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Combining futures of different types using cats

I have different types of futures.

import cats.Cartesian
import cats.instances.future._
import cats.syntax.cartesian._
import scala.concurrent.Future
import cats.implicits._

val aF : Future[Either[X, Y]] = getFuture(...)
val bF : Future[Either[X, Y]] = getFuture(...)
val cF = Future[List[Long]] = getFuture2(...)

val combinedFuture = Cartesian.tuple3(aF, bF, cF)
combinedFuture match {case (a, b, c) => 
   ...
}

But I am getting the error

Error:(36, 44) could not find implicit value for parameter cartesian: cats.Cartesian[scala.concurrent.Future]
      val combinedFuture = Cartesian.tuple3(aF, bF, cF)

But as you can see I imported all implicits, intances.future._ and syntax.

I am using Cats 0.9.0 on Scala 2.11.8

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1 answer


You are missing the implicit ExecutionContext

:

import scala.concurrent.ExecutionContext.Implicits.global


I've had this happen many times when using a template like type in Future[T]

, it's always an execution context that is easily forgotten, but makes the type class not properly resolved by implicits.

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