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Ordering

Sorting and reversing. Every sort here is stable, and every one buffers the whole sequence — they cannot emit a first element until they have seen the last, so none of them terminates on an infinite source.

Sorted

func Sorted[T cmp.Ordered](s Seq[T]) Seq[T]

Sorted yields the elements in ascending order, stably. NaN sorts first.

fmt.Println(catena.Sorted(catena.Of(3, 1, 2)).Collect())

[1 2 3]

SortedDesc

func SortedDesc[T cmp.Ordered](s Seq[T]) Seq[T]

SortedDesc yields the elements in descending order, stably.

fmt.Println(catena.SortedDesc(catena.Of(3, 1, 2)).Collect())

[3 2 1]

SortedBy

func (s Seq[T]) SortedBy[K cmp.Ordered](sel func(T) K) Seq[T]

SortedBy yields the elements sorted ascending by key, stably. sel is called exactly once per element (decorate-sort-undecorate).

// Stable, and the selector runs exactly once per element rather than
// once per comparison — so an expensive key is affordable. Stability
// shows here: kiwi and date are both 4 long, and kiwi came first.
words := catena.Of("kiwi", "fig", "banana", "date")
fmt.Println(words.SortedBy(func(s string) int { return len(s) }).Collect())

[fig kiwi date banana]

SortedByDesc

func (s Seq[T]) SortedByDesc[K cmp.Ordered](sel func(T) K) Seq[T]

SortedByDesc yields the elements sorted descending by key, stably. sel is called exactly once per element.

words := catena.Of("kiwi", "fig", "banana")
fmt.Println(words.SortedByDesc(func(s string) int { return len(s) }).Collect())

[banana kiwi fig]

SortedWith

func (s Seq[T]) SortedWith(cmp func(a, b T) int) Seq[T]

SortedWith yields the elements sorted by cmp, stably.

// A comparator, for orderings a single key cannot express.
fmt.Println(catena.Of("b", "A", "c").
  SortedWith(func(x, y string) int { return strings.Compare(strings.ToLower(x), strings.ToLower(y)) }).
  Collect())

[A b c]

Reversed

func (s Seq[T]) Reversed() Seq[T]

Reversed yields the elements in reverse order.

fmt.Println(catena.Of(1, 2, 3).Reversed().Collect())

[3 2 1]