diff options
| -rw-r--r-- | src/library/scala/collection/SeqLike.scala | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/src/library/scala/collection/SeqLike.scala b/src/library/scala/collection/SeqLike.scala index fdfb1f2efc..329273df5b 100644 --- a/src/library/scala/collection/SeqLike.scala +++ b/src/library/scala/collection/SeqLike.scala @@ -140,7 +140,15 @@ trait SeqLike[+A, +Repr] extends Any with IterableLike[A, Repr] with GenSeqLike[ if (isEmpty) Iterator(repr) else new PermutationsItr - /** Iterates over combinations. + /** Iterates over combinations. A _combination_ of length `n` is a subsequence of + * the original sequence, with the elements taken in order. Thus, `"xy"` and `"yy"` + * are both length-2 combinations of `"xyy"`, but `"yx"` is not. If there is + * more than one way to generate the same subsequence, only one will be returned. + * + * For example, `"xyyy"` has three different ways to generate `"xy"` depending on + * whether the first, second, or third `"y"` is selected. However, since all are + * identical, only one will be chosen. Which of the three will be taken is an + * implementation detail that is not defined. * * @return An Iterator which traverses the possible n-element combinations of this $coll. * @example `"abbbc".combinations(2) = Iterator(ab, ac, bb, bc)` |