我有一个函数get：T =>
scala.concurrent.Future [T]
我想迭代它像：
val futs: Iterator[Future[T]] = Iterator.iterate(get(init)){
_.flatMap(prev => get(prev))
}
但Iterator的类型是Future [T],处理这个迭代器并不容易.
How could I transfer that to
Process[?,T]
(也许T => Future [T]作为上下文类型F).
解决方法
不是超级好的解决方案,但有效
import scala.concurrent.ExecutionContext.Implicits.global
import scala.concurrent.{Future => SFuture}
import scala.language.implicitConversions
import scalaz.concurrent.Task
import scalaz.stream._
implicit class Transformer[+T](fut: => SFuture[T]) {
def toTask(implicit ec: scala.concurrent.ExecutionContext): Task[T] = {
import scala.util.{Success,Failure}
import scalaz.Syntax.either._
Task.async {
register =>
fut.onComplete {
case Success(v) => register(v.right)
case Failure(ex) => register(ex.left)
}
}
}
}
val init: Int = 0
def f(i: Int): SFuture[Int] = SFuture(i + 1)
val p = Process.repeatEval[Task,Int] {
var prev = init
f(prev).toTask.map(next => {prev = next; next})
}
println(p.take(10).runLog.run)
