Control.Effect.NonDet

Effects

newtype NonDet :: Effect where

An effect for nondeterministic computations

Constructors

FromList :: [a] -> NonDet m a

newtype Cull :: Effect where

An effect for culling nondeterministic computations.

Constructors

Cull :: m a -> Cull m a

data Cut :: Effect where

An effect to delimit backtracking within nondeterministic contexts.

Constructors

Cutfail :: Cut m a

Call :: m a -> Cut m a

data Split :: Effect where

An effect for splitting a nondeterministic computation into its head and tail.

Split is typically used as a primitive effect. If you define a Carrier that relies on a novel non-trivial monad transformer, then you need to make a ThreadsEff instance for that monad transformer to lift Split (if possible).

The following threading constraints accept Split:

• ReaderThreads
• StateThreads
• StateLazyThreads
• WriterThreads
• WriterLazyThreads

Constructors

Split :: (Maybe (a, m a) -> b) -> m a -> Split m b

Instances

Monoid s => ThreadsEff (WriterT s) Split

Defined in Control.Effect.Type.Split

Methods

threadEff :: Monad m => (forall x. Split m x -> m x) -> Split (WriterT s m) a -> WriterT s m a

ThreadsEff (StateT s) Split

Defined in Control.Effect.Type.Split

Methods

threadEff :: Monad m => (forall x. Split m x -> m x) -> Split (StateT s m) a -> StateT s m a

ThreadsEff (ReaderT s) Split

Defined in Control.Effect.Type.Split

Methods

threadEff :: Monad m => (forall x. Split m x -> m x) -> Split (ReaderT s m) a -> ReaderT s m a

ThreadsEff (StateT s) Split

Defined in Control.Effect.Type.Split

Methods

threadEff :: Monad m => (forall x. Split m x -> m x) -> Split (StateT s m) a -> StateT s m a

Monoid s => ThreadsEff (WriterT s) Split

Defined in Control.Effect.Type.Split

Methods

threadEff :: Monad m => (forall x. Split m x -> m x) -> Split (WriterT s m) a -> WriterT s m a

Monoid s => ThreadsEff (WriterT s) Split

Defined in Control.Effect.Type.Split

Methods

threadEff :: Monad m => (forall x. Split m x -> m x) -> Split (WriterT s m) a -> WriterT s m a

type Logic = Bundle '[NonDet, Cull, Cut, Split]

A pseudo-effect for connected NonDet, Cull, Cut, and Split effects.

Logic should only ever be used inside of Eff and Effs constraints. It is not a real effect! See Bundle.

Actions

choose :: Eff NonDet m => m a -> m a -> m a

Introduce two new branches stemming from the current one.

lose :: Eff NonDet m => m a

Fail the current branch and proceed to the next branch, backtracking to the nearest use of choose or fromList that still has unprocessed branches.

fromList :: Eff NonDet m => [a] -> m a

Introduce new branches stemming from the current one using a list of values.

cull :: Eff Cull m => m a -> m a

Cull nondeterminism in the argument, limiting the number of branches it may introduce to be at most 1.

cull (return True `choose` return False) == return True

cull (lose `choose` return False) == return False

cutfail :: Eff Cut m => m a

Fail the current branch, and prevent backtracking up until the nearest enclosing use of call (if any).

cutfail `choose` m == cutfail

cut :: Effs '[NonDet, Cut] m => m ()

Commit to the current branch: prevent all backtracking that would move execution to before cut was invoked, up until the nearest enclosing use of call (if any).

call (fromList [1,2] >>= \a -> cut >> fromList [a,a+3]) == fromList [1,4]

call ((cut >> return True) `choose` return False) == return True

call :: Eff Cut m => m a -> m a

Delimit the prevention of backtracking from uses of cut and cutfail.

call cutfail `choose` m = m

split :: Eff Split m => m a -> m (Maybe (a, m a))

Split a nondeterministic computation into its first result and the rest of the computation, if possible.

Note that split cutfail == cutfail. If you don't want that behavior, use split (call m) instead of split m.

Interpretations

runNonDet :: forall f m a p. (Alternative f, Carrier m, Threaders '[NonDetThreads] m p) => NonDetC m a -> m (f a)

Runs a NonDet effect.

Unlike runLogic and runCullCut, this doesn't provide any means of interacting with created branches through Split, Cull or Cut.

However, it also doesn't impose any primitive effects, meaning runNonDet doesn't restrict what interpreters are run before it.

Derivs (NonDetC m) = NonDet ': Derivs m

Prims  (NonDetC m) = Prims m

runNonDet1 :: forall m a p. (Carrier m, Threaders '[NonDetThreads] m p) => NonDetC m a -> m (Maybe a)

Runs a NonDet effect, but stop once the first valid result is found.

This is like runNonDet with the Alternative specialized to Maybe, but once a valid result is found, it won't run all other branches.

This is the equivalent of runCullCut @Maybe . cull or runLogic @Maybe . cull, but doesn't impose any primitive effects, meaning runNonDet1 doesn't restrict what interpreters are run before it.

