anyCommonElements from swift

/*
func anyCommonElements <T: SequenceType, U: SequenceType where T.Generator.Element: Equatable, T.Generator.Element == U.Generator.Element> (lhs: T, _ rhs: U) -> [T.Generator.Element] {
    var common : [T.Generator.Element] = []
    for lhsItem in lhs {
        for rhsItem in rhs {
            if lhsItem == rhsItem {
                common.append(lhsItem)
            }
        }
    }

   return common
}*/

trait Eq[A] {
  def eq(a1: A, a2: A): Boolean
}

trait SequenceType[T] {

}

implicit val constraint = new

def anyCommonElements[T <: SequenceType, U <: SequenceType](lhs: T, rhs: U)
                                                           (implicit cs: Constraint[T, U])
                                                           (implicit ev: Eq[T])
:  {
  val common = new ArrayBuffer[T#Generator#Element]
  for {
    li <- lhs
    ri <- rhs
    if ev.eq(li, ri)
  } {
    common += li
  }
  common
}