Open Janiczek opened 5 years ago
Here’s a use case.
I made a function that first asks my API for an AWS S3 signed URL, and then uploads a file to that signed URL (using Task.andThen
). Now I wanted to show the upload progress, but learned that Http.task
does not take a tracker
. It felt nice having a function that let me upload a file without having to think about the presigned URL, but now I have to break it up into two steps and use Http.request
instead.
Use case 2:
I wanted a waitAtLeast
function for my form submissions because sometimes that request would react before the user knew, additionally sometimes I raise a toast on the screen and don't want it to popup and disappear too quickly if the request is fast. If Cmd/Tasks were like Futures, I'd run a timer and the request in parallel and await both the results (ditching the timer) Parallelism isn't really supported in that sort of way. To get around that, I've used Task.andThen
like:
waitAtLeast : Int -> Task x a -> Task x a
waitAtLeast delay task =
-- Sure would be nice to have do notation here
-- do
-- start <- Time.now
-- value <- task
-- end <- Time.now
-- let toWait = end - start - delay
-- . . .
-- desugared into:
Time.now
|> Task.andThen
(\start ->
task
|> Task.andThen
(\value ->
Time.now
|> Task.andThen
(\end ->
let
toWait : Int
toWait =
delay
- Time.posixToMillis end
+ Time.posixToMillis start
in
if toWait <= 0 then
Task.succeed value
else
Process.sleep (toFloat toWait)
|> Task.andThen (\_ -> Task.succeed value)
)
)
)
Turning a Http.Request
into a Task
, I get the waitAtLeast
part I wanted, but now that it's a Task
I have no access to the tracker
.
@evancz ?
Is there a reason Task requests don't accept the
tracker
field to track progress?https://package.elm-lang.org/packages/elm/http/latest/Http#task compare to https://package.elm-lang.org/packages/elm/http/latest/Http#request