Network.RemoteData

data RemoteData e a

A datatype representing fetched data.

If you find yourself continually using Maybe (Either e a) to represent data loaded from an external source, or you have a habit of shuffling errors away to where they can be quietly ignored, consider using this. It makes it easier to represent the real state of a remote data fetch and handle it properly.

For more on the motivation, take a look at the blog post How Elm Slays A UI Antipattern. This is a port of that original Elm module.

Constructors

• NotAsked
• Loading
• Failure e
• Success a

Instances

• Generic (RemoteData e a) _
• (Eq e, Eq a) => Eq (RemoteData e a)
• Functor (RemoteData e)
• (Show e, Show a) => Show (RemoteData e a)
• Bifunctor RemoteData

  Maps functions to the Failure and Success values.

• Apply (RemoteData e)

  If both values are Success, the function is applied. If both are Failure, the first failure is returned.

• Bind (RemoteData e)
• Applicative (RemoteData e)
• Monad (RemoteData e)
• MonadThrow e (RemoteData e)
• MonadError e (RemoteData e)
• Foldable (RemoteData e)
• Traversable (RemoteData e)
• Bifoldable RemoteData
• Bitraversable RemoteData

toMaybe :: forall e a. RemoteData e a -> Maybe a

Convert a RemoteData to a Maybe.

fromMaybe :: forall e a. Maybe a -> RemoteData e a

Convert a Maybe to RemoteData.

fromEither :: forall e a. Either e a -> RemoteData e a

Convert an Either to RemoteData

maybe :: forall e a b. b -> (a -> b) -> RemoteData e a -> b

Takes a default value, a function, and a RemoteData value. If the data is Success, apply the function to the value, otherwise return the default.

See also withDefault.

withDefault :: forall e a. a -> RemoteData e a -> a

If the RemoteData has been successfully loaded, return that, otherwise return a default value.

_NotAsked :: forall a e. Prism' (RemoteData e a) Unit

_Loading :: forall a e. Prism' (RemoteData e a) Unit

_Failure :: forall a e. Prism' (RemoteData e a) e

_Success :: forall a e. Prism' (RemoteData e a) a

isNotAsked :: forall e a. RemoteData e a -> Boolean

Simple predicate.

isLoading :: forall e a. RemoteData e a -> Boolean

Simple predicate.

isFailure :: forall e a. RemoteData e a -> Boolean

Simple predicate.

isSuccess :: forall e a. RemoteData e a -> Boolean

Simple predicate.