How do I get the current time in Elm?

Question

I\'m running elm-repl to play around with the language.

I\'d like to see what the current time is. How would I do that? It doesn\'t appear to be possible with the c

Answer 1

The answer (for 0.18) from Simon H got me started in the right direction, but I did have some trouble working out how to actually do something with that time. (user2167582 adds a comment to Simon's answer which asks the same thing: how do you 'get the time out?').

My specific problem was that I wanted to include the current time in the body of a POST to the server.

I eventually solved that and was quite pleased with the end result -- the use of Task.andThen meant that I in my postTime function I can just use timestamp as a 'regular' float-valued parameter (which it is when the task gets run, I suppose).

My full SO answer is here.

Below is the solution I came up with and here it is in Ellie:

module Main exposing (..)

import Html exposing (..)
import Html.Events exposing (..)
import Http
import Json.Decode as JD
import Json.Encode as JE
import Task
import Time


type alias Model =
    { url : String
    }


type Msg
    = PostTimeToServer
    | PostDone (Result Http.Error String)


update : Msg -> Model -> ( Model, Cmd Msg )
update msg model =
    case msg of
        PostTimeToServer ->
            ( model, postTimeToServer model.url )

        PostDone _ ->
            ( model, Cmd.none )


view : Model -> Html Msg
view model =
    div []
        [ div []
            [ button [ onClick PostTimeToServer ] [ Html.text "POST the current time." ]
            ]
        ]


postTimeToServer : String -> Cmd Msg
postTimeToServer url =
    let
        getTime =
            Time.now

        postTime t =
            JD.string
                |> Http.post url (JE.float t |> Http.jsonBody)
                |> Http.toTask

        request =
            getTime                                            <<-- Here is
                |> Task.andThen postTime                       <<-- the key bit.
    in
        Task.attempt PostDone request


main =
    Html.program
        { init = ( Model "url_here", Cmd.none )
        , update = update
        , view = view
        , subscriptions = always Sub.none
        }