parallele_applicative_traversal.scala

#
# Is this code safe? It seems that it can broke at least at two point:
# - adding in a mutable structure from a parallele processing does not seems to be a good idea
# - throwing an exception for control flow (early out) is kind of acceptable for sequential loop, 
#   but what happen if two thread of the ".par" processing throw it at the same time ?
# If this is not the good way of doing that, how one process a sequence of things (could be vector
# in place of Seq, the genericity is not really needed here) so that:
# - the processing is parallelized,
# - there is an early out ?
#

def sequencePar[U,T](seq:Seq[U])(f:U => Option[T]) : Option[Seq[T]] = {
  val buf = scala.collection.mutable.Buffer[T]()
  seq.par.foreach { u => f(u) match {
    case None => return e
    case Some(x) => buf += x
  } }
  Some(buf)
}