Groups

An extractor object that yields the groups in the match. Using this extractor rather than the original Regex ensures that the match is not recomputed.

import scala.util.matching.Regex.Groups

val date = """(\d\d\d\d)-(\d\d)-(\d\d)""".r
val text = "The doc spree happened on 2011-07-15."
val day = date replaceAllIn(text, _ match { case Groups(_, month, day) => s"$month/$day" })