in-other-words-0.1.0.0: A higher-order effect system where the sky's the limit

Control.Effect.Unlift

Synopsis

# Effects

data Unlift b m a where Source #

A helper primitive effect for unlifting to a base monad.

Helper primitive effects are effects that allow you to avoid interpreting one of your own effects as a primitive if the power needed from direct access to the underlying monad can instead be provided by the relevant helper primitive effect. The reason why you'd want to do this is that helper primitive effects already have ThreadsEff instances defined for them, so you don't have to define any for your own effect.

The helper primitive effects offered in this library are -- in order of ascending power -- Regional, Optional, BaseControl and Unlift.

Unlift is typically used as a primitive effect. If you define a Carrier that relies on a novel non-trivial monad transformer t, then you need to make a ThreadsEff t (Unlift b) instance (if possible). threadUnliftViaClass can help you with that.

The following threading constraints accept Unlift:

• ReaderThreads

Constructors

 Unlift :: forall b m a. ((forall x. m x -> b x) -> b a) -> Unlift b m a

#### Instances

Instances details
 Carrier m => PrimHandler UnliftH (Unlift m) m Source # Instance detailsDefined in Control.Effect.Internal.Unlift Methods ThreadsEff (ReaderT i) (Unlift b) Source # Instance detailsDefined in Control.Effect.Type.Unlift MethodsthreadEff :: Monad m => (forall x. Unlift b m x -> m x) -> Unlift b (ReaderT i m) a -> ReaderT i m a Source #

# Actions

unlift :: Eff (Unlift b) m => ((forall x. m x -> b x) -> b a) -> m a Source #

# Interpretations

class (MonadBaseControl b m, forall x. Pure m x) => MonadBaseControlPure b m Source #

A constraint synonym for MonadBaseControl b m together with that StM m a ~ a for all a.

#### Instances

Instances details
 (MonadBaseControl b m, forall x. Pure m x) => MonadBaseControlPure b m Source # Instance detailsDefined in Control.Effect.Type.Unlift

unliftToFinal :: (MonadBaseControlPure b m, Carrier m) => UnliftToFinalC b m a -> m a Source #

Run a Unlift b effect, where the unlifted monad b is the final base monad of m

Derivs (UnliftToFinalC b m) = Unlift b ': Derivs m
Prims  (UnliftToFinalC b m) = Unlift b ': Prims m

runUnlift :: Carrier m => UnliftC m a -> m a Source #

Run a Unlift m effect, where the unlifted monad m is the current monad.

Derivs (UnliftC m) = Unlift m ': Derivs m
Prims  (UnliftC m) = Unlift m ': Prims m

threadUnliftViaClass :: forall b t m a. (MonadTransControlPure t, Monad m) => (forall x. Unlift b m x -> m x) -> Unlift b (t m) a -> t m a Source #

A valid definition of threadEff for a ThreadsEff (Unlift b) t instance, given that t is a MonadTransControl where StT t a ~ a holds for all a.

# Combinators for Algebras

powerAlgUnlift :: forall m p a. Algebra' p m a -> Algebra' (Unlift m ': p) m a Source #

Strengthen an Algebra p m by adding a Unlift m handler

powerAlgUnliftFinal :: forall b m p a. MonadBaseControlPure b m => Algebra' p m a -> Algebra' (Unlift b ': p) m a Source #

Strengthen an Algebra p m by adding a Unlift b handler, where b is the final base monad.

# Carriers

type UnliftToFinalC b = InterpretPrimC UnliftToFinalH (Unlift b) Source #

data UnliftC m a Source #

#### Instances

Instances details