An example of an awkward code pattern caused by interruptible completers

completers_awkward_code_pattern.scala

val resolvedParents = new util.ArrayList[Type]()
var remainingParents = tmpl.parents
while (remainingParents.nonEmpty) {
  val parent = remainingParents.head
  val resolved = resolveTypeTree(parent, lookupScope)
  // this is awkard and highly repetitive pattern
  resolved match {
    case CompletedType(tpe) => resolvedParents.add(tpe)
    case _: IncompleteDependency | NotFound => return resolved
  }
  remainingParents = remainingParents.tail
}