Run two commands at the same time in Elm

Question

In Elm, and specifically with the Elm Architecture when the app first starts the init function can return a Cmd Msg that is executed. We can use this for sending http requests or send a message to native Javascript via Elm ports.

My question is, how can I send multiple commands that should be executed in init?

For example I can do something like:

init : (Model, Cmd Msg) init =   (Model "" [], (Ports.messageToJs "Hello JS")) 

And I can do something like:

url : String url =      "http://some-api-url.com" ...  fetchCmd : Cmd Msg fetchCmd =     Task.perform FetchError FetchSuccess fetchTask   init : (Model, Cmd Msg) init =   (Model "" [], fetchCmd) 

How can I return both commands at same time from init?

I have seen Task.sequence and even Task.parallel but they appear to be good for running multiple tasks, not specifically commands.

Answer 1

Use Platform.Cmd.batch (docs):

init : (Model, Cmd Msg) init =   ( Model "" []   , Cmd.batch [fetchCmd, Ports.messageToJs "Hello JS")]   )