Futures.scala

Futures.scala

//Here is the example Scala code, it assumes a function called fetch which when given a URL will return a Future.
def getThumbnail(url: String): Future[Webpage] = {
        val promise = new Promise[Webpage]
        fetch(url) onSuccess { page =>
            fetch(page.imageLinks(0)) onSuccess { p =>
                promise.setValue(p)
            } onFailure { exc =>
                promise.setException(exc)
            }
        } onFailure { exc =>
            promise.setException(exc)
        }
        promise
    }
    
// Scala Futures have a method called flatMap, which takes a function that given value will return another Future. Here is an
//example of how the getThumbnail method can be simplified by using it.
   
    def getThumbnail(url: String): Future[Webpage] =
        fetch(url) flatMap { page =>
             fetch(page.imageLinks(0))
        }