lib: Extract keys and values from map

[kcreddy]

This adds a 2 functions to collections, namely keys and values that can be applied to a map and extract keys and values respectively into a list.

[kcreddy]

CI is failing because map doesn't maintain order when iterating using range. Any workarounds to make the tests pass?

[efd6]

I think a nice property to have would be to make zip(map_keys(m), map_values(m)) return the original map (well, a copy of it). This currently does not happen, but if it did, this test would pass. It adds an allocation cost to the map_values call and a sort CPU cost to both, but I think it is worth it.

[kcreddy]

Added new test into zip to test zip(map_keys(m), map_values(m))

[efd6]

Suggested change

	type kv struct {
	Key ref.Val
	Value ref.Val
	}
	if mapK.Size() != types.IntZero {
	canSort := true
	it := mapK.Iterator()
	ss := make([]kv, 0, n)
	for it.HasNext() == types.True {
	k := it.Next()
	v := mapK.Get(k)
	ss = append(ss, kv{k, v})
	_, ok := k.(traits.Comparer)
	if !ok {
	canSort = false
	}
	}
	if canSort {
	sort.Slice(ss, func(i, j int) bool {
	return ss[i].Key.(traits.Comparer).Compare(ss[j].Key) == types.Int(-1)
	})
	}
	type valComparer interface {
	ref.Val
	traits.Comparer
	}
	type kv struct {
	Key valComparer
	Value ref.Val
	}
	if mapK.Size() != types.IntZero {
	canSort := true
	it := mapK.Iterator()
	ss := make([]kv, 0, n)
	for it.HasNext() == types.True {
	k := it.Next()
	v := mapK.Get(k)
	ck, ok := k.(valComparer)
	if !ok {
	canSort = false
	}
	ss = append(ss, kv{ck, v})
	}
	if canSort {
	sort.Slice(ss, func(i, j int) bool {
	return ss[i].Key.Compare(ss[j].Key) == types.Int(-1)
	})
	}

[kcreddy]

Great, thanks for the recommendation here. Updated