An extractor object that yields the groups in the match. Using this extractor rather than the originalRegex ensures that the match is not recomputed.
import scala.util.matching.Regex.Groupsval date = """(\d\d\d\d)-(\d\d)-(\d\d)""".rval text = "The doc spree happened on 2011-07-15."val day = date replaceAllIn(text, _ match { case Groups(_, month, day) => s"$month/$day" })