Control.Effect.Internal.Select

Documentation

newtype Select s m a where

An effect for backtracking search.

Constructors

Select :: (forall r. (a -> m (s, r)) -> m r) -> Select s m a

Instances

Eff (Shift (s, r)) m => Handler (SelectH r) (Select s) m

Defined in Control.Effect.Internal.Select

Methods

effHandler :: EffHandler (Select s) m

select :: Eff (Select s) m => (forall r. (a -> m (s, r)) -> m r) -> m a

Perform a search: capture the continuation of the program, so that you may test values of a and observe what corresponding s each value would result in at the end of the program (which may be seen as the evaluation of a). When you find a satisfactory a, you may return the associated r.

The way higher-order actions interact with the continuation depends on the interpretation of Select. In general, you cannot expect to interact with the continuation in any meaningful way: for example, you should not assume that you will be able to catch an exception thrown at some point in the future of the computation by using catch on the continuation.

data SelectH r

Instances

Eff (Shift (s, r)) m => Handler (SelectH r) (Select s) m

Defined in Control.Effect.Internal.Select

Methods

effHandler :: EffHandler (Select s) m

newtype SelectC s r m a

Constructors

SelectC

Fields

• unSelectC :: ReinterpretC (SelectH r) (Select s) '[Shift (s, r)] (ShiftC (s, r) m) a

Instances

MonadBase b m => MonadBase b (SelectC s r m)

Defined in Control.Effect.Internal.Select

Methods

liftBase :: b α -> SelectC s r m α

MonadTrans (SelectC s r)

Defined in Control.Effect.Internal.Select

Methods

lift :: Monad m => m a -> SelectC s r m a

Monad (SelectC s r m)

Defined in Control.Effect.Internal.Select

Methods

(>>=) :: SelectC s r m a -> (a -> SelectC s r m b) -> SelectC s r m b

(>>) :: SelectC s r m a -> SelectC s r m b -> SelectC s r m b

return :: a -> SelectC s r m a

Functor (SelectC s r m)

Defined in Control.Effect.Internal.Select

Methods

fmap :: (a -> b) -> SelectC s r m a -> SelectC s r m b

(<$) :: a -> SelectC s r m b -> SelectC s r m a

MonadFail m => MonadFail (SelectC s r m)

Defined in Control.Effect.Internal.Select

Methods

fail :: String -> SelectC s r m a

Applicative (SelectC s r m)

Defined in Control.Effect.Internal.Select

Methods

pure :: a -> SelectC s r m a

(<*>) :: SelectC s r m (a -> b) -> SelectC s r m a -> SelectC s r m b

liftA2 :: (a -> b -> c) -> SelectC s r m a -> SelectC s r m b -> SelectC s r m c

(*>) :: SelectC s r m a -> SelectC s r m b -> SelectC s r m b

(<*) :: SelectC s r m a -> SelectC s r m b -> SelectC s r m a

MonadIO m => MonadIO (SelectC s r m)

Defined in Control.Effect.Internal.Select

Methods

liftIO :: IO a -> SelectC s r m a

MonadThrow m => MonadThrow (SelectC s r m)

Defined in Control.Effect.Internal.Select

Methods

throwM :: Exception e => e -> SelectC s r m a

MonadCatch m => MonadCatch (SelectC s r m)

Defined in Control.Effect.Internal.Select

Methods

catch :: Exception e => SelectC s r m a -> (e -> SelectC s r m a) -> SelectC s r m a

(Carrier m, Threads (FreeT (ContBase (m (s, r)) (s, r))) (Prims m)) => Carrier (SelectC s r m)

Defined in Control.Effect.Internal.Select

Associated Types

type Derivs (SelectC s r m) :: [Effect]

type Prims (SelectC s r m) :: [Effect]

Methods

algPrims :: Algebra' (Prims (SelectC s r m)) (SelectC s r m) a

reformulate :: Monad z => Reformulation' (Derivs (SelectC s r m)) (Prims (SelectC s r m)) (SelectC s r m) z a

algDerivs :: Algebra' (Derivs (SelectC s r m)) (SelectC s r m) a

type Derivs (SelectC s r m)

Defined in Control.Effect.Internal.Select

type Derivs (SelectC s r m) = Derivs (ReinterpretC (SelectH r) (Select s) '[Shift (s, r)] (ShiftC (s, r) m))

type Prims (SelectC s r m)

Defined in Control.Effect.Internal.Select

type Prims (SelectC s r m) = Prims (ReinterpretC (SelectH r) (Select s) '[Shift (s, r)] (ShiftC (s, r) m))

runSelect :: forall s a m p. (Carrier m, Threaders '[ContThreads] m p) => (a -> m s) -> SelectC s a m a -> m a

Run a Select s effect by providing an evaluator for the final result of type a.

Derivs (SelectC s r m) = Select s ': Derivs m

Prims  (SelectC s r m) = Prims m