Derivs (NonDetC m) = NonDet ': Derivs m

Prims  (NonDetC m) = Prims m

runCullCut :: forall f m a p. (Alternative f, Carrier m, Threaders '[NonDetThreads] m p) => CullCutC m a -> m (f a)

Runs connected NonDet, Cull, and Cut effects.

Unlike runLogic, this doesn't provide the full power of Split. This allows for a larger variety of interpreters to be run before runCullCut compared to runLogic, since Split is significantly harder to thread compared to Cull and Cut.

Derivs (CullCutC m) = Cull ': Cut ': NonDet ': Derivs m

Prims  (CullCutC m) = Regional CullOrCall ': Prims m

runLogic :: forall f m a p. (Alternative f, Carrier m, Threaders '[NonDetThreads] m p) => LogicC m a -> m (f a)

Runs connected NonDet, Cull, Cut, and Split effects -- i.e. Logic.

Derivs (LogicC m) = Split ': Cull ': Cut ': NonDet ': Derivs m

Prims  (LogicC m) = Split ': Regional CullOrCall ': Prims m

Split is a very restrictive primitive effect. Most notably, interpreters for effects with failure -- such as runError -- can't be used before runLogic. If you want to use such interpreters before runLogic, consider using runCullCut or runNonDet instead.

Threading constraints

type NonDetThreads = Threads ListT

NonDetThreads accepts the following primitive effects:

• Regional s
• Optional s (when s is a functor)
• Unravel p
• ListenPrim o (when o is a Monoid)
• WriterPrim o (when o is a Monoid)
• ReaderPrim i

Carriers

data NonDetC m a

Instances

MonadTrans NonDetC

Defined in Control.Effect.Internal.NonDet

Methods

lift :: Monad m => m a -> NonDetC m a

MonadBase b m => MonadBase b (NonDetC m)

Defined in Control.Effect.Internal.NonDet

Methods

liftBase :: b α -> NonDetC m α

Monad (NonDetC m)

Defined in Control.Effect.Internal.NonDet

Methods

(>>=) :: NonDetC m a -> (a -> NonDetC m b) -> NonDetC m b

(>>) :: NonDetC m a -> NonDetC m b -> NonDetC m b

return :: a -> NonDetC m a

Functor (NonDetC m)

Defined in Control.Effect.Internal.NonDet

Methods

fmap :: (a -> b) -> NonDetC m a -> NonDetC m b

(<$) :: a -> NonDetC m b -> NonDetC m a

MonadFail m => MonadFail (NonDetC m)

Defined in Control.Effect.Internal.NonDet

Methods

fail :: String -> NonDetC m a

Applicative (NonDetC m)

Defined in Control.Effect.Internal.NonDet

Methods

pure :: a -> NonDetC m a

(<*>) :: NonDetC m (a -> b) -> NonDetC m a -> NonDetC m b

liftA2 :: (a -> b -> c) -> NonDetC m a -> NonDetC m b -> NonDetC m c

(*>) :: NonDetC m a -> NonDetC m b -> NonDetC m b

(<*) :: NonDetC m a -> NonDetC m b -> NonDetC m a

MonadIO m => MonadIO (NonDetC m)

Defined in Control.Effect.Internal.NonDet

Methods

liftIO :: IO a -> NonDetC m a

MonadThrow m => MonadThrow (NonDetC m)

Defined in Control.Effect.Internal.NonDet

Methods

throwM :: Exception e => e -> NonDetC m a

MonadCatch m => MonadCatch (NonDetC m)

Defined in Control.Effect.Internal.NonDet

Methods

catch :: Exception e => NonDetC m a -> (e -> NonDetC m a) -> NonDetC m a

(Carrier m, Threads ListT (Prims m)) => Carrier (NonDetC m)

Defined in Control.Effect.Internal.NonDet

Associated Types

type Derivs (NonDetC m) :: [Effect]

type Prims (NonDetC m) :: [Effect]

Methods

algPrims :: Algebra' (Prims (NonDetC m)) (NonDetC m) a

reformulate :: Monad z => Reformulation' (Derivs (NonDetC m)) (Prims (NonDetC m)) (NonDetC m) z a

algDerivs :: Algebra' (Derivs (NonDetC m)) (NonDetC m) a

type Derivs (NonDetC m)

Defined in Control.Effect.Internal.NonDet

type Derivs (NonDetC m) = NonDet ': Derivs m

type Prims (NonDetC m)

Defined in Control.Effect.Internal.NonDet

type Prims (NonDetC m) = Prims m

data CullCutC m a

Instances

MonadTrans CullCutC

Defined in Control.Effect.Internal.NonDet

Methods

lift :: Monad m => m a -> CullCutC m a

MonadBase b m => MonadBase b (CullCutC m)

Defined in Control.Effect.Internal.NonDet

Methods

liftBase :: b α -> CullCutC m α

Monad (CullCutC m)

Defined in Control.Effect.Internal.NonDet

Methods

(>>=) :: CullCutC m a -> (a -> CullCutC m b) -> CullCutC m b

(>>) :: CullCutC m a -> CullCutC m b -> CullCutC m b

return :: a -> CullCutC m a

Functor (CullCutC m)

