andrewmacmurray / elm-delay

Utilities to delay updates after a set period of time

Elm Delay

Elm utilities to trigger updates after a delay

example: https://elm-delay-examples.surge.sh/

Why?

Sometimes you need to trigger updates after a period of time (i.e. to wait for a css transition or animation to complete) or maybe you need to chain a sequence of these updates (for more complex states).

This library provides utilities to express this more tidily.

How?

Send a single delayed Msg

To trigger a single update after a period of time pass Delay.after as a command to the elm runtime:

FirstMessage ->
    ( model
    , Delay.after 500 SecondMessage
    )

After triggering FirstMessage, 500ms later update will be called with SecondMessage

Send a sequence of delayed Msgs

Trigger ->
    ( model
    , Delay.sequence
        [ ( 1000, FirstMessage )
        , ( 2000, SecondMessage )
        , ( 1000, ThirdMessage )
        ]
    )

by sending a Trigger Msg:

• after 1000ms update will be called with FirstMessage
• then after 2000ms update will be called with SecondMessage
• then after 1000ms update will be called with ThirdMessage

As a convenience if you'd only like to start a sequence if the model is in a particular shape you can use Delay.sequenceIf

Trigger ->
    ( model
    , Delay.sequenceIf (not model.updating)
        [ ( 1000, FirstMessage )
        , ( 2000, SecondMessage )
        , ( 1000, ThirdMessage )
        ]
    )

If you'd like all the steps to have the same unit of time, use the Delay.withUnit helper

Trigger ->
    ( model
    , Delay.sequence 
        Delay.withUnit Delay.seconds
            [ ( 1, FirstMessage )
            , ( 2, SecondMessage )
            , ( 1, ThirdMessage )
            ]
    )

elm-delay's Issues

Different tool for integration tests

Currently using QUnit to do integration tests, could be nice to use cypress instead so failures could be tracked more easily in PRs / prevent merges if tests fail

Will this be upgraded to Elm 0.19?

Will this be upgraded to Elm 0.19? Thanks!

Elm-publish github action

Could be nice to auto publish new release to elm-package using this github action - https://github.com/dillonkearns/elm-publish-action

Default unit

Curious if anyone is using a mixture of TimeUnits? Was thinking about changing the api to have a default unit of milliseconds so it's a little cleaner:

Delay.after 500 SomethingTriggered

Delay.sequence
    [ ( 100, MsgOne )
    , ( 200, MsgTwo )
    , ( 100, MsgThree )
    ]

And maybe add some helpers to convert millis to other time units:

Delay.after (Delay.seconds 5) SomethingTriggered

seconds : Millis -> Millis
seconds millis =
    1000 * millis

@lenards given you've been using this recently do you have any thoughts?

Use github actions to deploy examples

Would be nice to automate deployment of examples

Run integration tests in CI

Would be nice to have tests run in CI - a bit tricky using QUnit as is but would be easier if #10 is implemented

Use elm-units for durations

Hi, one suggestion I have is to use elm-units instead or having your own API for dealing with durations. Then you can just have after : Duration -> msg -> Cmd msg, sequence : List ( Duration, msg ) -> Cmd msg, and sequenceIf : Bool -> List ( Duration, msg ) -> Cmd msg and anyone familiar with elm-units won't need to relearn how to specify what time units they want or do extra conversions if they are already using elm-units for other stuff.