffectF]) (eh :: [(Type -> Type) -> Type -> Type]). Choose <| ef => Eff (ChooseH ': eh) ef ~> Eff eh ef

ChooseH effect elaborator.

Convert a higher-order effect of the form

chooseH :: m a -> m a -> m a

into a first-order effect of the form:

choose :: m Bool

branch :: forall (ef :: [EffectF]) (eh :: [EffectH]) a. Choose <| ef => Eff eh ef a -> Eff eh ef a -> Eff eh ef a infixl 3

Faster than <|>.

choiceH :: forall (eh :: [EffectH]) (ef :: [EffectF]) a. (ChooseH <<| eh, Empty <| ef) => [a] -> Eff eh ef a

Selects one element from the list nondeterministically, branching the control as many times as the number of elements. Uses ChooseH.

runNonDetIO :: forall (eh :: [EffectH]) (ef :: [EffectF]) a. (UnliftIO <<| eh, IO <| ef) => Eff (ChooseH ': eh) (Empty ': ef) a -> Eff eh ef (Either SomeException a)

Interprets the NonDet effects using IO-level exceptions.

When empty occurs, an EmptyException is thrown, and unless all branches from chooseH fail due to IO-level exceptions, only the leftmost result is returned as the final result.

data EmptyException

Exception thrown when empty occurs in runNonDetIO.

Constructors

EmptyException

Instances

Exception EmptyException

Defined in Control.Monad.Hefty.NonDet

Methods

toException :: EmptyException -> SomeException

fromException :: SomeException -> Maybe EmptyException

displayException :: EmptyException -> String

Show EmptyException

Defined in Control.Monad.Hefty.NonDet

Methods

showsPrec :: Int -> EmptyException -> ShowS

show :: EmptyException -> String

showList :: [EmptyException] -> ShowS

module Data.Effect.NonDet