Proposal: Add hash sets to the standard library
Hash sets can be currently be done using AutoHashMap(K, void) but I'd argue that an actual hash set type would make working with them much nicer. Using a hash map, you have to explicitly access the key member of an Entry to get the value (and I sometimes accidentally try value first instead since when used as a set, the keys are the values), pass {} as the value every time you add something, and you have member functions that are meaningless when using it as a set. With a HashSet type you wouldn't have that cruft, and specific operations for working with sets could even be added if desired.
I wonder why this proposal is still awaiting approval. It doesn't seem to incur any harm to the standard library.
Personally, I am currently not sure what's the best way to perform quick Set O(n) computations, such as difference, intersection, union, etc. with AutoHashMap alone
Meanwhile, the author of the well-regarded golang-set library is writing ziglang-set.