chrisphelps

for {
  config <- configServiceResponse
  user <- userServiceResponse
  prefs <- getPreferencesForUser(user, config)
  items <- getItemsForUser(user).map{ item => personalizeItem(item, prefs) }
} yield format(items)

chrisphelps

public ListenableFuture<List<Item>> getUserItemsWithConfig(User user, ListenableFuture<Config> configFuture) {
  // transform on configFuture and call getItems(user, config)
  ...
}
public List<Item> getItems(User user, Config config) { ... }

ListenableFuture<User> user = getUser(args);
final ListenableFuture<Config> config = getConfig(args);

ListenableFuture<List<Item>> items = Futures.transform(user,

chrisphelps

for {
  config <- configServiceResponse
  user <- userServiceResponse
  items <- getItemsForUser(user)
  prefs <- getPreferencesForUser(user, config)
  personalized <- personalizeItems(items, prefs)
} yield format(personalized)

chrisphelps

implicit def toScalaFuture[T](lFuture: ListenableFuture[T]): Future[T] = {
  val p = Promise[T]
  Futures.addCallback(lFuture,
    new FutureCallback[T] {
      def onSuccess(result: T) = p.success(result)
      def onFailure(t: Throwable) = p.failure(t)
    })
  p.future
}

chrisphelps

ListenableFuture<User> user = getUser(args);

ListenableFuture<List<Item>> items = Futures.transform(user,
    new AsyncFunction<User, List<Item>>() {
        @Override
        public ListenableFuture<List<Item>> apply(User user) throws Exception {
          return getItemsForUser(user);
        }
      });

chrisphelps

Keybase proof

I hereby claim:

• I am chrisphelps on github.
• I am cjphelps (https://keybase.io/cjphelps) on keybase.
• I have a public key whose fingerprint is A077 D641 82C2 94A3 588C 44AE 585C 6AF1 721B B82C

To claim this, I am signing this object:

chrisphelps

class Foo (name: String) {
   def apply() = "Foo " + name + "results"
}

class Bar(name: String) {
  def apply()(implicit f: Foo) = "Bar"  + name + "results: " + f()
}

class Baz {
  implicit val myfoo = new Foo("production")

chrisphelps

f1 flatMap(a => for (b <- f2; c <- f3(b)) yield c * a)

f1 flatMap(a => f2 flatMap(b => for (c <- f3(b)) yield c * a))

f1 flatMap(a => f2 flatMap(b => f3(b) map(c => c * a)))

chrisphelps

val f1 = future { 5 }
val f2 = future { "str" }
val f3 = (s: String) => future { s + "vap" }

val f4 = for {
  a <- f1
  b <- f2
  c <- f3(b)
} yield c * a