Exts.RemoteData

A datatype representing fetched data.

If you find yourself continually using Maybe (Result Error a) to represent loaded data, 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.

type RemoteData e a

= NotAsked

| Loading

| Failure e

| Success a

Frequently when you're fetching data from an API, you want to represent four different states: * NotAsked - We haven't asked for the data yet. * Loading - We've asked, but haven't got an answer yet. * Failure - We asked, but something went wrong. Here's the error. * Success - Everything worked, and here's the data.

type alias WebData a =

RemoteData Error a

While RemoteData can accept any type of error, the most common one you'll actually use is when you fetch data from a REST interface, and get back RemoteData Http.Error a. Because that case is so common, WebData is provided as a useful alias.

map : (a -> b) -> RemoteData e a -> RemoteData e b

Map a function into the Success value.

mapFailure : (e -> f) -> RemoteData e a -> RemoteData f a

Map a function into the Failure value.

mapBoth : (a -> b) -> (e -> f) -> RemoteData e a -> RemoteData f b

Map function into both the Success and Failure value.

withDefault : a -> RemoteData e a -> a

Return the Success value, or the default.

fromResult : Result e a -> RemoteData e a

Convert a Result Error, probably produced from elm-http, to a RemoteData value.

asCmd : Task e a -> Cmd (RemoteData e a)

Convert a web Task, probably produced from elm-http, to a Cmd (RemoteData e a).

mappend : RemoteData e a -> RemoteData e b -> RemoteData e ( a, b )

Monoidal append - join two RemoteData values together as though they were one. If both values are Failure, the left one wins.

isSuccess : RemoteData e a -> Bool

State-checking predicate. Returns true if we've successfully loaded some data.

krisajenkins/elm-exts/25.1.0

Exts.RemoteData

Modules