An attempt to use the type inferencer to explicitly bind a protocol's typealias.

bind-protocol-types.swift

protocol TypeBinder {
  typealias BoundT
}

class TypeEvidence<T> : TypeBinder {
  typealias BoundT = T
  func array () -> Array<BoundT> { return [] }
}

class ObserverTyper<T> {
  class func bind <O: Observer where O.EventType == T> () -> TypeEvidence<O> { return TypeEvidence<O>() }
}

class Observable<T> : Stream<T> {
  // Breaks the type inferencer?
  // error: cannot convert the expression's type 'Array<$T2>' to type 'Observer'
  var observers = ObserverTyper<T>.bind().array()
  
  // but this works just fine ... so shouldn't the above work, too?
  func sendExample<OT, O: Observer where O.EventType == OT> (value: OT) {
    let observers = Array<O>()
    for observer in observers {
      observer.send(Event<OT>.Next(value))
    }
  }
}

class Stream<T> {
}

protocol Observer {
  typealias EventType
  func send(Event<EventType>)
}

enum Event<T> {
  case Next(T)
  //case Error(NSError)
  case Completed
}