Transform Future[A] to Future[Try[A]] or EitherT[Future, Throwable, A]

Question

How can I transform a Future[A] that might succeed or fail into a EitherT[Future, Throwable, A] or a Future[Try[A]].

future.transform(result => Success(result))
EitherT(future.transform(result => Success(result.toEither)))

Are there methods in the standard library or within Cats that achieve the above transformation?

Is `future.transform(Success(_))` not good? It is very simple and why do you need another library to do that? — SwiftMango, Sep 07 '20 at 19:08
I've expected Cats to have some utility function that simplified further processing. Right now I have for instance much code like this `OptionT(future.transform(result => Success(result.toOption))))` — Aki, Sep 07 '20 at 19:11
@texasbruce I've clarified the question. This is more specific what I expected, The question was initially asked a bit unfavorably. — Aki, Sep 07 '20 at 19:25

Mario Galic · Accepted Answer · 2020-09-07T22:19:51.150

2

attemptT of ApplicativeError can convert Future[A] to EitherT[Future, Throwable, A], for example

import cats.data.EitherT
import cats.implicits._

val f: Future[A] = ???
val v: EitherT[Future, Throwable, A] = f.attemptT

edited Sep 07 '20 at 22:19

answered Sep 07 '20 at 19:49

Mario Galic

@LuisMiguelMejíaSuárez No, I think if you want to actually work with `Throwable` value within `Left`, then something like `EitherT(f.attempt)` might work. – Mario Galic Sep 07 '20 at 21:08
1

@LuisMiguelMejíaSuárez Please see edited answer. – Mario Galic Sep 07 '20 at 22:13
1

@Aki you may want to see the edited answer too. – Luis Miguel Mejía Suárez Sep 07 '20 at 22:54

1 Answers1