Effect.Aff.Unlift

class MonadUnliftAff :: (Type -> Type) -> Constraintclass (MonadAff m) <= MonadUnliftAff m  where

Monads which allow their actions to be run in Aff.

MonadUnliftAff captures the opposite notion of MonadAff - while MonadAff allows an Aff to be lifted into another monad, MonadUnliftAff allows a monad other than Aff to be run in an Aff context.

Note that the laws given below require that a monad have no "monadic state", which essentially limits instances to ReaderT stacks with a base of Aff.

Instances should satisfy the following laws, which state that unliftAff is a transformer of monads for any given u returned by askUnliftAff:.

unliftAff u <<< pure = pure
unliftAff u (f =<< m) = unliftAff u <<< f =<< unliftAff u m

Members

• withRunInAff :: forall b. ((m ~> Aff) -> Aff b) -> m b

  Run an Aff with access to a runner function that is capable of running a monadic action m in Aff.

Instances

• MonadUnliftAff Aff
• (MonadUnliftAff m) => MonadUnliftAff (ReaderT r m)

newtype UnliftAff :: (Type -> Type) -> Typenewtype UnliftAff m

A newtype wrapper around a natural transformation from m to Aff.

Constructors

• UnliftAff (m ~> Aff)

unliftAff :: forall m. UnliftAff m -> m ~> Aff

Run an action directly in Aff. Use askUnliftAff or withUnliftAff to obtain an UnliftAff m value.

askUnliftAff :: forall m. MonadUnliftAff m => m (UnliftAff m)

Returns a natural transformation from m to Aff within an m context. This can subsequently be used to run m actions directly in Aff.

askRunInAff :: forall m a. MonadUnliftAff m => m (m a -> Aff a)

A monomorphic version of askUnliftAff which can be more convenient when you only want to use the resulting runner function once with a concrete type.

If you run into type issues using this, try using askUnlitAff instead.

withUnliftAff :: forall m a. MonadUnliftAff m => (UnliftAff m -> Aff a) -> m a

A version of withRunInAff that provides an UnliftAff wrapper instead of a rank-2 polymorphic function.

toAff :: forall m a. MonadUnliftAff m => m a -> m (Aff a)

Run the given action inside the Aff monad.