fused-effects-1.1.1.1: A fast, flexible, fused effect system.

Control.Effect.Cut

Contents

Description

Provides an effect to delimit backtracking in a given nondeterministic context. This effect is used in concert with NonDet.

Computations that signal failure with cutfail prevent backtracking within the nearest enclosing call.

Predefined carriers:

Since: 0.1.2.0

Synopsis

# Cut effect

data Cut m k where Source #

Cut effects are used with Choose to provide control over backtracking.

Since: 0.1.2.0

Constructors

 Cutfail :: Cut m a Call :: m a -> Cut m a

#### Instances

Instances details
 Algebra sig m => Algebra (Cut :+: (NonDet :+: sig)) (CutC m) Source # Instance detailsDefined in Control.Carrier.Cut.Church Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (CutC m) -> (Cut :+: (NonDet :+: sig)) n a -> ctx () -> CutC m (ctx a) Source #

cutfail :: Has Cut sig m => m a Source #

Fail the current branch, and prevent backtracking within the nearest enclosing call (if any).

Contrast with empty, which fails the current branch but allows backtracking.

cutfail >>= k = cutfail

cutfail <|> m = cutfail


Since: 0.1.2.0

call :: Has Cut sig m => m a -> m a Source #

Delimit the effect of cutfails, allowing backtracking to resume.

call cutfail <|> m = m


Since: 0.1.2.0

cut :: (Alternative m, Has Cut sig m) => m () Source #

Commit to the current branch, preventing backtracking within the nearest enclosing call (if any) on failure.

cut >> empty = cutfail


Since: 0.1.2.0

# Re-exports

class Monad m => Algebra sig m | m -> sig Source #

The class of carriers (results) for algebras (effect handlers) over signatures (effects), whose actions are given by the alg method.

