proposal: slices: add CollectKeys and CollectValues to collect from an iter.Seq2

[jmillikin]

Proposal Details

The slices package currently has Collect() to perform iter.Seq[T] -> []T, but it doesn't have similar helper functions for collecting the keys or values from an iter.Seq2[K, V].

I propose to add the following two functions to slices:

func CollectKeys[K, V any](seq iter.Seq2[K, V]) []K {
	var s []K
	for k := range seq {
		s = append(s, k)
	}
	return s
}

func CollectValues[K, V any](seq iter.Seq2[K, V]) []V {
	var s []V
	for _, v := range seq {
		s = append(s, v)
	}
	return s
}

[gabyhelp]

Related Issues and Documentation

• Package slices > func Collect ¶
• slices: add iterator-related functions #61899 (closed)

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

[gophun]

The composable way would be xiter.Keys and xiter.Values, as proposed here combined with a normal slices.Collect.

[seankhliao]

I think we'd prefer the composable versions as pointed out above