Come chiamare Scala Queue.enqueue (iter: Iterable [B])?

Question

In Scala di immutable.Queue, ci sono due metodi sia chiamato enqueue:

/** Creates a new queue with element added at the end 
    * of the old queue. 
    * 
    * @param elem  the element to insert 
    */ 
    def enqueue[B >: A](elem: B) = new Queue(elem :: in, out) 

    /** Returns a new queue with all elements provided by an `Iterable` object 
    * added at the end of the queue. 
    * 
    * The elements are prepended in the order they are given out by the 
    * iterator. 
    * 
    * @param iter  an iterable object 
    */ 
    def enqueue[B >: A](iter: Iterable[B]) = 
    new Queue(iter.toList reverse_::: in, out) 

non so come risolvere l'ambiguità e chiamare il secondo. Ecco cosa ho provato:

Welcome to Scala version 2.10.0 (Java HotSpot(TM) 64-Bit Server VM, Java 1.7.0_07). 
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scala> import collection.immutable.Queue 
import collection.immutable.Queue 

scala> val q: Queue[Int] = Queue(1,2,3) 
q: scala.collection.immutable.Queue[Int] = Queue(1, 2, 3) 

scala> q.enqueue(Iterable(4)) 
res0: scala.collection.immutable.Queue[Any] = Queue(1, 2, 3, List(4)) 

scala> q.enqueue[Int](Iterable(4)) 
<console>:10: error: overloaded method value enqueue with alternatives: 
    (iter: scala.collection.immutable.Iterable[Int])scala.collection.immutable.Queue[Int] <and> 
    (elem: Int)scala.collection.immutable.Queue[Int] 
cannot be applied to (Iterable[Int]) 
       q.enqueue[Int](Iterable(4)) 
        ^

Answer 1

Ingannevole, difficile!

I created a ticket su di esso. Vedi, sei stato ingannato dai tipi!

scala> q.enqueue(scala.collection.Iterable(4)) 
res8: scala.collection.immutable.Queue[Any] = Queue(1, 2, 3, List(4)) 

scala> q.enqueue(scala.collection.immutable.Iterable(4)) 
res9: scala.collection.immutable.Queue[Int] = Queue(1, 2, 3, 4) 

Il Iterable importato di default è il scala.collection.Iterable, che può essere sia mutabile o immutabile, ma la coda immutabile richiede l'immutabileIterable invece.