For-Comprehension with dynamic list of Futures

[C.D.]

Hi,

I love how powerful for comprehensions are, but I came across a case where I have a dynamic list of futures that need to be executed in parallel and when everything is completed, I would like to process that and return some value, and was not sure how to handle this. Just to exemplify:

def handleFutures(futures: List[Future[Any]]) : Future[String] = {

  for ( d1 <- futures(0)

         d2 <- futures(1) 

         ......

        ) yield { d1.toString + " : " + d2.toString + " : " + .... }

 }

As I mentioned, all the futures should be executed in parallel here and need to handle error cases as well.

What would you guys recommend using here?

Thanks in advance.

[√iktor Ҡlang]

On Tue, Oct 15, 2013 at 12:48 PM, C.D. <cab...@gmail.com> wrote:

Hi,

I love how powerful for comprehensions are, but I came across a case where I have a dynamic list of futures that need to be executed in parallel and when everything is completed, I would like to process that and return some value, and was not sure how to handle this. Just to exemplify:

def handleFutures(futures: List[Future[Any]]) : Future[String] = {

  for ( d1 <- futures(0)

         d2 <- futures(1) 

         ......

        ) yield { d1.toString + " : " + d2.toString + " : " + .... }

 }

for { list <- Future.sequence(futures) } yield list.mkString(" : ")

Cheers,

√

 

As I mentioned, all the futures should be executed in parallel here and need to handle error cases as well.

What would you guys recommend using here?

Thanks in advance.

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Viktor Klang
Director of Engineering

Typesafe

Twitter: @viktorklang

[√iktor Ҡlang]

as in:

scala> for { list <- Future.sequence(futures) } yield list.mkString(":")

res0: scala.concurrent.Future[String] = scala.concurrent.impl.Promise$DefaultPromise@3d36dff4

scala> res0 onComplete println

scala> Success(1:2:3:4:5:6:7:8:9:10)