Defined in Control.Effect.Internal.NonDet

Methods

fmap :: (a -> b) -> CullCutC m a -> CullCutC m b

(<$) :: a -> CullCutC m b -> CullCutC m a

MonadFail m => MonadFail (CullCutC m)

Defined in Control.Effect.Internal.NonDet

Methods

fail :: String -> CullCutC m a

Applicative (CullCutC m)

Defined in Control.Effect.Internal.NonDet

Methods

pure :: a -> CullCutC m a

(<*>) :: CullCutC m (a -> b) -> CullCutC m a -> CullCutC m b

liftA2 :: (a -> b -> c) -> CullCutC m a -> CullCutC m b -> CullCutC m c

(*>) :: CullCutC m a -> CullCutC m b -> CullCutC m b

(<*) :: CullCutC m a -> CullCutC m b -> CullCutC m a

MonadIO m => MonadIO (CullCutC m)

Defined in Control.Effect.Internal.NonDet

Methods

liftIO :: IO a -> CullCutC m a

MonadThrow m => MonadThrow (CullCutC m)

Defined in Control.Effect.Internal.NonDet

Methods

throwM :: Exception e => e -> CullCutC m a

MonadCatch m => MonadCatch (CullCutC m)

Defined in Control.Effect.Internal.NonDet

Methods

catch :: Exception e => CullCutC m a -> (e -> CullCutC m a) -> CullCutC m a

(Carrier m, Threads ListT (Prims m)) => Carrier (CullCutC m)

Defined in Control.Effect.Internal.NonDet

Associated Types

type Derivs (CullCutC m) :: [Effect]

type Prims (CullCutC m) :: [Effect]

Methods

algPrims :: Algebra' (Prims (CullCutC m)) (CullCutC m) a

reformulate :: Monad z => Reformulation' (Derivs (CullCutC m)) (Prims (CullCutC m)) (CullCutC m) z a

algDerivs :: Algebra' (Derivs (CullCutC m)) (CullCutC m) a

type Derivs (CullCutC m)

Defined in Control.Effect.Internal.NonDet

type Derivs (CullCutC m) = Cull ': (Cut ': (NonDet ': Derivs m))

type Prims (CullCutC m)

Defined in Control.Effect.Internal.NonDet

type Prims (CullCutC m) = Regional CullOrCall ': Prims m

data LogicC m a

Instances

MonadTrans LogicC

Defined in Control.Effect.Internal.NonDet

Methods

lift :: Monad m => m a -> LogicC m a

MonadBase b m => MonadBase b (LogicC m)

Defined in Control.Effect.Internal.NonDet

Methods

liftBase :: b α -> LogicC m α

Monad (LogicC m)

Defined in Control.Effect.Internal.NonDet

Methods

(>>=) :: LogicC m a -> (a -> LogicC m b) -> LogicC m b

(>>) :: LogicC m a -> LogicC m b -> LogicC m b

return :: a -> LogicC m a

Functor (LogicC m)

Defined in Control.Effect.Internal.NonDet

Methods

fmap :: (a -> b) -> LogicC m a -> LogicC m b

(<$) :: a -> LogicC m b -> LogicC m a

MonadFail m => MonadFail (LogicC m)

Defined in Control.Effect.Internal.NonDet

Methods

fail :: String -> LogicC m a

Applicative (LogicC m)

Defined in Control.Effect.Internal.NonDet

Methods

pure :: a -> LogicC m a

(<*>) :: LogicC m (a -> b) -> LogicC m a -> LogicC m b

liftA2 :: (a -> b -> c) -> LogicC m a -> LogicC m b -> LogicC m c

(*>) :: LogicC m a -> LogicC m b -> LogicC m b

(<*) :: LogicC m a -> LogicC m b -> LogicC m a

MonadIO m => MonadIO (LogicC m)

Defined in Control.Effect.Internal.NonDet

Methods

liftIO :: IO a -> LogicC m a

MonadThrow m => MonadThrow (LogicC m)

Defined in Control.Effect.Internal.NonDet

Methods

throwM :: Exception e => e -> LogicC m a

MonadCatch m => MonadCatch (LogicC m)

Defined in Control.Effect.Internal.NonDet

Methods

catch :: Exception e => LogicC m a -> (e -> LogicC m a) -> LogicC m a

(Carrier m, Threads ListT (Prims m)) => Carrier (LogicC m)

Defined in Control.Effect.Internal.NonDet

Associated Types

type Derivs (LogicC m) :: [Effect]

type Prims (LogicC m) :: [Effect]

Methods

algPrims :: Algebra' (Prims (LogicC m)) (LogicC m) a

reformulate :: Monad z => Reformulation' (Derivs (LogicC m)) (Prims (LogicC m)) (LogicC m) z a

algDerivs :: Algebra' (Derivs (LogicC m)) (LogicC m) a

type Derivs (LogicC m)

Defined in Control.Effect.Internal.NonDet

type Derivs (LogicC m) = Split ': (Cull ': (Cut ': (NonDet ': Derivs m)))

type Prims (LogicC m)

Defined in Control.Effect.Internal.NonDet

type Prims (LogicC m) = Split ': (Regional CullOrCall ': Prims m)