Since: 1.0.0.0

Minimal complete definition

alg

#### Instances

Instances details
 Source # Instance detailsDefined in Control.Algebra Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n NonEmpty -> Choose n a -> ctx () -> NonEmpty (ctx a) Source # Source # Instance detailsDefined in Control.Algebra Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n Maybe -> Empty n a -> ctx () -> Maybe (ctx a) Source # Source # Instance detailsDefined in Control.Algebra Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n [] -> NonDet n a -> ctx () -> [ctx a] Source # Algebra sig m => Algebra sig (Alt m) Source # This instance permits effectful actions to be lifted into the Alt monad, which eases the invocation of repeated alternation with <|>:a <|> b <|> c <|> dis equivalent togetAlt (mconcat [a, b, c, d])Since: 1.0.1.0 Instance detailsDefined in Control.Algebra Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (Alt m) -> sig n a -> ctx () -> Alt m (ctx a) Source # Algebra sig m => Algebra sig (Ap m) Source # This instance permits effectful actions to be lifted into the Ap monad given a monoidal return type, which can provide clarity when chaining calls to mappend.mappend <$> act1 <*> (mappend <$> act2 <*> act3)is equivalent togetAp (act1 <> act2 <> act3)Since: 1.0.1.0 Instance detailsDefined in Control.Algebra Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (Ap m) -> sig n a -> ctx () -> Ap m (ctx a) Source # Algebra sig m => Algebra sig (IdentityT m) Source # Instance detailsDefined in Control.Algebra Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (IdentityT m) -> sig n a -> ctx () -> IdentityT m (ctx a) Source # Source # Instance detailsDefined in Control.Algebra Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n IO -> Lift IO n a -> ctx () -> IO (ctx a) Source # Source # Instance detailsDefined in Control.Algebra Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n Identity -> Lift Identity n a -> ctx () -> Identity (ctx a) Source # Monad m => Algebra (Lift m) (LiftC m) Source # Instance detailsDefined in Control.Carrier.Lift Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (LiftC m) -> Lift m n a -> ctx () -> LiftC m (ctx a) Source # Algebra (Error e) (Either e) Source # Instance detailsDefined in Control.Algebra Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (Either e) -> Error e n a -> ctx () -> Either e (ctx a) Source # Monoid w => Algebra (Writer w) ((,) w) Source # Instance detailsDefined in Control.Algebra Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n ((,) w) -> Writer w n a -> ctx () -> (w, ctx a) Source # Algebra (Reader r) ((->) r :: Type -> Type) Source # Instance detailsDefined in Control.Algebra Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n ((->) r) -> Reader r n a -> ctx () -> r -> ctx a Source # Algebra sig m => Algebra (Choose :+: sig) (ChooseC m) Source # Instance detailsDefined in Control.Carrier.Choose.Church Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (ChooseC m) -> (Choose :+: sig) n a -> ctx () -> ChooseC m (ctx a) Source # Algebra sig m => Algebra (Empty :+: sig) (MaybeT m) Source # Instance detailsDefined in Control.Algebra Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (MaybeT m) -> (Empty :+: sig) n a -> ctx () -> MaybeT m (ctx a) Source # Algebra sig m => Algebra (Empty :+: sig) (EmptyC m) Source # Instance detailsDefined in Control.Carrier.Empty.Maybe Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (EmptyC m) -> (Empty :+: sig) n a -> ctx () -> EmptyC m (ctx a) Source # Algebra sig m => Algebra (Empty :+: sig) (EmptyC m) Source # Instance detailsDefined in Control.Carrier.Empty.Church Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (EmptyC m) -> (Empty :+: sig) n a -> ctx () -> EmptyC m (ctx a) Source # Algebra sig m => Algebra (NonDet :+: sig) (NonDetC m) Source # Instance detailsDefined in Control.Carrier.NonDet.Church Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (NonDetC m) -> (NonDet :+: sig) n a -> ctx () -> NonDetC m (ctx a) Source # (MonadIO m, Algebra sig m) => Algebra (Trace :+: sig) (TraceC m) Source # Instance detailsDefined in Control.Carrier.Trace.Printing Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (TraceC m) -> (Trace :+: sig) n a -> ctx () -> TraceC m (ctx a) Source # Algebra sig m => Algebra (Trace :+: sig) (TraceC m) Source # Instance detailsDefined in Control.Carrier.Trace.Ignoring Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (TraceC m) -> (Trace :+: sig) n a -> ctx () -> TraceC m (ctx a) Source # Algebra sig m => Algebra (Trace :+: sig) (TraceC m) Source # Instance detailsDefined in Control.Carrier.Trace.Returning Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (TraceC m) -> (Trace :+: sig) n a -> ctx () -> TraceC m (ctx a) Source # Algebra sig m => Algebra (Fail :+: sig) (FailC m) Source # Instance detailsDefined in Control.Carrier.Fail.Either Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (FailC m) -> (Fail :+: sig) n a -> ctx () -> FailC m (ctx a) Source # Algebra sig m => Algebra (Fresh :+: sig) (FreshC m) Source # Instance detailsDefined in Control.Carrier.Fresh.Strict Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (FreshC m) -> (Fresh :+: sig) n a -> ctx () -> FreshC m (ctx a) Source # Algebra sig m => Algebra (Fresh :+: sig) (FreshC m) Source # Instance detailsDefined in Control.Carrier.Fresh.Church Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (FreshC m) -> (Fresh :+: sig) n a -> ctx () -> FreshC m (ctx a) Source # Algebra sig m => Algebra (Cut :+: (NonDet :+: sig)) (CutC m) Source # Instance detailsDefined in Control.Carrier.Cut.Church Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (CutC m) -> (Cut :+: (NonDet :+: sig)) n a -> ctx () -> CutC m (ctx a) Source # Algebra sig m => Algebra (Cull :+: (NonDet :+: sig)) (CullC m) Source # Instance detailsDefined in Control.Carrier.Cull.Church Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (CullC m) -> (Cull :+: (NonDet :+: sig)) n a -> ctx () -> CullC m (ctx a) Source # Algebra sig m => Algebra (Reader r :+: sig) (ReaderT r m) Source # Instance detailsDefined in Control.Algebra Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (ReaderT r m) -> (Reader r :+: sig) n a -> ctx () -> ReaderT r m (ctx a) Source # Algebra sig m => Algebra (Reader r :+: sig) (ReaderC r m) Source # Instance