Scala Future with predicate in for comprehension

Jose Romero

comprehensionpredicatefuture•••

Idiomatic solution to have filter, conditionals, predicates in Futures' for-comprehension

Example of usage:

val f2 = for {
  i <- f1
  _ <- predicate( i == 2 )(new Exception("Test2"))
  j <- f3  // f3 will only run if the predicate is true
} yield "Test1"

import scala.concurrent.Future

def predicate(condition: Boolean)(fail: Exception): Future[Unit] = 
    if (condition) Future( () ) else Future.failed(fail)