public var error

class MyClass {
    ....
    var polySeq = Seq[MyType]_
    ....
    def MyMethod(...) = {
        ....
        polySeq = for (e <- coefs.zipWithIndex) yield { new MyType(e._1, e._2) }
        ....
    }
}

Error: type mismatch;
 found   : scala.collection.immutable.IndexedSeq[MyType]
 required: Seq[MyType] => Seq[MyType]
    polySeq = for (e <- coefs.zipWithIndex) yield { new MyType(e._1, e._2) }