detailsDefined in Control.Carrier.Reader Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (ReaderC r m) -> (Reader r :+: sig) n a -> ctx () -> ReaderC r m (ctx a) Source # Algebra sig m => Algebra (State s :+: sig) (StateT s m) Source # Instance detailsDefined in Control.Algebra Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (StateT s m) -> (State s :+: sig) n a -> ctx () -> StateT s m (ctx a) Source # Algebra sig m => Algebra (State s :+: sig) (StateT s m) Source # Instance detailsDefined in Control.Algebra Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (StateT s m) -> (State s :+: sig) n a -> ctx () -> StateT s m (ctx a) Source # Algebra sig m => Algebra (State s :+: sig) (StateC s m) Source # Instance detailsDefined in Control.Carrier.State.Strict Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (StateC s m) -> (State s :+: sig) n a -> ctx () -> StateC s m (ctx a) Source # Algebra sig m => Algebra (State s :+: sig) (StateC s m) Source # Instance detailsDefined in Control.Carrier.State.Lazy Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (StateC s m) -> (State s :+: sig) n a -> ctx () -> StateC s m (ctx a) Source # Algebra sig m => Algebra (State s :+: sig) (StateC s m) Source # Instance detailsDefined in Control.Carrier.State.Church Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (StateC s m) -> (State s :+: sig) n a -> ctx () -> StateC s m (ctx a) Source # Algebra sig m => Algebra (Throw e :+: sig) (ThrowC e m) Source # Instance detailsDefined in Control.Carrier.Throw.Either Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (ThrowC e m) -> (Throw e :+: sig) n a -> ctx () -> ThrowC e m (ctx a) Source # Algebra sig m => Algebra (Error e :+: sig) (ExceptT e m) Source # Instance detailsDefined in Control.Algebra Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (ExceptT e m) -> (Error e :+: sig) n a -> ctx () -> ExceptT e m (ctx a) Source # Algebra sig m => Algebra (Error e :+: sig) (ErrorC e m) Source # Instance detailsDefined in Control.Carrier.Error.Either Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (ErrorC e m) -> (Error e :+: sig) n a -> ctx () -> ErrorC e m (ctx a) Source # Algebra sig m => Algebra (Error e :+: sig) (ErrorC e m) Source # Instance detailsDefined in Control.Carrier.Error.Church Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (ErrorC e m) -> (Error e :+: sig) n a -> ctx () -> ErrorC e m (ctx a) Source # (Algebra sig m, Monoid w) => Algebra (Writer w :+: sig) (WriterT w m) Source # Instance detailsDefined in Control.Algebra Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (WriterT w m) -> (Writer w :+: sig) n a -> ctx () -> WriterT w m (ctx a) Source # (Algebra sig m, Monoid w) => Algebra (Writer w :+: sig) (WriterT w m) Source # Instance detailsDefined in Control.Algebra Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (WriterT w m) -> (Writer w :+: sig) n a -> ctx () -> WriterT w m (ctx a) Source # (Algebra sig m, Monoid w) => Algebra (Writer w :+: sig) (WriterT w m) Source # Instance detailsDefined in Control.Algebra Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (WriterT w m) -> (Writer w :+: sig) n a -> ctx () -> WriterT w m (ctx a) Source # (Monoid w, Algebra sig m) => Algebra (Writer w :+: sig) (WriterC w m) Source # Instance detailsDefined in Control.Carrier.Writer.Strict Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (WriterC w m) -> (Writer w :+: sig) n a -> ctx () -> WriterC w m (ctx a) Source # (Algebra sig m, Monoid w) => Algebra (Writer w :+: sig) (WriterC w m) Source # Instance detailsDefined in Control.Carrier.Writer.Church Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (WriterC w m) -> (Writer w :+: sig) n a -> ctx () -> WriterC w m (ctx a) Source # (Reifies s (Interpreter eff m), Algebra sig m) => Algebra (eff :+: sig) (InterpretC s eff m) Source # Instance detailsDefined in Control.Carrier.Interpret Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (InterpretC s eff m) -> (eff :+: sig) n a -> ctx () -> InterpretC s eff m (ctx a) Source # (LabelledMember label sub sig, Algebra sig m) => Algebra (sub :+: sig) (UnderLabel label sub m) Source # Instance detailsDefined in Control.Effect.Labelled Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (UnderLabel label sub m) -> (sub :+: sig) n a -> ctx () -> UnderLabel label sub m (ctx a) Source # (Algebra sig m, Monoid w) => Algebra (Reader r :+: (Writer w :+: (State s :+: sig))) (RWST r w s m) Source # Instance detailsDefined in Control.Algebra Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (RWST r w s m) -> (Reader r :+: (Writer w :+: (State s :+: sig))) n a -> ctx () -> RWST r w s m (ctx a) Source # (Algebra sig m, Monoid w) => Algebra (Reader r :+: (Writer w :+: (State s :+: sig))) (RWST r w s m) Source # Instance detailsDefined in Control.Algebra Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (RWST r w s m) -> (Reader r :+: (Writer w :+: (State s :+: sig))) n a -> ctx () -> RWST r w s m (ctx a) Source # (Algebra sig m, Monoid w) => Algebra (Reader r :+: (Writer w :+: (State s :+: sig))) (RWST r w s m) Source # Instance detailsDefined in Control.Algebra Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (RWST r w s m) -> (Reader r :+: (Writer w :+: (State s :+: sig))) n a -> ctx () -> RWST r w s m (ctx a) Source # Algebra (eff :+: sig) (sub m) => Algebra (Labelled label eff :+: sig) (Labelled label sub m) Source # Instance detailsDefined in Control.Effect.Labelled Methodsalg :: forall ctx (n :: Type -> Type) a. Functor ctx => Handler ctx n (Labelled label sub m) -> (Labelled label eff :+: sig) n a -> ctx () -> Labelled label sub m (ctx a) Source #

type Has eff sig m = (Members eff sig, Algebra sig m) Source #

m is a carrier for sig containing eff.

Note that if eff is a sum, it will be decomposed into multiple Member constraints. While this technically allows one to combine multiple unrelated effects into a single Has constraint, doing so has two significant drawbacks:

1. Due to a problem with recursive type families, this can lead to significantly slower compiles.
2. It defeats ghc’s warnings for redundant constraints, and thus can lead to a proliferation of redundant constraints as code is changed.

Since: 1.0.0.0

run :: Identity a -> a Source #

Run an action exhausted of effects to produce its final result value.

Since: 1.0.0.0