Scala flatMap over getConstructors method (reflection)

I'm trying to iterate over the constructors of a given class using reflection. The problem is that I need to do something to each element and then return only the ones that matches some predicate. the following code throws exception

classOf[String].getConstructors.flatMap(x=> doSomething(x); if(predicate(x)) Some(x) else None)

The exception:

argument expression's type is not compatible with formal parameter type;
 found   : java.lang.reflect.Constructor[_] => Iterable[java.lang.reflect.Constructor[?0(in value $anonfun)]] forSome { type ?0(in value $anonfun) }
 required: java.lang.reflect.Constructor[_] => scala.collection.GenTraversableOnce[?B]

I'm not sure if this can be done with for comprehension because I need to call do something on each element(not just for the ones that holds the predicate):

for{
    x <- c.getConsturctors
    //doSomething(x) ?? 
    if predicate(x)
}yield{
    //doSomething(x) - only for the ones that holds the predicate
    x
}

Calling c.getMethods works so I'm guessing it has something to do with the return type(Array[Methods] vs Array[Constructor[_]])...?