Eff.md

Module Control.Monad.Eff

Eff

data Eff :: # ! -> * -> *

The Eff type constructor is used to represent native effects.

See Handling Native Effects with the Eff Monad for more details.

The first type parameter is a row of effects which represents the contexts in which a computation can be run, and the second type parameter is the return type.

Instances

instance functorEff :: Functor (Eff e)
instance applyEff :: Apply (Eff e)
instance applicativeEff :: Applicative (Eff e)
instance bindEff :: Bind (Eff e)
instance monadEff :: Monad (Eff e)

Pure

type Pure a = Eff () a

The Pure type synonym represents pure computations, i.e. ones in which all effects have been handled.

The runPure function can be used to run pure computations and obtain their result.

runPure

runPure :: forall a. Pure a -> a

Run a pure computation and return its result.

untilE

untilE :: forall e. Eff e Boolean -> Eff e Unit

Loop until a condition becomes true.

untilE b is an effectful computation which repeatedly runs the effectful computation b, until its return value is true.

whileE

whileE :: forall e a. Eff e Boolean -> Eff e a -> Eff e Unit

Loop while a condition is true.

whileE b m is effectful computation which runs the effectful computation b. If its result is true, it runs the effectful computation m and loops. If not, the computation ends.

forE

forE :: forall e. Number -> Number -> (Number -> Eff e Unit) -> Eff e Unit

Loop over a consecutive collection of numbers.

forE lo hi f runs the computation returned by the function f for each of the inputs between lo (inclusive) and hi (exclusive).

foreachE

foreachE :: forall e a. Array a -> (a -> Eff e Unit) -> Eff e Unit

Loop over an array of values.

foreach xs f runs the computation returned by the function f for each of the inputs xs.